A Presença de Plantas Invasoras Afeta a Infestação de Tomateiros por Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) em um Agro-ecossistema do Semi-árido?RESUMO -O manejo integrado de Bemisia tabaci (Gennadius) exige o conhecimento quantitativo dos mecanismos de persistência de populações em hospedeiros não comerciais. Este trabalho investigou a preferência para oviposição de B. tabaci entre tomate e quatro espécies de plantas invasoras, e a flutuação populacional do inseto em condições de campo no semi-árido nordestino. Semanalmente, foram determinados o nível (número de ovos e ninfas por folha) e a densidade de infestação (número de ovos e ninfas por área foliar) nas cinco espécies. Observamos diferentes graus de atratividade, formando um gradiente de preferência para oviposição entre as espécies, sendo Acanthospermum hispidum a espécie mais infestada e Amaranthus deflexus a menos infestada. Foi detectada ainda uma infestação significativamente mais elevada em parcelas contendo apenas tomateiros, sugerindo um efeito de diluição da infestação do tomateiro quando na presença de invasoras. Plantas invasoras podem representar importantes reservatórios para a mosca branca e/ou seus inimigos naturais, ou ainda fontes de inóculo viral para plantas cultivadas. Sua inserção em programas de manejo integrado de B. tabaci em tomateiro depende de como estes fatores podem ser manipulados para a redução dos danos causados pelo inseto.PALAVRAS-CHAVE: Mosca branca, planta daninha, preferência hospedeira, caatinga ABSTRACT -Integrated Bemisia tabaci (Gennadius) management requires quantitative knowledge on the mechanisms of persistence of pest populations in non-commercial host plants. We investigated B. tabaci oviposition preference among tomato and four weed species, and the insect population fluctuation under field conditions in the semi-arid region. At weekly intervals, we determined the level (number of eggs and nymphs per leaf) and the density of infestation (number of eggs and nymphs per leaf area) in all species. We observed an oviposition preference gradient among the species, with different degrees of attractiveness; Acanthospermum hispidum was the most infested species whereas Amaranthus deflexus was the least infested one. We also detected a significantly higher infestation on tomato when planted solely, which indicates a dilution effect on tomato infestation in the presence of weeds. Weeds can act as important reservoirs for whiteflies and/or their natural enemies or even as viral sources for cultivated plants. Their incorporation in integrated B. tabaci management programs depends on how those variables can be manoeuvred for the reduction of insect damage.

Increase on intensive monocultures is an important threat to Caatinga biodiversity decrease. The use of chemical insecticides directly affects insect natural enemies of crops, but also non-target species. We aimed to test whether the diversity of sarcosaprophagous flies would be affected by agricultural management (conventional and organic). Adult dipterans were collected monthly, from July 2015 to January 2016, using a grid composed of 12 suspended traps distant 20 m from each other, baited with 150 g of sardine or bovine spleen, in each type of management. We first calculated α-diversity by Hill numbers, then evaluated the difference of diversity metrics by ANOVA. We also graphically visualise the species composition distribution by NMDS. We recorded a total of 4,651 specimens of 15 Calliphoridae and Sarcophagidae species. Chrysomya spp. were the dominant species (93.7% of all blowflies). Sarcophagidae species were sampled in low abundance, but with exclusive presence of some species in each treatment (e.g. B laesoxipha stallengi and Ravinia belforti in organic management). Although there was no difference on sarcosaprophagous fly diversity between treatments, we demonstrate empirically that mango plantations in the Caatinga harbour diverse and abundant assemblages of sarcosaprophagous dipterans, whose richness of species is comparable to other ecosystems such as rainforests and urban areas. Our results expand the known geographical range for forensically relevant species by providing a checklist of sarcosaprophagous dipterans that can thrive in agroecosystems in the Caatinga and, potentially, colonize cadavers disposed in that type of environment.