Influence of temperature on development and parasitism of Trissolcus vassilievi (Hym., Scelionidae), egg parasitoid of sunn pest, Eurygaster integriceps (Hem., Scutelleridae) under laboratory conditions
2010
Kasraee, N. | Moeeni Naghadeh, N. | Zamani, A. A. | Asgari, Sh. | Mahjoub, M.
Sunn pest, Eurygaster integriceps Put. (Hem., Scutelleridae), is the most important pest of wheat in Iran. Trissolcus vassilievi (Hym., Scelionidae) is one of the most important parasitoids that attack the eggs of sunn pest in Iran wheat fields. The effects of eight constant temperatures (15, 17, 20, 25, 30, 35, 37 and 40¢ªC) on developmental and percentage of parasitism of T. vassilievi were evaluated in laboratory under 65¡¾5% relative humidity and a photoperiod 16L:8D hours. The obtained results showed that T. vassilievi is able to develop at a broad range (15-37¢ªC) of temperature. No adult wasp was observed at 40¢ªC. There were significant differences among developmental times of wasps at various constant temperatures. The shortest developmental times of male and female wasps were occurred at 35¢ªC equal to 6.71¡¾0.17 and 7.24¡¾0.07 days, respectively. No significant differences were observed between development of males and females at a given temperature. The lowest and highest parasitism percentage of T. vassilievi, 31.00 ¡¾ 2.08 and 97.67 ¡¾ 1.45% were obtained at 40 and 25¢ªC, respectively. The lower developmental thresholds (T0) for males and females were calculated 10.86 and 11.11¢ªC. The thermal constant required for development of males and females of T. vassilievi were estimated 178.57 and 188.86 degree-days, respectively.
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