ICIPE Field Station, P.O. Box 1213, Port Sudan, Sudan.
J Insect Physiol. 2010 Jun;56(6):640-5. doi: 10.1016/j.jinsphys.2010.01.012. Epub 2010 Feb 11.
Previous studies had demonstrated stage differentiation in the cohesion (aggregation) pheromone systems of the desert locust, Schistocerca gregaria. In laboratory arena, the nymphal and adult stages responded aggregatively to their own pheromone, but dispersed evenly within the arena in the presence of the other. In the present study, we explored the effects of longer-term contact of field gregarious hopper bands and laboratory crowd-reared nymphs with the major constituent of the adult pheromone. During the first few days, hoppers in treated bands became relatively hyperactive. Over the next few days, their movements became random and they stopped marching as coherent groups, they started to roost for longer periods on vegetations, and they fragmented into smaller and smaller groupings and individuals. When attacked by birds, they demonstrated subdued levels of collective defensive behaviour compared to normal hoppers, and there were clear signs of increased predation and cannibalism at the roosting sites. In cage experiments, crowd-reared nymphs treated with the pheromone component became hyperactive, showed abnormal diel patterns and reduced feeding on plants but increased cannibalism. Our observations show that the major adult pheromone constituent has a solitarising effect on gregarious hoppers. The mechanism underlying this effect and the potential of the agent in desert locust control are discussed.
先前的研究表明，沙漠蝗的聚集（聚集）信息素系统存在阶段分化。在实验室竞技场中，若虫和成虫阶段对自身信息素表现出聚集反应，但在另一种信息素存在的情况下，它们在竞技场中均匀分散。在本研究中，我们探讨了野外群居蝗蝻带和实验室群体饲养的若虫与成虫信息素主要成分的长期接触的影响。在最初的几天里，处理过的蝗蝻带中的蝗蝻变得相对活跃。在接下来的几天里，它们的运动变得随机，不再像有组织的群体一样行军，它们开始在植被上长时间栖息，并且分裂成越来越小的群体和个体。当受到鸟类攻击时，与正常蝗蝻相比，它们表现出较弱的集体防御行为，并且在栖息点明显有更多的捕食和同类相食现象。在笼养实验中，用信息素处理的群体饲养的若虫变得活跃，昼夜节律模式异常，对植物的摄食量减少，但同类相食增加。我们的观察表明，主要的成虫信息素成分对群居蝗蝻具有独居作用。讨论了这种效应的机制以及该制剂在沙漠蝗防治中的潜力。
