Browsing by Author "Charles Sahayaraj"

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    Effect of sub lethal dose of insecticides on electrophysiological and behavioral response of Bracon brevicornis Wesmael (Braconidae : Hymenoptera) a parasitoid of coconut black headed caterpillar, Opisina arenosella Walker (Oecophoridae : Lepidoptera)
    (2012) Kesavan Subaharan; Charles Sahayaraj; Prasad, A.R.; Ravikumar, N.
    Bracon brevicornis Wesmael (Braconidae : Hymenoptera) is an effective parasitoid against coconut black headed caterpillar, Opisina arenosella Walker (Oecophoridae : Lepidoptera) a major pest on coconut. During outbreaks, chemical insecticides and bioagents are used in tandem to manage O. arenosella. Traditionally the impact of pesticides on beneficial arthropods was assessed by determining acute toxicity. In addition to direct mortality caused by insecticides, the sublethal effect on sensory physiology and behavior of parasitoids must be considered for complete analysis of their impact. The present study aims to investigate the impact of sub lethal dose of insecticides on B. brevicornis. In olfactory assay, the starved parasitoids oriented to food source, whilst the fed parasitoids responded more to host volatiles. In electrophysiological assay, the antennal responses of B. brevicomis to host volatiles were higher in female. Among the volatiles tested, the host frass and host haemolymph was most preferred by both sexes. Exposure of B. brevicornis to sublethal dose of imidacloprid, malathion and carbaryl (LD20) altered the orientation of B. brevicornis to host volatiles.