Influences of high temperature shock on the reproduction and development of the Wolbachia\|induced parthenogenetic parasitoid wasp, Encarsia formosa (Gahan)
Abstract:The effects of constant high temperature (31℃) and alternating high\|low temperature (31℃ for 16 hours and 25℃ for 8 hours) on reproduction and development of Wolbachia\|infected Encarsia formosa were investigated in the laboratory. When treated with constant high temperature, for the wasps, the reproduction ability decreased and the longevity shortened; for the offspring, the male ratio increased and adult emergence rate decreased. More than 45% males were induced from the 1st generation and male percentage of 3rd generation reached 81%. These results indicated that the high temperature was destructive to E. formosa population. Therefore, the environmental temperature should be paid attention when the wasp was reproduced in factory or applied in field in order to avoid the loss caused by high temperature. The sex ratio and the proportions of Wolbachia\|infected female of offspring recovered to as those of wasp untreated once the high\|temperature\|treated wasps were transferred to 25℃, whether they have been reared for 3 or 6 generations under 31℃. These results suggested that Wolbachia could adapt to environmental changes. In the treatment of alternating temperature, the percentage of male wasps (13%) was low although they were induced from the 2nd generation, indicating that short high temperature shocks could not influence the reproduction pattern of Wolbachia\|infected E. formosa. Whereas, if short high temperature shocks were maintained for several days, the sex ratio of Wolbachia\|infected E. formosa could be changed significantly.