ABSTRACT Yerba mate ampoule, Gyropsylla spegazziniana (Lizer and Trelles, 1919) is one of the main pests of yerba mate crops. This insect attacks sprouts leading to gall formation and defoliation. The nymph’s habit of living inside galls makes them difficult to access with chemical insecticides, hampering the effectiveness of chemical control. This study aimed to evaluate the systemic and contact activity of the azadirachtin-based product (via irrigation and spraying) on nymph and adult stages of the ampoule, both in laboratory and field conditions. In vitro interaction of the product with the fungus Beauveria bassiana (Balls.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) was also evaluated. After the exposure of nymphs to plants treated with azadirachtin, a reduction in adult emergence was recorded (65–99% depending on the concentration applied). It was observed 80% of adult mortality in plants previously treated with the product (residual effect) and 90% of mortality after direct pulverization of the product on the insects. The product did not affect B. bassiana fungal growth, conidial viability, and conidial production on culture media. A synergistic interaction was observed between the azadirachtin insecticide and the fungus in laboratory. In the field trial, after three applications by irrigation of azadirachtin, 67.9% reduction in the number of galls was achieved five weeks after the first application. No phytotoxic effect was observed on yerba mate plants treated with the product. The results of our study demonstrate that the azadirachtin-based product and its association with the fungus B. bassiana have potential in controlling G. spegazziniana.

RESUMO A ampola-da-erva-mate, Gyropsylla spegazziniana (Lizer e Trelles, 1919) é uma das pragas mais importantes da erva-mate. O inseto ataca as brotações, levando à formação de galhas e desfolhação. As ninfas vivem no interior das galhas, o que dificulta o contato com inseticidas químicos, reduzindo a eficiência dessa tática de controle. Este estudo visou avaliar a atividade sistêmica e de contato de um produto à base de azadiractina (via irrigação e pulverização) sobre ninfas e adultos da ampola, em condições de laboratório e campo. A interação in vitro do produto com o fungo Beauveria bassiana (Balls.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) também foi avaliada. Após a exposição de ninfas a plantas tratadas com azadiractina, houve redução na emergência de adultos (65–99% variando conforme a concentração utilizada). A mortalidade de adultos foi de 80% quando mantidos em plantas previamente pulverizadas com o produto (efeito residual) e de 90% quando receberam a pulverização diretamente de azadiractina. O produto não afetou o crescimento, viabilidade e a produção de conídios em meio de cultura. Foi observado sinergismo entre o produto e o fungo em condições de laboratório. Em condições de campo, após três aplicações de azadiractina via irrigação, houve redução de 67,9% na formação de galhas, após cinco semanas do início do experimento. Nenhum sintoma de fitotoxicidade foi observado nas plantas de erva-mate tratadas com o produto. Conclui-se que a o produto à base de azadiractina associado ao fungo B. bassiana tem potencial para controle de G. spegazziniana.

ABSTRACT Aiming to the red mite Oligonychus yothersi control in yerba-mate, the systemic action of an azadirachtin-based product (12 g of azadirachtin.L-1) was evaluated in the laboratory. To assess the activity on oviposition and mortality of the mite (1), three weekly applications of the product in an aqueous solution (30, 48, and 66 mg i.a..L-1) were performed. The applications were carried out in the soil, next to the base of yerba mate seedlings. After seven days of each application, leaves were removed for infestation with 15 adult mite females. To evaluate the activity in the development, survival, and reproduction of the progeny (2), yerba mate seedlings were irrigated with azadirachtin solution of 30 mg i.a..L-1 (recommended concentration). After seven days, leaves were removed and infested with adult females for oviposition and observation of the progeny. Reduction in fecundity (from 23.7 to 44.2%), fertility (27.4 to 48.1%), and an increase in mortality from 14.6 to 47.5% were observed in females fed on azadirachtin-treated plants. Continuous feeding on plants treated with azadirachtin solution significantly reduced oviposition, pre-oviposition period, and longevity of males. In addition, the viability of the egg-adult, and the duration of the egg-adult period increased. The potential of azadirachtin for the control of O. yothersi and its action from the irrigation of yerba mate plants was confirmed.

RESUMO: Visando incrementar a atividade do fungo Beauveria bassiana Unioeste 44 contra adultos da ampola-da-erva-mate (Gyropsylla spegazziniana), avaliou-se a associação do fungo com adjuvantes Aureo® e Assist®, para calda de aplicação. Os bioensaios foram relizados em contato direto e residual sobre insetos. Foram também avaliados in vitro os efeitos sobre alguns parâmetros biológicos do fungo. A associação fungo + adjuvantes resultou em mortalidade de 65 e 75%, sem diferença entre eles, porém, significativamente maior que a obtida com o fungo isoladamente. A mortalidade no contato residual foi menor, mas também houve vantagem na associação com adjuvantes, principalmente Assist® (48%), em relação ao Áureo® (16%). A conidiogênese nos cadáveres não foi afetada pelos adjuvantes no tratamento de contato direto. Contudo, houve incremento na conidiogênese no tratamento de associação com Assist® no contato residual. Apesar de afetarem a germinação e o crescimento do fungo, os adjuvantes foram considerados compatíveis com o fungo. Além da eficiência da associação, ambos adjuvantes não causaram fitotoxidade para a erva-mate, representando vantagens do seu uso no manejo da ampola.

ABSTRACT: Aiming to increase the activity of the fungus Beauveria bassiana (Unioeste 44) against adults of Gyropsylla spegazziniana, the combination of the fungus with adjuvants Aureo® and Assist® was evaluated for application. The bioassays were carried out in direct and residual contact with insects on yerba mate seedlings. The effects on some biological parameters of the fungus were also evaluated in vitro. The combination of the fungus and the adjuvants in direct contact resulted in mortality rates of 65 and 75% (Aureo® and Assist®, respectively), with no difference between them; however, the mortality rate was greater than that obtained with the fungus alone (47 %) (P < 0.05). Mortality from residual contact was lower, but the association with adjuvant Assist® (48%) compared to Aureo® (16%) was still advantageous. Conidiogenesis in cadavers was not affected by adjuvants in the treatment by direct contact. However, in residual contact, conidiogenesis increased with the Assist® addition. Despite affecting the germination and growth of the fungus, the adjuvants were considered compatible. In addition to the efficiency of their combination, neither adjuvant caused phytotoxicity to yerba mate seedlings, representing advantages of its use in G. spegazziniana population management.

ABSTRACT Gyropsylla spegazziniana is one of the most important pest of yerba mate by sap-sucking that lead to leaves deformation and there are no insecticides registered for its control. The present study describes a new technique to be used in bioassays with the insect. Galls were collected from infested yerba mate plants. In the laboratory, the galls were partially opened and distributed in plastic containers. The emerged adults were transferred to plastic containers with the perforated bottom and a central opening in the lid, and subjected to spraying. After that, insects were transferred to yerba mate seedlings in plastic cages and maintained in laboratory to daily assessment. The use of a lid with central opening prevented the insects escaping, and avoiding the previous anesthetic to spraying. The mortality was less than 10% after 10 days. The technique was considered adequate for maintenance and performance of laboratory bioassays.