Background: The bruchid Callosobruchus chinensis (L.) is one of the major store grain pest of pulses capable of attacking wide range of legumes viz., green gram, black gram, chick pea and pigeon pea and causes 50 per cent damage during storage within 3 to 4 months. The infestation starts in the field, but heavy damage is done in storage. Hence, the current study was aimed to evaluate the insecticidal, oviposition deterrent and antifeedant activity of certain plant extracts against pulse beetle, C. chinensis under storage condition.Methods: The aquous extracts (10%) of Vitex negundo, Pongamia glabra, Cassia angustifolia and Calotropis gigantea were evaluated against the pulse beetle, Callosobruchus chinensis Linn. were carried out at the Department of Agricultural Entomology, Imayam Institute of Agriculture and Technology, Thuraiyur during 2019-20. The commercial product Azadirachtin was kept as a check and the mortality rate was assessed every 24 Hours after treatment (HAT) for three days.Result: The mortality rate after 72HAT was 85.8-87.5% with V. negundo, followed by C. angustifolia (73.33-80.00%) and P. glabra (70.0-75.0%). Azadirachtin gave 100% mortality of the beetle. The oviposition deterrence percentage for pulse beetle, C. chinensis was found to be highest in Calotropis gigantea (37.66-68.16%) followed by Pongamia glabra (30.91-41.50) and Vitex negundo (7.58-46.75) per cent, respectively. The antifeedant activity for pulse beetle was found to be very high when treated with Azadirachtin where there was no food consumption. This was followed by V. negundo (0.1g) and C. angustifolia (0.2g).
An extensive survey was carried to study the diversity of predators associated with the mealybug complex in the cassava growing districts viz., Salem, Namakkal, Erode, Tiruppur and Coimbatore of Tamil Nadu, India from January to September, 2021. The survey revealed the dominance of Phenacoccus manihoti Matile-Ferrero 1977 (Hemiptera: Pseudococcidae) than other mealybug species in all the surveyed districts. The incidence of P. manihoti ranged from 12 to 90 per cent while Paracoccus marginatus Williams and Granara de Willink 1992 (Hemiptera: Pseudococcidae) incidence was found to be between 8 and 54 per cent. The incidence of Ferrisia virgata Cockerell 1893 (Hemiptera: Pseudococcidae) was found to be very low (8-16%) compared to other mealybug species. Association of total predators with P. manihoti were found to be maximum (30.87%) followed by the total predators with P. marginatus (6.49%) whereas 0.53 per cent of total predators associated with F. virgata. The fourteen different predators viz., Cryptolaemus montrouzieri Mulsant 1853 (Coleoptera: Coccinellidae), Menocheilus sexmaculatus Fabricius 1781 (Coleoptera: Coccinellidae), Anegleis cardoni Weise 1892 (Coleoptera: Coccinellidae), Hyperaspis maindroni Sicard 1929 (Coleoptera: Coccinellidae), Brumoides suturalis Fabricius 1798 (Coleoptera: Coccinellidae), Scymnus spp. (Coleoptera: Coccinellidae), Chrysoperla spp. (Neuroptera: Chrysopidae), Mallada spp. (Neuroptera: Chrysopidae), Spalgis epeus Westwood 1851 (Lepidoptera: Lycaenidae), Geocoris spp. (Hemiptera: Geocoridae), Cardiastethus spp. (Hemiptera: Anthocoridae), Diadiplosis spp. (Diptera: Cecidomyiidae), Oxyopes spp. (Araneae: Oxyopidae) and Argiope spp. (Araneae: Araneidae) were found to associated with the mealybug species viz.,P. manihoti, P. marginatus and F. virgata. Among the predators of the mealybug complex, the most relative abundant species were H. maindroni (11.74%) associated with P. manihoti and C. montrouzieri (6.49%) associated with P. marginatus followed by S. epeus (0.67%) associated with F. virgata. The diversity of predators assessed through Simpson’s Index of Diversity, Shannon-Wiener, Pielou’s Evenness and Margalef indices revealed highest species diversity, species richness and species evenness in Namakkal district.
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