A Groundnut Insect Identification Handbook for India. Information Bulletin No

Abstract

Citation: Wightman, J.A. and Ranga Rao, G.V. 1993. A Groundnut Insect Identification Handbook for India. Information Bulletin no. 39. (In En. Summaries in En, Fr.) Patancheru, A.P. 502 324, India: Interna- tional Crops Research Institute for the Semi-Arid Tropics. 64 pp. ISBN 92-9066-275-1. Order code IBE 039.

Groundnut or peanut (Arachis hypogaea L.) is an important oilseed crop in India. It is attacked by many insects throughout the country at different stages of plant growth, but only a few of the over 100 insects associated with this crop are economically important. This bulletin pro- vides short descriptions of the most important species, their biology, distribution, and damage symptoms. Color photographs are provided for easy identification of the pests, and appropriate control measures are suggested.

Cover: Red hairy caterpillar (Amsacta albistriga) on a groundnut leaf. A Groundnut Insect Identification Handbook for India

J.A. Wightman and G.V. Ranga Rao

ICRISAT Information Bulletin no. 39 International Crops Research Institute for the Semi-Arid Tropics Patancheru, Andhra Pradesh 502 324, India 1993 Copyright© 1993 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).

All rights reserved. Except for quotations of short passages for the purpose of criticism and review, no part of this publication may be reproduced, stored in retrieval systems, or transmitted in any form or by any means, electronic, mechanical, photo- copying, recording, or otherwise, without prior permission from ICRISAT. The Institute does not require payment for the non- commercial use of its published works, and hopes that this Copyright declaration will not diminish the bona fide use of its research findings in agricultural research and development.

The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of ICRISAT concerning the legal status of any country, territory, city, or area, or concerning the delimitation of its frontiers or boundaries. Where trade names are used, this does not constitute endorsement of or discrimination against any product by the Institute.

Sponsored by

National Dairy Development Board Anand 388 001, India Contents

Authors' note 1

Preface 2

Introduction 3

Defoliators Tobacco caterpillar/armyworm 6 Hairy caterpillars 10 Bihar hairy caterpillar 12 G r a m p o d borer 14 G r o u n d n u t leaf miner 18 G r o u n d n u t b u d borer 22 Tussock caterpillars 2 4 Gray weevils 2 6

S u c k i n g pests A p h i d s 2 8 Thrips 3 2 Jassids 3 6

R o o t a n d p o d feeders W h i t e g r u b s 3 8 Termites 4 2 Jewel beetle 4 4 Earwig 4 6 W i r e w o r m s a n d false w i r e w o r m s 4 8 Subterranean ants 5 0

S t o r a g e p e s t s G r o u n d n u t bruchid 5 2 R e d flour beetle a n d rice m o t h 5 4 Pod-sucking b u g 5 6

Authors' Note

This h a n d b o o k has b e e n published to help agricultural scientists, extension workers, a n d students identify t h e common insect pests of groundnut. A number of insects f o u n d on this crop are not pests; m a n y a r e even beneficial, b e c a u s e they feed on pest s p e c i e s . Illustrations of a f e w of t h e s e beneficial insects a r e i n c l u d e d , to em- p h a s i z e that it is important to d e t e r m i n e t h e role of insects f o u n d on crops rather t h a n to a s s u m e that all insects a r e harmful a n d so must be eliminated! Brief descriptions of the distribution a n d biology of the pests a r e g i v e n , together with suggestions for control m e a - sures, where appropriate. Chemical control should be u s e d only w h e r e essential, a n d preferably with the ad- vice of a plant protection specialist. It is not e a sy to identify insects, particularly from photographs. Reade r s are therefore r e c o m m e n d e d to collect a n d preserve insects f o u n d on their c r o p s , to seek help f r o m professio- nal entomologists to identify t h e m , a n d to maintain specimen collections for future reference.

ICRISAT scientists w o u l d like to receive f e e d b a c k on t h e impact of the r e c o m m e n d a t i o n s m a d e in this bulletin, particularly as insect r e s p o n s e to control m e a s u r e s is likely to vary in different varieties, envi- ronments, a n d farming systems.

1 P r e f a c e

In India, insect pests are often thought to be a major constraint to g r o u n d n u t p r o d u c t i o n . In t h e past, g r o u n d - nut w a s g r o w n m a i n l y a s a s e c o n d a r y c r o p i n s u b s i s - tence farming conditions, but in recent years t h e crop has g a i n e d i m p o r t a n c e d u e to t h e s h o r t a g e of edible oil in t h e country. F a r m e r s c o n s i d e r g r o u n d n u t to be a risky crop b e c a u s e of its n e e d for high inputs a n d its p e s t a n d d i s e a s e p r o b l e m s — g r o u n d n u t c r o p s a r e at- t a c k e d by several insect s p e c i e s at different s t a g e s of crop g r o w t h . Identification of a pest, a n d sufficient information on its biology, t h e extent of the d a m a g e it c a u s e s , a n d feasible control o p t i o n s are prerequisites to initiate a n y p e s t m a n a g e m e n t strategy. Information o n t h e s e p a r a m e t e r s is therefore d i s c u s s e d in this bulletin. T h i s information, supported by color photographs, will help scientists, students, a n d e x t e n s i o n workers identify t h e k e y insect pests of g r o u n d n u t . It is important to note that most g r o u n d n u t pests a r e of localized i m p o r t a n c e , often to e p i d e m i c proportions. It is a b u n d a n t l y clear that m o s t pest o u t b r e a k s a r e i n d u c e d b y poor m a n a g e - ment—excessive application of insecticides, ineffec- tive c r o p rotations, etc. ' C l o s e ' monitoring a n d early recognition of potential pest species will be very useful i n future p e s t m a n a g e m e n t p r o g r a m s .

2 Introduction

G r o u n d n u t (Arachis hypogaea L., Fig. 1) is a major oil- s e e d crop in India, o c c u p y i n g 8.6 million h a , of w h i c h 8 5 % i s rainfed a n d 1 5 % irrigated. T h e c r o p i s cultivated in 4 5 % of India's total oilseed area a n d a c c o u n t s for 5 5 % of the oilseeds p r o d u c e d in the country. G r o u n d - nut s e e d s contain approximately 5 0 % edible oil a n d 2 5 % protein. T h e h a u l m s r e m a i n i n g after p o d removal are u s e d as valuable, nutritious fodder. G r o u n d n u t oil- c a k e is an important cattle f e e d a n d a g o o d soil a m e n d - m e n t . A l t h o u g h India ranks first in area a n d production (7.2 million t) in the w o r l d , average yields a r e low (1 t ha- 1 in t h e rainy s e a s o n a n d 2 t h a- 1 in t h e postrainy s e a s o n ) . T h e low yields in the rainy s e a s o n a r e a s s o c i - ated with the low levels of inputs characteristic of rainfed agriculture in t h e tropics. Groundnut, being a leguminous plant, enriches the soil with nitrogen a n d is therefore valuable in crop rotations a n d soil improvement. It is often intercropped with a wide range of short-duration crops such as sorghum a n d millets (Fig. 2). Over 1 2 % of the groundnut produced in India is utilized as s e e d , 6% for domestic c o n s u m p t i o n , a n d 8 1 % for oil extraction; only 1 % i s exported. Most groundnut insect pests are sporadic in occur- rence a n d distribution. I n g e n e r a l , insects c a u s e 1 0 - 2 0 % crop loss. However, there a r e instances of total crop loss c a u s e d by a single pest s p e c i e s . A l t h o u g h m a n y insect s p e c i e s live a n d feed on t h e g r o u n d n u t crop, only a few c a u s e significant d a m a g e that results in large reductions in p o d a n d h a u l m yields. Although there is w i d e variation b e t w e e n g e n o t y p e s , groundnut plants have considerable natural resistance to insects. This resistance is d u e to t h e production of anti-insect c h e m i c a l s in t h e leaves a n d p o d s , t h e pres- e n c e of long a n d / o r d e n s e hairs on the leaves, a n d t h e ability of established c r o p s to recover from t h e removal of m o r e than half their leaf material with minimal reduc- tion in p o d yield.

3 T h e m a i n p e s t s o f g r o u n d n u t c a n b e m o r e o r less s p e c i f i c t o t h i s c r o p e.g., a p h i d a n d t h e g r o u n d n u t leaf m i n e r , or g e n e r a l f e e d e r s that a t t a c k a w i d e r a n g e of c r o p s e . g . , t o b a c c o caterpillar ( a r m y w o r m ) a n d t h e o t h e r d e f o l i a t o r s , w h i t e g r u b s , a n d t e r m i t e s . On t h e b a s i s of c u r r e n t l y a v a i l a b l e i n f o r m a t i o n , it is u n w i s e t o rate s u c h i n s e c t s a s t h e a s h w e e v i l a n d n o n - viruliferous t h r i p s a s b e i n g e c o n o m i c a l l y i m p o r t a n t . D a t a o n yield l o s s c a u s e d b y j a s s i d s (leaf h o p p e r s ) a r e not a l w a y s c o n v i n c i n g , a l t h o u g h t h e s e little i n s e c t s c a n u n d o u b t e d l y r e d u c e p r o d u c t i v i t y w h e n t h e y a r e p r e s e n t i n large n u m b e r s . V i r u s v e c t o r s a n d soil i n s e c t s p o s e different a n d difficult p r o b l e m s . T h e f o r m e r c a n c a u s e significant losses in yield if a virus-carrying populat i o n i n v a d e s a f i e l d , e v e n at low d e n s i t i e s . Soil i n s e c t s c a n a l s o c a u s e c o n s i d e r a b l e d a m a g e a t low p o p u l a t i o n d e n s i t i e s , a n d i n a d d i t i o n a r e difficult t o d e t e c t b e f o r e t h e d a m a g e o c c u r s .

In this b u l l e t i n , defoliators (all but o n e of t h e m caterpillars), s u c k i n g i n s e c t s (including virus v e c t o r s ) , soil i n s e c t s , a n d s t o r a g e i n s e c t s a r e d i s c u s s e d u n d e r s e p a - rate h e a d i n g s .

F i g u r e 1 . A h e a l t h y g r o u n d n u t c r o p . Figure 2. Groundnut intercropped with pearl millet.

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5 Defoliators

M a n y s p e c i e s o f leaf-eating caterpillars a r e f o u n d o n groundnut plants, but few are of economic importance. M o s t defoliators a r e p o l y p h a g o u s a n d s p o r a d i c in oc- c u r r e n c e . It is evident from past e x p e r i e n c e that groundnut crops can tolerate considerable defoliation. Natural control p r o c e s s e s usually k e e p defoliators at d e n s i t i e s well b e l o w their e c o n o m i c t h r e s h o l d levels. However, the indiscriminate use of insecticides can c a u s e pest o u t b r e a k s that have t h e potential to inflict total crop loss.

Tobacco caterpillar/tobacco armyworm

Spodoptera litura (Fab.)

(Lepidoptera: Noctuidae)

G r o u n d n u t fields in parts of K a r n a t a k a a n d t h e c o a s t a l a r e a s of A n d h r a P r a d e s h a n d Tamil N a d u a r e often a t t a c k e d b y this p e s t i n t h e postrainy s e a s o n . T h e adults are light b r o w n m o t h s with a w i n g s p a n of about 3 0 m m , a n d mottled forewings (Fig. 3 ) . E g g s a r e laid in clusters of several h u n d r e d s , usually on t h e up- per s u r f a c e o f leaves. T h e s e e g g m a s s e s , w h i c h m e a - s u r e a b o u t 4 x 7 m m , a p p e a r g o l d e n b r o w n b e c a u s e they are c o v e r e d with t h e b o d y s c a l e s of the female (Fig. 4 ) . T h e e g g s t a k e 2 - 3 d a y s t o h a t c h ; t h e larvae d i s p e r s e quickly f r o m t h e e g g b a t c h . Y o u n g larvae are light g r e e n . T h e later instars a r e d a r k g r e e n to b r o w n on their b a c k s , lighter u n d e r n e a t h , a n d h a v e p r o m i n e n t b l a c k spots on t h e thorax. T h e r e a r e often thin, light- c o l o r e d lines a l o n g t h e b o d y ( F i g . 5). L a r v a e c a n b e

Figure 3. Spodoptera litura adult. Figure 4. S. litura egg masses. Figure 5. S. litura larva.

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7 5 0 m m long before they p u p a t e . T h e p u p a e a r e reddish b r o w n a n d a r e f o u n d i n t h e soil c l o s e t o t h e plants. T h e p r e s e n c e of newly h a t c h e d larvae c a n be de- t e c t e d b y t h e 'scratch' m a r k s they m a k e o n t h e leaf surface (Fig. 6). T h e older larvae are night-feeders a n d a r e usually f o u n d in t h e soil a r o u n d t h e b a s e of plants d u r i n g the d a y . T h e y c h e w large a r e a s of t h e leaf, a n d c a n , at high population densities, strip a crop of its leaves (Fig. 7a,b). In s u c h c a s e s , larvae migrate in large g r o u p s from o n e field to another in search of f o o d . In a r e a s w h e r e g r o u n d n u t is g r o w n on light soils t h e caterpillars have b e e n s e e n boring into the p o d s (Fig. 8). In A n d h r a P r a d e s h , t h e insect has 12 generations a y e a r , e a c h lasting slightly m o r e t h a n a m o n t h in winter a n d less t h a n a m o n t h in t h e hot s e a s o n . In A n d h r a P r a d e s h this pest w a s o n c e limited to t o b a c c o crops, but o u t b r e a k s a r e now s p r e a d i n g . It is p r e s u m e d to have a d a p t e d to g r o u n d n u t as a result of t h e c o n t i n u o u s (relay) c r o p p i n g that b e c a m e possible following t h e development of irrigation schemes.

F i g u r e 6 . D a m a g e c a u s e d b y y o u n g S . litura l a r v a e . Figure 7a,b. Damage caused by later instar S. litura larvae. F i g u r e 8 . P o d s d a m a g e d b y S . litura l a r v a e .

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7a 7b

9 Hairy caterpillars

Amsacta albistriga Walk.

Amsacta moori Butler

(Lepidoptera: Arctiidae)

Several s p e c i e s of hairy caterpillars attack g r o u n d n u t . T w o important o n e s are t h e red hairy caterpillars: Am- sacta albistriga, f o u n d in s o u t h e r n India, a n d A. moori in t h e northern states. Both c a n be devastating, but a r e highly sporadic. A b o u t a d e c a d e a g o they w e r e c o n s i d - ered to be t h e key pests of groundnut, but their status h a s n o w c h a n g e d to t h e extent that they a r e unpredic- tably important in isolated pockets. B o t h s p e c i e s h a v e o n e generation a year. T h e adults e m e r g e f r o m the soil at the onset of t h e south- w e s t m o n s o o n (usually in J u n e ) . T h e y are b r o w n i s h - w h i t e m o t h s with a 4 0 - 5 0 m m w i n g s p a n (Fig. 9). T h e forewings a r e completely white in A. moori a n d b r o w n in A. albistriga. F e m a l e s lay 8 0 0 - 1 0 0 0 e g g s in clusters of 5 0 - 1 0 0 o n t h e host plants. T h e larvae are initially light b r o w n , but turn reddish as they g r o w (Fig. 10). Their 'hairiness' makes them conspicuous, especially the larger o n e s , w h i c h a r e up to 5 cm long. T h e y a r e gre- g a r i o u s a n d often migrate f r o m field to field in search of food after devastating t h e foliage in t h e field w h e r e they h a t c h e d . T h e larval p e r i o d lasts for about a m o n t h a n d p u p a - tion t a k e s place in t h e soil. T h e adults from t h e s e p u p a e do not e m e r g e until t h e next rainy s e a s o n .

F i g u r e 9. Amsacta albistriga a d u l t . F i g u r e 10. A. albistriga l a r v a .

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11 Bihar hairy caterpillar

Spilosoma (Diacrisia) obliqua (Walk.)

(Lepidoptera: Arctiidae)

This s p e c i e s is w i d e ly distributed in A n d h r a P r a d e s h , Assam, Bengal, Bihar, Haryana, Madhya Pradesh, Maharashtra, Punjab, and Uttar Pradesh. In recent y e a r s , it h a s b e c o m e an important g r o u n d n u t pest in the northern states. T h e r e are several generations per year. T h e adult is a b r o w n m o t h with a 4 0 - 5 0 mm w i n g s p a n , a n d a red a b d o m e n (Fig. 11). T h e forewings have black spots. E g g s are laid in clusters of 5 0 - 1 0 0 . T h e larvae (w h i c h c a n m e a s u r e up to 5 cm) are c o v e r e d with long yellowish to black hairs (Fig. 12). Their f e e d - ing behavior is similar to that of other s p e c i e s of hairy caterpillars. Pupation t a k e s place in leaf litter close to t h e host plants.

F i g u r e 11. Spilosoma obliqua a d u l t . F i g u r e 12. S. obliqua l a r v a .

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13 Gram pod borer

Helicoverpa armigera (Hubner)

(Lepidoptera: Noctuidae)

This s p e c i e s is widely distributed t h r o u g h o u t India. It c o m p l e t e s s e v e n or m o r e generations a year in t h e s o u t h e r n , a n d 3-4 generations per year in t h e northern states. T h e m o t h s h a v e a w i n g s p a n of about 40 m m , a n d dull b r o w n forewings (Fig. 13). T h e c r e a m y e g g s are laid singly on y o u n g leaves a n d flower b u d s (Fig. 14). T h e larvae are morphologically similar to the tobacco caterpillar but do not have black spots on t h e thorax. Most larvae are dark g r e e n i s h b r o w n , but they c a n also be pink, c r e a m , or a l m o s t b l a c k (Fig. 15). T h e y do not hide in soil during t h e d a y a n d are therefore easier to find in t h e foliage t h a n a r e t o b a c c o caterpillars. T h e d a m a g e c a u s e d by larvae to foliage is similar to that c a u s e d by t h e t o b a c c o a n d hairy caterpillars, but t h e p o d borer prefers to f e e d on flowers a n d b u d s . Pupation t a k e s place in t h e soil. This s p e c i e s is c o n - sidered important on g r o u n d n u t in coastal A n d h r a Pradesh, Tamil Nadu, and Karnataka, particularly in a r e a s w h e r e cotton (Gossypium spp) is extensively g r o w n a n d insecticide application is heavy. It is be- lieved that in t h e s e a r e a s t h e p o d borer migrates to g r o u n d n u t from nearby cotton fields.

F i g u r e 1 3 . Helicoverpa armigera a d u l t . F i g u r e 14. H. armigera e g g . F i g u r e 15. H. armigera l a r v a e .

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15 Control

Spodoptera, Helicoverpa, and hairy caterpillars

During t h e first 50 d a y s after s e e d l i n g e m e r g e n c e (DAE), if defoliation exceeds 25%, or if one or more larva per plant is f o u n d , then a p p l y endosulfan @ 3 5 0 mL a.i. h a -1, m o n o c r o t o p h o s @ 3 0 0 mL a.i. h a-1 , or f e n - valerate @ 1 0 0 m L a.i. h a-1 . Insecticide resistance has been detected in Spodop- tera a n d Helicoverpa species. Large larvae may, in any case, not be killed by insecticides. Crop monitoring is advisable. Farmers should be prepared to apply insecticide if pheromone trap catches exceed 100 moths per night, averaged over a w e e k , or if there are more t h a n 1 - 2 Spodoptera e g g m a s s e s per meter of c r o p row ( 7 - 1 2 plants). N o t e that t h e c r o p c a n w i t h s t a n d c o n s i d e r a b l e levels of defoliation after t h e s e e d s start d e v e l o p in g in t h e p o d without significant reductions in c r o p yield. T h e r e a r e a n u m b e r of ancillary control m e a s u r e s s u c h as village or w a t e r s h e d - b a s e d decisions about t h e best crop combinations, advisability of pesticide application (Fig. 16), a n d t h e o p t i m u m s o w i n g time to avoid pest attack. C r o p surveillance, p h e r o m o n e trapping (Fig. 17), a n d t h e relevant d e c i s i o n - m a k i n g p r o c e s s e s s h o u l d also be fully u n d e r s t o o d by f a r m a d v i s o r s . M o r e importantly, t h e r e a r e a n u m b e r of predators (e.g., spiders, Fig. 18; birds, Fig. 19; and ladybird beetles), parasites, and diseases—the 'natural e n e m i e s ' — w h i c h control t h e population densities of t h e s e pests.

F i g u r e 16. I n s e c t i c i d e a p p l i c a t i o n ; n o t e p r o t e c t i v e c l o t h i n g . Figure 17. Pheromone trap used to monitor the flight i n t e n s i t y of S. litura a n d H. armigera m o t h s . F i g u r e 18. S p i d e r p r e y i n g on S. litura l a r v a . Figure 19. Insectivorous bird (drongo, Dicrurus adsimilis) in a g r o u n d n u t f i e l d .

16 16 17

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17 Groundnut leaf miner

Aproaerema modicella (Deventer)

(Lepidoptera: Gelechiidae)

T h i s s p e c i e s is t h e key pest of g r o u n d n u t in m a n y parts of India (particularly t h e s o u t h e r n states) a n d in s o m e other A s i a n c o u n t r i e s . It has a limited r a n g e of hosts, a m o n g w h i c h s o y b e a n (Glycine max) is t h e m o s t fa- v o r e d alternative to g r o u n d n u t . T h e adult is a b r o w n i s h gray m o t h , only 6 mm long, with a 1 0 - m m w i n g s p a n ( F i g . 2 0 ) . Shiny white e g g s are laid singly, usually on t h e underside of t h e leaflets, c l o s e to t h e midribs, a n d a r e just visible to the n a k e d e y e (Fig. 21). Each female m o t h lays a b o u t 2 0 0 e g g s . T h e y o u n g larvae m i n e into the leaves as s o o n as they h a t c h (Fig. 2 2 ) . This m e a n s that an infestation is usually d e t e c t e d by the p r e s e n c e of s m a l l b r o w n blotches on (or in) t h e leaf. T h e m i n e s a r e a b o u t 1 mm long w h e n first noticeable (Fig. 2 3 ) . If a m i n e i s o p e n e d , t h e m i n u t e caterpillar c a n b e s e e n inside. T h e m i n e s e n l a r g e a s t h e larvae grow. W h e n they b e c o m e too large t o o c c u p y t h e m i n e , t h e larvae e m e r g e a n d w e b a d j a c e n t leaflets together, a n d c o n - t i n u e to f e e d on leaf tissue from inside t h e w e b b e d leaves. Pupation t a k e s place in t h e w e b b i n g . A severely a t t a c k e d field looks 'burnt' f r o m a dis- t a n c e (Fig. 2 4 ) . E p i d e m i c s c a n result in total c r o p loss. I n s o u t h e r n India this s p e c i e s c o m p l e t e s 3 - 4 g e n e r a - tions in a c r o p s e a s o n . Leaf miners are favored by t h e hot dry conditions of t h e postrainy s e a s o n .

F i g u r e 2 0 . Aproaerema modicella a d u l t . F i g u r e 2 1 . A. modicella e g g s . F i g u r e 2 2 . A. modicella larva inside a mine. F i g u r e 2 3 . E a r l y s y m p t o m s of A. modicella a t t a c k .

18 20 21

19 C o n t r o l . Insecticides, preferably dimethoate @200- 2 5 0 mL a.i. ha- 1 or m o n o c r o t o p h o s @ 1 5 0 - 2 0 0 mL a.i. ha- 1 should be applied if clouds of groundnut leaf miner m o t h s a r e s e e n flying in the c r o p p e d area w h e n they a r e d i s t u r b e d , or as s o o n as t h e first n e w m i n e s a r e s e e n . C h e m i c a l control is r e c o m m e n d e d if five or m o r e active larvae plant- 1 are f o u n d up to 30 d a y s after s e e d - ling e m e r g e n c e (DAE), 10 larvae plant- 1 at 50 DAE, or 15 larvae plant- 1 at 75 DAE or later. T h e role of natural e n e m i e s must be c o n s i d e r e d . For instance, if m o r e t h a n 5 0 % of t h e larvae a r e parasitized (the parasites that c a n be s e e n as m i n u t e white s p e c k s , no m o r e t h a n 1 mm long, a t t a c h e d to t h e o u t s i d e of t h e larvae), p o s t p o n e the spray, a n d m e a n w h i l e closely monitor the development of the pest population. T h e r e a r e a n u m b e r of agronomically a c c e p t a b l e pest-resistant groundnut varieties and genotypes available in India, e.g., I C G V 86031 (Fig. 2 5 ) . In m o s t parts o f t h e c o u n t r y , however, t h e y h a v e yet t o f i n d their w a y to f a r m e r s ' fields. ICRISAT is a n x i o u s to foster pro- c e d u r e s w h e r e b y scientists in t h e national a n d state p r o g r a m s m a k e u s e of available sources of resistance in b r e e d i n g p r o g r a m s .

F i g u r e 2 4 . F i e l d p l o t s w i t h d i f f e r e n t l e v e l s o f A. modicella d a m a g e . F i g u r e 2 5 . G r o u n d n u t v a r i e t y I C G V 8 6 0 3 1 , r e s i s t a n t to A. modicella.

20 24

21 Groundnut bud borer

Anarsia ephippias (Meyrick)

(Lepidoptera: Gelechiidae)

T h e g r o u n d n u t b u d borer o c c u r s i n northern India, a n d is normally c o n s i d e r e d to be a minor pest. Fully g r o w n larvae a r e c h o c o l a t e b r o w n in color (Fig. 26) a n d 1 0 - 1 5 mm long. Larvae prefer to bore into terminal buds and shoots (Fig. 27). Observations in Punjab indicate that this s p e c i e s c a n tunnel into t h e s t e m s .

F i g u r e 2 6 . Anarsia ephippias l a r v a . F i g u r e 2 7 . D a m a g e c a u s e d by A. ephippias l a r v a .

22 26

23 Tussock caterpillars

Euproctis spp

(Lepidoptera: Lymantridae)

Tu s s o c k caterpillars, t h e larvae of Euproctis s p p , f e e d on g r o u n d n u t leaves, b u d s , a n d flowers. Euproctis adults are m e d i u m - s i z e d m o t h s with a 20 mm w i n g s p a n (Fig. 2 8 ) . T h e caterpillars a r e easily r e c o g n i z e d by t h e p r e s e n c e of prominent, c o m p a c t tufts of short hair on t h e b a c k , n e a r the h e a d , etc. (Fig. 29). P o p u l a - tions are s e l d o m large e n o u g h to w a r r a n t pesticide application.

F i g u r e 2 8 . Euproctis a d u l t . F i g u r e 2 9 . Euproctis l a r v a .

24 28

25 Gray weevils

Myllocerus spp

(Coleoptera: Curculionidae)

Gray (or ash) weevils eat groundnut foliage, particular l y d u r i n g t h e r a i n y s e a s o n , n o t c h i n g o r s c a l l o p i n g t h e e d g e s o f l e a v e s ( F i g . 3 0 ) . T h e y a r e g e n e r a l l y o f m i n o r i m p o r t a n c e , b u t m a y p o s e p r o b l e m s i n s p e c i a l s i t u a - t i o n s like h y b r i d i z a t i o n b l o c k s b e c a u s e t h e y a l s o f e e d o n f l o w e r s . T h e s e i n s e c t s a r e not k n o w n t o h a v e a t - tained demonstrable pest status in farmers' fields.

F i g u r e 3 0 . G r o u n d n u t f o l i a g e d a m a g e d b y Myllocerus.

2 6 30

27 S u c k i n g P e s t s

Several s p e c i e s of insects f e e d on groundnut s a p . Among these, jassids, aphids, and thrips are common in all groundnut-growing areas. Their economic impor- t a n c e as direct pests is not clear, but is p r o b a b l y e x a g g e r a t e d b e c a u s e t h e d a m a g e they c a u s e i s c o n - s p i c u o u s . In contrast, t h e potential i m p o r t a n c e of a p h i d s a n d thrips as vectors of virus d i s e a s e s s h o u l d never be underestimated.

Aphids

Aphis craccivora Koch.

(Homoptera: Aphididae)

A p h i d s a r e f o u n d on g r o u n d n u t plants a n d other leguminous crops throughout India. Aphis craccivora re- p r o d u c e s without m a t i n g (in India). Individual adults are c a p a b l e of p r o d u c i n g about 100 n y m p h s in their 5 - 3 0 d a y life s p a n . T h e s e n y m p h s a r e dark b r o w n a n d turn into shiny-black adults in a b o u t 10 d a y s . W h e n the p o p - ulation density in t h e colony r e a c h e s a certain limit, w i n g e d individuals a r e f o u n d a m o n g t h e w i n g l e s s forms. T h e y fly a w a y to f o r m n e w c o l o n i e s . N y m p h s a n d adults suck s a p from t h e tender growing s h o o t s (Fig. 31), flowers (Fig. 3 2 ) , a n d p e g s , c a u s - ing stunting a n d distortion of t h e foliage a n d s t e m s . T h e y s e c r e t e a sticky fluid ( h o n e y d e w ) on t h e plant, w h i c h is t u r n e d black by a f u n g u s . T h e b l a c k e n e d h o n - e y d e w is c a l l e d s o o t y m o u l d . In the past, a p h i d s w e r e c o n s i d e r e d important only d u r i n g t h e early rainy s e a - s o n , but in recent y e a r s severe o u t b r e a k s have b e e n

F i g u r e 3 1 . Aphis craccivora on s h o o t s . F i g u r e 3 2 . A. craccivora on flowers.

2 8 31

2 9 noticed d u r i n g t h e postrainy s e a s o n at ICRISAT Center. S u c h o u t b r e a k s are sporadic a n d a r e m o r e intense during p e r i o d s of d r o u g h t stress. H e a v y rainstorms r e d u c e a p h i d population densities a n d favor t h e d e v e l o p m e n t of t h e fungal d i s e a s e s that kill t h e s e insects. A p h i d s are particularly s u s c e p t i b l e to predators like coccinellids, syrphids, l a c e w i n g s , a n d a n u m b e r of parasites. A l t h o u g h t h e feeding activity of a p h i d c o l o n i e s c a n retard plant g r o w t h , this s p e c i e s is potentially m o r e important as a virus vector. Fortunately, t h e m o s t important aphid-transmitted viruses (peanut stripe virus, Fig. 3 3 , a n d t h e g r o u n d n u t rosette virus c o m p l e x , Fig. 34) a r e either restricted in distribution or do not occur in S o u t h A s i a .

C o n t r o l . A p p l y d i m e t h o a t e @ 2 0 0 - 2 5 0 mL a.i. ha- 1 but only under d r o u g h t c o n d i t i o n s, w h e n t h e c r o p is y o u n g ( < 3 0 DAE), all terminal b u d s a r e infested with a p h i d s , a n d no l a d y b i r d s , syrphids, or l a c e w i n g s c a n be f o u n d .

Figure 33. Symptoms of peanut stripe virus disease. F i g u r e 3 4 . S y m p t o m s o f g r o u n d n u t r o s e t t e v i r u s d i s e a s e .

30 33

31 Thrips

Scirtothrips dorsalis Hood.

Thrips palmi Karny.

Frankliniella schultzei (Trybom)

Caliothrips indicus (Bagnall)

(Thysanoptera: Thripidae)

T h r i p s (Fig. 35) a r e small insects that live in t h e flowers a n d f o l d e d leaflets of g r o u n d n u t . T h e y a r e only about 2 mm l o n g , pale c r e a m in color, a n d a r e usually h i d d e n . For t h e s e r e a s o n s they a r e not c o n s p i c u o u s . T h e most important o n e s on g r o u n d n u t are Scirtothrips dorsalis, Thrips palmi, a n d Frankliniella schultzei. It is virtually i m p o s s i b l e to distinguish b e t w e e n s p e c i e s with the na- k e d e y e , a l t h o u g h their d a m a g e s y m p t o m s a r e slightly different. T h e e g g s a r e inserted into y o u n g g r o u n d n u t tissues. T h e n y m p h s p a s s t h r o u g h four instars (two n y m p h a l , a n d t h e ' p r e p u p a l ' a n d ' p u p a l ' instars) before b e c o m i n g adults. Under optimal conditions, the immature stages last a b o u t 1 5 d a y s . Adults live for 2 0 d a y s a n d lay 4 0 - 5 0 e g g s . T h e y c a n b e present a t a n y t i m e o f t h e year b u t a r e m o s t n u m e r o u s in t h e postrainy s e a s o n (at ICRI- SAT Center). T h e y h a v e a w i d e host r a n g e . N y m p h s a n d adults suck s a p f r o m t h e surface o f t h e leaflets with their rasping a n d s u c k i n g m o u t h p a r t s . T h i s results, initially, in w h i t e p a t c h e s on t h e u p p e r a n d necrotic p a t c h e s on t h e lower s u r f a c e of t h e leaves ( F i g . 3 6 ) . It c o n s i s t s of distortions of t h e y o u n g leaflets a n d patchy a r e a s of necrotic tissue that puncture a n d split as t h e leaflets grow. Injury is normally s e e n in s e e d l i n g s .

F i g u r e 3 5 . Thrips palmi adult (scanning electron m i c r o g r a p h , x 7 0 ) . Figure 36. Groundnut foliage damaged by thrips.

32 35

3 3 In severe infestations, particularly in the winter crop (November-sown in southern India), leaf distortion c a u s e s stunted plants. T h e effect o f s u c h d a m a g e o n yield is not precisely k n o w n , but is not serious. H o w - ever, f a r m e r s often a p p l y insecticides to kill thrips. This often results in o u t b r e a k s of m o r e serious pests. Thrips palmi t r a n s m i t s p e a n u t b u d necrosis virus (Fig. 3 7 ) , w h i c h c a n c a u s e w i d e s p r e a d plant d e a t h . T h e f e e d i n g activity of C. indicus is occasionally s e e n as a p a l e mottling on the leaves. T h i s s p e c i e s is of no e c o n o m i c significance.

C o n t r o l . Apply d i m e t h o a t e ( 5 ) 2 0 0 - 2 5 0 mL a.i. ha- 1 if there a r e m o r e t h a n five thrips per t e rmi n al (folded) leaf, only up to 30 DAE in the postrainy s e a s o n . Thereafter, it is not n e c e s s a r y to use insecticides for thrips control. Insecticide application d o e s not help to r e d u c e levels of b u d n e c r o s i s d i s e a s e . T h e r e a r e several varieties with resistance to thrips (Robut 33-1, Kadiri 3, and ICGS 8 6 0 3 1 ) , w h i c h s h o u l d be g r o w n in e n d e m i c areas to r e d u c e t h e risk of thrips d a m a g e a n d b u d necrosis d i s e a s e .

Figure 37. Symptoms of bud necrosis disease.

34 37

3 5 Jassids or leaf hoppers

Empoasca kerri Pruthi

Bachlucha spp

(Homoptera: Cicadellidae)

T h e c o m m o n e s t j a s s i d that attacks g r o u n d n u t is Em- poasca kerri (Fig. 3 8 ) , a l t h o u g h Bachlucha s p p c a n be a b u n d a n t in w e s t e r n India, especially in Gujarat. J a s s i d e g g s a r e inserted into t h e leaf tissue c l o s e to t h e midrib, or into t h e petiole. U n d e r n o r m a l conditions t h e e g g s h a t c h in about a w e e k , a n d n y m p h s d e v e l o p into adults in 10 d a y s . A b o u t 40 n y m p h s c a n be ex- p e c t e d from a single f e m a l e . H i g h density j a s s i d p o p u - lations a r e s e e n d u r i n g A u g u s t a n d S e p t e m b e r a n d F e b r u a r y a n d M a r c h . H i g h a n d well distributed rainfall a n d low t e m p e r a t u r e s e n c o u r a g e j a s s i d reproduction. Both adults a n d n y m p h s suck s a p f r o m y o u n g leaves, mostly f r o m t h e lower surface. T h e first s y m p - t o m of attack is a w h i t e n i n g of t h e veins. Chlorotic (yel- low) p a t c h e s t h e n appear, especially at t h e tips of leaflets, probably caused by a reaction between the jassids' salivary secretion and plant sap. Under severe infestation, t h e leaf tips b e c o m e necrotic in a typical V s h a p e , g i v i n g t h e c r o p a s c o r c h e d a p p e a r a n c e k n o w n a s 'hopper b u r n ' ( F i g . 39).

C o n t r o l . If m o r e t h a n 1 0 % of all leaves (not just t h o s e in the t o p c a n o p y ) h a v e t h e characteristic ' h o p p e r b u r n ' u p t o 3 0 D A E , a p p l y d i m e t h o a t e @ 2 0 0 - 2 5 0 m L a.i. ha-1.

F i g u r e 3 8 . Empoasca kerri a d u l t . F i g u r e 3 9 . S e v e r e E. kerri infestation.

36 38

37 R o o t a n d P o d F e e d e r s

Several kinds of insects f e e d on roots a n d p o d s . T h e root f e e d e r s a r e a l w a y s d a n g e r o u s to a crop b e c a u s e plants s u d d e n l y d i e , especially d u r i n g p e r i o d s of d r o u g h t . In t h e c a s e of p o d borers t h e d a m a g e is u s u - ally detected w h e n t h e c r o p is h a r v e s t e d , a n d it is not a l w a y s e a s y t o work out w h i c h insect c a u s e d t h e d a m - a g e , especially w h e n t h e p o d s have rotted. It is therefore difficult to m a k e r e c o m m e n d a t i o n s for t h e control of p o d borers, in particular, b e c a u s e t h e y a r e sporadic a n d e x t r e m e l y difficult to detect before t h e d a m a g e is d o n e .

White grubs or chafer larvae

Lachnosterna (=Holotrichia) consanguinea (Blanch.)

Lachnosterna serrata (Fab.)

(Coleoptera: Scarabeidae)

Of t h e 126 s p e c i e s of t h e g e n u s Lachnosterna (= Holo- trichia), 89 have been recorded in India. The most important o n e s are L. consanguinea a n d L. serrata. T h e former is c o m m o n in t h e light soils of R a j a s t h a n , P u n - j a b , H a r y a n a , a n d Gujarat. T h o u g h p r e s e n t i n t h e s o u t h e r n states, its i m p o r t a n c e there is restricted to a few p o c k e t s with s a n d y soil. Lachnosterna serrata is f o u n d throughout t h e country, but m o r e c o m m o n l y in t h e heavier soils of southern India. T h e adult beetles (called cockchafers) a r e 1 8 - 2 0 m m long a n d 7 - 9 m m w i d e (Fig. 4 0 ) . Mating takes place at t h e feeding sites. After f e e d i n g , t h e adults re- enter t h e soil to hide a n d lay e g g s . A single f e m a l e lays

F i g u r e 4 0 . Lachnosterna serrata a d u l t s . F i g u r e 4 1 . L. serrata e g g s . F i g u r e 4 2 . L. serrata larva.

38 40

39 2 0 - 8 0 w h i t e , roundish ( 2 . 0 - 2 . 5 m m diameter) e g g s , often in clusters (Fig. 41). E g g s hatch in 9 - 1 1 d a y s . T h e young grubs are translucent, white, and 5 mm long w h e n they hatch. T h e r e are three larval instars; fully g r o w n l a r v a e (Fig. 4 2 ) a r e larger t h a n a m a n ' s t h u m b , a n d w e i g h 3 - 4 g . T h e larvae f e e d o n soil organic mat- ter for a f e w w e e k s a n d t h e n eat roots. T h e y also d a m - a g e p o d s (Fig. 4 3 ) . Severely infested fields have large p a t c h e s of d e a d plants; t h e surviving plants a r e often s t u n t e d , a n d s h o w signs of wilt (Fig. 4 4 ) . Pupation t a k e s place in t h e soil ( 4 0 - 7 0 c m d e e p ) , w h e r e the insects remain a s p u p a e until t h e following year. T h e s e s p e c i e s h a v e o n e generation per year. T h e adult beetles e m e r g e with t h e first m o n s o o n s h o w e r s a n d f e e d at d u s k on t h e foliage of trees s u c h as n e e m (Azadirachta indica), a c a c i a ( A c a c i a spp), and others. Several other s p e c i e s o f w h i t e g r u b s also attack groundnut. All have a similar life cycle, except for a small-sized species (Maladera) w h i c h h a s m o r e t h a n o n e generation p e r g r o w i n g s e a s o n , especially in irrigated conditions. Another species, Leucopholis lepidophora Blanch., has a larval period of m o r e t h a n 1 year. It is reported to h a v e severely d a m a g e d t h e s u m m e r c r o p in riverbed a r e a s of K o l h a p u r district (Maharashtra). Plants with fibrous roots ( m o n o c o t y l e d o n s ) are able to w i t h s t a n d white g r u b attack better t h a n s p e c i e s with t a p roots (dicotyledons). C r o p s s u c h as pearl millet (Pennisetum glaucum) act as 'nurseries' for infestation.

F i g u r e 4 3 . P o d d a m a g e d b y w h i t e g r u b l a r v a e . Figure 44. Field severely infested with white grubs.

40 43

41 Termites or white ants

Microtermes spp

Odontotermes spp

(Isoptera: Termitidae)

Termites (Fig. 4 5 ) (mainly Microtermes a n d O d o n - totermes spp) c a n c a u s e d a m a g e to g r o u n d n u t plants i n several w a y s : (i) T h e y enter t h e root s y s t e m a n d burrow inside t h e root a n d s t e m (Fig. 4 6 ) ; this usually kills t h e plant. (ii) T h e y b o r e holes in t h e p o d s a n d d a m a g e t h e s e e d (Fig. 4 7 ) . (iii) T h e y r e m o v e t h e soft c o r k y tissue f r o m b e t w e e n t h e v e i n s of t h e p o d s . This is k n o w n a s scarification ( F i g . 4 8 ) . T h e y d o not usually d a m a g e t h e s e e d , but scarified p o d s a r e m o r e suscept- ible to infestation by Aspergillus s p p , w h i c h results in the production of aflatoxin, a potent carcinogen, in th e infected s e e d tissues. Termites are wi d e ly distributed in all g r o u n d n u t - g r o w i n g a r e a s in India. T h e y favor red a n d s a n d y soils, a n d a r e less of a p r o b l e m in post-rice g r o u n d n u t c r o p s a n d in Vertisols. Alates (winged forms) emerge from the soil at the onset of t h e m o n s o o n . Mating o c c u r s after a short dis- persal flight a n d pairs t h e n seek nest sites in t h e soil. In a f e w m o n t h s t h e foraging caste starts m o v i n g out of newly f o u n d e d c o l o n i e s in s e a r c h of f o o d . Soldiers, w h i c h have large m a n d i b l e s , d e f e n d their colony f r o m intruders. Colonies c a n e x t e n d several meters u n d e r g r o u n d . T h e y c a n b e d u g u p after c o n s i d e r a b l e effort, but c a n - not be c o n s i d e r e d d e s t r o y e d until the large (50 mm long) q u e e n is d e a d . Nests c a n often be d e t e c t e d by their familiar earth m o u n d s a n d ventilation d u c t s .

Figure 45. Termites (Microtermes s p ) . F i g u r e 4 6 . T e r m i t e d a m a g e t o s t e m a n d root. F i g u r e 4 7 . P o d s d a m a g e d b y t e r m i t e s . F i g u r e 4 8 . P o d s s c a r i f i e d b y t e r m i t e s .

42 45

47 48

4 3 Jewel beetle

Sphenoptera indica (Gory)

(Coleoptera: Buprestidae)

T h e adult is a shiny beetle, 10 mm long a n d 3 mm w i d e . T h e e g g s a r e laid singly o n t h e m a i n s t e m . T h e g r u b s , on h a t c h i n g , b o r e into t h e stem a n d tunnel into t h e root (Fig. 4 9 ) , c a u s i n g t h e plant to wilt a n d d i e . T h e larvae are slow m o v e r s , a n d c a n easily b e identified b y their globular head and elongated, dorsoventrally flattened b o d y . T h e y g r o w to a length of 2.5 c m . However, they often go u n r e c o g n i z e d in s o u t h e r n India d u r i n g b o t h t h e rainy a n d postrainy s e a s o n s . P u p a t i o n t a k e s place in t h e larval t u n n e l . T h e life s t a g e s a r e s h o w n in Figure 5 0 . Pest s u r v e y s d u r i n g t h e 1992 rainy s e a s o n revealed that this s p e c i e s w a s c a u s i n g up to 1 5 % plant mortality in t h e dry tracts of Raichur ( K a r n a t a k a ) , A n a n t a p u r , a n d Kurnool ( A n d h r a P r a d e s h ) .

F i g u r e 4 9 . R o o t s d a m a g e d by Sphenoptera indica. F i g u r e 5 0 . S. indica life stages.

44 49

4 5 Earwig

Anisolabis stali Dohrn

(Dermaptera: Forficulidae)

E a r w i g s are i m p o r t a n t in s o m e parts of s o u t h e r n India, particularly in clay soils. T h e i r e g g s (Fig. 51) a r e laid in clusters o f 2 0 - 1 0 0 , usually i n t h e soil, a n d s o m e t i m e s inside d a m a g e d p o d s . T h e e g g s hatch in a b o u t a w e e k . T h e five n y m p h a l instars r e s e m b l e t h e adults, w h i c h c a n live a s long a s 2 5 0 d a y s . T h e y c a n b e easily recog- n i z e d by their u n i q u e f o r k e d a b d o m i n a l tip. Both n y m p h s a n d adults bore into tender d e v e l o p i n g p o d s a n d feed on t h e s e e d s . Infested p o d s (Fig. 52) are p r o n e t o f u n g a l infestation.

F i g u r e 5 1 . Anisolabis stali with eggs. F i g u r e 5 2 . P o d d a m a g e d by A. stall.

46 51

47 Wireworms

(Coleoptera: Elateridae)

False wireworms

(Coleoptera: Tenebrionidae)

W i r e w o r m s (click beetle larvae) a n d false w i r e w o r m s (tenebrionid larvae) occasionally cause damage to g r o u n d n u t . Adult w i r e w o r m s (dusky b r o w n beetles) occur o n foliage a n d flowers; s o m e s p e c i e s apparently d o not f e e d . W i r e w o r m a n d false w i r e w o r m larvae are w h i t e or c r e a m , shiny, h a r d - b o d i e d , a n d virtually indis- tinguishable, e v e n to experts. T h e y feed on groundnut roots a n d p o d s (Fig. 5 3 ) . Fully g r o w n larvae are 2 . 5 - 3 . 5 c m long a n d 2 m m thick. P u p a t i o n t a k e s place in t h e soil. T h e biology of t h e w i r e w o r m s a n d false w i r e w o r m s that attack groundnut is not fully k n o w n . T h e y a r e m o r e likely to be f o u n d in clay soils.

F i g u r e 5 3 . P o d d a m a g e d b y w i r e w o r m s .

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4 9 Subterranean, doryline, blind, or red ants

Dorylus orientalis Westwood

Dorylus labiatus (Shuckerd)

(Hymenoptera: Formicidae)

Subterranean, doryline, blind, or red ants (Dorylus spp) bore into m a t u r e g r o u n d n u t p o d s . T h e y a r e a b o u t 5 mm long, r e d - b r o w n , a n d a r e rarely s e e n a l o n e o r a b o v e t h e soil surface. T h e y m a k e several neat, r o u n d holes, 0 . 5 - 2.0 m m i n diameter, a n d remove t h e s e e d completely, without leaving a n y soil inside t h e e m p t y shell (Fig. 54); termites, in contrast, refill t h e p o d cavity with soil. It is not k n o w n h o w c o m m o n this s p e c i e s is. It completely d e s t r o y e d an isolated c r o p at ICRISAT Center d u r i n g t h e 1989 postrainy s e a s o n , indicating that it h a s t h e potential to be a serious pest.

Control of soil insects

Soil insects a r e difficult a n d e x p e n s i v e to control with insecticides. A p p l y i n g c a r b o f u r a n (3 G) g r a n u l e s in t h e furrow @1 kg a.i. ha- 1 c a n be an effective prophylactic m e a s u r e . A s e e d treatment (with a n y insecticide) that is sufficient to protect a crop from all soil insects h a s not b e e n f o u n d ; however, t h e application of 2.5 mL a.i. of chlorpyriphos kg- 1 s e e d as a s e e d d r e s s i n g c a n s u p - press white grub populations. To control white grub adults, spray their feeding trees w i t h c a rb a ryl 50 WP (2 g L- 1 of water) 3 - 4 t i m e s until mid-July, ideally using a c o m m u n i t y a p p r o a c h . In e n d e m i c a r e a s , plowing deeply after harvesting t h e c r o p c a n also reduce the p o p u l a t i o n , mainly t h r o u g h bird predation a n d t h e de- struction of p u p a e .

F i g u r e 5 4 . P o d d a m a g e d by Dorylus orientalis.

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51 S t o r a g e P e s t s

Storing g r o u n d n u t in the p o d protects t h e s e e d against most post-harvest pests. T h e only e x c e p t i o n is t h e g r o u n d n u t bruchid (Caryedon serratus). T h e other in- s e c t s that a r e c o m m o n l y f o u n d f e e d i n g o n shelled g r o u n d n u t s include t h e rice m o t h (Corcyra cephalonica) a n d red flour beetle (Tribolium castaneum).

Groundnut bruchid

Caryedon serratus Olivier

(Coleoptera: Bruchidae)

T h e adult is a b r o w n beetle a b o u t 4 - 7 mm long a n d 5 m m w i d e , w i t h large h i n d legs (Fig. 5 5 ) . T h e translucent milky-white e g g s (1 mm long) are a t t a c h e d to t h e p o d w a l l . After h a t c h i n g , t h e larva b u r r o w s straight through t h e e g g shell a n d t h e p o d w a l l , a n d starts eating t h e s e e d . N o d a m a g e c a n b e s e e n a t this s t a g e without careful o b s e r v a t i o n . T h e first sign of attack is t h e a p p e a r a n c e of ' w i n d o w s ' cut into t h e p o d wall by t h e larva to a l l o w t h e adult to leave the p o d after e m e r g - ing from t h e pupal c o c o o n (Fig. 5 6 ) . Fully g r o w n larvae s o m e t i m e s c o m e out through t h e exit holes m a d e b y p r e v i o u s g e n e r a t i o n s . T h e y often leave t h e storage s a c k a n d p u p a t e in large n u m b e r s at t h e bottom of the pile of s a c k s . By this s t a g e , t h e g r o u n d n u t s e e d s are t o o b a d l y d a m a g e d for h u m a n c o n s u m p t i o n or oil ex- pulsion. U n d e r o p t i m u m c o n d i ti o ns , t h e life c y c l e takes about 4 0 d a y s . T h i s pest h a s b e e n f o u n d i n A n d h r a P r a d e s h , Gujarat, K a r n a t a k a , M a h a r a s h t r a , a n d Tamil N a d u . A systematic search of g r o u n d n u t storage g o d - o w n s throughout India is n e e d e d to establish t h e full extent of its severity a n d distribution.

F i g u r e 5 5 . Caryedon serratus a d u l t . F i g u r e 5 6 . C . serratus e g g s a n d l a r v a e ; d a m a g e d s e e d s a n d p o d s .

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53 Red flour beetle Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) Rice moth Corcyra cephalonica (Stainton) (Lepidoptera: Galleriidae)

T h e most c o m m o n pests of shelled groundnuts are t h e red flour beetle (Tribolium castaneum, Fig. 57) and rice moth (Corcyra cephalonica, Fig. 5 8 ) . T h e s e are consid- ered secondary pests b e c a u s e they are not c a p a b l e of infesting sound pods. T h e signs of d a m a g e c a n be easily recognized: the presence of w e b b i n g in the c a s e of rice moth infestation (Fig. 59), and powdery remnants—but no w e b b i n g — i n red flour beetle infestation (Fig. 60). Adult red flour beetles a r e 3 - 4 m m long, o b l o n g , a n d b r o w n i n color. A n adult c a n lay u p t o 4 5 0 individual e g g s , distributed a m o n g t h e p o d s o r s e e d . E g g s h a t c h i n 3 - 4 d a y s , a n d t h e slender cylindrical larvae start f e e d i n g on the s e e d . Pupation t a k e s place in t h e p r o d u c e without a c o c o o n . T h e p u p a l period m a y last for 7 - 1 0 d a y s a n d t h e adults c a n live u p t o 1 8 m o n t h s . T h e d e v e l o p m e n t a l period from e g g to adult m a y require about 2 0 d a y s under o p t i m u m w a r e h o u s e c o n d i - tions ( 3 5 °C, 7 0 % relative humidity). T h e rice m o t h h a s a w i n g s p a n o f 1 2 - 1 5 m m , a n d grayish b r o w n forewings. T h e f e m a l e lays up to 150 e g g s within a few d a y s of e m e r g e n c e . T h e c r e a m y w h i t e larvae start f e e d i n g on t h e s e e d immediately after they hatch. At maturity they construct white, silken cocoons for pupation. Development from egg to adult requires 3 0 - 3 5 d a y s under o p t i m u m storage conditions.

F i g u r e 5 7 . Tribolium castaneum a d u l t . F i g u r e 5 8 . Corcyra cephalonica a d u l t . F i g u r e 5 9 . D a m a g e c a u s e d by C. cephalonica. F i g u r e 6 0 . D a m a g e c a u s e d by T. castaneum.

54 57 58

55 Pod-sucking bug

Elasmolomus (Aphanus) sordidus (Fab.)

(Hemiptera: Lygaeidae)

This s p e c i e s is w i d e s p r e a d in India; it feeds on p o d s left in t h e field to d r y , or on s t o r e d p o d s . T h e adult is d a r k b r o w n , a p p r o x i m a t e l y 1 0 m m l o n g a n d 2 m m w i d e (Fig. 61). In t h e field, t h e f e m a l e s lay their e g g s in t h e soil or on g r o u n d n u t h a u l m s , but in storage e g g s a r e laid loosely a m o n g t h e g r o u n d n u t s o r o n s a c k s . T h e first instar n y m p h s h a v e a bright red a b d o m e n ; later instars b e c o m e progressively darker. All s t a g e s f e e d on s e e d s , perforating t h e p o d with their rostrum. T h i s c a u s e s t h e s e e d s t o shrivel a n d increases t h e free fatty acid content of t h e oil, p r o d u c i n g a rancid flavor.

Control of storage pests

Maintenance of optimum moisture content (not >5%) is a l w a y s critical in preventing t h e d e v e l o p m e n t of storage pests. For protection against storage pests, except for t h e g r o u n d n u t b r u c h i d , g r o u n d n u t s s h o u l d b e stored unshelled. Fumigation with celphos—3 g tablet per sack o f g r o u n d n u t (40 k g ) — a n d covering t h e s a c k s with a p o l y t h e n e s h e e t for 5 d a y s c a n effectively control bruchids without affecting seed viability. If groundnut s a r e stored a s s e e d , care s h o u l d b e t a k e n t o avoid b r e a k a g e . B r o k e n s e e d s s h o u l d not be stored for long periods. Dusting with an inert s u b s t a n c e s u c h as at- t a p u l g i t e - b a s e d clay dust (ABCD) c a n help to m i n i m i z e s t o r a g e insect p r o b l e m s .

F i g u r e 6 1 . Elasmolomus sordidus a d u l t .

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5 7 N o t e s

58 N o t e s

59 N o t e s

60 About ICRISAT

The semi-arid tropics (SAT) encompasses parts of 48 developing countries including most of India, parts of southeast Asia, a swathe across sub-Saharan Africa, much of southern and eastern Africa, and parts of Latin America. Many of these countries are among the poorest in the world. Approximately one sixth of the world's population lives in the SAT, which is typified by unpredictable weather, limited and erratic rainfall, and nutrient-poor soils.

ICRISAT's mandate crops are sorghum, pearl millet, finger millet, chickpea, pigeonpea, and groundnut; these six crops are vital to life for the ever-increasing populations of the semi- arid tropics. ICRISAT's mission is to conduct research which can lead to enhanced sustainable production of these crops and to improved management of the limited natural resources of the SAT. ICRISAT communicates information on tech- nologies as they are developed through workshops, networks, training, library services, and publishing.

ICRISAT was established in 1972. It is one of 18 nonprofit, research and training centers funded through the Consultative Group on International Agricultural Research (CGIAR). The CGIAR is an informal association of approximately 50 public and private sector donors; it is co-sponsored by the Food and Agriculture Organization of the United Nations (FAO), the World Bank, and the United Nations Development Programme (UNDP).

RP - 08861