I GRASSHOPPER ~~~r CONTROL IN NIGERIA EXTENSION BULLETIN 3 " (i .-) ( .-, c:.,_ GRASSHOPPER CONTROL IN NIGERIA Extension Bulletin No ........... By NATIONAL AGRICULTURAL EXTENSION AND RESEARCH LIAISON SERVICES, AHMADU BELLO UNIVERSITY, PMB 1067, ZARIA. NIGERIA .--·pun! tSEHrn 1998. ,_.J if' \ ACKNOWLEDGJ ·\11 · ~ TS A special acknowledgment is given to Professor Oba Oyidi whose work and publications on Grasshoppers in Nigeria was largely used for this bulletin. This publication is sponsored by the Federal Ministry of Agriculture, Ahuja, Nigeria. S. S. Okatahi and Oba Oyidi II TABLES OF CONTENTS Acknowledgement 11 Table of contents Ill 1. Introduction 2. Biology ofgrasshoppers 3. Reproduction of grasshopper 2 4. Control measure 12 * Cultural Control 12 * Mechanical Control 13 * Physical Control 14 * Cremical Control 14 * General remark on the use of chemicals 16 5. Spraying methods 16 6. Conclusion 17 References 18 111 Introduction Grasshopper are common 1gricultural pests. They feed on leaves and grains of millet, sorghurt,, maize, wheat, rice, sugarcane, fruit trees, graslands and vangelands. The variegated grasshoppers in particular can attack and cause total defoliation of cassava .. The pur­ pose of this bulletin is to provide a general and practical reference for Agricultural Extension workers who are often confronted with the prob­ lem of grasshopper control. The bulletin covers selected grasshopper species that cause problems on the field. Their characteristics, biology. habitats and host plants are discussed for the purpose of identification. Also, information on the cultural, physical and chemical control of the insect is adequately provided. It is hoped that the bulletin will prove useful to the Agricultural Extension Agents, officials of Pest Control Departments in the field, vocational agricultural teachers and literate farmers. For up-to-date information on chemical control and other con­ trol measures, the reader should consult the Federal Pest Control De­ partment (FPCD), the National Agricultural Extension and Liaison Services (NAERLS), of the National Agricultural Research Institute closest to you. 2. The Biology of Grasshoppers The grasshoppers belong to the order Orthoptera and in the supar-family Acridoides. There are about 230 known species of this family in Nigeria. Most of them are found in the Guinea and Sa­ vanna ecological zones where they attack grasses, forages and crops. However only few known species are very serious pests ofcrops. Among them are: Oedaleus senegalansis and 0. nigeriensis Aiolopus simulator and A. thalassinue Zonocerus variagatus Hieroglyphus daganensis Cataloipus fusccooarulipas and C. cymbiforun Kranssaria angulifera 1 The biology of these species is discussed in the text for the pur­ pose offield identification and application of appropriate control mea­ sures. General description Figure 1a is a diagram of grasshopper showing various parts of the insect. Grasshopper are characterized by having mandibulate mouth parts, large prothorax, large hind legs which are modified for jumping. The insects may be winged or may not be winged (apterous), when winged, the forewings are membraneous and adapted for flight. The cerci are unsegmented and the families usually have well developed ovipositor which is an organ for boring holes in the soil or plant tissue into which the eggs are laid. The eggs hatch into nymphal form, which molt and increase in size several times until they attain sexual maturity. The nymphal form is the feeding and destructive stage, while the adult the reproductive stage. 3. Reproduction of Grasshoppers Reproduction in grasshoppers usually occur in the rainy season. Females of most of the destructive species lay their eggs in bush or weedy ground bordering the crop upon which they feed. The eggs are laid in moist soil in holes which the female dig with its ovipositor, they are covered with a gelatinous fluid which hardens round them to form an egg pod. An egg pod may contain 30-100 eggs in most species, and several of these can be produced by the hoppers (fig. 1b) 2 --- Fig. la Fig. 1 b Grasshopper Parts 3 After an incubation period which varies from a few weeks to several moths the eggs hatch into nymphs or baby" insect which bear close resemblance to the parents. There are usually 4-8 nymphal instars depending on the species. The nymphs pass from one instar to another molting. They usually require 40 to 50 days to reach the adult stage. There may be two or more generations in a year depending on the species and weather conditions. Many species pass through the dry season in egg diapause (a resting period) and then begin to hatch in June or so during the following wet season. Oedaleus sa11egalansis and 0. nigerionsis O.senegalansis and 0. nigeriensis are regarded as the most noxious of the grasshoppers in Nigeria. They are medium size grasshoppers (adult are about 30-40mm long). 0 senegalansis's colour is usually brown but green forms are found occasionally. The medium carina (ridge along the centre of the dorsum) is pronounced but it is not crested. The pos­ terior margin ofthe pronotum is rounded as against angular in Oeda/eus nigeriensis (uvarov), which it resembles closely. The forewing has three or more whitish transverse areas but the hindwing is yellow at the base and largely smoky in the remaining area except the tip which is clear. I or · Fig. 2. Oedaleus senega/ensis 4 Distribution Oedaleus spp are widely distributed in the Guine~ and Savanna ecological zones of Nigeria but a1• more abundant in the Sudan Savanna zone. Host: The grasshoppers attack maize, millet and sorghum in Borno, Gongola., Kano, Bauchi and Sokoto States. These crops are usually attacked at the seedling and milky stages by both the nymphs and adults. They feed and cause the defoliation of the plants. Life-cycle: It has two generations in a year and survives the dry season in embrynonic diapause as eggs in the soil. Egg-laying is delayed until the beginning of wet season (between May and June) and the nymphs attack seedling cereals. The adults of this generation breed between July and September and produce a second generation which survives the following dry season in the egg stage in the ground. In very dry areas eggs may remain alive for more than a year. It is the adults ofthis second generation that usually attack late maturing sorghum and millet at the milky stage. Krausaria angulifera (Krausa) K. angulifera is a large and robust grasshopper with a crested dorsum. It has two pairs of yellow spots at the laternal sides of the prozona and the anterior pair are larger than the posterior ones. The antennae are yellow and filii form and the prosternal process is pointed and directed ventrally. The forewings have short yellowish horizontal bands and the hindwings are yellow. Distribution: It is widely distributed in the Sudan Savanna and Sahel zones ofNorthern Nigeria. 5 Fig.3: Krausaria angulifera (Krauss) Host: The grasshopper is a serious pest ofmillet and cowpea. It feeds on seedling millet, flower heads and milky grains. It eats the flowers and green pods of cowpea. It is also known to attack maize and then Tigare (Hausa) variety of sorghum in the Lake Chad flood plains. But it is predominantly associated with bush. Life-cycle: It has one generation in a year. The egg pod is a hard cap­ sule having a tough earthen wall. The eggs are laid in moist or dry sandly soil around the bases of shrubs or trees from September- Octo­ ber at the end of the wet season They undergo diapause in the dry season and most of them hatch in June in the following wet season. Eclosion (the hatching from the eggs) is not simultaneous but is continuos throughout the wet season. The result is that the nymphs are found from June - October or November. It is said to have 5 - 6 nymphal instars and a nymphal duration of 55 - 74 days. It has golden brown and green nymphs and the promotum ofthe nymph has a high crest. 6 Zonocarus variagatus (Linnaeus) Zonocerus variegatus is a medium size grasshopper. The adult is about 40mm long. It has variegated colours of yellowish - brown tho­ rax and body. The antennae are thick and black at the basal ~ and variagated at the tip. The followings are uniformly green and the hind wings are smoky and faintly transparent. Fig.4: Zonocerus variegatus Distribution: There are two seasonal populations. The dry season popu­ lation is found in the rain forest zones south of the rivers Niger and Benue where it swarms. The wet season population do ~ s not usually swarm and it is widely distributed throughout Nigeria. Crops attacked: the species is extremely polyphagous and it attacks a wide variety of arable crops, tree crops and vegetables. These include cassava, citrus, cocoa, cotton, maize, cowpea, yam, oil palm seedlings, banana, and sweet potato. It has a very strong preference for cassava plant. Nymphs and adults eat plant foliage, stems and fiuits, causing defoliation and death of~,. ., .J, :. ·,. .. ... ,. ..... ' !'· ... shady sqrubs. The eggs are laid in April or in early wet season. A female lays an average of four eggpods each containing 30 - 80 eggs. Eggs, which have been in diapause, hatch between October and No­ vember. The majority of the symphs pass through 6 nymphal instars before reaching the adult stage from late January to February. The wet season population lay eggs in September and the eggs hatch from December - March in the dry season depending on the locality. The adults emerge between late June and early August. Aiolopus simulatrix (Walk) A.simu/atrix is a medium size grasshopper (about 25mm long). It is economy pale brown in colour. The forewings have two whitish and two to three dark areas and the hind wings are clear. It has two dark hands on the external surface of the hind femur and it has no dark stripe on the dorsum and behind the eyes as it occurs inA.