Entomopathogenic fungi are often relied on as important components of integrated pest management in tropical agriculture, either as biopesticides or as naturally occurring microbes conserved in the environment. Tropical abiotic conditions are often well-suited for microbial growth, and tropical habitats can be teeming with microbial biodiversity. However, competitive interactions with other fungi and the need to overcome defenses of hosts adapted to high fungal loads may inhibit the ability of insect pathogens to control tropical pests. Here, we review the current literature on Beauveria bassiana and Metarhizium anisopliae inhabiting tropical environments and their potential use as biological control agents. In some cases there is not a clear distinction between temperate and tropical agroecosystems, such as in the level of organic matter or soil texture in agricultural soils. Therefore, the effects of these soil characteristics in temperate agroecosystems are likely applicable to tropical systems as well. In contrast, factors such as microbial biodiversity and seasonal fluctuation in environmental conditions can differ dramatically between temperate and tropical systems. Therefore, we discuss literature that can be generalized to tropical systems. Where temperate and tropical systems are likely to differ we synthesize the literature specifically for tropical agroecosystems. We also provide hypotheses to stimulate future work on latitudinal gradients and the relative importance of biotic and abiotic factors in governing entomopathogen prevalence and community composition. These hypotheses provide a path forward to developing theory guiding the conservation and augmentation of entomopathogenic fungi to prevent pest outbreaks.

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The Queensland fruit fly (Qfly), Bactrocera tryoni Froggatt, is a devastating pest of Australia’s commercial fruit systems. Fruit fly mitigation is heavily centered around the use chemical insecticides, with limited investigation into microbial control alternatives. The wet tropics of northern Queensland is a highly biodiverse ecosystem containing many species of insect pathogenic fungi, but it is unclear whether any of these entomopathogens could contribute to Qfly management programs. In laboratory trials, we investigated the potential for Qfly microbial control by 3 locally sourced strains of entomopathogenic fungi comprising 2 species, Metarhizium guizhouense (Chen and Guo) and Metarhizium lepidiotae (Driver and Milner). Additionally, we evaluated 2 different inoculation methods to derive the most effective way to expose the flies to conidia—either through dry conidia or in a conidial suspension. All 3 strains were successful in causing Qfly mortality. Metarhizium lepidiotae resulted in the highest mean mortality over the trials, while M. guizhouense resulted in the highest mortality in a single replicate. Laboratory experiments revealed exposure through dry conidia to be the most effective method to inoculate the flies. These results suggest that fungal entomopathogens could be a viable pathway to Qfly suppression.