RESUMO
ABSTRACT The rice stink bug, Tibraca limbativentris Stål (Hemiptera: Pentatomidae), is a significant pest of rice cultivation in Brazil and attacks plants during both vegetative and reproductive phases. Natural enemy surveys conducted in plantations located in Arari, Miranda do Norte, Matões do Norte, Santa Rita, and Viana (state of Maranhão, Brazil) led to the discovery of a new species of parasitoid, which is described in this study. Hexacladia lemosae Costa, Noyes & Machado sp. nov. (Hymenoptera: Encyrtidae) is the first species of its genus associated with T. limbativentris and develops as a gregarious endoparasitoid in adult stink bugs, occasionally in nymphs. The parasitoid emerges from the host while host is still alive.
RESUMO
ABSTRACT A new coccinellid species, Diomus leondai sp. nov. (Coleoptera: Coccinellidae: Diomini) is described from northeast Brazil, São Luis, municipality of Raposa, Cumbique. The specimens collected were found feeding on Phenacoccus solenopsis Tinsley and Phenacoccus sp. on the branches, leaves, and fruits of Abelmoschus esculentus L. Moench, Hibiscus acetosella Welw. ex. Hiern and Hibiscus sabdariffa L. (Malvaceae), and Capsicum spp. and Solanum lycopersicum L. (Solanaceae). Some concepts behind the definition and scope of the genus Diomus and tribe Diomini are analyzed, recognizing the need to better characterize its morphological aspects and establish its composition more precisely.
RESUMO
Abstract Aleurocanthus woglumi (Ashby, 1915) is an important agricultural pest that causes yield losses of 20-80% in citrus plants by removing plant nutrients while feeding and allowing the formation of sooty mold. The objective of this study was to evaluate physiological changes in citrus plants in response to A. woglumi infestation under field conditions. The experiment was conducted in a citrus orchard in Paço do Lumiar, Maranhão, Brazil. Thirty-two citrus plants were used, including eight of each of the following varieties: Tahiti lime, Tanjaroa tangerine, Nissey tangerine, and Ponkan tangerine. Four random plants with A. woglumi infestation and four plants free from this pest were selected from each variety. The physiological parameters evaluated were photochemical efficiency and gas exchange. Regarding photochemical efficiency, infested plants presented photoinhibition damage, with a performance index of 4.22. The gas exchange parameters of infested plants changed, with reductions in photosynthetic CO2 assimilation of 69.7% (Tahiti), 64% (Tanjaroa), 68.8% (Nissey) and 63.3% (Ponkan). Plants infested with A. woglumi also presented physiological changes; their photosynthetic CO2 assimilation, stomatal conductance, instantaneous transpiration, and performance indexes were affected. The infested citrus plants showed photoinhibition of photosystem II. The photosynthetic CO2 assimilation decreased approximately 70% in Tahiti lime, Tanjaroa tangerine, Nissey tangerine, and Ponkan tangerine plants infested with A. woglumi.
RESUMO
Avaliou-se a forma de utilizaçäo de pesticidas nos pólos de produçäo da Ilha de Säo Luís (MA), Brasil. Foram analisadas algumas hortaliças cultivadas tendo sido detectados resíduos do inseticida organofosforado metamidifós em amostras de tomate, pimentäo e coentro. Embora os níveis de contaminaçäo tenham sido relativamente baixos, a presença do pesticida atesta a falta de informaçäo do pequeno produtor rural, que aplica agrotóxicos de forma indiscriminada, sem obedecer os períodos de carência para cada cultura