Microgravity is a unique environment to elucidate host–parasite biology. Entomopathogenic nematodes (EPNs), model parasites, kill host insects with mutualistic bacteria and provide environmentally friendly pest control. It is unknown how microgravity affects a multistep insect invasion by parasites with mutualistic bacteria. EPNs respond directionally to electromagnetic cues and their sinusoidal locomotion is affected by various physical factors. Therefore, we expected microgravity to impact EPN functionality. Microgravity experiments during space flight on the International Space Station (ISS) indicated that EPNs successfully emerged from consumed insect host cadavers, moved through soil, found and infected bait insects in a manner equivalent to Earth controls. However, nematodes that developed entirely in space, from the egg stage, died upon return to Earth, unlike controls in microgravity and on Earth. This agricultural biocontrol experiment in space gives insight to long-term space flight for symbiotic organisms, parasite biology, and the potential for sustainable crop protection in space.

微重力是阐明宿主-寄生生物的独特环境。昆虫病原线虫（EPN），可以模拟寄生虫，用互生细菌杀死宿主昆虫，并提供对环境有害的害虫防治。未知微重力如何影响具有共生细菌的寄生虫对昆虫的多步入侵。EPN对电磁提示有方向性的响应，其正弦运动受各种物理因素的影响。因此，我们预计微重力会影响EPN功能。在国际空间站（ISS）上进行太空飞行期间进行的微重力实验表明，EPNs以与地球控制等效的方式成功地从消耗掉的昆虫宿主尸体中出来，穿过土壤，发现并感染了诱饵昆虫。但是，线虫从卵期开始就完全在太空中发育，与微重力控制和地球控制不同，它在返回地球时死亡。这项空间农业农业生物控制实验为共生生物，寄生生物的长期太空飞行提供了见识，并为太空中的可持续作物保护提供了潜力。