%O           w as pr ovided by the UK Department for International Devclopment (DfID)
Funding
in Crop Protection Programme. Dr. A. Polaszek, CAB International Institute of
Entomology provided <luthoritative identific<ltion of Trichograllllll(/ ell ilol1is collecteLl
both fro m sorghum and cotton.        We also wish to acknowledge the continued
Stlpport of))r. Roclomiro Ortiz, Director, Gen etic Resources Enhancemcnt Programme
(GREP),   ICRIS/\f for providing thc                                                  K.Y.S.
                                       facilitics. Mr. M. Dcvendar Rao and Mr.
Satyanarayana of ICRISAT provided invaluablc technical assistance.

%K           cotton, cropping systems, Helicoverpa armigera, sorghum, Triclzogral11ma
chilonis.

%A D R Jadhav
%A D. Russell
%A N J Armes
%A K R Kranthi
%I Eastern University, Sri Lanka
%V 2
%L icrisat4951
%J AGRIEAST: Journal of Agricultural Sciences
%P 6-16
%D 2000
%X 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.

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