Biorrational approaches for controlling bean weevils and the red palm mite in the neotropical region

• Ano de defesa: 2019
• Autor(a) principal: Viteri Jumbo, Luis Oswaldo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Pragas - Controle biológico; Canela; Cravo-da-índia; Besouros; Ácaro-vermelho-das palmeiras; Feijão - Doenças e pragas; Coco - Doenças e pragas; Entomologia agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/32363

The Neotropical region is characterized by having excellent climate conditions for producing a diversity of gramineous, legumes and fruits of economic importance. However, insect and mite pests have significantly constrained such agricultural production as these arthropods indirectly reduce yields or quality of the production. The control of such pests still is heavily dependent of synthetic compounds, which has threatened the environment and human health. Two relevant agricultural systems in the Neotropical region is the beans (e.g., Phaseolus vulgaris e Vigna unguiculata) and the coconut production, Cocus nucifera L., (and storage for the case of bean grains). Thus, in the present dissertation are described the investigations conducted aiming to provide novel biorational approaches for controlling insect pests that attack stored bean grains (i.e., the bruchid beetles Acanthoscelides obtectus (Say), Zabrotes subfasciatus (Boheman) and Callosobruchus maculatus (Fabricius)) as well as the red palm mite (i.e., Raoiella indica (Hirst)) that has caused severe losses in the coconut production in the Neotropical region. Firstly, the present dissertation dealt with the competitive abilities of bean weevils in different hosts. The next investigations were conducted aiming to evaluate the potential of essential oil extracted from clove (Syzygium aromaticum) and cinnamon (Cinnamomun zeylanicum) for controlling these bean weevils (including potential side-effects associated with sublethal exposures), and were compared with a commercial product Deltamethrin (Decis- 25 EC; 25 g a.i./L). Finally, experiments were conducted aiming to evaluate the potential of the lacewing Ceraeochrysa caligata (Banks) as biological agent for controlling the red palm mite R. indica. The results for the competition bioassays revealed that C. maculatus exhibits the best competitive abilities on cowpea beans, independently of its interspecific competitors (i.e., A. obtectus or Z. subfasciatus); although the weevil Z. subfasciatus also show hormetic responses in presence of moderate densities of the competitor C. maculatus on this host. On common bean grains the weevil C. maculatus can’t produce offspring. The toxicological bioassays with essential oils revealed that A. obtectus exhibited equally susceptibility to clove (LD50 = 43.6 (38.9-49.3) µL of essential oil/kg bean) and cinnamon (LD50 = 46.8 (42.3-51.4) µL of essential oil/kg bean) essential oils. Furthermore, there was a trade-off between reproductive fitness and susceptibility to insecticides accordingly to the host where A. obtectus was being reared. Clove and cinnamon essential oils also exhibited insecticidal activities against C. maculatus similar to the synthetic insecticide Deltamethrin (Clove: LD50 = 78.2 (71.6-84.8)µL of essential oil/kg bean; cinnamon: LD50 = 131 (124.0- 137.0)µL of essential oil/kg bean; deltamethrin: LD50 = 83.7 (80.6-86.6)µL of a.i/ kg−1 bean). Females of C. maculatus exposed to sublethal doses of clove (LD20 = 48.6µL−1 ) and cinnamon (LD20 = 106.2µL−1 ) significantly reduced oviposition. In the last part of this dissertation, the results revealed than the predatory behavior of C. caligata feeding upon R. indica is dependent of the larval development of the predator and prey size. It is clearly demonstrated that C. caligata (especially at the second-instar stage) has potential as a tool for the ecological management of the red palm mite. The results reveal that essential oils of clove and cinnamon, and the natural enemy C. caligata are alternatives for the integrated management of stored grain pests and the red palm mite respectively.