Whitlock J W, Orwin P M, Stahlschmidt Z R
University of the Pacific, Stockton, CA 95211, USA.
J Exp Biol. 2025 Jul 15;228(14). doi: 10.1242/jeb.250210. Epub 2025 Jun 11.
Glyphosate is the most used herbicide worldwide, and it can be toxic to off-target species, such as insects. Although GLY-based herbicides (GBHs) can influence insect microbiomes, little is known about its cascading effects on fitness-related traits, such as life history or stress tolerance, especially in the context of long-term, multigenerational exposure. Thus, we exposed the variable field cricket, Gryllus lineaticeps, to GBH within and across generations to examine the potential role of GBH in developmental plasticity and evolution. Specifically, we measured its effects on life-history traits (e.g. developmental duration, adult body size and mass, and a life-history trade-off between investment into reproduction and flight), stress (heat and desiccation) tolerance and the gut microbiome. One generation of exposure to GBH reduced desiccation tolerance, which was also lower in flight-capable individuals. However, after 11 generations of exposure to GBH, this cost of GBH disappeared, and GBH exposure instead increased adult body size and mass in flight-incapable individuals. Flight capacity had a stronger effect on the gut bacterial community than GBH exposure, where flight-capable individuals contained more than twice as many Family Oscillospiraceae and fewer than half as many Family Erysipelotrichaceae. The effects of both flight capacity and GBH on the microbiome were only evident in generation 1. Together, our results indicate that GBH exposure may have quite modest long-term effects on stress tolerance and the gut microbiome. However, GBH may facilitate the evolution of flightlessness given its potential benefits to flight-incapable individuals, which exhibit greater reproductive potential and tolerance to climate stressors compared with flight-capable individuals.
草甘膦是全球使用最广泛的除草剂，它可能对非目标物种（如昆虫）有毒。尽管基于草甘膦的除草剂（GBHs）会影响昆虫的微生物群落，但对于其对与适应性相关的性状（如生活史或应激耐受性）的级联效应知之甚少，尤其是在长期、多代暴露的情况下。因此，我们让条纹黑蟋蟀（Gryllus lineaticeps）在代内和代间接触GBH，以研究GBH在发育可塑性和进化中的潜在作用。具体而言，我们测量了其对生活史性状（如发育持续时间、成虫体型和体重，以及繁殖投入与飞行之间的生活史权衡）、应激（热和干燥）耐受性和肠道微生物群落的影响。一代接触GBH会降低干燥耐受性，这种耐受性在有飞行能力的个体中也较低。然而，在接触GBH 11代后，GBH的这种代价消失了，相反，GBH暴露增加了无飞行能力个体的成虫体型和体重。飞行能力对肠道细菌群落的影响比GBH暴露更强，有飞行能力的个体中螺旋体菌科的数量是无飞行能力个体的两倍多，而丹毒丝菌科的数量不到无飞行能力个体的一半。飞行能力和GBH对微生物群落的影响仅在第1代中明显。总之，我们的结果表明，GBH暴露可能对应激耐受性和肠道微生物群落产生相当适度的长期影响。然而，鉴于GBH对无飞行能力个体可能具有的益处，它可能促进无飞行能力的进化，与有飞行能力的个体相比，无飞行能力个体表现出更大的繁殖潜力和对气候应激源的耐受性。
