Density of Diachasmimorpha longicaudata (Ashmead) and host Ceratitis capitata (Wied) larvae for the increase of parasitoid female production

ABSTRACT: The objective of the present study was to evaluate the ratio of Ceratitis capitata larvae/female of Diachasmimorpha longicaudata that results in the increase of parasitism and the production of females in the progeny. We used 8-day-old copulated D. longicaudata females with oviposition parasite experience and third instar larvae of C. capitata from rearing stock maintained at the Laboratory of Biological Control of Universidade Estadual de Montes Claros (Unimontes). Five densities of C. capitata larvae (10, 20, 30, 40, and 50) were offered to parasitoid females that were at five different densities (1, 2, 5, 10, and 15). The larvae were exposed to the parasitoid females by means of “parasitism units” in adapted cages for 1 hour. Sex ratio, percentage of parasitism, and pupal mortality were evaluated. Both host larval density and female parasite density influenced parasitism, female progeny production, and pupal mortality. Higher female production was observed in the progeny in ratios of 1:1 and 2:1 (larvae/females). Ratios above 1:2 reduced the sex ratio, and ratios below 1:1 caused high pupal mortality rates. The females had higher parasitism activity when they were in groups dividing the same space. Equal ratios of Ceratitis capitata larvae and parasitoid females resulted in improved efficiency in progeny females.

摘要：本研究旨在探究可提升寄生率（parasitism）并增加子代（progeny）雌性个体数量的地中海实蝇（Ceratitis capitata）幼虫与长尾全裂茧蜂（Diachasmimorpha longicaudata）雌蜂的接种比例。本实验采用8日龄已交配且具有寄生产卵经历的长尾全裂茧蜂雌蜂，以及取自蒙特斯克拉鲁斯州立大学（Unimontes）生物防治实验室饲养种群的地中海实蝇三龄幼虫。实验设置5个梯度的地中海实蝇幼虫密度（10、20、30、40、50），分别接入密度为1、2、5、10、15头的寄生蜂（parasitoid）雌蜂群中。通过改良笼具中的"寄生试验单元（parasitism units）"使幼虫与寄生蜂雌蜂接触1小时，随后统计子代性比（sex ratio）、寄生率及蛹死亡率（pupal mortality）。研究结果显示，寄主幼虫密度与寄生蜂雌蜂密度均对寄生率、子代雌性产量及蛹死亡率存在显著影响。当幼虫与雌蜂比例为1:1及2:1时，子代雌性个体产量更高；当比例高于1:2时，子代性比会下降，而比例低于1:1时则会引发较高的蛹死亡率。共享同一空间的群居寄生蜂雌蜂具备更高的寄生活性。当地中海实蝇幼虫与寄生蜂雌蜂的接种比例相等时，可提升子代雌性个体的繁育效率。