Combinations of entomopathogenic nematode (EPN) species are sometimes more or less effective than individual species for the management of insect pests. We hypothesized that these outcomes are due in part to dispersal rates that differ when EPN species are conspecific or heterospecific. Dispersal rates of three heterorhabditid species, six steinernematid species, and mixtures of some were assessed using image analysis of nematodes on water agar. The dispersal rates between the genera differed significantly and were unrelated to the estimated body mass or the putative foraging strategy, including that of the recently named Steinernema khuongi, characterized here as a cruise forager (actively search for hosts). Heterorhabditis indica dispersed more rapidly on agar when combined with S. diaprepesi, but not with S. glaseri. The presence of S. diaprepesi in soil microcosms also increased the proximity of H. indica to Galleria mellonella host insects, while H. indica presence reduced the number of G. mellonella killed by S. diaprepesi. Nevertheless, increasing the H. indica dispersal rate did not increase its insecticidal effectiveness, likely due to competition with the more virulent S. diaprepesi. Rather, the effect of combining the species on the mortality of G. mellonella was additive. Our results suggest that interspecific EPN communication affects not only orientation but also dispersal rate, with potential impacts on biological control and the subsequent fitness of each species.

昆虫病原线虫 (EPN) 物种的组合有时或多或少比单个物种对害虫的管理更有效。我们假设这些结果部分是由于当 EPN 物种是同种或异种时不同的分散率。使用水琼脂上的线虫图像分析评估了三种异线虫物种、六种 steinernematid 物种和一些混合物的扩散率。属之间的传播率差异显着，与估计的体重或假定的觅食策略无关，包括最近命名的Steinernema khuongi，这里被描述为巡航觅食者（积极寻找宿主）。Heterorhabditis indica与S. diaprepesi，但与S. glaseri 无关。土壤微观世界中S. diaprepesi的存在也增加了H. indica与Galleria mellonella宿主昆虫的接近度，而H. indica 的存在减少了S. diaprepesi杀死的G. mellonella 的数量。然而，增加H. indica 的传播率并没有增加其杀虫效果，这可能是由于与毒性更强的S. diaprepesi 的竞争。相反，组合物种对G. mellonella死亡率的影响是添加剂。我们的研究结果表明，种间 EPN 通信不仅影响方向，而且影响扩散速率，对生物控制和随后每个物种的适应性都有潜在影响。