The corn leafhopper, Dalbulus maidis (Hemiptera, Cicadellidae), is an important pest of maize in Latin America, transmitting plant pathogens that impact grain production. Recently, mycopesticides have been considered as an alternative for the biological control of D. maidis populations, but there is controversy surrounding the efficacy of these products. We assessed the susceptibility of D. maidis to invertebrate-pathogenic fungi and, for the first time, investigated the protective role of the protein-lipid coat of brochosomes on the insect integument as a barrier against infections. Adult mortality was lower than 35% seven days after exposure to maize plants sprayed with water + surfactant-based conidia suspensions of 31 fungal strains from three different genera (Beauveria, Cordyceps and Metarhizium). Direct application of conidia suspensions on adults did not increase significantly the mortality rates when compared to adults exposed to contaminated surfaces. Conidia in water + surfactant readily adhered and germinated on detached forewings of D. maidis from which brochosomes were removed, but wings coated with this protein-lipid layer repelled droplets. Dry conidia easily adhered to brochosome-coated wings and their germination was not affected, although the methodical self-cleaning behavior of the adults effectively dislodged most conidia (either in suspensions or as a dry powder) from insect’s body after treatment. In conclusion, brochosomes and self-cleaning together efficiently prevent adhesion of conidia to D. maidis cuticle, serving as important barriers against fungal invasion and decreasing insect mortality. Our study highlights the importance of combining mycopesticides with effective adjuvants in spray applications to enhance infection rates and successfully control D. maidis populations.

玉米叶蝉Dalbulus maidis （半翅目，叶蝉科）是拉丁美洲玉米的重要害虫，传播影响粮食生产的植物病原体。最近，真菌杀虫剂被认为是对D.maidis种群进行生物控制的替代方案，但围绕这些产品的功效存在争议。我们评估了D. maidis对无脊椎动物致病真菌的敏感性，并首次研究了昆虫外皮上纤维蛋白-脂质外壳作为感染屏障的保护作用。接触用水+基于表面活性剂的来自三个不同属（白僵菌、冬虫夏草和绿僵菌）的 31 种真菌菌株的分生孢子悬浮液喷洒的玉米植物 7 天后，成虫死亡率低于 35%。与暴露于污染表面的成虫相比，直接对成虫施用分生孢子悬浮液并没有显着增加死亡率。水+表面活性剂中的分生孢子很容易在去除了支气管体的D. maidis分离的前翅上粘附并发芽，但涂有这种蛋白质-脂质层的翅会排斥液滴。干燥的分生孢子很容易粘附在包有支气管体的翅膀上，并且它们的发芽没有受到影响，尽管成虫有条理的自洁行为在处理后有效地将大多数分生孢子（悬浮液或干粉）从昆虫体内移出。总之，支气管体和自清洁共同有效地防止分生孢子粘附到D.maidis角质层上，成为防止真菌入侵和降低昆虫死亡率的重要屏障。 我们的研究强调了在喷雾应用中将霉菌杀虫剂与有效助剂相结合以提高感染率并成功控制D. maidis种群的重要性。