Evaluation On Trichogramma Strains For Controling Helicoverpa Argmigera In Xinjiang

EVALUATION ON TRICHOGR4IIMA STRAINS FOR CONTROLING HELICOVERPA ARGMIGERA IN XINJIANG Abstract The four geographical Trichograrnma strains (tentatively named Akesu ,Tulufan ,Kashi and Kuerle ) from Xinjiang , and two Trichograinina strains (tentatively named U桰,U---lI) from Uzbekistan, were evaluated for attacking the cotton bollworm, Jlelicoverpa argmigera, in Xinjiang. I observed their performances under different temperatures and humidities, their fecundity and longevity when provided with different sugar food, and oviposition behavior. The strains?preferences to the cotton bollworm were also observed. I used a regimen of temperatures by 2O~C,250C,270C,3O 0C and 350C, combined with a regimen of relative humidities by 45%, 55%, 73% and 83% respectively. The data were subjected to ANOVA. The optimum growth condition for U條I was 25?70C with relative humidity 55?5%. The optimum temperature for Kashi and Tulufan was 25?O~C, and 25?7~C for the others (Akesu, Kuerlle and U桰), under the optimum relative humidity 75?5%. Low or high temperature, and low relative humidity, were harm to their growth. The sex ratio was male梑iased under high temperature (350C). The adult longevity and development rate of the six strains were obviously decreased with declining temperature , but were less affected by the relative humidity. The Trichogramma strains obviouly increased their fecundity and longevity when feeding on the sugar food. I Iound that the grape sugar was most effective, fo] lowed by honey and cane sugar. The Thiehcwrawzuia strain Akosu was experimented on the effects of their experience (whether nwiting, oviposition or not) and age (O?4h, 24?8h, 48?2h) on oviposi tion behavior on the eggs of 3 (憃rcvm cophnIonic~i. The result showed that duration of the host finding and host examination were decreased with oviposition experience and were shorter for younger females (O?8h). Basing on the above experiments, I conducted tests for screening Trichograininu strains by liassan?s method (1988) using 270C with relative humiditY 75% and 16 hours light in laboratory. The result showed that three out of the six strains were more effective for attacking the eggs of ileiicoverpa argmigera with strain U桰l being the most efective among the three (U桰l, Akesu and Kuerle). The other three strains behaved relatively poor.