Haddi Khalid, Mendes Marcos V, Barcellos Marcelo S, Lino-Neto José, Freitas Hemerson L, Guedes Raul Narciso C, Oliveira Eugênio E
Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brasil.
Science without Border Associate Researcher, Programa de Pós-Graduação em Entomologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-000, Brasil.
PLoS One. 2016 Jun 10;11(6):e0156616. doi: 10.1371/journal.pone.0156616. eCollection 2016.
Environmental stress in newly-emerged adult insects can have dramatic consequences on their life traits (e.g., dispersion, survival and reproduction) as adults. For instance, insects sublethally exposed to environmental stressors (e.g., insecticides) can gain fitness benefits as a result of hormesis (i.e., benefits of low doses of compounds that would be toxic at higher doses). Here, we experimentally tested whether sublethal exposure to the insecticide imidacloprid would hormetically affect the sexual fitness of newly-emerged adults of the Neotropical brown stink bug Euschistus heros (Hemiptera: Heteroptera: Pentatomidae), which is the most abundant and prevalent insect pest in Neotropical soybean fields. We evaluated the sexual fitness of four couple combinations: unexposed couples, exposed females, exposed males, and exposed couples. Sublethal exposure to dry residues (i.e., contact) of imidacloprid (at 1% of recommended field rate) did not affect insect survival, but led to higher mating frequencies when at least one member of the couple was exposed. However, the average mating duration was shortened when only females were exposed to imidacloprid. Moreover, exposed males showed higher locomotory (walking) activity, lower respiration rates and induced higher fecundity rates when mated to unexposed females. Although the reproductive tracts of exposed males did not differ morphometrically from unexposed males, their accessory glands exhibited positive reactions for acidic and basic contents. Our findings suggest that males of the Neotropical brown stink bug hormetically increase their sexual fitness when cued by impending insecticidal stress in early adulthood.
新羽化的成年昆虫所面临的环境压力会对其成年后的生活特性（如扩散、生存和繁殖）产生显著影响。例如，受到环境压力源（如杀虫剂）亚致死剂量影响的昆虫，可能会因毒物兴奋效应（即低剂量化合物产生的有益效果，而高剂量时这些化合物则具有毒性）而获得适应性优势。在此，我们通过实验测试了新羽化的成年新热带褐蝽（Euschistus heros，半翅目：异翅亚目：蝽科）亚致死剂量接触杀虫剂吡虫啉是否会通过毒物兴奋效应影响其性适应性，新热带褐蝽是新热带大豆田最常见且分布广泛的害虫。我们评估了四种配对组合的性适应性：未接触组、雌性接触组、雄性接触组和雌雄均接触组。亚致死剂量接触吡虫啉干残渣（即接触）（以推荐田间用量的1%）不会影响昆虫的生存，但当配对中的至少一方接触时，会导致更高的交配频率。然而，仅雌性接触吡虫啉时，平均交配持续时间会缩短。此外，当与未接触的雌性交配时，接触过的雄性表现出更高的运动（行走）活性、更低的呼吸速率，并诱导出更高的繁殖率。尽管接触过的雄性的生殖道在形态测量上与未接触的雄性没有差异，但其附属腺对酸性和碱性物质呈现阳性反应。我们的研究结果表明，新热带褐蝽的雄性在成年早期受到即将到来的杀虫压力提示时，会通过毒物兴奋效应提高其性适应性。
