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.

Bioatividade do extrato aquoso de sementes de nim sobre Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) em três formas de aplicação / Bioactivity of aqueous neem seeds extract on the Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) in three ways of application

No presente trabalho, avaliaram-se as atividades translaminar, sistêmica e de contato do extrato aquoso de sementes de Azadirachta indica A. Juss. (nim) sobre a traça-do-tomateiro Tuta absoluta (Meyrick). Foram realizados três experimentos envolvendo extratos aquosos de sementes de nim em concentrações de 0,5; 1,0; 5,0 e 10,0 g por 100 mL de água. Esses extratos foram aplicados no solo, na superfície adaxial de folíolos de tomateiro e diretamente sobre as lagartas. Quando os extratos foram aplicados no solo, em vasos contendo plantas de tomate, houve mortalidade de 48,3 a 100,0 por cento das lagartas, indicando que foram absorvidos e translocados na planta. Também ocorreu mortalidade larval de 57,0 a 100,0 por cento quando os extratos foram aplicados na superfície adaxial do folíolo, evidenciando o efeito translaminar. Quando foi aplicado diretamente sobre lagartas com seis dias de idade, observou-se mortalidade de 52,4 a 95,4 por cento, demonstrando a ação de contato do composto e seu potencial para controle da traça-do-tomateiro.

This work, aimed to study the translaminar, systemic and contact action of aqueous neem seeds extracts on the tomato leafminer Tuta absoluta (Meyrick). Three experiments with aqueous neem seeds extracts at concentrations of 0.5; 1.0; 5.0 and 10.0g/100 mL of water were conducted. These extracts were applied in the soil, in adaxial surface of the tomato plant foliole and directly over the insect. When the extracts were applied in the soil of pots containing tomato plants, the larval mortality rate was 48.3 percent to 100.0 percent, indicating that the extracts were absorbed and transferred inside the plant. There was also a larval mortality of 57.0 percent to 100.0 percent when the extracts were applied over the foliole adaxial surface, which shows the translaminar action. When the extracts were applied directly over larvae six days old, the larval mortality rate was 52.4 percent to 95.4 percent, which shows the action of contact of the extracts and its potential to control the tomato leafminer.