Fitzgerald Terrence D, Wolfin Michael, Young Ryan, Meyer Katelyn, Fabozzi Elizabeth
Department of Biological Sciences, State University of New York, Cortland, NY 13045, USA.
Barton Lab, Department of Entomology, Cornell University, 630 West North Street, Geneva, NY 14456, USA.
Insects. 2016 Oct 31;7(4):59. doi: 10.3390/insects7040059.
The behavioral biology of the first instar larva of was studied from the time of eclosion until the colony penetrated and initiated excavation of the host plant. Hatching from an egg stick was asynchronous, requiring 20 h for the entire cohort to eclose at 50%-70% RH and significantly longer at a lower range of RHs. On eclosion, neonates aggregated in an arena at the base of their egg stick and did not attempt to excavate the cladode until an average of 25 caterpillars had collected, approximately 15 h after the onset of egg hatch. Typically only a single entrance hole was formed, limiting the active process of excavating to one or a few individuals at-a-time until the host was fully penetrated and enlarged internally. Olfactometer tests showed that the neonates are strongly attracted to volatile chemicals released when caterpillars chewed into the cladode, accounting for the strong fidelity of the whole cohort to the initial site of penetration. In one instance, the caterpillars were observed to deal with an explosive release of mucilage by imbibing the liquid until the flooded zone was drained and the caterpillars could reenter the plant through the original entrance hole. Once inside the cladode, marked individuals adopted a regular cycle of defecating at the surface at a mean interval of approximately 10 min when followed for 35 successive cycles. Blanket spraying cladodes with a mandibular gland extract prior to hatching led to the independent dispersal of neonates and a failure to form an arena. When the cladode was impenetrable at the site of eclosion, the active cohort of unfed neonates set off together in search of a new site, marking and following a persistent trail that allowed late-to-eclose caterpillars to join their departed siblings. The adaptive significance of these observations is discussed in the context of the life history of the caterpillar.
对[昆虫名称未给出]一龄幼虫从羽化直至群体穿透并开始挖掘寄主植物这段时间的行为生物学进行了研究。从卵块孵化是不同步的，在相对湿度50%-70%时，整个群体羽化需要20小时，而在较低相对湿度范围内所需时间明显更长。羽化时，初孵幼虫聚集在卵块底部的一个场地中，直到平均有25只毛虫聚集在一起，即卵孵化开始约15小时后，才开始尝试挖掘叶状枝。通常只形成一个入口孔，一次将挖掘活动限制在一个或几个个体，直到寄主被完全穿透并在内部扩大。嗅觉计测试表明，初孵幼虫对毛虫啃咬叶状枝时释放的挥发性化学物质有强烈吸引力，这解释了整个群体对初始穿透部位的高度忠诚度。有一次观察到，毛虫通过吸食黏液来应对黏液的突然释放，直到淹没区域的液体排干，毛虫才能通过原来的入口孔重新进入植物。一旦进入叶状枝，被标记的个体以大约10分钟的平均间隔在表面规律排便，连续观察了35个周期。孵化前用下颌腺提取物对叶状枝进行全面喷洒，导致初孵幼虫独立分散，无法形成场地。当羽化地点的叶状枝无法穿透时，未进食的活跃初孵幼虫群体一起出发寻找新地点，留下并跟随一条持久的踪迹，使晚羽化的毛虫能够加入已离开的兄弟姐妹。在毛虫的生活史背景下讨论了这些观察结果的适应性意义。
