Dispersal by bagworm larvae, Metisa plana: effects of population density, larval sex, and host plant attributes |
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Authors: | Marc Rhainds Gerhard Gries Cheng Tuck Ho Poh Soon Chew |
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Institution: | Department of Biological Sciences, Simon Fraser University, Canada,;Oil Palm Research Station, Golden Hope Plantations Berhard, Banting, Selangor, Malaysia and;Applied Agricultural Research Sdn. Bhd., Sungei Buloh, Selangor, Malaysia |
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Abstract: | Abstract 1. The work reported here investigated the incidence of dispersal by bagworm larvae Metisa plana (Walker) (Lepidoptera: Psychidae), a species with apterous females and winged males. 2. A mark–recapture study conducted in a plantation of oil palm revealed that a significant proportion of larvae undertakes multiple episodes of ballooning, and suggested that ballooning represents a strategy for foraging both within and between hosts. 3. Experiments conducted in a controlled cage environment indicated that increasing population density and defoliation of oil palm both promote dispersal by larvae. 4. Neonatal larvae typically remained on the host where they emerged, indicating that pupation site of late-instar females influences the distribution of their progeny, and suggesting a high level of genetic relatedness in localised bagworm populations. 5. Density-dependent dispersal may generate relatively uniform distributions of M. plana in plantations of oil palm, by simultaneously stabilising populations on heavily infested palms and redistributing larvae on lightly infested palms. 6. The rate of ballooning was greater for female than for male larvae, possibly resulting from the sex-specific impact of population density on reproductive success or from late-instar females seeking suitable oviposition sites for their future progeny. |
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Keywords: | Bagworm ballooning density- and defoliation-dependent processes dispersal flightless females Metisa plana sex-specific larval adaptation |
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