Impact of Withdrawal of Pesticide Application against Papaya Mealybug, Paracoccus marginatus Williams and Granara De Willink on the Biodiversity of Natural Enemy Complex in Small Scale Papaya Farming System in Tamil Nadu

Abstract

Observations on the incidence of mealybug, Paracoccus marginatus Williams and Granara de Willink and spider and ants associated with it were recorded in 10 papaya fields each (total of 30 fields) falling in three categories viz. 1) Abandoned and severely infested fields released with parasitoid Acerophagus papayae, 2) Infested but yielding fields released with A. papayae. and 3) Fields with 2–4 months old crop without parasite release in Tamil Nadu. The P. marginatus incidence was reduced to an extent of 7–33 per cent with very low intensity in parasitoid released fields. Six species of spiders viz. Clubiona spp. crab spider, Thomisus spp., Jumping spider Phidippus sp., Plexippus sp., Araneus sp. wolf spider, Lycosa pseudoannulata were found and the most predominant one was Araneus sp. Nine species of coccinellids, viz. Brumoides suturalis (Fabricius), Cheilomenes sexmaculata (Fabricius), Coccinella septumpunctata Linnaeus, Coccinella nigrita Fabricus, Cryptolaemus montrouzieri Mulsant, Hippodamia variegata (Goeze), Hyperaspis maindroni Sicard, Nephus regularis Sicard and Scymnus coccivora Ayyar recorded from the fields. Two species of chrysopids, Chrysoperla zastrowi silemi (carnea) and Mallada sp. were observed. Parasitoids A. papayae and Torymus sp. (Torymidae) only were found. Four species of ants viz., Camponotus compressus (Fabricius), Camponotus sericeus (Fabricius), Camponotus parius Emery and Tapinoma melanocephalum (Fabricius) were found to be associated with mealybug. Avoidance of insecticide spraying resulted in the appearance of notable number of biocontrol organisms in papaya fields in Tamil Nadu.