热浪胁迫对松墨天牛繁殖特性的影响

Effects of heat wave stress on the reproductive properties of Monochamus alternatus(Coleoptera:Cerambycidae)

【目的】松墨天牛Monochamus alternatus是我国南方松林重要蛀干害虫,也是松材线虫Bursaphelenchus xylophilus病的主要媒介昆虫。探究热浪(heat wave)事件对松墨天牛繁殖特性的影响,可为全球气候变暖背景下其种群动态和松材线虫病流行规律的预测预报提供理论依据。【方法】对松墨天牛16日龄成虫进行模拟热浪处理(40℃持续72 h),随后将其置于室温(25℃)交配产卵,每周为1个观测周期,统计成虫的单雌日均产卵量、卵长、卵历期和孵化率等生殖参数及子代幼虫体重的变化规律。【结果】热浪处理组单雌日均产卵量与对照组无显著差异。热浪处理组卵长在第1个观测周期内比对照组短0.09 mm,第2个观测周期以后反超并一直长于对照组。热浪处理组卵历期在第1个观测周期内比对照组长1.16 d,第2个观测周期内即与对照组相同,并在此后短于对照组。热浪处理组卵孵化率由91.83%下降至63.04%,直至第4个观测周期才恢复至与对照组水平。从子代幼虫体重来看,无论初孵幼虫体重如何变化,饲养28 d后热浪处理组与对照组子代幼虫体重均会达到同一水平。【结论】实验室内模拟单次热浪事件短期会对松墨天牛的生殖参数产生负面影响,但随着热浪胁迫解除松墨天牛成虫的繁殖能力能在较短时间内恢复,通常在7 d后即可恢复至正常水平,甚至得到一定的促进,对热浪胁迫表现出“毒物兴奋”响应。推测在气候变暖条件下,松墨天牛仍能在原分布区保持较高的种群密度。

【Aim】Monochamus alternatus is an important wood-boring pest of pine forests in southern China,and also the main vector insect of Bursaphelenchus xylophilus.Investigating the effects of heat wave events on the reproductive properties of M.alternatus can provide a theoretical basis for the prediction of its population dynamics and the epidemiological pattern of B.xylophilus under the context of global warming.【Methods】The 16-day-old adults of M.alternatus were subjected to a simulated heat wave treatment(40℃for 72 h),subsequently placed at the room temperature(25℃)and allowed to mate and oviposit.The variation rules of the reproductive parameters,such as daily average number of eggs laid per female,egg length,egg duration and hatching rate,and the body weight of offspring larvae were observed every week as an observation period.【Results】There was no significant difference in the daily average number of eggs laid per female between the heat wave treatment group and the control group.Egg length in the heat wave treatment group was 0.09 mm shorter than that in the control group in the 1st observation period,and then exceeded and remained longer than that in the control group after the 2nd observation period.The egg duration in the heat wave treatment group was 1.16 d longer than that in the control group in the 1st observation period,and then was the same as that in the control group in the 2nd observation period and shorter than that in the control group thereafter.The hatching rate of eggs in the heat wave treatment group decreased from 91.83%to 63.04%until the 4th observation period when it recovered to the same level as that in the control group.In terms of the body weight of offspring larvae,the heat wave treatment group and the control group reached the same level after 28 d of rearing,regardless of the variation in the body weight of the newly hatched larvae.【Conclusion】The heat wave event simulated in the laboratory has a negative impact on the reproductive parameters of M.alternatus in the short period.However,after relieving of heat wave stress,the reproductive ability of adult M.alternatus can be restored in a relatively short period of time,usually returning to normal levels after 7 d,and is even promoted to a certain extent,demonstrating its poisonous euphoria response to the heat wave stress.These results indicate that M.alternatus can still maintain a high population density in its original distribution area under the climate warming conditions.