Major Insect Pests of Nigerian Crops PDF

Major Insect Pests of Nigerian Crops (A) CEREAL CROPS 1. Maize borers Busseola fusca (Fuller) Sesamia calamistes Hmps Eldana saccharina Wlk Mussidia nigrivenella Rag Life History and Damage: Eggs are deposited in batches between the leaf sheath and the plant stem, lar...

Major Insect Pests of Nigerian Crops (A) CEREAL CROPS 1. Maize borers Busseola fusca (Fuller) Sesamia calamistes Hmps Eldana saccharina Wlk Mussidia nigrivenella Rag Life History and Damage: Eggs are deposited in batches between the leaf sheath and the plant stem, larvae hatch from the eggs, feed on the leaf funnel and work their way down the stem causing the growing points to die (dead heart). Bored stems may lodge, young plants may die and yield reduced in older plants. The cobs of mature maize may be infested by E. saccharina while damage by M. nigrivenella continue on the cob in storage. Control: i. Early planting/Good husbandry ii. Destruction of crop residue after harvesting iii. Plant resistant varieties iv. Apply chemical control -Carbaryl (Vetox 85WP®), Carbofuran. Other field insect pest of maize is: Maize leaf hopper- Cicadulina spp (vector of streak disease in maize) 2. Weevils Maize weevils: Sitophilus zeamais Motschulsky Rice weevils: Sitophilus oryzae L. Life history: Adult females lay eggs in grains and these hatches and pupate within the grains. Adult weevils and larvae fee on grains reducing them to powder. They are field to store pest. Other maize storage pests are: Larger Grain borer- Prostephanus truncatus (Horn) Lesser Grain borer- Rhyzopertha dominica (Fabricius) (B) GRAIN LEGUMES Field Insect Pest of Cowpea Flower thrips: Megalurothrips sjostedti (Trybom) Sericothrips occipitalis (Hood) Life history and damage: Eggs are laid on parts of the plant. These hatch into pale yellowish nymphs. Damage: adults and nymphs feeds on the shoots, flower buds and pollen may also be found on young pods. They cause distortion and drying up of flowers and severe attacks may lead to flower shedding. 1 Control: i. Cultural control: Reduced thrips infestation has been observed on cowpea intercropped with sorghum, millet and cassava. ii. Resistant varieties: Varieties such as TVx 3236 have been developed and found to be resistant to thrips damage. iii. Chemical control: control with insecticides such as Cymbush, Azodrin, Nuvacron, Deltamethrin, Monocrotophos as soon as flowering starts (35 DAP) Pod suckers: Anoplocnemis curvipes F. Riptortus dentipes F. Mirperus jaculus Thunb. Acanthormyia tomentosicollis Life history: Eggs are laid on pods, stems and leaves. The nymphs hatch out and feed on all parts of the plant until they are fully developed. Damage: Both adult and nymphs feed by sucking sap from the green pods causing dumping of the seed coat, pod abscission, abortion, deformation through premature drying or shriveling, incomplete pod fill and deformation and abortion of seed. Control: i. Farm sanitation: weed management ii. A solution of 9% neem seed kernel extract (wt/vol) decreased insects’ survival. iii. Chemical control using cypermethrin and dimethoate Pod borers: Maruca testulalis (Geyer) Cydia ptychora (Meyrick) Life history: Female moth place their eggs on the bracts of flower buds or in axils of leaves. The young larvae bore into the flowers, feeding inside and causing flowers to drop. Young stems, terminal shoots and peduncles are also damaged. Signs of larval feeding include the webbing of flowers, leaves and pods and the presence of frass on the shoot tips and pods. Control Cultural control: Avoid monocropping Chemical control using Cymbush, Azodrin, Nuvacron starting 35 DAP and continue weekly. Biological control e.g. Bracon hancocki for C. ptychora Major Storage Insect Pest of Cowpea Cowpea seed beetle: Callosobruchus maculatus F. Life history: The whitish eggs are laid on pods and seeds in storage. The developing larvae bore into the seeds and eat all the content. An emergent hole of the adult is made after about 25-30 days. Control 1. Non-chemical control Mixing cowpea with a dried powder of the hot brown pepper, Piper guineense Neem kernel powder at 5-10g/100g seed Mixing with refind palm oil and vegetable oil at 5-10ml/kg seed 2. Chemical control: Admixing with pirimphos-methyl (Phostoxin) and actellic dust 2 Other field insect pests of Cowpea are Leaf beetle defoliator Ootheca mutabilis Sahl (C) TREE CROPS/CASH CROPS 1. Cocoa The major pests of cocoa are the mirids, also known as capsids Brown cocoa mirids, Sahlbergella singularis Hagl Black cocoa mirid, Distantiella theobroma (Dist.) Cocoa mosquito: Helopeltis bergrothi Reut. Life history: Eggs are deposited in the green shoots, stems and pods. The eggs hatch in 2-3 weeks and the young nymphs begin to feed on the trees at night and rest during the day behind pods where leaves join the branches and where branches meet. Damage: Cocoa mirids adults and nymphs feed intensively on cocoa pods, stalks, shoots and stems causing considerable damage including death of terminal shoot and consequently loss in yield. Mirids attack on pods may cause pod deformation, distortion or bean decay depending on the severity of the attack. Control: Cultural: Pruning of infested tissue and shade management Avoid breaks in the canopy Chemical control: Spray with recommended insecticide during the period of high infestation Note: Spraying against mirids on young cocoa trees should start in June and continue at monthly interval until February. Other major pests of cocoa Long-horn beetles: Tragocephala castnia (Thompson) Cocoa mealy bugs: Plannococcus njalensis (Laing) Plannococcus citri (Risso) Cocoa Ear perforator: Characoma Strictograpta Cocoa shield bug, Bathycoelia thalassina H and S. Red banded thrips, Selenothrips rubrocintus (Giard) (D) Coffee Coffee leaf rollers: Epicampoptera glauca (Hmps) Life history: The female moth lays their eggs in a long chain on leaf surfaces. Damage: Young larvae feed inside the underside surface of the leaf thereby reducing the productivity of plants. Control: Insecticide by spraying recommended insecticide (E) Citrus Citrus swallow tail butterfly – Papilio demodocus Life history: Egg which are spherical with white and black markings are laid singly on new citus leaves. 3 Damage: Larvae attack young leaves usually feeding at the leaf edge but can cause complete defoliation. Control: Physical control: Eggs and larvae from young trees should be removed and destroyed Scouting for the pest is important to detect early infestations. Chemical control: In case of serious attack synthetic pyrethroids (Cypermethrin, Permethrin) can be applied. Other major pests Spiny bollworm- Earias biplaga Fruit piercing moth – Achaea lienardi Ophideres fullonia (F) ROOTS AND TUBERS (i) Field insect pests of Cassava Whiteflies: Bemisia tabaci Genn. Life history and Damage: Adult flies are very small insects about 1.5mm long. The female lay over 100 eggs on the underside surface of the leaves. Adult have piercing and sucking mouthparts and feed on plant sap. During feeding, the insect transmits African cassava mosaic virus which is a major disease of cassava in Nigeria in which the yield losses may be 20-60%. The insect also secretes honey dew which encourages the growth of sooty moulds over the leaves. Control: Resistant varieties Diseased plant should be destroyed Apply contact insecticides which are directed at the underside of the leaves can be used, e.g. Cypermethrin. Other field insect pests of Cassava are: Grasshopper: Zonocerus variegatus L. Cassava green spider mite: Mononychellus tanajoa Bondar Cassava mealy bugs Planococcus citri (Risso) (ii) Insect pests of Yam Grater yam beetles, Heteroligus meles (Billberger) Lesser yam tuber beetle, Heteroligus appius (Burmeister) Life history and damage: Adult H. meles beetles are about 23-33 mm in length. First attack setts just after planting and continue to feed for 4-5 months. Adult feeding produces 1-2 cm holes in the tubers which reduces market value and may encourage plant decay. Control Chemical: Application of insecticides such as pirimiphos-methyl, diazinon and carbofuran granules at planting time. 4 (G) HORTICULTURAL CROPS (FRUITS AND VEGETABLES) (i) Okra Flea beetle: Podagrica uniformis Jacoby Podagrica sjostedti Jacoby Life history and damage: Adult lay eggs in the soil. Larvae hatch and feed on roots before pupation in the soil. Larvae feed on the roots. Adult beetles feed on the leaves causing numerous small holes. Injuries reduces plant yield and delay plant development. Control: Cultural: Intercropping with Amaranthus sp. may help reduce pest population Chemical: Recommended chemical include Cypermethrin and Deltamethrin. Start spraying 5 days after germination and every two weeks until 15 days into fruit harvest. Other field insect pests includes; Cotton aphids, Aphis gossypii Glov. Whitefly, Bemisia tabaci Genn (ii) Tomato Fruit worm: Helicoverpa armigera Life history and Damage: Larvae bore into fruits causing damage and allow entry of fungal pathogens. This sequence of events leads to fruit drop when fruits are attacked, their market values are reduced if they are not completely lost Control: Spray with Permethrin starting from flowering stage at 2 weeks intervals and throughout fruiting period 5