BACKGROUND: The invasion of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) into the New World has made it possible for this pest to hybridize with a native American species, H. zea (Boddie), under natural conditions. We investigated the viability and development of hybrids of these two Helicoverpa species. We reared the parental species and evaluated crosses between H. armigera males and H. zea females and vice versa, two intercrosses between hybrids, and eight backcrosses between hybrids and parental species. We estimated the length of immature stages, fecundity, survival, sex ratio, and heterosis. RESULTS: Although hybridization occcurred, with heterosis during the development of immatures, reproductive incompatibilities also were observed between the parental species and between hybrids from subsequent crosses. The interspecific crosses between hybrids and backcrosses confirmed the possibility of introgression events and their perpetuation in field populations. The results indicate that hybridization events are favored at high population levels, while at low population levels the 'species identities' will be maintained.
CONCLUSIONS:The possibility of interspecific gene flow and its perpetuation through successive crosses and backcrosses suggests several recommenations for management. Populations of both species should be maintained at an equilibrium level to reduce the chance of interspecific crosses, which are presumably more likely to occur during pest outbreaks. The existence of hybridization and resistance to different active pesticide ingredients should be monitored. All practices related to managing the resistance of these pests to chemical and biological insecticides should be systematized to reduce the chance of selecting for resistant individuals.
Atualmente, uma das questões preocupantes da sociedade é o fator utilização e gerenciamento de resíduos sólidos. Grande parte desses são disponibilizados em aterros sanitários, resultando em problemas ambientais e de saúde pública. A poluição ambiental é algo alarmante, especialmente em relação aos resíduos produzidos por indústrias de grande porte. O uso desses subprodutos como matéria-prima e transformação em novos produtos comercializáveis e/ou de viabilidade econômica, apresentase como uma alternativa tecnológica sustentável às empresas e setores públicos. Neste livro são apresentadas pesquisas relevantes e atuais sobre algumas formas de mitigar os efeitos nocivos dos resíduos sólidos, as tendências e diagnóstico, análise de riscos, gestão integrada, metodologia PDCA, assim como, os custos de acondicionamento, coleta, secagem, processamento, armazenamento e transporte desses resíduos.
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