Entomopathogenic fungi as the microbial frontline against the alien Eucalyptus pest Gonipterus platensis in Brazil

Abstract

The eucalyptus snout beetle (ESB), Gonipterus platensis, is endemic to Australia but has become a major invasive, destructive pest of Brazilian eucalyptus plantations. Efforts to develop insecticides based on entomopathogenic fungi against ESB are limited by the lack of known virulent strains. We therefore explored the virulence of indigenous Brazilian strains of major entomopathogenic fungi—Beauveria spp. and Metarhizium anisopliae—against ESB adults. We found widely varying virulence and later capacities for conidial production on infected adult cadavers. Two strains stood out, B. bassiana IBCB-240 and M. anisopliae IBCB-364, as especially lethal for ESB adults under laboratory conditions, sporulated abundantly on infected insects, and also outperformed comparable strains used in commercial mycoinsecticides. Notably, B. bassiana IBCB-240 exhibited lower LT50 values at low inoculum levels (≤ 107 conidia mL−1) and smaller LC50 values than M. anisopliae IBCB-364. Taken together, this study emphasizes natural variation in virulence among indigenous Beauveria and Metarhizium strains against ESB adults and identifies fungal strains with superior lethality to existing commercialized strains for managing this eucalyptus pest in Brazil.

Actions for Monitoring the Gonipterus Pest in Eucalyptus on the Cantabrian Coast

“…Studies are currently underway in other countries on options such as the use of pheromone traps [30] and the deployment of Steinernema diaprepesi (an entomopathogenic nematode), which, due to its mutual association with bacteria, reproduces and kills the pupae of G. platensis through septicaemia [31]. Additionally, two strains of entomopathogenic fungi have been discovered in Brazil that are especially lethal for adults of G. platensis [32].…”

“…Steinernema diaprepesi was also identified as the entomopathogenic nematode that can control the pest due to the mutual association with bacteria that reproduce and kill the pupae of G. platensis through septicaemia [31]. Two strains of entomopathogenic fungi that are especially lethal for the adults of G. platensis [32] have been found in Brazil. On the Iberian Peninsula, studies have been conducted on the viability of A. inexpectatus in the parasitisation of G. platensis [26,33,34] and on its interrelation with A. nitens [35].…”

From the dual cyclone harvest performance of single conidium powder to the effect of Metarhizium anisopliae on the management of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae)

“…The pure conidia with 98.0 ± 1.013% germination rate [20] were suspended in Tween 801 [Sigma, Germany] (0.1%) and their quantity calibrated to the concentrations of 1 x 10 6 , 10 7 , 10 8 and 10 9 of conidia/ml to evaluate the pathogenicity, lethal concentration 50 and 90 (LC 50 , LC 90 ) and lethal time 50 and 90 (LT 50 , LT 90 ) of the fungus. Then, 2 ml of conidial suspension per concentration were sprayed using a Potter spray tower [Burkard, UK] (from lowest to highest concentration) on ten T. peregrinus adults and ten T. peregrinus third instar nymphs (separately), from the laboratory rearing stock for each of the three replications.…”

Bioefficacy of Euphorbia peplus latex as an antifeedant and insecticide against Gonipterus platensis larvae on Eucalyptus globulus

“…In Brazil, entomopathogenic fungi (Beauveria spp. and Metarhizium anisoplliae) have been evaluated against G. platensis adults, identifying fungal strains with superior lethality than existing commercialized strains (Jordan et al 2021). Pest management could be improved further by controlling other life stages (larvae, pupae, and adults), using other techniques such as increasing the diversity of biological control agents, exploring environmentally friendly biopesticides, selecting and/ or developing Eucalyptus genotypes with tolerance to infestation, and silvicultural control (Schöroder et al 2020).…”