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Impact of Sorghum on Natural Parasitism of helicoverpa armigera (hubner) by Trichogramma Chilonis IIhii in Cotton in Southern India,

Eastern University, Sri Lanka
Publication Date
  • Sorghum


Field trials were condu cted on three cotton hybrids (MECH 1, MECH 12, and RCH 2) grown alone, and with a sorghum hybrid (CSH as a neighbouring crop at two 1) villages, RavulapaJly and Sankeypally, in Ranga Reddy district. Cotton hybrids grown neighbouring to sorghum had significantly higher levels of egg parasitism by TricllOgraJrlma chilonis than in a monocrop. The enhanced level of parasitis m was due to a temporal shift in the T. chilonis population from sorghum to cotton during the cropping season. Paras it ism on sorghum increased slowly in relation to host egg density at both the'village sites and reached a peak of 70% and 60% by mid-September at Ravulapally and S a nkey pally respectively. The mean clutch size on sorghum was 2.06, w i th a maximum of 5 parasitoids emerged per egg. Parasitism of Helicoverpa eggs on cotton by T. chilollis r eac hed a maximum of 68% in mid-October annigera as a neighbouring crop to sorghum and 45% as a 1110nocrop. The mean when grown clutch size on cotton was 2.24, with a maximum of 5 parasitoids emerged per egg. Among the three cotton hybrids tested, parasiti9m was significantly higher on MECH 12 e i t h er grown alone or neighbouring to sorghum.The results are discllssed in terms of the dyn a mi c s of T. chi/ollis buildup on sorghum ancl its subsequent migration to cotton management strategy to suppress the population carryover of H. annigera on as a cotlon.

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