1 Deanship of Scientific Research, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
J Insect Sci. 2013;13:84. doi: 10.1673/031.013.8401.
Entomopathogenic nematodes are generally considered beneficial organisms. However, they can affect beneficial insects such as parasitoids. The interaction between the entomopathogenic nematodes Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) and Steinernema carpocapsae Weiser, and the parasitoid Microplitis rufiventris Kokujev (Hymenoptera: Braconidae) was investigated in the laboratory. In non-parasitized hosts, Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) larvae exposed to H. bacteriophora showed a higher percent mortality than those exposed to S. carpocapsae. Both nematodes were able to invade and propagate in non-parasitized S. littoralis larvae and those parasitized by M. rufiventris. Both nematode species reproduced in Microplitis-parasitized hosts, but there was a higher number of nematodes in non-parasitized larvae. S. carpocapsae yielded higher numbers of infective juveniles than H. bacteriophora. Generally, the number of nematodes harvested increased as their host's size increased. The interaction between the nematodes and parasitoid favored the nematodes when the nematodes were inoculated during the parasitoid egg stage or the young parasitoid larvae, thus giving the nematodes a better chance to grow and reproduce, resulting in the death of the parasitoid larvae. Conversely, when the nematodes were inoculated during the late larval instar of the parasitoid, the competition partially favored the wasp, thus giving approximately 50% of the wasps a better chance to develop, emerge, and reproduce, providing evidence that both nematodes and wasps could reproduce in the same host. Egg maturation of female wasps derived from nematode-infected hosts was not significantly different than those from control hosts. The combined application of nematodes and parasitoids may be beneficial if the detrimental effects of the nematodes on the parasitoid could be avoided by precisely timing the application strategies. It is clear that Microplitis larvae and the nematodes share the host larva and engage in a trophic interaction with each other. Intraguild predation is briefly discussed.
昆虫病原线虫通常被认为是有益的生物。然而，它们会影响到一些有益昆虫，例如寄生蜂。在实验室中，研究了昆虫病原线虫异小杆线虫 Poinar（小杆目：异小杆科）和斯氏线虫 Steinernema carpocapsae Weiser，以及寄生蜂金小蜂 Microplitis rufiventris Kokujev（膜翅目：姬蜂科）之间的相互作用。在未被寄生的宿主中，棉铃虫幼虫暴露于异小杆线虫中比暴露于斯氏线虫中的死亡率更高。两种线虫都能够入侵和繁殖在未被寄生的棉铃虫幼虫和被金小蜂寄生的幼虫中。两种线虫都在被金小蜂寄生的宿主中繁殖，但在未被寄生的幼虫中，线虫的数量更多。斯氏线虫产生的感染性幼虫数量高于异小杆线虫。通常，随着宿主大小的增加，收获的线虫数量增加。当线虫在寄生蜂卵期或年轻的寄生蜂幼虫期接种时，线虫和寄生蜂之间的相互作用有利于线虫，从而使线虫有更好的机会生长和繁殖，导致寄生蜂幼虫死亡。相反，当线虫在寄生蜂幼虫后期接种时，竞争部分有利于寄生蜂，从而使大约 50%的寄生蜂有更好的机会发育、出现和繁殖，这表明线虫和寄生蜂都可以在同一宿主中繁殖。来自感染线虫宿主的雌蜂的卵成熟没有明显不同于来自对照宿主的雌蜂的卵成熟。如果通过精确的应用策略避免线虫对寄生蜂的有害影响，那么线虫和寄生蜂的联合应用可能是有益的。很明显，金小蜂幼虫和线虫共享宿主幼虫，并相互进行营养相互作用。简要讨论了同类相食。
