Pigeonpea and Chickpea Insect Identification Handbook

Abstract

Reed, W., Lateef, S.S., Sithanantham, S., and Pawar, C. S. 1989. P i g e o n p e a a n d c h i c k p e a i n s e c t i d e n t i f i c a t i o n h a n d - book. Information Bulletin no. 26. Patancheru, Andhra Pradesh 502 324: India. International Crops Research I n s t i t u t e f o r t h e S e m i - A r i d T r o p i c s .

P i g e o n p e a a n d c h i c k p e a a r e t h e t w o m a j o r p u l s e c r o p s t h a t a r e a t t a c k e d b y s e v era l i n s e c t p e s t s a t d i f f e r e n t s t a g e s o f p l a n t g r o w t h t h r o u g h o u t t h e s e m i - a r i d t r o p i c s . M a n y o f t h e m c a u s e s e v e r e y i e l d l o s s e s i n t h e s e c r o p s . T h i s b u l l e t i n p r o v i d e s a s h o r t d e s c r i p t i o n o f t h e s e i n s e c t s , t h e i r b i o l o g y , distribution, and damage symptoms. It includes brief i n f o r m a t i o n o n t h e o p t i o n s a v a i l a b l e t o c o n t r o l t h e s e pests, a s w e l l a s d e s c r i p t i o n a n d i l l u s t r a t i o n s o f s e ve ral b e n e f i c i a l insects like parasites, predators, and pollinators. Th e t e x t i s s u p p o r t e d b y s e v e ra l c o l o r p h o t o g r a p h s t o h e l p i d e n t i f y t h e pests.

T h e I n t e r n a t i o n a l C r o p s R e s e a r c h I n s t i t u t e f o r t h e S e m i - A r i d T r o p i c s i s a n o n p r o f i t , s c i e n t i f i c , r e s e a r c h a n d t r a i n - i n g I n s t i t u t e r e c e i v i n g s u p p o r t f r o m d o n o r s t h r o u g h t h e C o n s u l t a t i v e G r o u p o n I n t e r n a t i o n a l A g r i c u l t u r a l R e s e a r c h . D o n o r s t o I C R I S A T i n c l u d e g o v e r n m e n t s a n d a g e n c i e s o f Australia, Belgium, Canada, Federal Republic of Ger- many, Finland, France, India, Italy. Japan, Netherlands , Norway, Sweden, Switzerland, United Kingdom, United S t a t e s o f A m e r i c a , a n d t h e f o l l o w i n g i n t e r n a t i o n a l a n d private organizations: Asian Development Bank, Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ), Inter - national Development Research Centre, International F u n d f o r A g r i c u l t u r a l D e v e l o p m e n t , T h e E u r o p e a n E c o n o m i c Community, The Opec Fund for International Develop- m e n t , T h e W o r l d B a n k , a n d U n i t e d N a t i o n s D e v e l o p m e n t P r o g r a m m e . I n f o r m a t i o n a n d c o n c l u s i o n s i n t h i s p u b l i c a - t i o n d o n o t n e c e s s a r i l y r e f l e c t t h e p o s i t i o n o f t h e a f o r e - m e n t i o n e d g o v e r n m e n t s , a g e n c i e s , a n d i n t e r n a t i o n a l a n d private organizations.

Cover: Helicoverpa armigera l a r v a damaging pigeonpea pods. Pigeonpea and Chickpea Insect Identification Handbook

W. Reed, S.S. Lateef, S. Sithanantham, and C.S. Pawar

Entomologists, ICRISAT

ICRISAT

Information Bulletin no. 26 International Crops Research Institute for the Semi-Arid Tropics Patancheru, Andhra Pradesh 502 324, India

1989 Credits

Editing: V. Sadhana

Designing: S . M . S i n h a

Photography: A . B . C h i t n i s ; H.S. D u g g a l ; D . G . Faris; I C A R D A ; I C R I S A T E l e c t r o n M i c r o s c o p y U n i t ; I C R I S A T P h o t o L i b r a r y ; S.S. Lateef; W. R e e d ; S. S i t h a n a n t h a m

Artwork: P. S a t y a n a r a y a n a

Typesetting: I C R I S A T C o m p o s i n g U n i t

A l l r i g h t s reserved. E x c e p t f o r q u o t a t i o n s o f s h o r t pas- s a g e s f o r t h e p u r p o s e o f c r i t i c i s m a n d review, n o p a r t o f t h i s p u b l i c a t i o n m a y b e r e p r o d u c e d , s t o r e d i n retrieval s y s t e m s , o r t r a n s m i t t e d , i n a n y f o r m o r b y a n y m e a n s , electronic, mechanical, photocopying, recording, or o t h e r - w i s e , w i t h o u t p r i o r p e r m i s s i o n o f I C R I S A T . T h e I n s t i t u t e d o e s n o t r e q u i r e p a y m e n t f o r t h e n o n c o m m e r c i a l use o f its p u b l i s h e d w o r k s , a n d h o p e s t h a t t h i s C o p y r i g h t d e c l a r a - t i o n w i l l n o t d i m i n i s h t h e b o n a f i d e u s e o f its r e s e a r c h f i n d i n g s i n a g r i c u l t u r a l r e s e a r c h a n d d e v e l o p m e n t i n o r f o r t h e s e m i - a r i d t r o p i c s .

T h e o p i n i o n s i n t h i s p u b l i c a t i o n a r e t h o s e o f t h e a u t h o r s a n d n o t n e c e s s a r i l y t h o s e o f I C R I S A T . W h e r e t r a d e n a m e s are u s e d t h i s d o e s n o t c o n s t i t u t e e n d o r s e m e n t o f o r d i s - c r i m i n a t i o n a g a i n s t a n y p r o d u c t b y t h e I n s t i t u t e .

I S B N 9 2 - 9 0 6 6 - 1 7 1 - 2 Contents

Pigeonpea

Pests Attacking Roots

N o d u l e - d a m a g i n g Fly 10 T e r m i t e s 13

Pests of Stem

J e w e l Beetles 14 S t e m Weevils 17 S t e m Flies 18 C o w B u g s 2 1 S c a l e Insects 22

Pests of Foliage

J a s s i d s 25 A p h i d s 2 6 E r i o p h y i d Mites 29 R e d S p i d e r Mites 30 W h i t e f l i e s 33 B u d - s u c k i n g B u g s 3 4 L e a f - c u t t e r Bees 37 G r a s s h o p p e r s a n d L o c u s t s 3 8 L e a f - d a m a g i n g Weevils 41 O t h e r Leaf- a n d F l o w e r - d a m a g i n g Beetles 4 2 L e p i d o p t e r a n D e f o l i a t o r s 4 5 Leaf W e b b e r s 46 O t h e r Leaf W e b b e r s a n d Tiers 4 9

Pests of Flowers and Pods

T h r i p s 5 0 Blister Beetles 53 B u d Weevils 5 4 P o d Weevils 5 7 P o d - s u c k i n g B u g s 5 8 P o d B o r e r s 6 2 L a b t a b P o d B o r e r s 66 B l u e B u t t e r f l i e s 6 9 L e g u m e ( C o w p e a ) P o d B o r e r 7 0 P l u m e M o t h s 7 3 L i m a B e a n P o d B o r e r 7 4 P o d f l i e s 7 7 P o d W a s p 7 8 B r u c h i d s 8 1

Chickpea

Pests Attacking Roots/Stems

N o d u l e - d a m a g i n g Flies 8 5 S i t o n a W e e v i l s 8 6 T e r m i t e s 8 9 S o i l B e e t l e s 9 0 C u t w o r m s 9 3

Pests of Foliage and Pods

A p h i d s 9 4 L e a f m i n e r s 9 6 A r m y w o r m 9 8 P o d B o r e r s 101 S e m i l o o p e r 105

Pests of Stored Seeds

B r u c h i d s 106

Other Animal Pests of Pigeonpea a n d Chickpea

B i r d s 109 R o d e n t s 109

Beneficial Insects

P o l l i n a t o r s 110 N a t u r a l E n e m i e s 113 P r e d a t o r s 113 P a r a s i t o i d s 116 I n s e c t D i s e a s e s 119 Authors' Note

T h i s h a n d b o o k has b e e n p u b l i s h e d t o h e l p a g r i c u l t u r a l s c i e n t i s t s a n d s t u d e n t s t o i d e n t i f y t h e c o m m o n insect a n d o t h e r a n i m a l p e s t s o f p i g e o n p e a a n d c h i c k p e a . A n u m b e r o f i n s e c t s f o u n d o n t h e s e c r o p s a r e n o t pests a n d m a n y are e v e n b e n e f i c i a l , b e c a u s e t h e y f e e d u p o n t h e p e s t s p e c i e s . I l l u s t r a t i o n s of a f e w of t h e s e b e n e f i c i a l i n s e c t s a r e g i v e n here, t o e m p h a s i z e that i t i s i m p o r t a n t t o first d e t e r m i n e t h e r o l e o f i n s e c t s f o u n d o n o u r c r o p s r a t h e r t h a n a s s u m i n g t h a t all i n s e c t s a r e h a r m f u l a n d s o m u s t b e e l i m i n a t e d ! Brief d e s c r i p t i o n s o f t h e d i s t r i b u t i o n a n d b i o l o g y o f t h e pests are given, together with suggestions for control measures, w h e r e a p p r o p r i a t e . C h e m i c a l c o n t r o l s h o u l d o n l y b e u s e d w h e r e e s s e n t i a l a n d p r e f e r a b l y w i t h t h e a d v i c e o f a p l a n t p r o t e c t i o n specialist. It is n o t e a sy to i d e n t i f y insects, par- t i c u l a r l y f r o m p h o t o g r a p h s . O u r r e a d e r s a r e t h e r e f o r e r e c o m m e n d e d t o c o l l e c t a n d p r e s e r v e i n s e c t s f o u n d o n t h e i r c r o p s , a n d t o seek h e l p f r o m p r o f e s s i o n a l e n t o m o l o - g i s t s t o i d e n t i f y t h e m a n d t o m a i n t a i n s p e c i m e n c o l l e c t i o n s f o r f u t u r e r e f e r e n c e .

Acknowledgement

T h e a u t h o r s g r a t e f u l l y a c k n o w l e d g e v a l u a b l e a s s i s t a n c e f r o m s e v e ra l c o l l e a g u e s a t I C R I S A T a n d f r o m t h e C o m - m o n w e a l t h Institute o f E n t o m o l o g y , U K . Pigeonpea

Pigeonpea (Cajanus cajan (L.) Millsp.) is an erect, w o o d y , perennial s h r u b that is c o m m o n l y g r o w n as an a n n u a l . It is very i m p o r t a n t as a field c r o p in India, eastern A f r i c a , a n d in the Caribbean region, but it is also g r o w n as a backyard or h e d g e c r o p in most c o u n t r i e s in the t r o p i c s and subtropics. Its seed is harvested a n d eaten while green (mainly in Africa and the Caribbean) or w h e n m a t u r e (mainly in India). T h e plants are also used for fodder, as fuel w o o d , for b a s k e t - m a k i n g , and in c o n s t r u c t i o n . T h e c r o p is well k n o w n as a soil improver, for its roots penetrate deep, its nodules ( c o n t a i n i n g rhizobia) fix n i t r o g e n , a n d the shed leaves add a considerable q u a n t i t y of o r g a n i c matter to the soil. Pigeonpea is most c o m m o n l y g r o w n as an intercrop, w i t h i n a wide variety of s h o r t - d u r a t i o n c o m p a n i o n c r o p s (Fig. 1). Pigeonpea g r o w s slowly d u r i n g t h e early vegetative stage and does not c o m p e t e with the c o m p a n i o n crops but after these are harvested, the p i g e o n p e a plants g r o w on to give a c o m p l e t e c a n o p y . L o n g - d u r a t i o n plants can g r o w to a height of 3 m or more. Pigeonpea is a host for many insects. Over 150 species have been reported to feed on it in India alone, and m o r e will be found. However, most of these herbivorous insects are relatively rare or s p o r a d i c in their d i s t r i b u t i o n a n d so are not regarded as pests. A small publication s u c h as this c a n n o t deal with all of t h e m , so o n l y the m o r e i m p o r t a n t insects are illustrated. A l t h o u g h m a n y insects feed u p o n p i g e o n p e a f r o m the seedling stage, most of the e c o n o m i c d a m a g e is caused by pests that feed u p o n f l o w e r s and pods. Insects may cause c o n s i d e r a b l e loss of leaves, but tests have s h o w n that the plant can adequately c o m p e n s a t e for defoliation d u r i n g

Continued

Figure 1. A pigeonpea/sorghum intercrop.

Figure 2. It is difficult to spray tall crops.

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8 the vegetative stage, so that there is little reduction in seed yield. At the flowering stage, well-grown, medium- and l o n g - d u r a t i o n pigeonpea is generally t o o tall and dense to be treated effectively by insecticides applied manually (Fig. 2). M o r e a t t e n t i on is n o w being given to short- d u r a t i o n , sole crops of pigeonpea, w h i c h flower w h e n about 1 m tall. Such crops can be conveniently treated with insecticides (Fig. 3). Short-duration, determinate genotypes w i t h large, w h i t e seeds are particularly popular, but these are susceptible to insect d a m a g e and must be adequately protected. At ICRISAT, efforts have been made to identify sources of resistance to the major pests, particularly to Helicoverpa armigera and Melanagromyza obtusa a n d to i n c o r p o r a t e these resistances into a g r o n o m i c a l l y suitable cultivars. Most of these developed lines (Fig. 4) will p r o d u c e greater yields in farmers' fields with no or minimal pesticide application.

Figure 3. Short-duration pigeonpea can be sprayed easily.

Figure 4. Pigeonpea genotype bred for pod borer resistance.

9 Pests Attacking Roots

Nodule-damaging Fly Rivellia angulata H e n d e l (Diptera: Platystomatidae)

Distribution. In India, this species has been reported to attack p i g e o n p e a root n o d u l e s (Fig. 5), a n d there are s i m - ilar reports f r o m Africa. In t h e A m e r i c a s , A f r i c a , a n d A u s - tralasia, other species have been f o u n d to attack several legumes.

S y m p t o m s . D a m a g e o c c u r s w h e n larvae a t t a c k r o o t nodules. The larvae penetrate the nodules, making them h o l l o w , a n d feed u p o n t h e active, n i t r o g e n - f i x i n g p o r t i o n s (Fig. 6) Heavy attacks, usually in Vertisols, have resulted in t h e d e s t r u c t i o n of m o r e t h a n 9 0 % of t h e n o d u l e s . T h e plants may show yellowing, indicating nitrogen deficien c y and reduced g r o w t h .

D e s c r i p t i o n a n d b i o l o g y . T h e flies have black b a n d s o n their w i n g s (Fig. 7), a n d lay their eggs on plants a n d in the soil. T h e larvae disperse to t h e root nodules w h e r e t h e y feed and g r o w . T h e fully g r o w n , c r e a m - c o l o r e d larva is 10 mm l o n g . P u p a t i o n o c c u r s in the soil. O n e g e n e r a t i o n can be c o m p l e t e d in about 4 weeks.

C o n t r o l . N o c o n t r o l measures can b e r e c o m m e n d e d . A p p l i c a t i o n of large doses of insecticides to the soil has not been s u c c e s s f u l a n d is also not e c o n o m i c . A d d i n g nitrogen fertilizer to the soil m i g h t alleviate t h e nutrient d e f i c i e n c y caused b y n o d u l e d a m a g e .

Figure 5. Nodules containing rhizobia fix nitrogen for the plant.

Figure 6. Nodule damaged by Rivellia a n g u l a t a larva.

Figure 7. R. a n g u l a t a adult.

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12 T e r m i t e s Odontotermes s p p Microtermes s p p (Isoptera: Termitidae)

Distribution. Termites are c o m m o n t h r o u g h o u t t h e t r o p - ics and subtropics.

S y m p t o m s . In young plants, wilting and death of plants can sometimes be associated with a hole in the stem, just below the soil surface. When the stem and roots are split, small, white termites {Microtermes spp) are seen in tunnels. The stems of some large plants are coated or 'sheeted' with earth, under which the termites (Odonto- termes spp) feed upon the stem surface (Fig. 8). Termites often attack plants that are damaged or dying due to disease or mechanical injury. It is unusual for termites to attack healthy pigeonpea plants in most soils and areas.

D e s c r i p t i o n a n d bi ol ogy . Termites, commonly known as white ants, are social insects that form colonies, usually in chambers below the soil surface. The 'workers' (Fig. 9), w h i c h are seen in and on plants, collect plant material and stock the 'fungus gardens' (food stores) in some of the chambers. The workers are small (4 mm) and have a soft, white body and a brown head. The 'soldiers', which protect the colonies, have a larger head and well-developed mand- ibles. The queen, which is cosseted in one of the under- g r o u n d chambers, can grow to several centimeters in length, with most of its body consisting of a distended abdomen.

C o n t r o l . Seed treatment with aldrin or H C H is recommended in some areas where plant damage is c o m m o n . Where termites form large mounds that hinder cultivation, nests can be poisoned by drenching them with solutions of these insecticides. In general, however, with adequate cultivation and rapid g r o w t h of healthy plants, termite damage seldom results in crop loss.

Figure 8. Plant damaged by Odontotermes sp.

Figure 9. Workers of Odontotermes sp.

13 Pests of Stem

Jewel Beetles Sphenoptera indica Laporte & Gory (Coleoptera: Buprestidae)

Distribution. This insect is fairly c o m m o n , but in central and southern India it is sporadic. It feeds on several legumes including p i g e o n p e a and g r o u n d n u t .

S y m p t o m s . T h e larva tunnels in the stem above a n d below the g r o u n d level. A p r o m i n e n t gall may f o r m a r o u n d the stem at g r o u n d level (Fig. 10), but similar galls are found when other insects, including weevil larvae, feed on t h e s t e m . W i l t i n g a n d d e a t h i s caused w h e n y o u n g plants are attacked, but older plants may survive w i t h little reduction in pod p r o d u c t i o n .

D e s c r i p t i o n a n d b i o l o g y . T h e white, a p p a r e n t l y legless larvae g r o w to a length of 20 mm or more, w i t h a characteristic bulb at the head and t h o r a x r e g i o n . P u p a t i o n takes place in the t u n n e l in the root or stem. T h e adult beetle is dark but iridescent, w i t h a jewel-like shine w h i c h gives this beetle its c o m m o n name (Fig. 11). Little is k n o w n of its biology.

C o n t r o l . N o c o n t r o l m e a s u r e s are s u g g e s t e d . W h e n d a m a g e is seen, it is t o o late to take remedial a c t i o n , but destruction by b u r n i n g o l d , infested stems may reduce attacks in the next season.

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Figure 10. Sphenoptera indica larva and stem damage.

Figure 11. S. indica pupa and adult in split stem.

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Figure 12. Seedlings damaged by Alcidodes sp.

Figure 13. Alcidodes fabricii (right) and A. collaris (left).

16 S t e m Weevils Alcidodes fabricii (Fabricius.) Alcidodes collaris ( P a s c o e . ) (Coleoptera: Curculionidae)

Distribution. C o m m o n in central and southern India.

S y m p t o m s . Y o u n g plants are girdled by the adult so the upper p o r t i o n of the plant wilts and dries; stem breakage may also o c c u r (Fig. 12).

D e s c r i p t i o n a n d b i o l o g y . T h e adult beetle (6 mm long) of A. fabricii is dark red or b r o w n with white longitudinal stripes, and A. collaris is black with white transverse bands on the elytra (Fig. 13). T h e eggs are laid on the stem, in w h i c h the white larvae develop.

C o n t r o l . These pests seldom cause sufficient damage to merit any c o n t r o l measures. They may kill a few young plants but neighboring plants g r o w to fill the spaces.

17 S t e m Flies Ophiomyia phaseoli ( T r y o . ) Ophiomyia centrosematis ( M e i j e r e ) (Diptera: Agromyzidae)

Distribution. Ophiomyia phaseoli is c o m m o n in Africa, Asia, a n d Australasia, f e e d i n g in t h e s t e m s of several legumes, including p i g e o n p e a ; O. centrosematis has been reared f r o m pigeonpea stems at IC RI S A T Center, but may be rare on this crop.

S y m p t o m s . T h e upper stems of y o u n g plants wilt, and the plants may die. Close e x a m i n a t i o n of the stem at the base of the wilted p o r t i o n will reveal a larva or p u p a r i u m .

D e s c r i p t i o n a n d b i o l o g y . The s h i n y black fly, w h i c h is 2 mm long (Fig. 14), lays its e g g s o n upper leaf surfaces. T h e white larva tunnels d o w n a leaf vein into the stem w h e r e it feeds and pupates.

C o n t r o l . This pest is s e l d o m f o u n d in large n u m b e r s in pigeonpea to be of c o n c e r n but it is a major pest in other legumes, including beans. On those crops, systemic soil insecticides such as phorate have been recommended for c o n t r o l .

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Figure 14. Ophiomyia centrosematis adult and damage caused by it's larva.

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20 C o w B u g s Otinotus oneratus W. Oxyrachis tarandus F. (Hemiptera: Membracidae)

Distribution. C o m m o n in central and southern India.

S y m p t o m s . T h e bugs suck the green stems. Heavy infestations can result in the f o r m a t i o n of c o r k y calluses, wilting, and reduced plant vigor.

D e s c r i p t i o n a n d b i o l o g y . The g r e y - b r o w n adult bugs (7 mm long), w h i c h have t h o r n - l i k e projections on the t h o r a x (Fig. 15), lay their eggs on the stems (Fig. 16). T h e n y m p h s e x u d e a sugary (honey dew) liquid w h i c h is used by ants (Fig. 17), w h i c h in return may help to protect the bugs f r o m natural enemies. T h e c o m m o n name of cow bug is derived f r o m this habit of providing 'milk' to the ants.

C o n t r o l . No specific control measures are r e c o m m e n d e d . Insecticides used to c o n t r o l major pests, particularly d i m e t h o a t e , will reduce the p o p u l a t i o n s of this m i n o r pest.

Figure 15. Oxyrachis tarandus adults.

Figure 16. Cowbug eggs.

Figure 17. Ants visiting areas infested by O t i n o t u s oneratus.

21 Scale Insects Ceroplastodes cajani M a s k e l l Icerya purchasi M a s k e l I (Hemiptera: Coccidae)

Distribution. Several species, genera, and families of scale insects are k n o w n to feed upon pigeonpea stems in Africa and Asia.

S y m p t o m s . The scale-like insects can be seen on stems and sometimes on leaves. Generally, these insects are not major pests when pigeonpea is grown as an annual, but they build up and attack perennials. One species, Laccifer lacca whose secretion provides us with lac, an important product, is sometimes cultivated on pigeonpea in Asia, but Acacia spp are more c o m m o n l y grown as the host-plants of this insect.

D e s c r i p t i o n a n d bi ol ogy . Young nymphs are mobile and can be spread by w i n d . A d u l t females are sedentary and are usually f o u n d in colonies (Fig. 18). Scale insects are often protected from their numerous natural enemies by ants, which feed upon their secretions. Ceroplastodes cajani is the most c o m m o n scale insect on pigeonpea in India. Icerya purchasi (Fig. 19), a polyphagous widely spread species, is one of the more colorful scale insects found on this plant.

C o n t r o l . Scale insects can be controlled directly by the use of systemic insecticides, especially d u r i n g the mobile- crawler stage. Alternatively, destruction of ant colonies will soon result in a buildup of the many natural enemies of the scale insects that will control them.

Figure 18. Ceroplastodes cajani.

Figure 19. Icerya purchasi.

22 18

19 20

24 Pests of Foliage

Jassids Empoasca fabae ( H a r r i s ) Empoasca kerri Pruth i Jacobiasca lybica ( d e B e r y e v e n ) (Hemiptera: Cicadellidae)

Distribution. Jassids have been f o u n d on pigeonpea in most areas where the crop is g row n . They are not easily identified to the species level and assistance of specialists is usually needed. In India, Empoasca kerri is the species most c o m m o n l y reported f r o m p i g e o n p e a and other legumes. Jacobiasca lybica has been r e p o r t e d f r o m pigeonpea in Africa, and Empoasca fabae from the Ameri- cas and the Caribbean.

S y m p t o m s . The attacked leaflets become cup shaped and yellow at the edges (Fig. 20). Heavy attacks result in the leaflets turning red-brown, with subsequent defoliation and stunting.

D e s c r i p t i o n a n d b i o l o g y . These small green insects (2.5 mm) feed by sucking on the leaflets. They are found on both upper and lower leaf surfaces. The adults fly when disturbed. The nymphs (Fig. 21) resemble the adults, but have no wings and run sideways when disturbed. The eggs are inserted in the veins on the underside of leaflets. One generation can be completed in 2 weeks under optimum conditions.

C o n t r o l . Heavy infestations, sufficient to cause yield loss, have been seen in northern India a n d in Kenya. Sev- eral insecticides, including dimethoate and endosulfan have been found to adequately control this pest.

Figure 20. Jassid-damaged leaves.

Figure 21. Empoasca kerri nymph.

25 A p h i d s Aphis craccivora K o c h Aphis fabae S c o p o l i Myzus persicae ( S u l z e r ) Macrosiphum s p p (Hemiptera: Aphididae)

Distribution. Several species of aphids have been reported from pigeonpea, but A. craccivora is t h e most c o m m o n , both in Asia and Africa.

S y m p t o m s . A p h i d s colonies are seen on y o u n g stems, leaflets, and pods. Y o u n g leaves of seedlings become twisted (Fig. 22) and the heavy infestation can cause wilting.

Description and biology. A. craccivora is c o m m o n on several legume crops including pigeonpea (Fig. 23). T h e adults are black and shiny, up to 2 mm long and some are w i n g e d . The n y m p h s are similar to the adults but are smaller, with a light wax covering that makes them look grey and dull. A. fabae is similar, but the adults are less shiny and are a c o m b i n a t i o n of dark b r o w n and green rather than black. M. persicae and Macrosiphum spp on pigeonpea are usually green. All these aphids p r o d u c e a new generation in a week, and infestations build up very quickly.

C o n t r o l . A p h i d colonies on pigeonpea seldom thrive for long, probably because of the natural e n e m y activity. Rain also results in a large r e d u c t i o n in infestation. Several systemic insecticides, including dimethoate adequately control aphids and can be used if needed.

Figure 22. Seedling affected by aphids and ladybird predator.

Figure 23. Aphids on pigeonpea.

26 22

27 24

28 E r i o p h y i d M i t e s Aceria cajani Channabasavanna (Acarina: Eriophyidae)

Distribution. This mite has been identified o n l y in India, w h e r e it is w i d e s p r e a d a n d c o m m o n . It is the vector of the p i g e o n p e a sterility mosaic disease, the most d a m a g i n g disease of this c r o p in India. However, disease s y m p t o m s that may indicate the presence of this mite have been reported f r o m other c o u n t r i e s also.

S y m p t o m s . As a result of the t r a n s m i s s i o n of the sterility mosaic disease, infected plants develop light green or c h l o r o t i c leaves w h i c h have mosaic patterns (Fig. 24). Most infected plants do not bear flowers, hence the name of the disease.

Description and biology. T h e mites (Fig. 25) are difficult to see w i t h the naked eye. T h e y are 0.2 mm long, light pink, s p i n d l e s h a p e d , a n d are n o r m a l l y f o u n d feeding o n t h e underside of leaflets. T h e eggs, w h i c h are milky white, are f o u n d on vegetative terminals. Many n y m p h s are f o u n d on y o u n g f o l d e d leaflets. Plant-to-plant infestation o c c u r s by the w i n d dispersal of infective mites.

C o n t r o l . It is best to prevent this mite, a n d the sterility m o s a i c disease by the use of resistant p i g e o n p e a varieties. Several insecticides i n c l u d i n g d i m e t h o a t e a n d phorate, a n d acaricides s u c h as d i c o f o l , help c o n t r o l these mites effectively.

Figure 24. Symptoms of sterility mosaic disease on pigeonpea plant and inset, close up of disease symptoms.

Figure 25. Electron micrograph of Aceria cajani.

29 Red Spider Mites Schizotetranychus cajani G u p t a Tetranychus s p p (Acarina: Tetranychidae)

Distribution. Red spider mites are f o u n d on p i g e o n p e a t h r o u g h o u t India and eastern A f r i c a . In India, S. cajani is the most c o m m o n l y reported species.

S y m p t o m s . Y e l l o w o r w h i t e spots a p p e a r o n t h e upper surface of t h e a t t a c k e d leaflets (Fig. 26). Heavy infestation results in partial d e f o l i a t i o n . T h e mites c a n be seen w i t h t h e naked eye. Most are f o u n d on t h e lower s u r f a c e of t h e leaflets.

D e s c r i p t i o n a n d b i o l o g y . T h e a d u l t mites (0.5 m m ) are oval a n d velvety red ( F i g . 27). T h e y e l l o w e g g s are laid on the u n d e r s u r f a c e of the leaflet a n d t h e n y m p h s are active, feeding on t h e u n d e r s u r f a c e , w i t h i n t h e silk w e b b i n g that t h e y p r o d u c e . O n e g e n e r a t i o n is c o m p l e t e d in less t h a n t w o w e e k s u n d e r ideal c o n d i t i o n s . D i s p e r s i o n may b e through wind-carried individuals.

C o n t r o l . Red spider mite attacks on p i g e o n p e a are sel- d o m severe e n o u g h t o merit c o n t r o l , e x c e p t o n plants g r o w n in g r e e n h o u s e s . Most w i d e l y used cultivars appear to be relatively resistant to these mites. Several insecticides i n c l u d i n g d i m e t h o a t e and most a c a r i c i d e s are normally effective in c o n t r o l l i n g these mites. H o w e v e r , s o m e Tetranychus spp have d e v e l o p e d c o n s i d e r a b l e resistance to pesticides, particularly under greenhouse conditions .

30 26

Figure 26. Pigeon pea lea ves damaged by red spider mites and inset, closeup of damaged leaf.

Figure 27. Schizotetranychus cajani.

31 28

Figure 28. Symptoms of yellow mosaic disease.

32 Whiteflies Bemisia tabaci ( G e n n . ) (Hemiptera: Aleyrodidae)

Distribution. These insects are c o m m o n across the Americas, Europe, Africa, Australia, and Asia on many species of wild and domesticated host plants.

S y m p t o m s . Whitefly is important as the vector of a virus that causes the yellow mosaic disease (Fig. 28) on pigeonpea in India.

Description and biology. The adults are small insects (1 mm) with white, w a x - p o w d e r e d wings. Eggs are laid on the undersurface of leaflets. The first instar n y m p h crawls about on the leaflet surface until it finds a suitable site for feeding. It then remains at that site, feeding by sucking and g r o w i n g into a flat, oval shaped, scale-like 'puparium' fringed by wax filaments. One generation can be c o m - pleted in less than 30 days.

C o n t r o l . Whiteflies have not been recorded as being of sufficient pest status on pigeonpea to merit any control measures, even t h o u g h the yellow mosaic disease is fairly c o m m o n in postrainy-season pigeonpea in India. Several insecticides including dimethoate and monocrotophos are reported to control this insect.

33 B u d - s u c k i n g Bugs Campylomma s p p Creontiades pallidus ( R a m b i r ) Eurystylus s p p Taylorilygus vosseleri (Poppius.) ( H e m i p t e r a : M i r i d a e )

Distribution. Several species of bugs have been recorded on pigeonpea. Taylorilygus vosseleri has been reported to feed on pigeonpea in eastern Africa, but this species is more d a m a g i n g on c o t t o n . Several other mirid species, including Campylomma spp, Creontiades pallidus, and Eurystylus spp, are c o m m o n on pigeonpea in India.

S y m p t o m s . The bugs suck the vegetative and flowering buds and may cause d e f o r m a t i o n of the leaves and abor- tion of flower buds.

D e s c r i p t i o n a n d b i o l o g y . Campylomma spp are small, green, elongate, and ovoid bugs. T h e adults are about 2 mm long. Creontiades pallidus adults are about 8 mm long and pale green (Fig. 29). Eurystylus spp and T. vosseleri are mottled b r o w n bugs, a b o u t 4 mm l o n g . T h e eggs are inserted into the soft tissue of the plants. One generation of these bugs can generally be completed in as short a time as 2 weeks.

C o n t r o l . As most plants p r o d u c e far m o r e buds than are required, yield is rarely reduced by these insects. Specific control measures are not likely to be required for these bugs, but they can be c o n t r o l l e d by most of the insecticides that are used to control major pests.

34 29

Figure 29. Creontiades pallidus.

35 30

Figure 30. Leaflets damaged by M e g a c h i l e sp.

Figure 31. M e g a c h i l e sp bee.

36 Leaf-cutter Bees Megachile s p p (Hymenoptera: Megachilidae)

Distribution. Widely distributed throughout the tropics.

S y m p t o m s . Neat, semi-circular portions are cut from the leaflets of pigeonpea (Fig. 30) by several species of Megachile.

D e s c r i p t i o n a n d bi ol ogy . Female bees carry pieces of leaf to their nests w h i c h are formed in the soil, in rotten w o o d , or in crevices. The adult bees, w h i c h are of a range of colors and sizes, are a m o n g the more important pollinators of pigeonpea (Fig. 31). Megachile is not a social insect like the honey bee, but is 'solitary' for each female forms its o w n nest filling it with a paste of honey and pollen in which eggs are laid.

C o n t r o l . Damage has never been reported to be extensive enough to merit control measures.

37 G r a s s h o p p e r s a n d Locusts Catantops erubescens W a l k . Colemania sphenerioides ( B o l i v a r ) Cyrtacanthacris tatarica (L.) Patanga succincta (L.) Schistocerca gregaria F o r s k . (Orthoptera: Acrididae)

Distribution. Many genera and species of grasshoppers and locusts have been reported to feed on p i g e o n p e a in Africa (Phymateus spp, Zonocerus spp, and Schistocerca spp) a n d in India, but few are of sufficient density a n d regular incidence to cause major c o n c e r n . In India, several species i n c l u d i n g C. tatarica (Fig. 32) and t h e Deccan wingless grasshopper, C. sphenerioides (Fig. 33), feed on the leaflets, but the d a m a g e s e l d o m results in noticeable yield reduction, except in locust outbreaks, w h e r e most plants including pigeonpea are defoliated.

S y m p t o m s . Defoliation, in case of locust outbreaks as mentioned above. O n e grasshopper that causes unusual damage to p i g e o n p e a is Catantops erubescens (Fig. 34a). It girdles branches of the p i g e o n p e a plant w h i c h t h e n wither and die (Fig. 34b).

C o n t r o l . No c o n t r o l measures are n o r m a l l y required, as the densities of these insects s e l d o m reach e c o n o m i c thresholds.

38 32 33

34a 34b

Figure 32. Cyrtacanthacris tatarica.

Figure 33. Colemania sphenerioides.

Figure 34a. Catantops erubescens.

Figure 34b. Pigeonpea branches damaged by C. erubescens.

39 35

40 Leaf-damaging Weevils Myllocerus undecimpustulatus F a u s t Nematocerus s p p Phyllobius s p p Systates s p p (Coleoptera: Curculionidae)

Distribution. Myllocerus spp and Phyllobius spp are widespread in India on pigeonpea and several other host plants. Nematocerus spp and Systates spp have been f o u n d on pigeonpea in Africa. Other genera and species of weevils are also reported to feed on pigeonpea leaves.

S y m p t o m s . Adult weevils chew the leaflets, generally at the margins, causing a ragged effect (Fig. 35). Larvae live in the soil, where they feed mainly on roots.

D e s c r i p t i o n a n d bi ol ogy . The adults of M. undecimpustulatus, w h i c h are 5 mm long have 11 small black spots on their ash-grey bodies (Fig. 36), w h i c h gives them the c o m m o n name ash weevil. The grubs are white, apodous, and stout. They pupate in the soil.

C o n t r o l . The adults and larvae do not cause sufficient damage to pigeonpea to merit separate control measures. However, on other crops, particularly on some varieties of cotton, M. undecimpustulatus is a major pest in some localities, and insecticides, including monocrotophos, have been recommended for its control.

Figure 35. Leaf damaged by Myllocerus sp.

Figure 36. Myllocerus undecimpustulatus.

41 O the r Leaf- a n d F l o w e r - d a m a g i n g Beetles

Cheilomenes s p p Luperus s p p Epilachna s p p Monolepta s p p (CoIeoptera: Podagrica s p p Coccinellidae) (Coleoptera: Chrysomelidae)

Oxycetonia versicolor F. Holotrichia sp p (Coleoptera: Cetonidae) Adoretus s p p (Coleoptera: Scarabaeidae)

Distribution. A d u l t beetles of several genera other t h a n weevils, also feed on p i g e o n p e a leaves in India and in Africa. A few of these have been listed above.

S y m p t o m s . Leaves are eaten. S o m e of the beetles are not seen on the leaves because they feed o n l y at night and hide during the day.

D e s c r i p t i o n a n d b i o l o g y . T h e coccinellids, c o m m o n l y referred to as ladybird beetles, are small and usually brightly colored with dark spots. The Epilachna spp are herbivorous, but Cheilomenes spp n y m p h s and adults are predatory on small insects including aphids. However, in the absence of their prey, Cheilomenes spp adults c h e w holes in leaves, possibly to o b t a i n moisture. The c h r y s o - melids are generally shiny, metallic beetles; Podagricaspp are flea beetles, so called because they j u m p . Oxycetonia versicolor (Fig. 37), a brilliantly c o l o r e d and dorsally flat- tened beetle with a large s c u t e l l u m feeds on pollen. H o l o - trichia (Lachnosterna) spp are larger beetles, a n d are important because their larvae (white grubs) c o n s i d e r a b l y damage a range of c r o p s by feeding on their roots. A d o r e - tus spp are brightly c o l o r e d , shiny beetles, whose larvae feed on roots.

C o n t r o l . These beetles are s e l d o m present in p o p u l a - tions large e n o u g h to cause extensive d a m a g e to p i g e o n - pea and so do not merit specific c o n t r o l measures.

42 37

Figure 37. Oxycetonia versicolor.

43 38

39 40

Figure 38. Moths of (L to R): Amsacta albistriga, Amsacta collaris, Spilosoma obliqua, Acanthoplusia orichalcea, Chrysodeixis chalcites, Euproctis lunata, and Euproctis subnotata.

Figure 39. Amsacta albistriga larva.

Figure 40. Chrysodeixis chalcites larva.

Figure 41. Euproctis subnotata larvae.

44 Lepidopteran Defoliators Amsacta s p p . Spilosoma (Diacrisia) obliqua ( W a l k e r . ) (Lepidoptera: Arctiidae)

Chrysodeixis chalcites E s p e r Acanthoplusia (Trichoplusia) orichalcea (F.) (Lepidoptera: Noctuidae)

Euproctis s p p (Lepidoptera: Lymantridae)

Distribution. T h e s e p o l y p h a g o u s L e p i d o p t e r a (Fig. 38) are w i d e l y d i s t r i b u t e d in Asia and A f r i c a . T h e y feed upon the leaves, buds, and flowers of many plants.

S y m p t o m s . T h e d a m a g e caused i s o b v i o u s o n p i g e o n - pea, w h e r e t h e larvae feed u p o n leaves a n d inflorescence.

D e s c r i p t i o n a n d b i o l o g y . T h e Amsactaspp and S. obliqua are c o m m o n l y k n o w n as 'hairy caterpillars' for they are d e n s e l y c o v e r e d w i t h l o n g hair (Fig. 39). Chrysodeixis chalcites (Fig. 40) a n d Acanthoplusia orichalceaare s e m i - loopers. T h e f o r m e r is green and the latter is also green but w i t h w h i t e lateral lines a n d black spines. Euproctisspp are 'tussock caterpillars' so called because they have p r o m i - nent, c o m p a c t tufts of short hair (Fig. 41). T h e hair of these a n d o t h e r caterpillars cause skin rashes a n d irritation so care must be taken while handling t h e m .

C o n t r o l . P o p u l a t i o n s of these larvae on p i g e o n p e a are s e l d o m large e n o u g h to merit pesticide use. However, there are o c c a s i o n a l reports of severe d e f o l i a t i o n , particularly by Amsactaspp. Several insecticides i n c l u d i n g e n d o - sulfan n o r m a l l y give adequate c o n t r o l .

45 Leaf W e b b e r s Grapholita (Cydia) critica M e y r . Leguminivora ptychora ( M e y r . ) (Lepidoptera: Tortricidae)

Distribution. Grapholita critica ( f o r m e r l y k n o w n as Eucosma critica) is c o m m o n t h r o u g h o u t t h e p i g e o n p e a - g r o w i n g areas of India a n d Leguminivora ptychora is c o m m o n o n several l e g u m e s , i n c l u d i n g p i g e o n p e a , i n eastern A f r i c a .

S y m p t o m s . Leaflets are w e b b e d t o g e t h e r w i t h silk (Fig. 42a) a n d t h e larva feeds w i t h i n t h e w e b . As t h e w e b o f t e n i n c l u d e s t h e t e r m i n a l b u d , f u r t h e r g r o w t h of that s h o o t is p r e v e n t e d . I n f e s t a t i o n s start a t t h e s e e d l i n g stage a n d m a y persist t o t h e r e p r o d u c t i v e stage w h e n t h e larvae f e e d inside f l o w e r b u d s (Fig. 42b) a n d in y o u n g p o d s .

D e s c r i p t i o n a n d b i o l o g y . G. critica is a s m a l l b r o w n m o t h (Fig. 43) that lays its e g g s on t h e leaf b u d s a n d y o u n g leaves. T h e c r e a m - y e l l o w larva ties leaflets t o g e t h e r a n d feeds inside t h e w e b , r e a c h i n g a l e n g t h of a b o u t 10 mm before p u p a t i n g in t h e w e b .

C o n t r o l . A l t h o u g h leaf w e b b e r s m a k e y o u n g p i g e o n p e a c r o p s look u n t i d y , t h e y a p p a r e n t l y c a u s e n o yield loss. T h e p l a n t s p r o d u c e side s h o o t s t o c o m p e n s a t e f o r t h e loss o f t e rmi n a l b u d s . If i n s e c t i c i d e s are not used, t h e m a n y parasites a n d p r e d a t o r s s o o n b r i n g t h i s pest u n d e r c o n t r o l . T h e larvae inside the w e b s are well p r o t e c t e d f r o m c o n t a c t i n s e c t i c i d e s . H o w e v e r , w h e r e necessary, s y s t e m i c insecti- c i d e s s u c h a s m o n o c r o t o p h o s o r o n e w i t h s o m e f u m i g a n t a c t i o n s u c h as d i c h l o r v o s c a n be a p p l i e d .

Figure 42a. G r a p h o l i t a c r i t i c a larva on webbed leaves.

Figure 42b. Pigeonpea bud damaged by G. c r i t i c a larva.

Figure 43. G. c r i t i c a moth.

46 42a

42b

47 44 45

Figure 44. Caloptilia soyella larva and a rolled-up leaflet.

Figure 45. Damage caused by A p r o a e r e m a modicella.

48 Other Leaf Webbers and Tiers

O t h e r leaf w e b b e r s a n d tiers that feed o n p i g e o n p e a i n c l u d e Maruca testulalis (see page 70); the leaf tier Anar- sia ephippias (Meyr.) (Lepidoptera: Gelechiidae)—a small b r o w n larva that folds individual leaflets; the leaf roller Caloptilia soyella Van Dev. (Lepidoptera: Gracillaridae)— a green larva that rolls the leaflets f r o m the tips (Fig. 44); a n d the g r o u n d n u t leaf miner Aproaerema modicella Dev. (Lepidoptera: Gelechiidae), w h o s e feeding p r o d u c e s white or light b r o w n patches on the f o l d e d leaflets (Fig. 45). With the e x c e p t i o n of M. testulalis, these larvae s e l d o m , if ever, c a u s e sufficient d a m a g e o n p i g e o n p e a t o merit c o n t r o l measures.

49 Pests of Flowers and Pods

T h r i p s Megalurothrips usitatus ( B a g n a l l ) (Thysanoptera: Thripidae)

Distribution. Several genera and species of t h r i p s have been recorded on p i g e o n p e a . In India, the most c o m m o n species appears to be Megalurothrips usitatus, w h i c h feeds on flowers (Figs. 46 a n d 47). In eastern A f r i c a , other Megalurothrips species are c o m m o n on p i g e o n p e a and are considered important.

S y m p t o m s . Heavy infestation of thrips can lead to shed- d i n g o f b u d s a n d flowers.

D e s c r i p t i o n a n d b i o l o g y . T h e black adults (1 m m ) and n y m p h s are easily seen w i t h the naked eye, particularly w h e n they are on yellow flower petals. O n e g e n e r a t i o n c a n be c o m p l e t e d within 3 weeks.

C o n t r o l . In India, the p o p u l a t i o n b u i l d up of t h r i p s on p i g e o n p e a is generally not large e n o u g h to cause substantial d a m a g e and do not, therefore, merit specific c o n t r o l measures. In most cases, insecticides used to c o n t r o l major pests s u c h as e n d o s u l f a n or d i m e t h o a t e also reduce thrips p o p u l a t i o n s .

50 46

Figure 46. Megalurothrips usitatus.

Figure 47. Electron micrograph of M. usitatus.

51 48b

48a

48c

52 Blister Beetles Mylabris pustulata Thunberg Mylabris s p p Coryna s p p (Coleoptera: Meloidae)

Distribution. Mylabris pustulata and other Mylabris spp are w i d e s p r e a d and c o m m o n in India. Several species of Mylabris and Coryna have been recorded f r o m pigeonpea in Africa.

S y m p t o m s . A d u l t beetles feed on the flowers and greatly reduce the numbers of pods that are set.

D e s c r i p t i o n a n d b i o l o g y . Mylabris pustulata (25 mm) is one of the larger species, the adults having very o b v i o u s black and red c o l o r a t i o n (Fig. 48a). Other genera and species are of varying sizes but most are c o n s p i c u o u s l y c o l o r e d . Their name is derived f r o m the blisters on h u m a n skin caused by the exudate ( c o n t a i n i n g cantharidine), w h i c h is p r o d u c e d by the beetles w h e n they are disturbed. Eggs are usually laid in the soil. T h e larvae of most species are generally beneficial because they feed upon insects in the soil.

C o n t r o l . In locations w h e r e p i g e o n p e a is g r o w n over large areas, blister beetles cause little d a m a g e because they are spread across the c r o p . However, in small pigeonpea plots that are in the f l o w e r i n g stage d u r i n g the period of peak adult activity ( A u g u s t - O c t o b e r in southern India), most of the flowers may be eaten by this pest and crop loss may be substantial. T h e beetles can be c o n t r o l l e d manually by p i c k i n g them by hand (Fig. 48b) or collecting them w i t h an insect net (Fig. 48c) and c r u s h i n g t h e m , since they are slow m o v i n g , but care s h o u l d be taken to protect the s k i n . Most insecticides are not very effective against these beetles, but synthetic pyrethroids work reasonably well.

Figure 48a. Mylabris pustulata.

Figure 48b. Handpicking of beetles.

Figure 48c. Collection of beetles using an insect net.

53 B u d Weevils Indozocladius (Ceutorhynchus) asperulus ( F a u s t ) (Coleoptera: Curculionidae)

Distribution. Widely distributed in peninsular India.

S y m p t o m s . Larve feed and pupate inside the flower buds, making them hollow. In severe attacks, the n u m b e r of flowers is reduced substantially.

D e s c r i p t i o n a n d b i o l o g y . T h e small ( 2 m m ) b r o w n i s h weevil (Fig. 49) lays its eggs on t h e b u d s a n d t h e w h i t e larvae develop singly inside the buds.

C o n t r o l . This is generally a m i n o r pest a n d so does not merit specific control measures.

Figure 49. Indozocladius asperulus.

54 49

55 50

Figure 50. Apion benignum.

56 P o d Weevils Apion clavipes Gerstaecker Apion benignum ( F a u s t ) (Coleoptera: Apionidae)

Distribution. Apion clavipes is regarded as a major pigeonpea pest in some areas ot northwest India and in East Africa. A. benignum is occasionally f o u n d in s o u t h e r n India. In other areas, these weevils are relatively u n c o m m o n .

S y m p t o m s . Larvae d a m a g e the green seeds in pods but t h e d a m a g e is usually noticed only after adults emerge, c u t t i n g their w a y out of t h e p o d . T h e beetles also chew small holes in leaflets and flowers.

D e s c r i p t i o n a n d b i o l o g y . A d u l t s are small black weevils (Fig. 50), larvae are creamy white, There does not seem to be any published i n f o r m a t i o n regarding the biology of these pests.

C o n t r o l . There are no p u b l i s h e d reports of c o n t r o l measures but several pesticides i n c l u d i n g dimethoate, m o n o - c r o t o p h o s , and the synthetic pyrethroids can control these pests effectively.

57 P o d - s u c k i n g B u g s Anoplocnemis s p p Clavigralla gibbosa S p i n o l a Clavigralla scutellaris (Westwood) Clavigralia tomentosicollis S t a l . Riptortus s p p (Hemiptera: Coreidae)

Piezodorus sp Dolicoris indicus (Stal.) Nezara viridula (L.) (Hemiptera: Pentatomidae)

Distribution. Anoplocnemis spp and Riptortus spp are f o u n d on several hosts in Africa and Asia. Clavigralla gibbosa is the most important p o d - s u c k i n g bug on pigeonpea in India; C. (Acanthomia) tomentosicollis is the most important in Africa; and C. scutellaris is c o m m o n in Africa and Asia. Nezara viridula is f o u n d on many legumes and other hosts t h r o u g h o u t the tropics and subtropics; D. indicus is c o m m o n in India; and Piezodorus sp in southeast Asia and in Australia. Several other genera and species of Coreidae and Pentatomidae are also occasionally f o u n d on this crop.

S y m p t o m s . A l l t h e s e b u g s , s u c k d e v e l o p i n g seeds t h r o u g h the pod wall. The seeds b e c o m e shrivelled with dark patches (Fig. 51). Such seed does not germinate and is not acceptable as h u m a n f o o d .

Description and biology. T h e adults of Anoplocnemis spp, w h i c h are usually black or b r o w n (Fig. 52), are the largest (30 m m ) of these bugs. Riptortus spp (18 mm) are mainly b r o w n a n d are smaller (Fig. 53). Clavigralla bugs are b r o w n - g r e y ; C. scutellaris (12 m m ) is the largest a n d is broader than both C. gibbosa (Fig. 54a) and C. tomentosi-

Continued

58 51 52

53 54a

54b

Figure 51. Bug-damaged (left) and healthy seed (right).

Figure 52. Anoplocnemis sp.

Figure 53. Riptortus sp.

Figure 54. Clavigralla gibbosa: (a) adult and (b) eggs.

59 55 56

60 collis, both of w h i c h are about 10 mm long. Nezara viridula (15 m m ) is normally green (Fig. 55), but can be completely yellow or green and yellow and D. indicus is b r o w n with light mo t t l i n g (Fig. 56). These bugs lay their eggs in c l u m p s on the leaf and p o d surfaces (Fig. 54b, 57). T h e y o u n g n y m p h s that feed by s u c k i n g the green tissue are usually f o u n d in g r o u p s . The large n y m p h s and adults can feed on seed t h r o u g h pod walls. O n e generation takes 4 weeks or more depending on the temperature.

C o n t r o l . Insecticides, particularly those with some systemic action such as d i m e t h o a t e and m o n o c r o t o p h o s , are usually effective in c o n t r o l l i n g these pests. In eastern Africa some pigeonpea g e n o t y p e s have been reported to have considerable resistance to the sucking bugs, so s c r e e n i n g for resistance may be a useful strategy for the management of these pests.

Figure 55. Nezara viridula adult.

Figure 56. Dolicoris indicus.

Figure 57. Close up of N. viridula eggs.

61 P o d Borers Helicoverpa (Heliothis) armigera ( H u b n e r ) Helicoverpa zea ( B o d d i e ) Helicoverpa punctigera (Wallengren) Heliothis virescens (F.) (Lepidoptera: Noctuidae)

Distribution. Helicoverpa armigera (Fig. 58) is widely distributed on many host plants t h r o u g h o u t the tropics and s u b t r o p i c s but not in the A m e r i c a s w h e r e it is replaced by H. zea and Heliothis virescens. In Australia, both Heli- coverpa punctigera and H. armigera attack pigeonpea.

S y m p t o m s . Helicoverpa spp destroy buds, flowers, and pods. If flowers and p o d s are not available, t h e y feed u p o n leaflets (Fig. 59), leaving the veins. On pods, c o n s p i c u o u s holes are m a d e by the entry of larvae. Usually d e v el o pi n g and partly matured seeds are eaten completely. At times a p o r t i o n of the seed and testa remain.

D e s c r i p t i o n a n d b i o l o g y . Helicoverpa spp lay their small white eggs (Figs. 60 and 61), usually singly, on the upper and outer surfaces of leaves, flowers, pods, and stems. T h e y o u n g larvae feed by s c r a p i n g green tissue and

Continued

Figure 58. Male (left) and female (right) moths of Helico- verpa armigera.

Figure 59. H. armigera damaging pigeonpea leaves.

Figure 60. H. armigera egg.

Figure 61. Electron micrograph of H. armigera egg.

62 58

60 61

63 62

Figure 62. H. armigera damaging pods.

Figure 63. Color range of H. armigera larvae.

Figure 64. H. armigera pupa.

64 the older larvae chew voraciously into buds, flowers, and pods, leaving characteristic r o u n d holes (Fig. 62). The large larvae (27 mm long) are yellow, g r e e n , pink, orange, b r o w n , or black (Fig. 63), but all have characteristic light and dark stripes along each side. Pupation is normally in the soil or in plant debris (Fig. 64). One generation can be c o m p l e t e d in just over 4 weeks u n d e r favorable conditions.

C o n t r o l . Several insecticides, including endosulfan and synthetic pyrethroids, give g o o d c o n t r o l , particularly if applied soon after the eggs hatch. However, considerable resistance to many insecticides has been reported in these insects in areas where crops have been sprayed inten- sively. Helicoverpa spp have many parasites and predators. In some areas these give adequate control and pesticide use may lead to an increase in Helicoverpa populations t h r o u g h the reduction of these natural enemies. Some pigeonpea genotypes have considerable tolerance to these pests, so host-plant resistance can be a useful method of avoiding damage.

65 L a b l a b P o d Borers Adisura atkinsoni ( M o o r e ) (Lepidoptera: Noctuidae)

Distribution. A. atkinsoni is w id e ly distributed in s o u t h - ern India. It is a m a j o r pest of Dolichos lablab, a n d is often f o u n d in low n u m b e r s on p i g e o n p e a . T w o other species, Adisura marginalis Wlk. and Adisura stigmatica Warr. are also occasionally f o u n d o n p i g e o n p e a .

S y m p t o m s . The larvae bore into buds, flowers, and green pods.

D e s c r i p t i o n a n d b i o l o g y . T h e green larva, 15 mm l o n g , is very similar to Helicoverpa armigera, and is often c o n - fused with this pest in the field (Fig. 65). It can be distin- guished by its b r o w n lateral stripes. Pupation takes place in the soil; the m o t h has yellowish b r o w n f o r e w i n g s and white h i n d w i n g s (Fig. 66). O n e generation is c o m p l e t e d in about 4 weeks.

C o n t r o l . C o n t r o l is rarely needed because this pest is o n l y f o u n d in low n u m b e r s on p i g e o n p e a . However, insecticides used to c o n t r o l other major pests s u c h as e n d o s u l - fan can also c o n t r o l this insect.

66 65

Figure 65. Larva of Adisura sp. Figure 66. Adisura marginalis moths.

67 67

68a 68b

Figure 67. Lampides boeticus butterfly larva, pupa, and butterfly, and inset, butterfly in action.

Figure 68. L. boeticus; (a) eggs and (b) larva.

68 Blue Butterflies Lampides boeticus (L.) Catochrysops strabo (Fabricius) (Lepidoptera: Lycaenidae)

Distribution. Both these species are widely distributed in Asia and L. boeticus (Fig. 67) is c o m m o n in eastern Africa. Larvae are found on several cultivated and wild legumes.

S y m p t o m s . The larvae chew leaves, buds, flowers, and pods.

Description and biology. Small, blue, beautifully sculp- ted eggs are laid singly on buds (Fig. 68a). The larvae, w h i c h are 12 mm long, are green, oval, and flat (Fig. 68b). Pupation occurs in soil or in plant debris. One generation is completed in about 5 weeks.

C o n t r o l . A l t h o u g h these butterflies are c o m m o n and lay many eggs on the pigeonpea plants, relatively few larvae are f o u n d on the crop, probably because natural enemies reduce their numbers. Specific control for these insects is rarely required but endosulfan or other pesticides that control major pests can be used.

69 L e g u m e ( c o w p e a ) P o d B o r e r Maruca testutalis ( G e y e r ) (Lepidoptera: Pyralidae)

Distribution. C o m m o n on many legume species t h r o u g h - out the tropics and subtropics.

S y m p t o m s . T h e larva w e b s t o g e t h e r leaves, buds, a n d pods and feeds inside these w e b s (Fig. 69, 70a).

D e s c r i p t i o n a n d b i o l o g y . T h e m o t h (Fig. 71) lays yellow, oval eggs in small batches, c o m m o n l y on terminals. T h e larva, 14 mm l o n g , is w h i t i s h - g r e e n with rows of c o n - s p i c u o u s black spots on t h e dorsal surface (Fig. 70a, b). However, t h e spots are not clearly seen on t h e y e l l o w - green prepupae. P u p a t i o n takes place in the w e b or on t h e soil surface in a silk c o c o o n . In o p t i m u m c o n d i t i o n s , one generation can be completed in less than 3 weeks.

C o n t r o l . This is a major pest of p i g e o n p e a and other grain legumes in many areas of Africa and central India. Several insecticides i n c l u d i n g e n d o s u l f a n kill t h e larvae but as the w e b s protect t h e m f r o m c o n t a c t insecticides, careful application is required. This pest is particularly destructive to d e t e r m i n a t e - t y p e p i g e o n p e a . As there are differences in g e n o t y p e susceptibility, it may be possible to develop cultivars resistant to this insect.

Figure 69. Maruca testulalis larva in a web of leaves and flowers, and inset, prepupa in silk cocoon.

Figure 70a. M. testulalis larva on webbed flowers and pods.

Figure 70b. Close up of M. testulalis larva damaging a flower.

Figure 71. M. testulalis moth.

70 69

70a 71

70b

71 72

Figure 72. Larva (green) and pupa (red) of Exelastis atomosa.

Figure 73. E. atomosa moth.

72 P l u m e M o t h s Exelastis atomosa (Walsingham) Sphenarches anisodactylus Wlk. (Lepidoptera: Pterophoridae)

Distribution. Both these species are w i de l y distributed in Asia and eastern A f r i c a , but E. atomosa is generally m o r e c o m m o n on p i g e o n p e a and is a major pest in several areas of India. S. anisodactylus is m o r e c o m m o n on lablab bean.

S y m p t o m s . T h e larvae c h e w into the buds, flowers, a n d p o d s , and small holes are seen in the buds and tender pods.

Description and biology. T h e p l u m e m o t h caterpillars are particularly n u m e r o u s on postrainy-season pigeonpea and are generally c o n s i d e r e d as i m p o r t a n t pests. The green oval eggs of E. atomosa are laid singly on buds and pods. The larvae 14 mm long, are green or b r o w n , spindle s h a p e d , and covered with short spines and larger hair. The pupae, w h i c h look like the larvae, are usually f o u n d att- a c h e d to the p o d surface or on the pedicel (Fig. 72). The adults have b r o w n , plume-like wings (Fig. 73). One generation can be c o m p l e t e d in about 4 weeks.

C o n t r o l . E. atomosa can be easily c o n t r o l l e d by several insecticides, including endosulfan. Its many natural enemies prevent it f r o m b u i l d i n g up into large populations.

73 Lima Bean Pod Borer Etiella zinckenella Treitschke (Lepidoptera: Pyralidae)

Distribution. This species is widely distributed on several legumes in the tropics and semitropics.

S y m p t o m s . The larva is generally f o u n d in m a t u r i n g and dried pods. Infestations build up at the end of the p i g e o n - pea season, particularly w h e n temperatures are high. Fae- cal granules are f o u n d inside the damaged pods.

Description and biology. White elliptical eggs are laid in small g r o u p s on the developing pods. The y o u n g larvae are green, but turn red later (Fig. 74). T h e y feed inside t h e pod, reaching a length of 14 m m . Pupation takes place in the soil. The m o t h has grey f o r e w i n g s but with a white costal margin and the hind wings are pearly and translucent (Fig. 75). One generation can be completed in 4 weeks under favorable conditions.

C o n t r o l . In India, it is generally a minor pest on p i g e o n - pea and will seldom merit specific c o n t r o l , but in southeast Asia, it is of some c o n c e r n and can be controlled by systemic insecticides.

74 74

Figure 74. Etiella zinckenella larvae in damaged pods.

Figure 75. E. zinckenella moth.

75 76

78 79

Figure 76. Female fly of Melanagromyza obtusa.

Figure 77. M. obtusa eggs inside the pod and inset, closeup of egg.

Figure 78. M. obtusa larva.

Figure 79. M. chalcosoma puparia.

Figure 80. M. obtusa larva, puparia, and seed damage.

76 Podflies Melanagromyza obtusa M a l l o c h Melanagromyza chalcosoma S p e n c e r (Diptera: Agromyzidae)

Distribution. Melanagromyza obtusa is a widespread and major pest of p i g e o n p e a in Asia, and extends to A u s - tralasia. Reports of this species in Africa are probably erroneous because the species usually f o u n d there is M. chalcosoma, a c o m m o n pest in the pods of several legumes including pigeonpea.

S y m p t o m s . There are no obvious external s y m p t o m s of podfly attack till the fully g r o w n larvae chew holes in the pod walls leaving a " w i n d o w " t h r o u g h w hi ch the flies emerge after pupation in the p o d . Damaged seeds are of no value.

D e s c r i p t i o n a n d b i o l o g y . The small black fly (Fig. 76) lays eggs (Fig. 77) t h r o u g h the wall of the developing pod and the white legless larva, 3 mm long (Fig. 78), feeds inside the green seed. In the case of M. chalcosoma, t w o o r more larvae often develop and pupate in one seed (Fig. 79) but in M. obtusa, generally only one larva develops in one seed (Fig. 80). The b r o w n p u p a r i u m is formed inside the p o d but outside the seed. One generation takes about 3 week under o p t i m u m conditions.

C o n t r o l . As all stages of development take place inside the p o d , only systemic insecticides such as dimethoate and m o n o c r o t o p h o s are effective, but nonsystemic insecticides like endosulfan help in killing the adults. A closed season d u r i n g w h i c h no pigeonpea pods are available s h o u l d reduce infestation. It is best to avoid g r o w i n g a mixture of cultivars of differing durations in an area because this will provide pods over a long period and allow several generations to develop. Some pigeonpea genotypes are m u c h m o r e susceptible to egg laying than others, so it may be possible to select resistant cultivars.

77 P o d W a s p Tanaostigmodes cajaninae L a S a l l e (Hymenoptera: Tanaostigmatidae)

Distribution. This pest is w i d e l y distributed on p i g e o n - pea in India. It is c o m m o n on research stations but it is rare in farmers' fields.

S y m p t o m s . Y o u n g pods are attacked and either do not g r o w at all, or the locules that are not attacked may develop normally, while the attacked locules remain un- developed (Fig. 81). T h e exit hole m a d e by the e m e r g i n g wasp is smaller than that of podfly.

D e s c r i p t i o n a n d b i o l o g y . The small wasp ( 2 m m long) lays translucent, flat, oval eggs on the flower and on the y o u n g p o d . T h e white, a p p a r e n t l y legless larva (2 mm long) feeds on the y o u n g seed a n d inner p o d wall (Fig. 82). P u p a t i o n o c c u r s in the same locules. O n e g e n e r a t i o n is c o m p l e t e d in less than 3 weeks.

C o n t r o l . This insect is promoted to pest status on research stations w h e r e a range of cultivars are g r o w n , w h i c h p r o - vide p o d s over long periods, a l l o w i n g t h e pest to build up over m a n y generations in every year. The pest can be c o n t r o l l e d by restricting the range of d u r a t i o n of cultivars g r o w i n g in an area. T h e use of pesticides s u c h as e n d o s u l - fan appears to kill s o m e of the natural enemies but not the pest itself. Systemic pesticides s u c h as d i m e t h o a t e , will reduce p o p u l a t i o n densities since it is an internal feeder.

78 81

Figure 81. Symptoms of damage caused by Tanaostig- modes cajaninae. On the left is an undamaged pod.

Figure 82. Larva, pupa, and adult of T. cajaninae.

79 83

Figure 83. Callosobruchus sp eggs and exit holes on pods.

Figure 84. Callosobruchus sp in and on damaged seeds.

80 B r u c h i d s Callosobruchus maculatus (F.) Callosobruchus analis (F.) Callosobruchus chinensis (L.) (Coleoptera: Bruchidae)

Distribution. The bruchid, Callosobruchus maculatus is c o m m o n on pigeonpea and s o m e other grain legumes w o r l d w i d e , both in pods in the field a n d in stored seed. O t h e r species i n c l u d i n g C. analis (F.) and C. chinensis (L.) are also f o u n d in the stored seed, but are less c o m m o n .

S y m p t o m s . The pests attack nearly mature and dried pods. T h e r o u n d exit hole and the white eggs on the pod wall are c o n s p i c u o u s (Fig. 83). Infested stored seed can be r e c o g n i z e d by the eggs on the seed surface a n d the r o u n d exit holes with the 'flap' of seed coat.

D e s c r i p t i o n a n d b i o l o g y . The mottled b r o w n beetle, 3 mm long, lays its eggs on pods or seeds. The white larva b u r r o w s into the p o d or seed t h r o u g h the base of the egg a n d then feeds and develops into a pupa inside the seed, f r o m w h i c h the adult emerges t h r o u g h a neat cylindrical hole (Fig. 84). One generation takes 4-weeks or more, d e p e n d i n g on the temperature and humidity. This pest can be destructive to stored seed.

C o n t r o l . Pods should be harvested as soon as they mature and the seed sun dried before it is placed in a clean, beetle-proof storage container (metal, w o o d , earthenware, or plastic). Fumigation w i t h a range of c h e m i c a l s has been reported to control infestations in stored seed. A coating of edible oils or of inert clays can prevent further development of b r u c h i d s in the stored seeds.

81 Chickpea

C h i c k p e a (Cicer arietinum L.) (Fig. 85), also k n o w n as Bengal g r a m (and has 30 other c o m m o n names), has far fewer pests than pigeonpea. T h e relatively low o c c u r r e n c e of pests a n d o t h e r insects on t h i s c r o p is p r o b a b l y c a u s e d by t w o major factors:

1. C h i c k p e a is a 'cool season' legume c o m m o n l y g r o w n in temperate climates, s o w n immediately before or after winter. Its vegetative g r o w t h o c c u r s d u r i n g , or just after winter, when insect p o p u l a t i o n s are generally low.

2. C h i c k p e a is covered w i t h g l an du l a r t r i c h o m e s (c l u b- shaped hair) that e x u d e an acidic liquid (mainly malic acid) w h i c h evidently deters m a n y potential herbivores f r o m feeding o n this c r o p (Fig. 86).

T w o main types o f c h i c k p e a are c o m m o n l y g r o w n (Fig. 87). T h e 'kabuli' type has large white seeds and is a p o p u l a r h u m a n f o o d in m a n y countries, particularly in the Mediter- ranean area. T h e 'desi' type generally has smaller, c o l o r e d seeds (yellow, b r o w n , green, or black) and is most c o m - m o n i n t h e Indian s u b c o n t i n e n t a n d i n M e x i c o . T h i s t y p e i s used b o t h as f o o d by h u m a n beings a n d as feed for animals. In general, the kabuli plants and seeds are m u c h m o r e susceptible to insect attack t h a n t h e desi t y p e .

82 85

86 87

Figure 85. Chickpea plant, Cicer arietinum L.

Figure 86. Acid exudate drops on leaflets.

Figure 87. K a b u l i (light) and desi (dark) chickpea seeds.

83 88

Figure 88. Nodules containing rhizobia on chickpea roots.

Figure 89. Larvae of Metopina sp damaging nodules.

84 Pests Attacking Roots/Stems

Nodule-damaging Flies Metopina ciceri D i s n e y ( D i p t e r a : P h o r i d a e )

Distribution. Recorded only f r o m peninsular India.

S y m p t o m s . T h e r e are plenty of nodules c o n t a i n i n g rhizobia on c h i c k p e a roots (Fig. 88), w h i c h help fix nitrogen in the soil. At times small holes are seen in these nodules w h i c h w h e n cut open are f o u n d to be extensively t u n n e l e d with varying degrees of d e c o m p o s i t i o n .

D e s c r i p t i o n a n d b i o l o g y . The small white larvae (<1 mm long) and b r o w n pupae can be seen in the tunnels in t h e n o d u l e (Fig. 89). T h e tiny flies appear to be variable in their m o r p h o l o g y . Very little is k n o w n of their biology.

C o n t r o l . T h e c r o p loss resulting f r o m s u c h nodule d a m - age has not been quantified but specific c o n t r o l measures may not be r e q u i r e d . Soil insecticides may reduce the damage.

85 Sitona Weevils Sitona macularius ( M a r s h a m ) (Coleoptera: Curculionidae)

Distribution. This pest is c o m m o n in countries surround- ing the Mediterranean.

S y m p t o m s . The larvae feed mainly on roots and nodules of legumes, including chickpea. Heavy attacks lead to stunted, yellow plants. The adults feed upon leaves, cut- ting typical U-shaped notches f r o m the edge of the leaflets.

D e s c r i p t i o n a n d b i o l o g y . The brown and white adults (4 mm long) (Fig. 90) emerge in winter and lay eggs in the soil. The cream-colored larvae feed mainly on nodules. There is only one generation per year.

Control. This weevil prefers lentil and seldom, if ever, damages more than 5% of chickpea plants or nodules in any field. Consequently, the damage to chickpea does not merit specific control measures.

86 90

Figure 90. Sitona macularius.

87 91

Figure 91. Damage caused by Microtermes sp.

88 T e r m i t e s Odontotermes s p p Microtermes s p p (Isoptera: Termitidae)

Distribution. A l t h o u g h these termites are widespread, t h e y generally cause little d a m a g e to this crop but are i m p o r t a n t in s o m e locations and soil types.

S y m p t o m s . Plants attacked by Microtermes spp are w i l t e d or dead and have a small entrance hole at or below the g r o u n d level (Fig. 91). T h e roots a n d stem are t u n n e l e d and the termites are f o u n d inside. Odontotermes spp cover the stems w i t h earth sheeting under w h i c h they feed. Ter- mite attacks are often associated w i t h plants that have been w e a k e n e d by disease or d a m a g e d mechanically.

D e s c r i p t i o n a n d b i o l o g y . T h e white, b r o w n - h e a d e d , a n t - l i k e insects f o u n d in a n d a r o u n d the plants are the 'worker' adults. T h e y collect plant material and carry it to u n d e r g r o u n d c h a m b e r s w h e r e it is i n c o r p o r a t e d in 'fungus gardens', w h i c h provide f o o d for the termite larvae.

C o n t r o l . D a m a g e is rarely serious e n o u g h to merit specific c o n t r o l measures, but dressing the seed with aldrin has been f o u n d to reduce attacks in s o m e trials in northern India. Where termite m o u n d s obstruct cultivation and other o p e r a t i o n s s u c h as i r r i g a t i o n , nests can be killed by d r e n c h i n g w i t h insecticides, before or after levelling.

89 Soil Beetles Gonocephalum s p p (False wire worms) (Coleoptera: Tenebrionidae)

Distribution. Widespread in India and Africa.

S y m p t o m s . A t t a c k e d seedlings wilt or, s o m e times are cut at g r o u n d level. E x a m i n a t i o n s h o w s d a m a g e by feeding by the adult beetle, on t h e stem at or b e l o w g r o u n d level (Fig. 92). A search of the soil a r o u n d t h e plants reveals the insects.

D e s c r i p t i o n a n d b i o l o g y . T h e beetles, 10 mm in length, are black and flat. Very little is k n o w n of the b i o l o g y of these beetles.

C o n t r o l . A l t h o u g h seedlings are killed by this insect, there has not been a report of infestations that kill m o r e than a small p e r c e n t a g e of plants in t h e field. If a d e q u a t e seed rates are used, n e i g h b o r i n g plants usually c o m p e n - sate for the loss of seedlings and no specific c o n t r o l measures are required.

90 92

Figure 92. Gonocephalum sp adult damaging a seedling.

91 93

Figure 93. Seedling damaged by cutworm.

Figure 94. Agrotis ipsilon moth.

Figure 95. Cutworm larva.

92 C u t w o r m s Agrotis ipsilon (Hufnagel) Agrotis s p p ( L e p i d o p t e r a : N o c t u i d a e )

Distribution. Agrotis ipsilon is widespread and p o l y p h a - g o u s t h r o u g h o u t the tropics a n d subtropics. Other species of Agrotis are of localized i m p o r t a n c e .

S y m p t o m s . Seedlings are cut t h r o u g h at or below g r o u n d level (Fig. 93). A search in the soil a r o u n d such seedlings will reveal the larvae.

D e s c r i p t i o n a n d b i o l o g y . T h e large m o t h s (25 m m long) of A. ipsilon have b r o w n f o r e w i n g s and pearly h i n d - w i n g s w i t h a b r o w n m a r g i n (Fig. 94). The c r e a m - c o l o r e d eggs are laid singly on the plants or soil surface. Larvae feed on t h e foliage. T h e large larvae, 45 mm long, w h i c h are g r e y - b l a c k (Fig. 95), hide beneath the soil surface d u r i n g t h e day and feed at night. Pupation takes place in the soil. O n e generation can be c o m p l e t e d in 6 weeks.

C o n t r o l . A l t h o u g h c u t w o r m s are not o f w i d e s p r e a d i m p o r t a n c e as pests of c h i c k p e a , they can be very damaging in s o m e localities, k i ll i n g m o r e t h a n 3 0 % of t h e seedlings in s o m e fields. Sprays of e n d o s u l f a n , heptachlor, or aldrin have been reported to give adequate c o n t r o l , and p o i s o n e d bran baits have also been r e c o m m e n d e d for use in e n d e m i c areas. However, p o p u l a t i o n s of these insects are usually heavily parasitized and so c o n t r o l is seldom needed. W h e n d a m a g e is n o t i c e d it is usually t o o late to use insecticides e c o n o m i c a l l y .

93 Pests of Foliage and Pods

Aphids Aphis craccivora ( K o c h ) Acyrthosiphon pisum ( H a r r i s ) (Hemiptera: Aphididae)

Distribution. Both these species are w i d e l y distributed and f o u n d on a wide range of legumes in all regions where chickpeas are cultivated.

S y m p t o m s . The aphids feed on stems, leaflets (Fig. 96), and pods (Fig. 97). The plants wilt w h e n large colonies build up on t h e m . However, stunt disease causes the most damage in chickpea (Fig. 98). This is caused by bean leaf-roll virus w h i c h is transmitted by these aphids. Stunt disease limits plant g r o w t h , and leaflets are small and reddish b r o w n (yellow in kabuli types). Scraping the lower part of the stem reveals brown phloem w h i ch is characteristic of this disease.

D e s c r i p t i o n a n d b i o l o g y . Aphis craccivora (1.6 mm long) is a black shiny a p h i d while A. pisum (2 mm long) is grey-green. Winged parthenogenetic females are carried by the w i n d . Many that land on chickpea may be deterred and fly off or be killed by the acid exudate. Plants with colonies have little or no exudate. It is not k n o w n whether this is because the aphids feed on the exudate or whether colonies develop on plants that p r o d u c e little exudate. The nymphs resemble the adults and one generation can be completed in less than 2 weeks.

C o n t r o l . A p h i d s are seldom n u m e r o u s e n o u g h on chickpea to merit control measures but stunt disease causes substantial losses in s o m e years in some areas. Several chickpea genotypes are k n o w n to be resistant to this disease so the best means of c o m b a t i n g it is by the use of resistant cultivars.

Figure 96. Aphis craccivora on leaves.

Figure 97. A. craccivora on pods.

Figure 98. Symptoms of stunt disease.

94 96

95 L e a f m i n e r s Liriomyza cicerina ( R o n d a n i ) Chromatomyia horticola ( G o u r e a u ) (Diptera: Agromyzidae)

Distribution. Liriomyza cicerina is common and causes d a m a g e in t h e c h i c k p e a - g r o w i n g areas s u r r o u n d i n g the Mediterranean. However, recent w o r k has s h o w n that many of the leaf mines o c c u r r i n g early in t h e season in these areas are caused by an unidentified species of Agromyza. Liriomyza sp has been reported to cause d a m - age in Mexico. In India, leaf mines are occasionally seen on c h i c k p e a leaflets but these are reported to be caused by C. horticola.

Figure 99. Damage caused by Liriomyza cicerina. 99

96 S y m p t o m s . The pale, serpentine mines in w h i c h t h e larvae f e e d c a n be clearly seen on t h e u p p e r s u r f a c e of the leaflets (Fig. 99). Heavy attacks lead to defoliation.

D e s c r i p t i o n a n d b i o l o g y . T h e adult flies (1.5 mm long) w h i c h are black and yellow, p u n c t u r e the upper surface of t h e leaflets w i t h their ovipositor and feed on the plant juices. This results in a stippled pattern on s o m e leaflets. S m a l l , w h i t e eggs are laid in s o m e of these punctures. T h e e g g hatches within 4 days and the yellow, maggot-like larvae t u n n e l s t h r o u g h t h e p a r e n c h y m a , f o r m i n g a mine. T h e larva reaches full size (3 mm long) in about a week and pupates either in the leaf or, m o r e c o m m o n l y , in the soil. T h e life cycle is c o m p l e t e d in a b o u t 3 weeks. It is sus- pected that the p u p a e survive the s u m m e r and winter in diapause.

C o n t r o l . Heavy attacks by leaf miners can cause substantial defoliation and yield loss so c o n t r o l measures may be required in s o m e areas. L o w dosages of m o n o c r o t o p h o s (0.025 kg a.i. ha-1) have been f o u n d to give g o o d c o n t r o l and s h o u l d be applied d u r i n g the vegetative stage to prevent b u i l d u p of infestations. Late-sown crops suffer most d a m a g e , so early s o w i n g helps reduce losses. Deep plow- ing to reduce e m e r g e n c e f r o m puparia has been sug- gested as a c o n t r o l measure. In s o m e areas, parasites give adequate c o n t r o l of the leafminers, e.g., heavy parasitism of the first generation larvae has been reported f r o m Spain. Differences in susceptibility to d a m a g e a m o n g genotypes has been reported, so screening and breeding for plant resistance may be profitable.

97 A r m y w o r m Spodoptera exigua ( H i i b n e r ) (Lepidoptera: Noctuidae)

Distribution. Spodoptera exigua is a widely distributed p o l y p h a g o u s pest t h r o u g h o u t most of the tropics and s u b - tropics, but it is not reported f r o m South America.

S y m p t o m s . The green larvae feed mainly u p o n leaflets and occasionally on pods. Heavy infestations can defoliate plants.

D e s c r i p t i o n a n d b i o l o g y . The m o t h s (13 m m ) have g r e y i s h - b r o w n forewings and opalescent h i n d w i n g s with a dark edge (Fig. 100). Pinkish-white, oval eggs (0.5 mm long) are laid in c l u m p s (of up to 150 eggs in each c l u m p ) on leaves of m a n y plants, but rarely on c h i c k p e a . T h e larvae w h i c h feed on c h i c k p e a are generally f o u n d to have dispersed f r o m egg masses laid on the weeds nearby. The green larvae h a t c h after t w o o r m o r e d a y s a n d disperse (Fig. 101). They generally hide d u r i n g the day but feed actively at night. The fully g r o w n larva (25 mm long) buries itself in the soil w h e r e it pupates. O n e g e n e r a t i o n can be c o m p l e t e d in less than 4 weeks under ideal conditions. W h e n large populations of larvae are present in an area, they crawl across fields and destroy most green plants in their path.

C o n t r o l . A l t h o u g h these larvae are c o m m o n o n c h i c k p e a in m a n y parts of Asia, they seldom reach p o p u l a t i o n s large e n o u g h to cause substantial d a m a g e and yield loss. This may be because they have a w i d e range of natural enemies. They are reported to be a major pest of chickpea in Mexico and have b e c o m e resistant to several insecticides in that c o u n t r y . S y n t h e t i c p y r e t h r o i d s may be most effective in c o n t r o l l i n g these insects.

98 100

101

Figure 100. Spodoptera exigua moths.

Figure 101. S. exigua larvae.

99 Figure 102. Species of Helicoverpa and Heliothis moths recorded from chickpea.

100 Pod Borers Helicoverpa (Heliothis) armigera ( H u b n e r ) Helicoverpa zea ( B o d d i e ) Helicoverpa punctigera (Wallengren) Helicoverpa assulta ( G u e n e e ) (Lepidoptera: Noctuidae) Heliothis virescens (Fabricius) Heliothis viriplaca (Hufnagel) Heliothis peltigera (Denis & Schiffermuller)

Distribution. Helicoverpa armigera is p o l y p h a g o u s and is w i d e l y d i s t r i b u t e d in t h e t r o p i c s a n d s u b t r o p i c s , but in the A m e r i c a s , H. zea and Heliothis virescens are f o u n d . In A u s t r a l i a , b o t h H. armigera a n d H. punctigera attack c h i c k p e a . In West Asia, H. viriplaca a n d H. peltigera (Fig. 102) are also f o u n d on the c r o p ; H. assulta is occasionally reported f r o m c h i c k p e a in India.

S y m p t o m s . T h e larvae feed on all green parts a n d defoliate y o u n g c r o p s in s o u t h e r n India (Fig. 103). Most d a m a g e is c a u s e d to the p o d s in w h i c h the large larvae cut r o u n d holes in t h e p o d wall a n d d e v o u r the seed inside (Fig. 104).

D e s c r i p t i o n a n d b i o l o g y . H. armigera is a large b r o w n m o t h (20 mm long) w h i c h is active at night. It lays eggs, usually singly, mostly on the u n d e r s i d e s of leaflets (Fig. 105). Y o u n g larvae feed by s c r a p i n g the surface of leaflets a n d t h e older larvae c h e w into leaflets, b u d s , flowers, and pods. T h e f u l l y g r o w n larva (40 mm long) may be of several s h a d e s of y e l l o w , p i n k , r e d , b r o w n , or black, but most of t h o s e f o u n d on c h i c k p e a are g r e e n . All larvae have characteristic a n d distinct light a n d dark b a n d s a l o n g their sides. T h e fully g r o w n larvae b u r y t h e m s e l v e s in the soil or a m o n g plant debris to p u p a t e . O n e g e n e r a t i o n can be

Continued

101 c o m p l e t e d in as little as 4 weeks u n d e r o p t i m u m c o n d i - tions. Other species have similar life histories.

C o n t r o l . S o m e chickpea g e n o t y p e s have considerable resistance to Helicoverpa spp and it is hoped that resistant cultivars will soon b e c o m e available to farmers. Several insecticides, including endosulfan and synthetic pyrethroids give g o o d c o n t r o l , particularly if a p p l i e d w h e n the larvae are small. However, considerable resistance to several insecticides has been r e p o r t e d in t h i s species in areas where intensive insecticide use is c o m m o n . As these pests have m a n y natural enemies, pesticide use may lead to an increase in Helicoverpa and Heliothis populations t h r o u g h a reduction of the natural enemies. Insecticides should be used o n l y o n w e l l - g r o w n c r o p s and o n l y w h e n the p o p u l a - tions of larvae reach the ' e c o n o m i c threshold'. At I C R I - SAT, insecticide use appears to be profitable on g o o d c r o p s w h e n t w o or m o r e small larvae are f o u n d per plant. Insecticide dusts can be conveniently used on this c r o p , because the dust adheres to the exudate-covered plants.

Figure 103. Helicoverpa armigera feeding on leaves.

Figure 104. Pod damage caused by H. armigera.

Figure 105. H. armigera eggs.

102 103

104

105

103 106

Figure 106. Semilooper damage to pods.

104 S e m i l o o p e r Autographs nigrisigna ( W a l k e r ) ( L e p i d o p t e r a : N o c t u i d a e )

Distribution. Several s e m i l o o p e r s have been reported to f e e d on c h i c k p e a , b u t t h e m o s t i m p o r t a n t appears to be A. nigrisigna w h i c h is of s o m e i m p o r t a n c e in n o r t h e r n India, particularly o n Kabuli type c h i c k p e a .

S y m p t o m s . T h e larvae feed u p o n leaflets and pods. W h e n p o d s are a t t a c k ed , m u c h of t h e p o d wall is eaten (Fig. 106). T h i s is in contrast with the neat, r o u n d hole, characteristic of Helicoverpa d a m a g e .

Description and biology. T h e large, typically patterned m o t h s lay t h e i r e g g s i n c l u m p s (of 4 0 e g g s o r m o r e i n e a c h c l u m p ) on the leaflets. T h e larvae, w h i c h are green semi- l o o p e r s , feed u p o n leaflets a n d on pods, r e a c h i n g a length of 15 m m . Pupation takes place in the soil.

C o n t r o l . M a n a g e m e n t of t h i s pest is not very different f r o m that of H. armigera, for t h e t w o species tend to o c c u r in m i x e d p o p u l a t i o n s . E n d o s u l f a n has been reported to give adequate c o n t r o l .

105 Pests of Stored Seeds

Bruchids Callosobruchus analis (Fabricius) Callosobruchus chinensis (L.) Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)

Distribution. These pests are widespread, a n d are f o u n d in the stored seeds of several legumes, including chickpea, in most areas of t h e tropics and subtropics.

S y m p t o m s . Bruchids are seldom f o u n d in chickpea pods in the fields, but they may infest t h e p o d s if they are left on the plants for several weeks after maturity. The white eggs are seen on the pods and the pod wall has a neat circular hole f r o m w h e r e the adult w o u l d have e m e r g e d . These bruchids are very c o m m o n in stored seed, w h e r e the eggs a n d the cylindrical e m e r g e n c e holes are o b v i o u s s y m p - toms of infestation (Fig. 107).

Description and biology. T h e identification o f these b r u c h i d s to the species level needs m u c h expertise. Adults are small (3.0 mm long) b r o w n beetles w h i c h lay their eggs on t h e seed surface (and rarely on m a t u r e pods in t h e field). The y o u n g larva hatches t h r o u g h the base of the egg and bores straight t h r o u g h the seed coat. T h e hatched eggs, therefore, seem to be intact. The white larva develops and pupates inside the seed. Populations build up q u i c k l y in stored seed because one g e n e r a t i o n is c o m - pleted in 4-5 weeks and because each female lays more than 100 eggs.

C o n t r o l . Stored seed can be protected f r o m b r u c h i d s by keeping clean seed in pest-proof containers. Fortunately, c h i c k p e a g r o w i n g in t h e field is rarely a t t ac k e d , so freshly harvested grain is usually free f r o m b r u c h i d s . S u n d r y i n g before placing the grain in a clean store s h o u l d ensure that storage losses are minimal. It is possible to protect seed chemically, either by f u m i g a t i o n or by the a d m i x t u r e of insecticides, including malathion. Where small quantities of seed are to be used for s o w i n g , as on research stations, m o t h balls (naphthalene) can be mixed with the seed to

106 prevent infestation. Another method of protecting seeds is to coat t h e m with small quantities of vegetable oil or mix neem (Azadirachta indica) leaves or seeds in the stored grain. Some chickpea seeds are more susceptible to b r u - chid attack than others, kabuli types being particularly susceptible. In general, smaller seeds with rough seed coats are less susceptible, but as these characteristics are undesirable from the consumer viewpoint, breeding appears to offer little scope, except where the seeds are used as animal feed or c o n s u m e d after removing the seed coat.

Figure 107. Callosobruchus sp damage in stored seeds. 107

107 108 109

110

Figure 108. Bird (parakeet)-damaged pigeonpea pod.

Figure 109. Bird (parakeet)-damaged chickpea pod.

Figure 110. Sown pigeonpea seed damaged by rats.

108 O t h e r Animal Pests of Pigeonpea a n d C h i c k p e a

Birds

Several species of birds attack both pigeonpea and chickpea, s o m e at s o w i n g a n d in t h e seedling stage, and others at the m a t u r e pod stage. In Syria, it has been reported that c h i c k p e a plants are d a m a g e d by birds pecking out the s o w n seed and the y o u n g seedlings. In many areas in India, parakeets particularly cause substantial damage to pods of both p i g e o n p e a a n d c h i c k p e a (Figs. 108 and 109).

C o n t r o l . Scaring away birds f r o m fields at the seedling a n d maturity stages will reduce losses. However, several birds are insectivorous and are k n o w n to be important predators of Helicoverpa on chickpea, so bird-scaring will be c o u n t e r p r o d u c t i v e d u r i n g t h e green p o d stage w h e n Helicoverpa infestations are present.

Rodents

Rats and other rodents d a m a g e c h i c k p e a s and p i g e o n - peas, b o t h in t h e field a n d in the stores. Seeds are d u g up and eaten by rats s o o n after s o w i n g (Fig. 110). Green c h i c k p e a p o d s are taken f r o m plants to the rats' burrows, the o p e n i n g s of w h i c h are often s u r r o u n d e d by discarded p o d husks. Rodents also eat stored seeds, so rat proof s t o r a g e is needed if t h e grain is to be stored for a considerable d u r a t i o n . F u m i g a t i o n of rat b u r r o w s using zinc p h o s - phide or other chemicals, and the use of baits c o n t a i n i n g rodenticides help reduce rat populations. However, care must be taken to ensure that other mammals, including m a n , are not harmed.

109 Beneficial Insects

Pollinators

Many insects i n c l u d i n g H y m e n o p t e r a , Diptera, a n d L e p i - doptera visit p i g e o n p e a flowers to feed on nectar and pollen (Figs. 111 and 112). Several of these carry pollen on their bodies and are likely to be involved in cross pollina- t i o n . The major pollinators are bees; b o t h t h e social (Apis spp) and solitary bees (e.g., Megachile spp, Fig. 31). In c h i c k p e a , relatively f e w insects visit t h e f l o w e r s a n d there is very little cross p o l l i n a t i o n .

Figure 111. Apis dorsata pollinating pigeonpea.

Figure 112. X y l o c o p a sp pollinating pigeonpea.

110 111

112

111 113a 113b

114 115

116 117

112 Natural Enemies

M a n y insect a n d a n i m a l species feed u p o n the insect pests o n p i g e o n p e a , a n d there are substantial n u m b e r s o n c h i c k p e a also. Insects a n d o t h e r a n i m a l s that c a t c h a n d eat these pests partly or w h o l l y are k n o w n as p r e d a t o r s . A n i m a l s that feed a n d d e v e l o p on or in t h e b o d i e s of other insects are k n o w n as parasites a n d t h o s e that kill their hosts are referred to as parasitoids. T h e s e natural e n e m i e s can be so a b u n d a n t that t h e p o p u l a t i o n s of insect pests are r e d u c e d to levels that c a u s e little c r o p d a m a g e . In s u c h cases, insecticides need not be applied. It is not possible to illustrate all t h e natural enemies of these pests in a small p u b l i c a t i o n like this, so a f e w repre- sentative e x a m p l e s have been g i v e n . It is essential t h a t a n y o n e a t t e m p t i n g t o c o n d u c t research o n pest m a n a g e - m e n t or a n y o n e involved in e x t e n s i o n activities s h o u l d be able to d i s t i n g u i s h b e t w e e n pests and the beneficial insects f o u n d on these c r o p s . A c o m p r e h e n s i v e r e c o r d of different parasites a n d p r e d a t o r s of these pests will be p u b l i s h e d in t h e near f u t u r e .

Predators

M a n y p r e d a t o r s (Figs. 113-122) feed on insect pests that attack p i g e o n p e a a n d c h i c k p e a . For e x a m p l e , o n I C R I S A T f a r m we o b s e r v e d m o r e t h a n 20 species of insects that prey on H. armigera eggs a n d larvae. In a d d i t i o n to the preda- t o r y insects, several species of spiders, lizards, and birds have been observed to feed on H. armigera larvae.

Figure 113a. Ootheca, an egg case, of praying mantis.

Figure 113b. A praying mantis predator on pigeonpea.

Figure 114. Robber fly, a Helicoverpa predator.

Figure 115. Dragon fly, a Helicoverpa predator.

Figure 116. A spider predator on pigeonpea.

Figure 117. The king crow or drongo, a Helicoverpa predator.

113 118 119

120a 120b

Figure 118. Chrysopa sp., a predator on pigeonpea.

Figure 119. A reduviid feeding on Helicoverpa larva.

Figure 120. Cheilomenes sexmaculatus, an aphid predator; (a) grub and (b) adult.

114 Figure 121. A mud wasp carrying a Helicoverpa larva.

Figure 122. A mud wasp's nest packed with Helicoverpa larvae.

115 Parasitoids

Several parasitoids have been r e c o r d e d f r o m a m o n g the p i g e o n p e a a n d c h i c k p e a pests. F o r e x a m p l e , m o r e t h a n 2 5 species of insects have been r e c o r d e d as being parasitic on H. armigera in s o u t h c e n t r a l India. All these are h y m e - nopteran and d i p t e r a n ; s o m e e x a m p l e s are illustrated here (Figs. 123-125). Nematodes also parasitize H. armigera larvae, especially d u r i n g the rainy season. T h e s e n e m a t o d e s , Ovomermis albicans (Fig. 126) g r o w to 10 cm or m o r e . T h e y coil up inside H. armigera larvae, a n d kill t h e m before p u p a t i o n by c o n s u m i n g a n d d i s r u p t i n g the internal o r g a n s of the host.

Figure 123. Life stages of Eucelatoria bryani, a Helicoverpa parasite.

Figure 124. Pupae of A p a n t e l e s (wasp) parasite on pigeonpea.

Figure 125. Pupa of Compoletis chlorideae parasite, a major enemy of Helicoverpa.

Figure 126. O v o m e r m i s a l b i c a n s , a nematode parasite on Helicoverpa larvae.

116 123

124 125

126

117 127a 127b

128

Figure 127a. H. armigera larva infected by nuclear poly- hedrosis virus on pigeonpea.

Figure 127b. H. armigera cadaver full of brown liquid containing virus particles.

Figure 128. H. armigera larva killed by nuclear polyhedro- sis virus on chickpea.

118 Insect Diseases

There are several disease-causing organisms including f u n g i , bacteria, a n d viruses, that infect a n d kill insects. H o w e v e r , s u c h diseases are beneficial w h e n t h e y infect t h e insect pests. An e x a m p l e of a beneficial viral disease that causes c o n s i d e r a b l e mortality to a m a j o r pest is the N u c l e a r P o l y h e d r o s i s Virus (NPV) that infects H. armigera. T h i s v i r u s a p p e a r s t o b e fairly c o m m o n a n d w i d e s p r e a d , for i t has been r e p o r t e d to infect this pest in A f r i c a , Asia, a n d Australasia. Infected larvae become sluggish, stop fee d i n g , a n d e v e n t u a l l y die. T h e i n f e c t e d larvae are often f o u n d h a n g i n g head d o w n w a r d f r o m t w i g s (Figs. 127a, b, a n d 128). T h e cadavers are full of b r o w n liquid w h i c h c o n t a i n s t h e v i r u s p a r t i c l e s (Fig. 127b). If s u c h d e a d larvae are c r u s h e d a n d m i x e d w i t h water, t h e m i x t u r e can be used as a c h e a p i n s e c t i c i d e . T h i s infects larvae that feed u p o n f o l i a g e or p o d s c o n t a m i n a t e d by t h e virus particles and t h u s c o n t r o l s t h e pest. H o w e v e r , infected larvae take a w e e k o r m o r e t o die a n d can c a u s e substantial d a m a g e d u r i n g that p e r i o d . A l s o , t h e v i r u s is inactivated by s u n - light, so s u c h s p r a y s are not persistent unless m i x e d w i t h s o m e stabilizers.

119 Notes

120