RESUMO
Essential oils of aromatic plants represent an alternative to classical pest control with synthetic chemicals. They are especially promising for the alternative control of stored product pest insects. Here, we tested behavioral and electrophysiological responses of the stored product pest Tribolium confusum, to the essential oil of a Brazilian indigenous plant, Varronia globosa, collected in the Caatinga ecosystem. We analyzed the essential oil by GC-MS, tested the effects of the entire oil and its major components on the behavior of individual beetles in a four-way olfactometer, and investigated responses to these stimuli in electroantennogram recordings (EAG). We could identify 25 constituents in the essential oil of V. globosa, with anethole, caryophyllene and spathulenole as main components. The oil and its main component anethole had repellent effects already at low doses, whereas caryophyllene had only a repellent effect at a high dose. In addition, the essential oil abolished the attractive effect of the T. confusum aggregation pheromone. EAG recordings revealed dose-dependent responses to the individual components and increasing responses to the blend and even more to the entire oil. Our study reveals the potential of anethole and the essential oil of V. globosa in the management of stored product pests.
Assuntos
Antenas de Artrópodes/fisiologia , Comportamento Animal/efeitos dos fármacos , Repelentes de Insetos , Magnoliopsida/química , Óleos Voláteis , Tribolium/fisiologia , Animais , Repelentes de Insetos/química , Repelentes de Insetos/farmacologia , Óleos Voláteis/química , Óleos Voláteis/farmacologiaRESUMO
Os crisopídeos são importantes predadores e são encontrados em diversos agroecossistemas. A temperatura é um dos fatores determinantes para o desenvolvimento dos insetos, sendo que existe um gradiente de variação aceitável para cada espécie. Portanto, objetivou-se com este estudo verificar a influência de diferentes temperaturas sobre o desenvolvimento embrionário e pós-embrionário de C. raimundoi assim como verificar as conseqüências nas diferentes gerações. As fases jovens foram criadas em três ambientes com temperaturas constantes de 19,0, 25,0 e 31,0ºC e em um ambiente externo sem controle dos fatores abióticos. Foram observados a duração do período embrionário, do primeiro, segundo e terceiro ínstares, a duração do período larval, pupal e ovo-adulto, assim como, a sobrevivência em cada estágio, estádio e a porcentagem de emergência. O desenvolvimento embrionário e pós-embrionário diferiu entre as gerações F2 e F4. Quanto à influência de diferentes temperaturas para a geração F2, os indivíduos criados a 31,0ºC demonstraram redução na taxa de desenvolvimento com relação aos outros dois ambientes. Para a geração F4, observou-se que as diferentes temperaturas influenciaram no desenvolvimento, sendo que a 19,0ºC houve prolongamento do mesmo.
The green lacewings are important predators and are found in several agroecosystems. The temperature is one of the decisive factors for the development of insects, and there is an acceptable variation gradient for each species. Therefore, the purpose of this study was not only to check the influence of different temperatures on the embryonic and post-embryonic development of Chrysoperla raimundoi, as well as check the consequences in the different generations. The immature stages were reared at four different environmental conditions, three of them with constant temperatures (19,0, 25,0 e 31,0ºC) and the fourth rearing place was external to the laboratory without control of the abiotic factors. The duration of the embryonic period, first, second and third larval instar, pupal stage, and from egg to adult were evaluated; also the survival rate of each instar and stage and the emergence rate were calculated. The embryonic and post embryonic development differed between the generations F2 and F4. Also, the influence of different temperatures for the generation F2 among individuals created at 31,0ºC showed reduction on the development rate regarding the other two environments. It was possible to observe that the generation F4 has its development influenced by different temperatures, and the 19,0ºC temperature prolonged its development.
RESUMO
Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) é um predador encontrado em vários agroecossistemas, predando insetos pequenos e de tegumento mole. Seu alto potencial reprodutivo e elevada capacidade de busca o tornam capazes de predar ovos e larvas de Plutella xylostella (L.) (Lepidoptera: Plutellidae) nas partes mais internas da cabeça do repolho, onde outros inimigos naturais não conseguem. Essas características podem favorecer a utilização desse predador no controle biológico dessa praga. Neste trabalho, o objetivo é avaliar o desenvolvimento, reprodução e capacidade de predação de C. claveri, quando ovos e larvas de P. xylostella foram ofertados em condições de laboratório. Foram avaliadas as seguintes dietas: 1) ovos; 2) larvas de segundo ínstar; 3) ovos + larvas de segundo ínstar. O desenvolvimento e a viabilidade das formas imaturas de C. claveri foi melhor nas dietas que continham ovos da presa. A oviposição e longevidade também foram maiores nessas dietas, independentemente da presença de larvas. Contudo, o tipo de dieta não afetou a razão sexual e o peso das larvas no oitavo dia de vida. Em média, cada larva de C. claveri foi capaz de predar 1611 ovos ou 135 larvas de segundo ínstar de P. xylostella durante seu desenvolvimento. O predador foi capaz de aumentar a população 218 vezes a cada 42 dias, alimentando-se, exclusivamente, de ovos da presa. Concluiu-se que o predador apresenta potencial para ser utilizado no controle biológico de P. xylostella.
Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) is a predator found in several agricultural ecosystems and it preys on small and soft body insects. Its high reproductive potential and forage capacity makes it able of preying eggs and larvae of Plutella xylostella (L.) (Lepidoptera: Plutellidae) internally hidden on cabbage head, where other natural enemies usually do not reach. These characteristics are important when choosing this predator to be used within biological control programs. This search evaluated the C. claveri development, reproduction, as well as the consumption of P. xylostella eggs and larvae under laboratory conditions. Therefore, it was evaluated the following diets: 1) eggs; 2) larvae of second ínstar; 3) eggs + larvae of second ínstar. The development and the viability of the immature forms of C. claveri were better in the diets containing eggs of P. xylostella. Also, the egg laying and adult longevity were greater with these diets, independently of the larvae presence. However, the diet type did not affect the sexual rate and the weight of the larvae after eight days of living. On average, each C. claveri larva was able of preying 1611 eggs or 135 second-ínstar larvae of P. xylostella during its development. The predator was able to increase its population 218 times after 42 days, feeding exclusively on P. xylostella eggs. Based on these results, this predator presents a great potential of being used within biological control programs of P. xylostella.
