Brassica aphid (Hemiptera: Aphididae) populations are conditioned by climatic variables and parasitism level: a study case of Triângulo Mineiro, Brazil

Abstract

AbstractCosmopolitan pests such asBrevicoryne brassicae, Lipaphis pseudobrassicae, andMyzus persicae(Aphididae) cause significant damage to Brassicaceae crops. Assessment of the important biotic and abiotic factors that regulate these pests is an essential step in the development of effective Integrated Pest Management programs for these aphids. This study evaluated the influence of leaf position, precipitation, temperature, and parasitism on populations ofL. pseudobrassicae, M. persicae, andB. brassicaein collard greens fields in the Triângulo Mineiro region (Minas Gerais state), Brazil. Similar numbers ofB. brassicaewere found on all parts of the collard green plants, whereasM. persicaeandL. pseudobrassicaewere found in greatest numbers on the middle and lower parts of the plant. While temperature and precipitation were positively related to aphid population size, their effects were not accumulative, as indicated by a negative interaction term. AlthoughDiaeretiella rapaewas the main parasitoid of these aphids, hyperparasitism was dominant; the main hyperparasitoid species recovered from plant samples wasAlloxysta fuscicornis. Parasitoids seem to have similar distributions on plants as their hosts. These results may help predict aphid outbreaks and gives clues for specific intra-plant locations when searching for and monitoring aphid populations.