Caryedon serratus (Olivier)
Common name: Peanut beetle, ground seed beetle.
Taxonomic placing: Insecta, Holometabola, Coleoptera, Bruchidae.
Geographical distribution : Cosmopolitan. CABI Distribution Maps of Pests, Series A, Map #318, 1973.
Host plants: Peanuts (Arachis hypogaea Linnaeus), Tamarind (Tamarindus indica Linnaeus) and Acacia spp.
Morphology: Adults 4-5 mm long, body reddish-brown with darker spots. The Prothorax](entry/Prothorax) is trapezoid, with dense, grey pubescence, and the hind legs are enlarged. Larva (grub) whitish with a brown head.
Life history: The females lay several hundred eggs, more in shelled groundnut than in tamarind and unshelled groundnuts, gluing them to the surface of the shells or kernels. The newly hatched larva burrows straight through the eggshell and pod wall, and eats the kernel, feeding only within a single seed. Development requires about 10 weeks at 25°C.
Economic importance: The pest damages peanuts as well as tamarinds. Infestations cause reductions in food value, in the quality of the oil and in reduced seed germination. Such damage is particularly significant when the peanuts are destined for confectionery purposes. The heat and moisture generated by the insects increases mold growth and the development of aflatoxins in groundnuts.
Management
Monitoring: The presence of larval emergence holes and of cocoons outside the pods attest to the pest’s presence. The damage to seeds can be seen when infested pods are opened.
Horticultural methods: Cleaning grain stores, keeping them airtight, maintaining temperatures below 20°C and hermetically sealed packaging can conserving seed viability. Storing groundnuts in jute bags greatly restricts the movement of adults into and out of bags.
Chemical control: Extracts of several plants {such as neem seeds) reduced beetle egg hatching and larval development, but had little effect on the adults.
Biological control: An application of an isolate of the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin totally reduced progeny emergence and had some a repellent effect on the beetle. Several parasitoids attack the pest in Acacia pods, including the pteromalid Anisopteromalus calandrae (Howard).
References
Bhogeesh B. M., Arati, P. and Thirumalaraju G. T. 2012. Biology and Management of Caryedon serratu on stored Groundnut. Lambert Academic Publishing, 104 pp.
Ekesi, S., Egwurube, E.A., Akpa, A.D. and Onu, I. 2001. Laboratory evaluation of the entomopathogenic fungus, Metarhizium anisopliae for the control of the groundnut bruchid Caryedon serratus on groundnut. Journal of Stored Products Research 37: 313–321.
El Atta, H.A. and Ahmed, A. 2002. Comparative effects of some botanicals for the control of the seed weevil Caryedon serratus Olivier (Col., Bruchidae). Journal of Applied Entomology 126: 577–583.
Oaya, C.S., Malgwi, A.M. and Samaila, A. E. 2012. Damage potential and loss caused by the groundnut bruchid Caryedon serratus Olivier [Coleoptera: Bruchidae) on stored groundnut and tamarind in Yola. IOSR Journal of Agriculture and Veterinary Science 1: 58-62.