Diversity of Predators Associated with the Mealybug Complex in Cassava Growing Districts of Tamil Nadu, India

Abstract

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.