Diversity of insect fauna associated with summer and monsoon cowpea [Vigna unguiculata (L.) walp.]

Cowpea [Vigna unguiculata (L.) Walp.], is one of an important pulse grown throughout the world. The cowpea crop helps in fixation of atmospheric nitrogen; besides, it supports the natural enemies' population. The study on diversity of pestiferous insect associated with cowpea crop help to understand the population dynamics of these pests depending on location and seasons. These diversity studies are useful to formulate management practices which are area specific.

An extensive survey was conducted at different locations (Udaipur, Bhilwara, Banswara, Chittorgarh and Pratapgarh) of southern Rajasthan during summer (Zaid) and monsoon (Kharif) seasons of 2019 and 2020. The randomly selected plants were observed for pestiferous insect population to calculate different diversity indices.

The insect pest complex of cowpea categorized into 5 orders viz., Hemiptera, Thysanoptera, Coleoptera, Diptera and Lepidoptera comprising 14 families. The pestiferous fauna includes population of flea beetle, jassids, whiteflies, sap sucking bugs, leaf miner, thrips, aphids, spotted pod borer and lycaenid caterpillar. During the study, it was found that overall species richness was more during the monsoon season as compared to that during the summer. The relative diversity of aphids was the maximum on account of the clumped distribution and exponential growth. In 2019, the maximum diversity was recorded in Banswara (Simpson index= 6.49 and Shannon index= 2.04) during monsoon; whereas, in 2020, the maximum diversity was recorded in Bhilwara (Simpson index= 4.03 and Shannon index= 1.81) during summer.