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Resposta cairomonal do parasitóide Anagyrus spec. nov. próx. pseudococci (Girault) (Hymenoptera, Encyrtidae) à feromona sexual de Planococcus ficus (Signoret) (Hemiptera, Pseudococcidae)
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Investigou-se a resposta cairomonal do parasitóide Anagyrus spec. nov. próx. pseudococci (sensu Triapitsyn et al., 2007) à feromona sexual de Planococcus ficus (Signoret), através de ensaios em olfactómetro estático e em pomares de citrinos. A existência de resposta cairomonal à melada de Planococcus citri (Risso) foi averiguada em ensaios de comportamento em placa de Petri e olfactómetro. A influência da experiência de postura em P. citri, na resposta do parasitóide à feromona sexual deste hospedeiro, foi testada em ensaios de olfactómetro. A micromorfologia das sensilas da antena de fêmeas do parasitóide foi analisada ao microscópio electrónico de varrimento, de modo a identificar os quimiorreceptores, possivelmente envolvidos na selecção do hospedeiro. As fêmeas do parasitóide de Israel mostraram resposta significativa à feromona sexual de P. ficus, sugerindo ser inata, uma vez que o parasitóide foi criado em P. citri. As fêmeas de Sicília não responderam à feromona sexual de P. ficus, o que, aliado a pequenas diferenças na distribuição e número de sensilas na antena do parasitóide, pode evidenciar uma diferença na resposta cairomonal entre a população de Sicília e as de Portugal e Israel. A melada de P. citri parece induzir comportamento de retenção no parasitóide. Contudo, não foi evidenciada resposta cairomonal em olfactómetro, podendo sugerir que a melada é utilizada como cairomona de contacto, na localização do hospedeiro. Não foi registada resposta significativa à feromona sexual de P. citri, mesmo após experiência de postura neste hospedeiro. A antena da fêmea do parasitóide possui sete tipos de sensilas: trichodea, exclusivamente mecanorreceptora; chaetica do tipo 1 e 2, presumivelmente quimiorreceptoras de contacto; e chaetica do tipo 3 e 4, basiconica e placodea, todas assumidas como olfactivas. As sensilas chaetica do tipo 2 e 4 parecem estar envolvidas na discriminação do hospedeiro.
This study was aimed at confirming the kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci (sensu Triapitsyn et al., 2007) to the sex pheromone of Planococcus ficus (Signoret), and determine the nature of this response. Essays on static olfactometer and field experiments in citrus orchards were conducted. The existence of kairomonal response to the honeydew of Planococcus citri (Risso) was tested, using olfactometer and behaviour studies in arenas. The influence of oviposition experience in P. citri on the parasitoid response to the sex pheromone of this host was analysed in olfactometer. The micromorphology of antennal sensilla in parasitoid females was studied, using scanning electron microscopy, to identify chemical receptors possibly involved in host selection. The female wasps from Israel showed a significant response to the sex pheromone of P. ficus, suggesting an innate behaviour, since the parasitoid was originated from P. citri. The females from Sicily did not respond to sex pheromone of P. ficus. This result, combined with small differences detected in the distribution and number of sensilla in female antennae, may suggest a difference between the kairomonal response of Sicily population and those from Portugal and Israel. Planococcus citri honeydew seems to induce an arrestment behaviour in the parasitoid. However, no kairomonal response was detected in olfactometer, suggesting the use of honeydew as a contact kairomone to locate its host at short distance. No significant response was registered to the sex pheromone of P. citri, even after the female wasp has oviposited in this host. The female antennae have seven types of sensilla: trichodea, exclusively mechanosensilla; chaetica types 1 and 2, presumably contact chemosensilla; and chaetica type 3 and 4, basiconica and placodea, all presumed to be olfactory. Sensilla chaetica type 2 and 4 are thought to be directly involved in host discrimination.
This study was aimed at confirming the kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci (sensu Triapitsyn et al., 2007) to the sex pheromone of Planococcus ficus (Signoret), and determine the nature of this response. Essays on static olfactometer and field experiments in citrus orchards were conducted. The existence of kairomonal response to the honeydew of Planococcus citri (Risso) was tested, using olfactometer and behaviour studies in arenas. The influence of oviposition experience in P. citri on the parasitoid response to the sex pheromone of this host was analysed in olfactometer. The micromorphology of antennal sensilla in parasitoid females was studied, using scanning electron microscopy, to identify chemical receptors possibly involved in host selection. The female wasps from Israel showed a significant response to the sex pheromone of P. ficus, suggesting an innate behaviour, since the parasitoid was originated from P. citri. The females from Sicily did not respond to sex pheromone of P. ficus. This result, combined with small differences detected in the distribution and number of sensilla in female antennae, may suggest a difference between the kairomonal response of Sicily population and those from Portugal and Israel. Planococcus citri honeydew seems to induce an arrestment behaviour in the parasitoid. However, no kairomonal response was detected in olfactometer, suggesting the use of honeydew as a contact kairomone to locate its host at short distance. No significant response was registered to the sex pheromone of P. citri, even after the female wasp has oviposited in this host. The female antennae have seven types of sensilla: trichodea, exclusively mechanosensilla; chaetica types 1 and 2, presumably contact chemosensilla; and chaetica type 3 and 4, basiconica and placodea, all presumed to be olfactory. Sensilla chaetica type 2 and 4 are thought to be directly involved in host discrimination.
Descrição
Tese de mestrado em Ecologia e Gestão Ambiental, apresentada à Universidade de Lisboa, através da Faculdadede Ciências, 2007
Palavras-chave
Parasitologia Controlo de pragas Teses de mestrado