Bioecology and management of mealybug phenacoccus solenopsis Tinsley Hemiptra Pseudococcidae on Bt cotton

Abstract

Investigations were carried out on survey, seasonal fluctuation of mealybug, newlinePhenacoccus solenopsis Tinsley and its natural enemies, crop loss assessment, estimation of newlineEIL, biology of mealybug, biology of the predator Cryptolaemus montrouzieri Muls. and newlineefficacy of insecticides including biological agents against mealybugs were undertaken during newline2008-09 and 2009-10 at MARS, Raichur and Department of Entomology, College of newlineAgriculture, Dharwad. newlineMealybug incidence was moderate to severe in Raichur, Bellary and Gulbarga newlinedistricts while its incidence was low in Dharwad, Haveri and Belguam districts of North newlineKarnataka on Bt cotton. The peak activity of the parasitoids was observed mainly from newlineJanuary to March in both the years. Mean per cent parasitoid emergence from mealybugs newlinecollected at various places was highest in TBP and UKP areas as compared to other districts newlinein both the years. There were more than 15 alternate host plants of P. solenopsis belonging to newlineeight families found across the cotton growing districts of North Karnataka. Among them, newlineAbutilon indicum L. (Malvaceae) and Parthenium hysterophorus L. (Asteraceae) were the newlinemajor weed hosts. newlineSteep increase in the mealybug population was observed from January and reached newlinepeak in March in both the years of study. Initially parasitoid population was low and peak newlineactivity started during first week of January which gradually increased up to 34.62 per cent newlineand 34.64 per cent during the last week of March 2008-09 and 2009-10 seasons, newlinerespectively. Among different parasitoids, Aenasius bambawalei Hayat was the dominant newlinespecies. Total life cycle of P. solenopsis female and male was 38.47 and 20.33 days, newlinerespectively. The total life cycle of Cryptolaemus montrouzieri was 28.82 and 24.71 days newlinewhen reared on the mealybug nymphs and adult female, respectively. newlineCrop loss estimation due to mealybug damage indicated that cotton plants did not newlinesurvive at all the damage levels at 60 days after sowing in both the years. Cotton newlineyield was severely affected due to different levels