Efficacy of Entomopathogenic Fungal Formulations against Elasmolomus pallens (Dallas) (Hemiptera: Rhyparochromidae) and Their Extracellular Enzymatic Activities

Abstract

Elasmolomus pallens are post-harvest insect pests of peanuts that are becoming resistant to chemical insecticides. In this, we study evaluated the effect of conidial formulations on entomopathogenic fungi against E. pallens to reduce the adverse effects. Fungal conidia were formulated and applied on sterile filter papers at varying concentrations (1 × 104–1 × 108 conidia mL−1) inside plastic containers. The test insects were exposed and maintained in a relative humidity of 80 ± 10% for 10 d at room temperature (25 ± 2 °C). Mortality was recorded every 24 h. Dose–response bioassay (LC50 and LC90) values for Aspergillus flavus formulated in oil were 1.95 × 106 and 3.66 × 109 conidia/mL, whereas formulations in Tween 80 had 9.36 × 107 and 6.50 × 109 conidia/mL. However, oil-formulated Metarhizium anisopliae had 3.92 × 106 and 2.57 × 108 conidia/mL, with 6.85 × 106 and 5.37 × 108, for formulations in Tween 80. A. flavus had LT50 values of 3.3 and 6.6 days, whereas M. anisopliae had LT50 values of 3.6 and 5.7 d. Maximum protease, chitinase, and lipase activities of 2.51, 0.98, and 3.22 U/mL, respectively, were recorded for A. flavus, whereas values of 2.43, 0.93, and 3.46 were recorded for M. anisopliae. The investigated pathogens demonstrate potential against E. pallens; therefore, their applicability under field conditions requires further investigation.

Discovery of entomopathogenic fungi across geographical regions in southern China on pine sawyer beetle Monochamus alternatus and implication for multi-pathogen vectoring potential of this beetle

“…Entomopathogenic fungi harbor diverse biological "weapons" and apply several strategies to kill target insect hosts, including enzymatic degradation, physical penetration of integuments, propagation within host body cavity (hemocoel), and/or mycotoxin excretion (Mannino et al, 2019;Litwin et al, 2020). For parasitic entomopathogenic fungi, the first step to colonize host body surface relies on the efficient release of protease, chitinase, and lipase to degrade cuticles (Sevim et al, 2012;Umaru and Simarani, 2022), and these three extracellular enzymes are direct indicators of their insecticidal activity (Mustafa and Kaur, 2009;Grewal et al, 2021). In this study, A. austwickii isolated from M. alternatus showed moderate chitinase activity while higher protease and lipase activities, which correlated with its obvious infection phenotype and higher mortality rate, compared to other species (Figures 2, 3).…”

Diversity of endophytic fungi of rice plants in Padang City, Indonesia, entomopathogenic to brown planthopper (Nilaparvata lugens)

“…isolates is assumed due to differences in genetic and physiological characteristics between isolates such as the excretion of extracellular enzymes. Virulent isolates have higher enzyme activity than avirulent (Umaru and Simarani 2022). The virulence of entomopathogenic fungi against insects can be correlated with the activity of extracellular chitinase enzymes (Dhawan and Joshi 2017).…”

Entomopathogenic Fungi: An Eco-Friendly Synthesis of Sustainable Nanoparticles and Their Nanopesticide Properties

“…Different EPFs have different host choices and, hence, can be specialists or can infect a variety of insect hosts making them a generalist pathogen. Other pathogenic organisms such as protozoans, viruses, and bacteria needed to be ingested or enter the host body in some way to cause the infection, but entomopathogenic fungi can utilize the nutrients present in the body cuticle of the insect pest to colonize the host body, hence making them a good entomopathogenic agent to utilize [ 43 ].…”