Improving mycoinsecticides for insect biological control

Abstract

The desire for decreased reliance on chemical pesticides continues to fuel interest in alternative means for pest control including the use of naturally occurring microbial insect pathogens. Insects, as vectors of disease causing agents or as agricultural pests, are responsible for millions of deaths and significant economic losses worldwide, placing stresses on productivity (GDP) and human health and welfare. In addition, alterations in climate change are likely to affect insect ranges, expanding their access to previously constrained geographic areas, a potentially worrisome outcome. Metarhizium anisopliae and Beauveria bassiana, two cosmopolitan fungal pathogens of insects found in almost all ecosystems, are the most commonly applied mycoinsecticides for a variety of insect control purposes. The availability of the complete genomes for both organisms coupled to robust technologies for their transformation has led to several advances in engineering these fungi for greater efficacy and/or utility in pest control applications. Here, we will provide an overview of the fungal-insect and fungal-plant interactions that occur and highlight recent advances in the genetic engineering of these fungi. The latter work has resulted in the development of strains displaying (1) increased resistance to abiotic stress, (2) increased cuticular targeting and degradation, (3) increased virulence via expression of insecticidal protein/peptide toxins, (4) the ability to block transmission of disease causing agents, and (5) the ability to target specific insect hosts, decrease host fecundity, and/or alter insect behaviors.

Genetic improvement of the nematicidal fungus Lecanicillium attenuatum against Heterodera glycines by expression of the Beauveria bassiana Cdep1 protease gene

“…Furthermore, expression of the Beauveria bassiana Pr1A-like cuticle-degrading protease (Cdep1) gene in Lecanicillium lecanii resulted in greater virulence to insects (Zhang et al, 2016). Thus, genetic engineering has proved to be a powerful tool with which to manipulate fungal virulence particularly of insect and nematode pathogens to improve their efficacy (Fan et al, 2012;Ortiz-Urquiza et al, 2015). Lecanicillium attenuatum is an important nematophagous fungus with potential as a biopesticide against SCN (Chen and Chen, 2003).…”

Enhancing the utilization of host trehalose by fungal trehalase improves the virulence of fungal insecticide

“…The use of entomopathogenic microbes for biological control has, however, been limited because they are often less effective and more costly than chemical insecticides (El-Sheikh et al 2011;Wang and St Leger 2007). Genetic engineering has become an effective way to enhance the insecticidal efficacy of fungi (Ortiz-Urquiza et al 2015). Entomopathogenic fungi have been genetically engineered to express endogenous genes encoding cuticle-degrading enzymes for enhancing the efficacy against pest insects (Fang et al 2005;St Leger et al 1996).…”

Storage of Beauveria bassiana Conidia Suspension: A Study Exploring the Potential Effects on Conidial iability and Virulence against Dermanyssus gallinae De Geer, 1778 Acari: Dermanyssidae

“…The entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae are the most promising bio controllers against both agricultural [1,2] and medical/veterinary pests, including some important arthropods ticks and mites, which parasitize humans and/or animals, i.e., Rhipicephalus sanguineus, Rhipicephalus (Boophilus) microplus, Psoroptes spp., Dermanyssus gallinae [3][4][5][6][7].…”