Faculty of Agronomy, Royal University of Agriculture, Dangkor District, P.O. Box 2696, Phnom Penh, Cambodia.
Centre for Crop Health, Institute for Life Sciences and the Environment, University of Southern Queensland, Toowoomba, QLD, 4350, Australia.
Sci Rep. 2021 Jan 26;11(1):2188. doi: 10.1038/s41598-021-81647-0.
Kuschelorhynchus macadamiae is a major pest of macadamias in Australia, causing yield losses of up to 15%. Our previous studies have shown the weevil is susceptible to Beauveria bassiana and Metarhizium anisopliae. The aim of this study was to investigate horizontal transmission of both fungal species to healthy weevils from both infected adults and weevil cadavers. In a confined environment the mortality of healthy adults caused by the transmission of conidia from live fungus-infected adults was < 50%. Under similar experimental conditions, the mortality of healthy adults reached 100% when exposed to conidiated cadavers. However, when conidiated cadavers were used in more spacious environments (insect cages), the mortality of adults was < 80%. Using scanning electron microscopy, it was observed that all healthy adults had conidia attached to all external parts of the body. This suggests that although the conidia were readily transferred to the adults, the lower mortality in the larger insect cages could be the result of an unfavourable environmental factor such as low humidity. The presence of conidia attached to all the adults indicated that they did not show any discriminatory behaviour such as avoidance of conidiated cadavers infected by these two fungal species. The results from this study show that there is potential for enhanced control of adult K. macadamiae via transmission from either fungus-infected adults or conidiated cadavers and this could strengthen sustainable pest management in macadamias.
澳洲坚果曲颊象鼻虫是澳大利亚澳洲坚果的主要害虫，可导致高达 15%的产量损失。我们之前的研究表明，象鼻虫易受球孢白僵菌和绿僵菌的影响。本研究旨在调查这两种真菌从感染的成虫和象鼻虫尸体向健康象鼻虫的水平传播。在封闭环境中，从活体真菌感染成虫传播的分生孢子对健康成虫的致死率<50%。在类似的实验条件下，当暴露于有分生孢子的尸体时，健康成虫的死亡率达到 100%。然而，当使用有分生孢子的尸体在更宽敞的环境（昆虫笼）中时，成虫的死亡率<80%。使用扫描电子显微镜观察到，所有健康的成虫都有分生孢子附着在身体的所有外部部位。这表明，尽管分生孢子很容易转移到成虫身上，但在较大的昆虫笼中死亡率较低可能是由于不利的环境因素，如低湿度。所有成虫都附着有分生孢子，这表明它们没有表现出任何歧视行为，如避免被这两种真菌感染的有分生孢子的尸体。本研究的结果表明，通过受真菌感染的成虫或有分生孢子的尸体传播，有可能增强对成年澳洲坚果曲颊象鼻虫的控制，从而加强澳洲坚果的可持续害虫管理。
