Insecticidal potential of Bacillus thuringiensis for the biological control of neotropical brown stink bug

Abstract

Euschistus heros (Hemiptera: Pentatomidae) is considered a major insect pest in soybean production in Brazil. The indiscriminate application of pesticides to fields leads to reduction in biodiversity, selection of resistant populations, emergence of new pest outbreaks, and damage to non‐target organisms. The objective of this research was to evaluate the effects of exposure to Cry proteins present in new isolates of Bacillus thuringiensis Berliner, commercial formulations, and Bt soybean on E. heros development. The feeding preference of E. heros for Bt‐ vs. non‐Bt soybean was also evaluated. All treatments caused significant mortality to E. heros except the Bt soybean. Tests with combinations of isolated Bt‐toxins indicated that combinations had greater efficacy than other treatments (>98% mortality). The results demonstrate that E. heros is susceptible to B. thuringiensis toxins, which may contribute to the management of this insect in soybean agro‐ecosystems.

Insecticidal Effect of Cry Toxins Produced by Bacillus thuringiensis on Diceraeus melacanthus (Dallas, 1851) and Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae)

“…In the present study, the Cry1Ac protein caused low mortality (33.3%) in D. melacanthus and reasonable mortality (61.9%) for E. heros in a direct exposure to the toxin. The susceptibility to Cry toxins was evidenced for E. heros nymphs exposed in the absence of substrate, but only the combination of toxins (contained Cry2, Cry1, and Cry9 proteins) resulted in the highest mortality and efficiency (> 98%) (Schünemann et al, 2018). B. thuringiensis' spectrum of action may depend on the combination of individual Cry toxins revealing synergisms between them (Estruch et al, 1997;Schünemann et al, 2018).…”

“…While studies show that the hemipteran insects are susceptible to Cry protein toxicity (Porcar et al, 2009;Dorta et al, 2010;Melatti et al, 2010;Salazar-Magallon et al, 2015;Torres-Quintero et al, 2016;Schünemann et al, 2018;Torres Cabra et al, 2019;da Costa et al, 2021), brief is the knowledge about the effect of Cry toxins on pentatomids (Schünemann et al, 2014). Research using Cry proteins directly on insects in the Heteroptera suborder are scarce and focused on the effects that genetically-modified (GM) plants (plants expressing insecticidal crystalline proteins derived from B. thuringiensis) can also have on non-target organisms and in the third trophic level of the food chain (Wellman-Desbiens & Côté, 2005;da Cunha et al, 2012;Silva et al, 2014).…”

“…In additional, other studies showed that the Cry1Ac toxin caused ultrastructural changes in the digestive cells of the predatory stink bug P. nigrispinus when it fed on S. frugiperda that had consumed GM Bt-cotton expressing the toxin (da Cunha et al, 2012). Nevertheless, mortality or impacts were not observed for E. heros fed on GM Bt-soybean plants expressing the Cry1Ac protein (Silva et al, 2014;Schünemann et al, 2018). In the present study, the Cry1Ac protein caused low mortality (33.3%) in D. melacanthus and reasonable mortality (61.9%) for E. heros in a direct exposure to the toxin.…”

Fatores ambientais e tempo de degradação foliar de neonicotinóides no controle químico de insetos sugadores em soja

“…A soja (Glycine max L.) é uma leguminosa economicamente importante, rica em proteína e óleo e fornecedora de outros componentes relevantes a saúde como o amido, fibras e minerais (CHAUDHARY et al, 2015 (FONSECA et al, 2014;SCHÜNEMANN et al, 2018). No Brasil, o nível de controle é de 2 percevejos m -1 na produção de grãos e de 1 percevejo m -1 para produção de sementes (BUENO et al, 2013).…”

“…). O potencial produtivo e a qualidade dos grãos da soja podem ser afetados pelo ataque de insetos pragas (RICH;KOCH, 2016;SCHÜNEMANN et al, 2018;EDUARDO et al, 2018).Os percevejos são as pragas mais importantes da soja, pois se alimentam das vagens e grãos, causando perdas de rendimentos e afetando a qualidade da semente(KRINSKI et al., 2013; SOSA-GÓMES et al, 2014). Os percevejos podem ocasionar danos irreversíveis à cultura, pois, ao se alimentarem, sugam diretamente os grãos, danificando o produto comercializado(ROCHA et al,2014).…”