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GRASSHOPPER ~~~r CONTROL IN NIGERIA

EXTENSION BULLETIN

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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.

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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

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TABLES OF CONTENTS

Acknowledgement 11

Table of contents Ill

1. Introduction

2. Biology of grasshoppers

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

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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 pur­pose of this bulletin is to provide a general and practical reference for Agricultural Extension workers who are often confronted with the prob­lem 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 con­trol measures, the reader should consult the Federal Pest Control De­partment (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 Sa­vanna ecological zones where they attack grasses, forages and crops. However only few known species are very serious pests of crops. Among them are:

Oedaleus senegalansis and 0. nigeriensis Aiolopus simulator and A. thalassinue Zonocerus variagatus Hieroglyphus daganensis Cataloipus fusccooarulipas and C. cymbiforun Kranssaria angulifera

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The biology of these species is discussed in the text for the pur­pose offield identification and application of appropriate control mea­sures.

General description Figure 1 a 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. 1 b)

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Fig. la

Fig. 1 b Grasshopper Parts

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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 pos­terior margin of the 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.

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Fig. 2. Oedaleus senega/ensis

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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 of this 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 pro sternal 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.

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Fig.3: Krausaria angulifera (Krauss)

Host: The grasshopper is a serious pest of millet 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 cap­sule having a tough earthen wall. The eggs are laid in moist or dry sandly soil around the bases of shrubs or trees from September - Octo­ber 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.

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Zonocarus variagatus (Linnaeus) Zonocerus variegatus is a medium size grasshopper. The adult is

about 40mm long. It has variegated colours of yellowish - brown tho­rax 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 popu­lation 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, :.

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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 No­vember. 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. thalassimts.

Fig. 5: Aiolopus simulatrix (Walk)

Host.s: It attacks mainly cereal crops including sorghum, millet, rice and wheat in the Chad Basin Life-cycle: It produces only one generation in a year in the wet season.

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It survives the prolonged dry season in reproductive diapwse as imma­ture adults which hide in the soil cracks at night and in the afternoon when temperatures are high. The adult emerge in large numbers in the morning to bask in the sun. Egg-laying is delayed until the beginning of the raininsg season.

Hieroglyplrus dagane11sis (Krauss) The grasshopper is medium in size, light yellowish green and

large head. The forewings are light yellowish green, the hind wings are colourless. The pro no tum has dorsovental grooves which forms letter "A" when the insect is placed on its back with the head to the left of the person holding it. There is no presternal process.

Distribution: The grasshopper is found in pest proportions in Sokoto, Kaduna, Kano, Bauchi and Borno states.

Fig. 6: Hieroglyplms daganensis.

Host: The species has a strong preference for swamp rice in its feeding habits for which reason it is called the rice grasshopper. Life-cycle: Oviposition occurs towards the end of the wet season in

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September-October. The eggs undergl' '"'ryonic diapause and hatch in the early wet season of the following } t.. 1ere <ll e usually 6 - 8 nymphal instars and the nymphs life lasts 2-3 mon th .

Cataloipus fuscocoeruleipes (S. jostedt) ) This species is a greenish grasshopper. The female is large and \ the male is slender. It has irregular dark spots on the forewings and · clear hind wing·s. There are two pairs of unequal spots on each side of

the prozona. The dorsum has a medium band which extends between the eyes to the top of the face. The presternal process is straight and blunt.

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Fig. 7: Cataloipus fuscocoeruleipes

Distribution: It is widely distributed in the Northern Guinea and Sudan savanna. In Sudan savanna they are associated with reserve forests or bush tickets. Host: It is a serious pest of maize. It will also destroy tomato if planted near the breeding ground. Life-cycle: Oviposition takes place in September at the end of the wet season and the eggs survive the dry season in diapause and hatch in June in the darly raining season of the following year. The species dis­plays sexual dimorphism in its development. The enymphs are brown and the males usually have 6 nymphal instars and an average of 12

weeks,nymphallife. The large female has 7-8 nymphal in stars and 15 -17 weeks nymphal life.

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.. Table 1: A summary table of the Grasshoppers description, distribution and Ufecycle.

IJrasshoppcr Sp. Description Host & Distribution

. Oedaleus nigeriensis Brownish to greenish grasshopper Pest attack soi'!1J!um, nuUet, 0 . senegalensis 25-30mm long. The top of the thorax maize, yam, tobacco and

is yellowwish-green and the whtish vegetables. stripes. The pests are most abundant in

in the Sudan zone, but a lso occur in the Savannah and N. Guinea zones.

. Kraussaria angalifera A large robust grasshopper Serious pests of mill d. and with a crested dorsum. cowpea, also attack soi'!1J!um. Forewings have short It is widely distributed in the yellowish horizontal bands, Sahel and Sudan Savannah.

hindwing~> are yellow ..

. Zonocerus variegatus The thorax and body are Crops attacked include cassava, yellowish-brown. The citrus, maize, yam, oi.l palm forewings are green and seedling~>. The pests are most the antenna arc black prevalent in the Guinea and with 2-3 red rings on each. Rain forest zones.

. Aiolopus simulatri.x It is a palo-brown medium It occurs mainly in the Chad size grasshopper. The fore:>- Basin where it attacks soi'!1J!um, wings have two whitish and millet. rice and wheat. 2-3 dark spots.

. Hieroglyphus The grasshopper is medium Species occur mainly on swamp daganesis in size and it is light yellow rice. It is prevalent in the Sudan

green. llte hind wings are and sahel ian zones. colourless.

. Cataloipus This specie is a greenish It is a serious pest of maize and fuscococruleipes grasshopper. It has irregular attack tomato as well. It is widely

dark spots on the forewings distributed in the Northern and clear hindwings. Guinea and Sudan Savannah.

Life Cycle

Egg.<; are laid in the soil around May and June. Their aduhs breed between July and September to produce or second generation which survive the dry season in the egg stage. These eggs hatch in May or June at the beginning of the rains

The eg;;s are laid in moist or dry sandy soil around the bases of shrubs from Sep-tember or Od.ober. They undergo diapouse in the dry season and hatching begin in June

to Od.ober.

The female deposit egg.<; capsules in the soil during the rainy season. The nymphs develop into adults by the start of the rainy season.

Egg.<; are laid on clay soil in the Chad flood plains. h survives the prolonged dry season in reproductive diapause as nymphs.

Egg.<; are laid towards the end of the wet season in September-October. The egg.<; undergo diapause and hatch at the beginning of the rains.

Egg.<; are laid in September. lltey survive thf dry season in diapuase and hatch in June. llte specie displays sexual dimorphismin its phism in its development.

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4. Control Measure Grasshoppers can effectively be cont1 oiled through integration

of cultural, physical and chemical control m<> thods. The following are highlights of the various methods.

a. Cultural Control The following are cultural control measures that farmer should adopt and practice to reduce grasshopper population or their damage.

i. Grow resistant crops or varieties: Usually groundnut is not at­tacked by grasshoppers. Also, the short-duration sorghum grown in parts of the Northern states does not suffer severe grasshopper dam­age. It is usually left virtually untouched by grasshoppers where millet and cowpea are present. ii. Use of barrier crops: sorghum can be used as a barrier crop in the said areas and elsewhere wherever the grasshoppers present are known to prefer millet to sorghum. In such cases the first 20 - 25 rows of the crop field abutting on the bush-lands, which are the reservoirs of grasshoppers that attack millet crop, should be planted to sorghum. Careful local observations may help identify additional suitable barrier crops.

m. Tray crops: Zonocerus variegatus nymphs can feed on a vari­ety of plants, but they like to congregate on garden-egg plants. Rows of this crop should not be grown close to the oviposition sites (shade of mango, guava, and other trees along rivulets in the Northern belt of Nigeria) and then at intervals. The rows ofthis trap crop should be kept under careful watch and treated with a residual pesticide every week till the invasion lasts. -·

and oviposition sites.

v. .Dig the soil under trees in crop field-particularly close to their trunks-to expose grasshopper egg pods.

b. Mechanical control Methods that may employ labour, machines or tools.

i. Collect the egg pods dug out in the operations listed above,or seen during routine ploughing, harrowing or tilling of soil. ii . Trenching: n case oflocusts and in grasshoppers, when nymphs are in high density, it may be worthwhile to organise trenching. A long trench 60cm wide x 45cm deep cleaned of vegetation on its sides can be used. A good number of children, with twigs in hands, moving to­

wards the trench can drive the nymphs into the trench. Spray the nymphs with insecticides. The same trench can be used year again after weed­ing or cleaning. Farmers are advised to dig trenches at strategic loca­tions in the direction from which the nymphs of grasshoppers usually come.

Tillage Tillage kills grasshoppers in several ways: It can bury their eggs

so deep that young hoppers do not hatch: It can also bring the eggs to the surface where they are destroyed by the drying action of sun and wind. Tillage right after harvest will make the soil unattractive to egg laying and will assist in destroying eggs already laid. Where soils are heavy, ploughing with moldboard ploughs 13 em deep or more can pre­

vent the emergence of young grasshoppers.

Early planting Where possible early planting as a cultural control measure is

recommended. Crops planted early make considerable growth before grasshoppers hatch. Such crops are able to withstand a longer period of

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grasshopper feeding then late planted crops.

c. Physical control Methods employing physical factors of the environmenl.

i. Light trapping: A number of grasshopper, especially Oedaleus, and Hieroglyphus are attracted to light at night. The attraction is more on dark nights, and if the light '" white and is reflected from white surface. A bush lamp hanging on the outside wall of a house above a bucket :Y.. filled with water can serve as an improvised light trap.

ii. Water trapping: Oedaleus adults are attracted to water during September to October. Once they fall in water, they mostly die in it. Where feasible, water traps should be operated as a n. 1t ing.

d. Chemical control In the event of grasshopper epidemic outbreak, chemical control

provides a quick solution. A wide range of insecticides can be used to control grasshopper. There include members of chlorinated hydrocar­bons, organephosphates. Carbonates and synthetic pyrethroids. The insecticides from chlorinated hydrocarbon group are generally very ef­fective, but they can leave residues on crops and pastures forage. Ex­amples: Toxaphene and Gamalin 20. (These cehmicals are now banned from usage)

The organophosphate insecticides for grasshopper control are also highly effective, and if properly used, do not leave harmful residues; though their killing properties do not last as long as the chlorinated hydrocarbons. Examples are diazinon dimethoate, malting folithion, and Agrothion.

The carbonate compounds also give adequate control of grass­hoppers and has about the same residual life as the orgenophosphates. Members ofthis group used include Carbaryl (or vetox). Propoxur and

Unden. The pyrthroid group include Decamethrine, Cymbush and Ka-

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rate. They are ideal for vegetable crops which need early harvesting since the chemicals have little residual property. The table below shows list of some insecticides recommended for grasshopper control and the dosage required.

Table 2: Some insecticides recommended for grasshopper control and the application rate.

Insecticide Group Dose rate

Dimethoate 40 EC Organophospurus 125m) insecticide in 10 litres of water (for nymph): 150mls in 10 litres of water (for adults)

Fenitrothion 50EC Organophospurus 1 OOml in I 0 litres of water (for nymphal control) 120mls in 10 litres ofwater (for adult control).

Agrocide 26 Organophosphurus Apply 0.9kg in 45kg dusa, mix thoroughly with 9 lit res of water and spread in the morning.

Carbaryl85 vetox Carbonate Apply 2kg ofVetox 85 in 225 litres of water per ha. Or take 8 levels of standard match box per 9 litres (2 gallons) of water.

Propoxur 70.w.p. Carbonate 86gm in 10 litres of water and apply at 1 00 1 ha. Or dust the egg beds with the chemical

Karate 25 EC Pyrethroid Add 80mls in 10 litres of water or spray 800ml Karate in 1 00 litres of water per hectare.

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e. General remark on the use of the c •cmicals From table 1 above it can be seen that low dosages of the chemi­

cals are recommended to kill the nymphs, especially if present in short, dense, succulent vegetation. High dosages are needed for the adults as well as nymphs if occurring in tall dense maturing vegetation, and also treatment of barrier strips. It should be remembered that grasshoppers are easier controlled at the nymphal stage than adult stage which may then require aerial spraying.

To protect cotton plant, spray nearly wasteland from which grass­hoppers are migrating.

To protect cereal crops spray the margins of the crop fields. To protect vegetables, treat hatching areas, margin rows, idle land adjoin­ing the crops to destroy the hoppers before they move into the fields .

f. Spraying Before applying spray, read the instructions that follow under

"Dosages", "Application Procedures", and "Precautions" Since grasshoppers do most of their feeding at the early hours of

the morning, spraying operations should be done at that time using preferably, motorised sprayer, except of course the chemical formula­tion is ULV or ED.

5. Spraying methods Precautions I . Pesticides used improperly can be injurious to man, animals, and plants. Foil ow the directions and heed all precautions on the labels.

2. Store pesticides in original containers under lock and key out of the reach of children and animals - and away from food and feed.

3. Do not apply pesticides when there is danger of drift, and when honey bees or other pollinating insects are visiting plants.

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4. Avoid prolonged inhalation of pesticides sprays or dusts; wear protective clothing and equipment. If your hands become contaminated with a pesticide, do not eat smoke or drink until you have washed.

5. In case a pesticide is swallowed or gets in the eyes, follow the first aid treatment given or the label, and get proper medial attention.

6. Conclusion In efforts to control outbreaks of grasshoppers, an integration of

chemicals and non-chemical control measures should be adopted. Chemicals, though effective are often costly to use and hazardous to both man and the environment. By introducing cultural or physical control measures at the appropriate time and place, the use of chemi­cals can be minimised and at the same time achieving effective grass­hopper control.

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REFERENCES

Anon (1968) Insect pests of Nigerian Crops. The University of Ife/ Ministry of Agriculture/Western Nigeria and the United States Agency for lnternayional Development Cooperating. p.63.

Anon ( 1983): International Crops Research Institute for the semi-Arid Tropics (ICRISAT) Information Bulletin No. 12.

Oyidi, S. 0 . ( 1978): The ecological distribution, seasonal incidence and breeding patterns of Acridoidea (Orthoptera) in Zaria Area, Ni­geria, Samaru Miscellenous Paper; 70.

Oyidi. S. 0. (1985): The breeding system of some grasshoppers and locusts in Northern Nigeria. Samaru Miscellenous Paper: 105.

Pogou G. B. and Fishpoil L. D. C (1992) A revision of the Grasshop­per Genus Orthochtha and Allies (Orthoptera: Acrididae: Acridines) NRI Overseas Development Administration. p.4

Steedman, A. (Ed) (1990) Locust Handbook (3 rd Edition) Chatham: Natural Resources Institute, United Kingdom. P.113-128

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