Sousa Nathália A, Rodrigues Juscelino, Luz Christian, Humber Richard A
Laboratório de Patologia de Invertebrados, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Goiás, Brazil; USDA-ARS Emerging Pests and Pathogens Research Unit, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, USA.
Laboratório de Patologia de Invertebrados, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
J Invertebr Pathol. 2023 Mar;197:107898. doi: 10.1016/j.jip.2023.107898. Epub 2023 Feb 16.
Aedes aegypti, an important vector of viral diseases affecting humans in the tropics, generally oviposits just above the water line of small artificial bodies of water. Within the first hours after being deposited eggs are highly susceptible to desiccation, and the chorion undergoes profound processes of sclerotization. Most uneclosed eggs remain viable for months, and their susceptibility to entomopathogenic fungi turns them into reasonable targets for focal control strategies. This study explored the sensitivity of newly deposited eggs to Metarhizium humberi IP 46 conidia. Immediate exposure of eggs oviposited onto a wet, conidium-treated substrate or application of conidia onto eggs within the first 72h after deposition revealed no clearly higher ovicidal effect caused by pre-germinating or germinating conidia or by further fungal development during this initial phase of chorionic sclerotization and embryogenesis than occurs on fully sclerotized eggs. Fungal application techniques, whether direct or indirect, seemed to matter little at the low concentrations applied here; using higher conidial concentrations of the entomopathogen might yield greater mortality of eggs regardless of their physiological age. Quite apart from the data on the biocontrol potential of M. humberi against A. aegypti eggs, these studies demonstrate that the bleaching of highly melanized egg chorions allows detailed visualization of early events of pathogenic fungal attachment, germination, penetration, and initial development inside a target insect.
埃及伊蚊是热带地区影响人类的病毒性疾病的重要传播媒介，通常在小型人工水体的水线以上产卵。产下的卵在最初几个小时内极易干燥，卵壳会经历深刻的硬化过程。大多数未孵化的卵能存活数月，它们对昆虫病原真菌的易感性使它们成为局部控制策略的合理目标。本研究探讨了新产下的卵对亨伯木霉IP 46分生孢子的敏感性。将产在湿润的、经分生孢子处理的基质上的卵立即暴露，或在产卵后的头72小时内将分生孢子施用于卵上，结果显示，在卵壳硬化和胚胎发育的初始阶段，预发芽或发芽的分生孢子或真菌的进一步发育所产生的杀卵效果，并不比在完全硬化的卵上更明显。在这里使用的低浓度下，无论是直接还是间接的真菌施用技术似乎影响不大；使用更高浓度的昆虫病原分生孢子可能会使卵的死亡率更高，而不论其生理年龄如何。除了关于亨伯木霉对埃及伊蚊卵的生物防治潜力的数据外，这些研究还表明，高度黑化的卵壳的漂白可以详细观察到致病真菌在目标昆虫体内附着、发芽、穿透和初始发育的早期事件。
