DINÂMICA POPULACIONAL E CONTROLE DE Gyropsylla spegazziniana (Hemiptera: Aphalaridae) UTILIZANDO Beauveria bassiana (Hypocreales: Cordycipitaceae) E PRIMEIRO REGISTRO DA ASSOCIAÇÃO NATURAL ENTRE ESSAS ESPÉCIES

Abstract

The yerba mate psyllid or tea ampul, Gyropsylla spegazziniana, is currently one of the most relevant pests in mate tea crops, Ilex paraguariensis. In Brazil, chemical control is not permitted in this crop. One of the main alternatives studied for the control of this insect is biological control with the entomopathogenic fungus Beauveria bassiana. Despite its relevance, there is little current information on the population dynamics and control of this insect, and until now there have been no reports of natural association between these two species, an important characteristic that would indicate a natural susceptibility of the insect to the fungus. The objective of this work was to study the population dynamics of G. spegazziniana and to test for the first time in the field the fungus B. bassiana (isolate Unioeste 44, previously selected) as a biological control agent for this insect. For this, population monitoring of G. spegazziniana adults was carried out by installing yellow sticky traps in a commercial yerba mate crop with no history of phytosanitary treatments. Population monitoring revealed that the tea ampul is present year-round, with population peaks between November and January. Two population control tactics for this insect with B. bassiana Unioeste 44 were tested: spraying a conidial suspension and attraction-infection devices with dry conidia and diatomaceous earth, at different times of the year. Both tactics were able to significantly reduce adult tea ampul population, anticipating the population decline by up to two weeks compared to untreated areas. Parallel to the study of the population dynamics of G. spegazziniana, it was documented the unprecedented natural occurrence of B. bassiana infecting tea ampul adults. This fungus was isolated, and taxonomic identification, molecular characterization, and assessment of pathogenicity, virulence, and resistance to UV radiation and heat were performed. The isolated fungus was identified as B. bassiana Unioeste 116, highly virulent to G. spegazziniana adults (above 80% mortality), with conidial productivity even higher than the isolate Unioeste 44, used as a standard for comparison. The results confirm the potential of B. bassiana, especially isolates Unioeste 44 and 116, as promising biological control agents for G. spegazziniana and candidates for commercial products.