Metarhizium anisopliae is a valuable grist for biocontrol in beta‐cypermethrin‐resistant Blattella germanica (L.)

Abstract

BACKGROUND The widespread use of chemical insecticides has resulted in the development of resistance in German cockroaches worldwide, and biopesticides based on entomopathogenic fungi as active ingredients have become a promising alternative strategy. Resistance can change many of the physiological and biochemical characteristics of insect pests, such as cuticle thickness, detoxification enzyme activity, and even intestinal flora composition. Thus, potential interactions between pathogenic fungi and insecticide resistance may lead to unpredictable changes in pest susceptibility to fungi. RESULTS Beta‐cypermethrin‐resistant German cockroaches were more susceptible to infection with the fungus Metarhizium anisopliae regardless of age and sex. Histopathological results showed that the infection of resistant strains (R) by M. anisopliae was visibly faster than that of susceptible strains (S). The gut microbiota of the S strain indicated a stronger ability to inhibit fungi in vitro. The abundance of Parabacteroides, Lachnoclostridium, and Tyzzerella_3 decreased significantly in the R strain, and most demonstrated the ability to regulate glucose and lipid metabolism, and antifungal infections. The expression levels of Akirin, BgTPS, and BgPo genes in the R strain were significantly lower than those in the S strain, while BgChi and CYP4G19 gene expression were significantly higher. The mortality of cockroaches infected with M. anisopliae decreased to varying degrees after RNA interference, reflecting the role of these genes in antifungal infection. CONCLUSIONS Results confirmed that insecticide resistance may enhance cockroach susceptibility to fungi by altering intestinal flora and gene expression. Fungal biopesticides have high utilization value in pest control and insecticide resistance management strategies. © 2021 Society of Chemical Industry.

Contribution of insect gut microbiota and their associated enzymes in insect physiology and biodegradation of pesticides

“…In addition, the secretion of chitinase enzymes from the population of insect gut bacteria significantly contributed to host antagonism against entomopathogens and nutrition ( Indiragandhi et al, 2007 ). Pesticide-resistance cockroach species such as German cockroaches, American cockroaches, and Oriental cockroaches are rich sources of insect gut microbiota and play a crucial role in insect physiology ( Zhang X. C. et al, 2022 ). For example, the effect of beta-cypermethrin resistance development in cockroaches ( Blattella germanica ) by the gut microbial population and their genetic association with host growth was investigated.…”

The Application of Entomopathogenic Fungi Metarhizium anisopliae, Beauveria bassiana, and Trichoderma harzianum for Coptotermes curvignathus and Cryptotermes cynocephalus Termite Control in Indonesia

“…Capric acid has been used in botanical products for the control of mosquitoes to interrupt disease transmission and is known to cause mortality in mosquito populations (Maw and House, 2012). It has also been indicated as one of the safer options for insecticides that would not endanger nontarget species like fish (Hikal et al, 2017;Zhang et al, 2022).…”