Eficiência de fungos entomopatogênicos no controle de moscas das-frutas (Diptera: Tephritidae) e gorgulho-da-goiaba (Coleoptera: Curculionidae) em plantio comercial de goiabeira Psidium guajava L. 1753 (Myrtaceae)

Abstract

Fruit flies (Diptera: Tephritoidea) and the guava weevil Conotrachelus psidii (Coleoptera: Curculionidae) are considered the main pests of Psidium guajava fruits. Faced with increasing restrictions on the use of chemical products, due to toxicity to human health and insect resistance to insecticides, the search for sustainable alternatives for pest control has intensified. It is emphasized that the control of insect pests in guava cultivation is essential for its economic viability. In this context, the objective of this research was to evaluate, in a commercial guava plantation, the action of two registered bioinsecticides Metarril®, active ingredient Metarhizium anisopliae, and Boveril®, active ingredient Beauveria bassiana), in the control of emergent of Anastrepha species (Diptera: Tephritidae) and Conotrachelus psidii (Coleoptera: Curculionidae) in soil sprayed with the fungi entomopathogenic. The two experiments were conducted in a commercial guava tree orchard, located in the district of Santa Terezinha, Itaporã, Mato Grosso do Sul, Brazil. To facilitate pest species contact with the fungi, each inoculum was incorporated into water containing a compatible adjuvant and sprayed onto the soil surface every seven days. The experimental design was a complete randomized block with 7 treatments and 4 replications, totaling 28 plots. Each plot was represented by a single plant. The treatments used were: Control (T), Metarril® with 1 application (Ma 1), Boveril® with 1 application (Bb 1), Metarril® with 2 applications (Ma 2), Boveril® with 2 applications (Bb 2), Metarril® with 3 applications (Ma 3), and Boveril® with 3 applications (Bb 3). The fungi were applied to the soil as a suspension, with varying numbers of applications, and the emergence of adults was monitored in cages. Newly emerged fruit fly and guava weevil adults were collected and transported to the Frugivorous Insects Laboratory at the Universidade Federal da Grande Dourados. Mortality data were subjected to Bayesian analysis (using Jamovi, Jasp, and R software). Control efficiency was calculated using Abbott's formula. For fruit flies: Both fungi were efficient, causing mortality of fruit flies. Metarhizium anisopliae demonstrated superiority in mortality over the control (BF₁₀ = 6.63), and B. bassiana also showed higher mortality (BF₁₀ = 1.65). Three applications showed strong evidence of superiority compared to no application (BF₁₀ = 6.19). However, comparisons between 1, 2, and 3 applications did not reveal statistically strong differences in mortality (BF₁₀ < 1). The highest control efficiency for M. anisopliae was 53.9% with 1 application. For B. bassiana, the highest efficiency was 50.6%, achieved with 2 and 3 applications. The efficiency of the fungi was lower in 2021 compared to 2022. For the guava weevil, both fungi were more effective than the control. B. bassiana stood out with very strong evidence of superiority over the control (BF₁₀ = 33.69). M. anisopliae was also effective, but with weaker evidence over the control (BF₁₀ = 1.59). Bayesian evidence for a substantial difference between the fungi was anecdotal (BF₁₀ = 1.31 for B. bassiana vs. M. anisopliae), indicating that both are viable, with B. bassiana numerically superior. There was no strong statistical evidence of difference in efficacy between 1, 2, or 3 applications among themselves (BF₁₀ < 1). The comparison between the control and 3 applications showed the strongest evidence (BF₁₀ = 3.86). In terms of efficiency, 2 and 3 applications of B. bassiana provided the highest efficiency (73.3%). M. anisopliae achieved its highest efficiency (58.6%) with only one application. Both fungi, M. anisopliae and B. bassiana, demonstrated potential to control both the species of fruit flies and the guava weevil, with adult mortality being influenced by the type of fungus and by the number of applications. Soil-based control with entomopathogenic fungi of these newly emerged pests species is viable in the field, constituting a tool for Integrated Pest Management (IPM) in fruit growing.