38 research outputs found

    The importance of alternative host plants as reservoirs of the cotton leaf hopper, Amrasca devastans, and its natural enemies

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    Many agricultural pests can be harboured by alternative host plants but these can also harbour the pests’ natural enemies. We evaluated the capacity of non-cotton plant species (both naturally growing and cultivated) to function as alternative hosts for the cotton leaf hopper Amrasca devastans (Homoptera: Ciccadellidae) and its natural enemies. Forty-eight species harboured A. devastans. Twenty-four species were true breeding hosts, bearing both nymphal and adult A. devastans, the rest were incidental hosts. The crop Ricinus communis and the vegetables Abelmoschus esculentus and Solanum melongena had the highest potential for harbouring A. devastans and carrying it over into the seedling cotton crop. Natural enemies found on true alternative host plants were spiders, predatory insects (Chrysoperla carnea, Coccinellids, Orius spp. and Geocoris spp.) and two species of egg parasitoids (Arescon enocki and Anagrus sp.). Predators were found on 23 species of alternative host plants, especially R. communis. Parasitoids emerged from one crop species (R. communis) and three vegetable species; with 39 % of A. devastans parasitised. We conclude that the presence of alternative host plants provides both advantages and disadvantages to the cotton agro-ecosystem because they are a source of both natural enemy and pest species. To reduce damage by A. devastans, we recommend that weeds that harbour the pest should be removed, that cotton cultivation with R. communis, A. esculentus, and S. melongena should be avoided, that pesticides should be applied sparingly to cultivate alternative host plants and that cotton crops should be sown earlier

    Longitudinal Study of Daily Hassles in Adolescents in Arab Muslim Immigrant Families

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    This study investigated which daily hassles (i.e., Parent, School, Peer, Neighborhood, and Resource) were perceived by Arab Muslim immigrant adolescents as most stressful over a three-year time period and according to child's gender and mother's immigration status (i.e., refugee or non refugee). Data were collected at three time points during adolescence and analyzed using doubly multivariate analysis of covariance (MANCOVA) with linear and quadratic trends. School and Parent hassles were greater than other hassles at every time point. Main effects of time, immigration status, and father's employment, but not child's gender, were statistically significant. School and Parent hassles increased while Peer and Resource hassles decreased over time. Adolescents with refugee mothers reported greater School and Neighborhood and fewer Parent hassles than those with non refugee mothers. Adolescents with unemployed fathers reported significantly more School and Neighborhood hassles. Study findings identify two at risk subgroups: those adolescents with refugee mothers and/or those adolescents with unemployed fathers; and pinpoint problematic daily hassles. Additional research is needed to explore vicarious trauma effects as a potential underlying reason for the pattern of daily hassles noted in adolescents with refugee mothers
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