Various insect pests attack groundnut crops at various stages of the crop's life in the field and during storage.
The field insects pest are categorized as follows:
- Major Sucking pests: Trips, Jassids, and Aphids;
- Major defoliators: leaf miner, tobacco caterpillar, gram borer, and hairy caterpillar;
- Major soil insect pests: white grubs, termites, earwigs, and jewel beetle [1].
Sucking Pests attacking groundnut
Trips (Scirtothrips dorsalis): These are small insects that reside in flowers and fodder leaves where they finish their life cycles and can be seen at any time of the year. White patches on older leaves and necrotic patches on younger leaf surfaces, which distort their shape, particularly in seedlings, are damage symptoms.
Jassids (Empoasca kerri): Both nymph and adult suck sap from the lower surface of young leaves; damage symptoms are whitening of leaf veins and the appearance of yellow patches at the tip of the leaflets of upper older leaves, typically in "V" appearance.
Aphids (Aphis craccivora): These are dark brown nymphs that develop into shiny black adults who gather into masses on young leaves, leaf buds, flowers, and aerial pegs and desap through phloem vessels. Symptoms will be yellowing of the plant and curly leaves. They secrete a sticky fluid on the plant, which is turned black by fungus.
As a control measure for sucking pests, the growing resistance varieties are recommended. Seed treatment with Imidacloprid (Gaucho 70WS) @2 ml/kg seeds, spraying dimethoate @ 200-250 ml a.i./ha when the crop is young and all terminal buds are infested with aphids or more than five thrips per terminal leaf are observed up to 30 days after emergence (DAE) or more than 10% of all leaves have characteristic 'hopper burn' up to 30 DAE [2].
Defoliator Pests
Leaf miner (Aproaerema modicella): After passing through all of its instars, the larvae emerge out and form a web with adjacent leaflets. Larvae continuously feed on the leaf tissue from inside the webbed leaves. From a distance, crops that have been badly attacked appear to be burning.
As a management precaution for leaf miner, spray Dimethoate @ 200-250 mL a.i. or monocrotophos @ 150 mL a.i. per ha if 5 or more active larvae per plant up to 30 DAE. As the number of larvae increases along with the days, installing pheromone traps @ 25 traps/ha and setting up light traps for destroying the moths is recommended [3].
Tobacco Caterpillar (Spodoptera litura): This pest lays eggs in masses on the leaves; however, part of the life cycle takes place in the soil. The larvae can be recognized by their distinctive pale green color with the presence of dark markings. The immature larvae feed by scraping beneath the surface of the leaves, leaving the vein and outer layers giving the fabric a surface. They defoliate totally, leaving only the stems. The second and middle-aged larvae feed by making small holes in the leaf; subsequent larvae feed voraciously on the entire lamina, petioles, and tender twigs; sometimes, they feed on the flowers and bore the tender groundnut pods. Generally, older larvae are night feeders.
Gram Pod borer (Anisolabis stalli): This pest feeds on several agriculture and horticulture crops. The adult lays single eggs on tender plant parts. The characteristic identification of this pest is dark greenish yellow/brown with variation in color. The damage is similar to tobacco and hairy caterpillars. The larvae prefer to feed on flowers and buds, pods, etc. They do not hide in the soil during the daytime.
Management of Tobacco caterpillar and gram pod borer, planting of sunflower and castor bean trap crops on borders and in the groundnut field (1 plant per 20 m2 ), and destroying egg masses on trap crops manually removing groundnut plants. Since both pests are nocturnal in habit, control measures are to be taken up either in the early morning or late evening hours. Application of NPV @ 250 LE/ha, neem seed kernel extract @ extract obtained from 10 kg neem fruit power/ha. Spraying of monocrotophos @ 300 mL a.i. or fenvalerate @ 100 mL a.i. or indoxacarb @ 70mL a.i. or Spinosad @45 mL a.i./ha If the defoliation increases and the presence of more larvae are observed. Setting up of pheromone trap (10 traps/ha) is advised.
Hairy Caterpillars (Amscata albistriga, Arachis moor, and Spilosoma obliqua): This pest outbreak is extremely sporadic and destructive. Young larvae feed by scrapping the underside of the leaves; mature larvae are voracious feeders which feed on leaves, flowers, and growing points and defoliate the crop, presenting a cattle-grazed field. The larvae of this pest are visible due to their hair, which is originally light brown but turns reddish as they grow, and they frequently move from field to field in quest of food.
As a precautionary measure, for red hairy caterpillars, digging a 15-20 cm deep trench all around the field and placing Ipomea or some other plant twigs in them can restrict the migrating caterpillars in the trench where they could be destroyed manually or by spraying fenvalerate @ 1mL/ L water [3].
Groundnut Soil pests
White Grubs (Lachnosterna consanguinea, Lachnosterna serrate): This pest's damage to roots begins in the early stage of its life cycle and peaks in the third stage when the larvae are most active. Plants show varying degrees of wilting and ultimately die. Plants that are damaged can be removed with ease. Additionally, grubs damage the pods by scratching the nutshell, and the roots show a sharp cut. Patches of dead plants can be seen throughout the field, which subsequently become widespread and cause extensive damage. The pest eggs will reside in the soil, and the larvae will remain there until next year. Adult beetles emerge with the first monsoon showers [4].
Termites (Microtermes spp., Odontotermes spp.): In particular sandy and red soil, this pest attacks the tap root and hollows out, causing wilting and premature death of plants. They also feed on pod shells by removing the corky material between the strands of vascular tissues. This characteristic damage is called scarification [5].
Earwig (Demoptera stali): Nymphs and adults both bore into the tender and matured pods and feed on kernels. The bored holes are mostly filled with sand particles, excreta, and decayed pulp. The inside of earwig-infected pods will be empty inside without any kernels or only partially fed kernels. Rarely the fecal & sand materials can be seen.
Management of soil pests followed by applying carbofuran 3G granules in the furrow @ 1kg a.i./ha and treating seeds with chlorpyriphos 20 EC @ 12.5 mL/kg seed for protection against white grubs in the initial stages. When the adult grub is feeding on crop plants, spraying of carbaryl 50 WP @ 2g/L of water 3-4 times until mid-July months, ideally using a community approach. For termites, mounds should be destroyed in and around the field; removal of plant residues and debris from the field and timely harvest can help to minimize the termite damage [4, 5].
Storage insect pests
Groundnut bruchids (Caryedon serratus): These pests damage both pods and kernels. The adult lays eggs on pods and kernels. The young larvae cut through the shell and burrow into the kernel and feed; Bruchid's cocoon looks papery white, and tough can be seen on the kernels.
Red flour beetle (Tribolium castaneum) and rice moth (Corcyra cephalonica): The characteristic damage of these pests is webbing in the case of rice moth and powdery remnants without webbing in the case of red flour beetle. Identification marks for red flour beetles are oblong in shape and brown in color, whereas the rice moth has grayish-brown forewings.
Management measures of groundnut storage peats
Development and attack of storage pests can be captured if the seed moisture content is kept low (not more than 5%); sanitary storage measures include spray of malathion 1.25% or deltamethrin 0.04% on the walls, floor, and roof of the warehouses or godowns before storage. Fumigation with aluminum phosphide 3 g tablet per sack of groundnut (40 g) and covering the sacks with a polyethylene sheet for five – eight days can effectively control storage pests [6].
References:
- N.Nigam, 2015. Groundnut at a glance.
- Rajasekhara R. K., Induced host plant resistance in the management of sucking insect pests of Groundnut, 2022. Annals of Plant Protection Sciences, vol:10, issue:1, ISSN:0971-3573.
- Nataraja M. V ., Kuldeep Singh Jadon, Prasanna Holajjer, Thirumalaisamy P.P., Poonam Jasrotia and Ram Dutta (2014) "Integrated Pest and Disease Management in Groundnut" Directorate of Groundnut Research, P. B. No. 05, Junagadh-3 62 001, Gujarat, India, Technical bulletin, No 02/2014, page 19.
- Nataraja M.V., Kuldeep S. Jadon, Ram Dutta, Savalia S.D., White grubs and their management in groundnut, Directorate of Groundnut Research, P. B. No. 05, Junagadh-3 62 001, Gujarat, India.
- Logan, J., Rajagopal, D., Wightman, J., & Pearce, M. 1992. Control of termites and other soil pests of groundnuts with special reference to controlled release formulation of non-persistent insecticides in India and Sudan. Bulletin of Entomological Research, 82(1), 57-66. doi: 10.1017/S000748530005149X
- http://agritech.tnau.ac.in/org_farm/orgfarm_prac_agri_groundnut_storage.html
Further reading
Groundnut: Plant Information, History, Uses and Nutrition Value
Principles of selecting the best varieties of Groundnut: A Comprehensive Guide
Groundnut Soil requirement, Soil preparation and Planting
Weed Management in Groundnut Farming
Fertilizer requirement for Groundnut Cultivation
Irrigation Requirement and Methods for Groundnut Cultivation
Groundnut Diseases and Management Practices
Groundnut Insects, Pests, and their Management
