Sublethal exposure to pyriproxyfen does not impair the abilities of the backswimmer Buenoa amnigenus to prey upon Aedes aegypti larvae.

Pyriproxyfen is a juvenile hormone analogue that is commonly used to control the immature stages of mosquitoes in both artificial and natural water reservoirs. Recently, concerns have been raised regarding the community effectiveness of pyriproxyfen in preventing vector-transmitted diseases. Such concerns have been based on the unintended effects on non-target organisms and the selection of resistant mosquito populations. This investigation was, therefore, conducted to evaluate the toxicity of pyriproxyfen to Aedes aegypti (Diptera: Culicidae) larvae and the backswimmer Buenoa amnigenus (Hemiptera: Notonectidae), a naturally occurring mosquito larvae predator. We also assessed the abilities of backswimmers exposed to sublethal levels of pyriproxyfen to prey upon mosquito larvae (L2) under three larval densities (3, 6, or 9 larvae/100 mL of water) using artificial containers. Our results revealed that pyriproxyfen killed backswimmers only at concentrations higher than 100 µg active ingredient [a.i.]/L, which is 10 times higher than that recommended for larvicidal field application (i.e, 10 µg a.i./L). The abilities of backswimmers exposed to sublethal levels of pyriproxyfen (100 µg a.i./L) to prey upon mosquito larvae were not affected. Harmful effects on the backswimmer predatory abilities were detected only at concentrations of 150 µg a.i./L and when there was a higher prey availability (i.e., 9 larvae/100 mL of water). Together, our findings indicate that the reduced community effectiveness of this insecticide derives from factors other than its detrimental effects on non-target organisms such as backswimmers.

A new species of Buenoa Kirkaldy (Hemiptera, Heteroptera, Notonectidae) from Rio de Janeiro, Brazil / Uma nova espécie de Buenoa Kirkaldy (Hemiptera, Heteroptera, Notonectidae) ocorrente no Rio de Janeiro, Brasil

Members of Buenoa are restricted to the Western Hemisphere, with the greatest diversity of species in South America. There are about 50 described species and approximately 20 of them have been reported from Brazil. Buenoa pseudomutabilis Barbosa, Ribeiro and Nessimian, sp. nov. is described here from Maricá, Rio de Janeiro State. This species resembles B. mutabilis Truxal, 1953 because males have a stridulatory area on inner surface of forefemur, forefemur narrowed at apex, with length more than three times its width at apex, and rostral prong longer than third rostral segment. Males of B. pseudomutabilis sp. nov. can be readily recognized by the presence of 21 to 25 teeth in the stridulatory comb of foretibia, whereas in B. mutabilis the stridulatory comb of foretibia consists of approximately 33 to 38 teeth. Males of B. pseudomutabilis sp. nov. bear one nodule on each ventral laterotergite 1 of abdomen. A key to male species of Buenoa occurring in Rio de Janeiro State, including the new species, is provided.

Os representantes de Buenoa restringem-se ao hemisfério ocidental, sendo a América do Sul a região que abriga o maior número de espécies descritas. Das 50 espécies descritas, cerca de 20 ocorrem no Brasil. Buenoa pseudomutabilis Barbosa, Ribeiro & Nessimian, sp. nov. é descrita com base em representantes de Maricá, Estado do Rio de Janeiro, sendo similar à B. mutabilis Truxal, 1953 quanto à presença de uma área estridulatória na superfície interna do fêmur anterior dos machos, pelo aspecto estreito do ápice desse fêmur (com o comprimento maior que três vezes a largura do seu ápice) e pelo dente lateral do rostro maior que o seu terceiro segmento. Espécimes machos de B. pseudomutabilis sp. nov. podem ser distinguidos facilmente pela presença de um pente com 21 a 25 dentes na tíbia anterior, enquanto o dos machos de B. mutabilis consiste de aproximadamente 33 a 38 dentes. Os machos de B. pseudomutabilis sp. nov. apresentam um nódulo em ambos os lados do primeiro tergito látero-ventral do abdome. Uma chave de identificação para os representantes machos das espécies de Buenoa ocorrentes no Rio de Janeiro com a espécie nova incluída é fornecida.