Lime sulfur to control citrus flat mite and its interactions with the entomopathogenic fungus Lecanicillium muscarium

Lime sulfur is one of the few products indicated to control Brevipalpus yothersi in Brazilian organic citrus orchards. Other strategies, such as the use of entomopathogenic fungi should be evaluated, and Lecanicillium muscarium is one of the basic choices for pest management. Knowledge of the interactions between lime sulfur and this entomopathogen is critical for developing control strategies. With this goal, it was conducted the toxicological characterization of lime sulfur to B. yothersi and the compatibility evaluation with L. muscarium. Finally, the effects of L. muscarium and lime sulfur mixtures on B. yothersi control were evaluated. Product evaluation for B. yothersi was done through direct and residual contact bioassay, and different concentrations of lime sulfur mixed in potato dextrose agar culture medium were used to evaluate compatibility with L. muscarium. Lime sulfur was effective against adults of B. yothersi and caused eggs unviability of up to 71.0%, at a dose of 80 L per 2,000 L of H2O. The lethal concentration (LC50 and LC99) of lime sulfur estimated for mite adults were 246.62 and 858.5 µg of sulfur per mL of H2O (ppm a.i.). Lime sulfur concentrations of 180 to 560 ppm a.i. showed promise for use in combination with L. muscarium. However, concentrations of 1,000 and 5,600 ppm significantly reduced colony size and the number of spores/colony. The mixture of 100 and 180 ppm a.i. of lime sulfur with L. muscarium (108 conidia·mL­1) was not able to reduce the lethal time of entomopathogen on B. yothersi.

Lethal and sublethal effects of pesticides used in Brazilian citrus groves on Panonychus citri (Acari: Tetranychidae) / Efeitos letais e subletais de agrotóxicos utilizados em citros sobre o ácaro Panonychus citri (Acari: Tetranychidae)

Pesticides have been blamed as the principal factor responsible for biological disequilibrium favoring the population increase of Panonychus citri (McGregor) in Brazilian citrus groves. In order to generate subsidies for the integrated management of this pest, we evaluated the lethal and sublethal effects of pesticides used in citrus on P. citri. We tested 18 pesticides by evaluating mortality of adult female, egg viability and adult avoidance. For imidacloprid, pyriproxyfen, dimethoate, deltamethrin, lambda-cyhalothrin and lime sulfur, the principal insecticides used in Brazilian orchards, the oviposition behavior and the incidence of adult females on discontinuous pesticide residues were evaluated. The pesticides which caused adult P. citri mortality were: abamectin (94%), dimethoate (86%), lime sulfur (69%), fenpropathrin (44%), diafenthiuron (25%) and lambda-cyhalothrin (23%). The pesticides affecting egg viability were: fenpropathrin (53%), dimethoate (30%) and lime sulfur (22%). Fenpropathrin, lambda-cyhalothrin and lime sulfur caused repellent effects of 55, 45 and 22%, respectively. P. citri preferred areas untreated with deltamethrin, lambda-cyhalothrin and lime sulfur for oviposition and permanence, but the species could not distinguish areas treated with imidacloprid, pyriproxyfen and dimethoate. The insecticides abamectin, dimethoate and diafenthiuron affected survival and did not cause changes in P. citri behavior. These pesticides should be used mainly in periods P. citri occurs. On the other hand, fenpropathrin, lambda-cyhalothrin, lime sulfur and deltamethrin affect dispersal behavior, oviposition and P. citri incidence and their use should be avoided.(AU)

O intenso uso de pesticidas na citricultura tem sido apontado como o principal fator responsável por desequilíbrios biológicos, favorecendo o aumento populacional de Panonychus citri (McGregor) na citricultura brasileira. Para gerar subsídios ao manejo integrado dessa praga, avaliaram-se os efeitos letais e subletais de agrotóxicos utilizados em citros sobre P. citri. Avaliaram-se 18 agrotóxicos na mortalidade de fêmeas adultas, viabilidade de ovos e repelência de P. citri. Foram também avaliados o comportamento de oviposição e a incidência de P. citri em superfícies com áreas tratadas e não tratadas com imidacloprid, piriproxifem, dimetoato, deltametrina, lambda-cialotrina e calda sulfocálcica, por serem os principais inseticidas utilizados nos pomares brasileiros. Os pesticidas que causaram mortalidade em adultos de P. citri foram abamectina (94%), dimetoato (86%), calda sulfocálcica (69%), fempropatrina (44%), diafentiurom (25%) e lambda-cialotrina (23%). Os pesticidas que afetaram a viabilidade de ovos foram fempropatrina (53%), dimetoato (30%) e calda sulfocálcica (22%). Quanto aos efeitos subletais, fempropatrina, lambda-cialotrina e calda sulfocálcica ocasionaram repelências de 55, 45 e 22%, respectivamente. P. citri preferiu áreas não tratadas com deltametrina, lambda-cialotrina e calda sulfocálcica para oviposição e permanência. Em contraste, P. citri não foi capaz de distinguir superfícies tratadas com imidacloprid, piriproxifem e dimetoato. Os inseticidas abamectina, dimetoato e diafentiurom afetaram a sobrevivência e não causaram mudanças no comportamento de P. citri, podendo ser utilizados principalmente em períodos que P. citri ocorre. Em contrapartida, fempropatrina, lambda-cialotrina, calda sulfocálcica e deltametrina afetaram o comportamento de dispersão e oviposição de P. citri e deveriam ser evitados.(AU)