Fitness consequences of cannibalism in the fall armyworm, Spodoptera frugiperda
We investigated the consequences of cannibalism for some correlates of fitness in the fall armyworm, spodoptera frugiperda (Lepidoptera: Noctuidae). The benefits gained by cannibals were ascertained by comparing survival, development rate, and pupal weight of larvae that had fue opportunity to cannibalize with those that did not, at two levels of food availability. Larvae in the cannibalism treatments were provided with a conspecific one instar younger than themselves on five dates throughout larval development. Cannibalism was frequent; given the opportunity alllarvae predated at least one younger conspecific. The frequency of cannibalism was not affected by the sex of fue cannibal or by fue availability of alternative food. However, cannibals suffered a significant reduction in survival at both high and low food availability. Furthermore, cannibals had a lower pupal weight in fue high food treatment and a reduced development rate in fue low food treatment. The only detectable fitness benefit associated with cannibalism was a positive correlation between the number of victims consumed and development rate under conditions of low food availability. On balance, cannibalism appears to be costly; alternative explanations for its occurrence in this speciesa re discussed. Key words: cannibalism, fall armyworm, food availability, larval development, spooopterfaru giperda, survival.
| Main Authors: | , , , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | Spodoptera frugiperda, Larvas, Canibalismo, Artfrosur, |
| Online Access: | http://beheco.oxfordjournals.org/content/10/3/298.full |
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| Summary: | We investigated the consequences of cannibalism for some correlates of fitness in the fall armyworm, spodoptera frugiperda (Lepidoptera: Noctuidae). The benefits gained by cannibals were ascertained by comparing survival, development rate, and pupal weight of larvae that had fue opportunity to cannibalize with those that did not, at two levels of food availability. Larvae in the cannibalism treatments were provided with a conspecific one instar younger than themselves on five dates throughout larval development. Cannibalism was frequent; given the opportunity alllarvae predated at least one younger conspecific. The frequency of cannibalism was not affected by the sex of fue cannibal or by fue availability of alternative food. However, cannibals suffered a significant reduction in survival at both high and low food availability. Furthermore, cannibals had a lower pupal weight in fue high food treatment and a reduced development rate in fue low food treatment. The only detectable fitness benefit associated with cannibalism was a positive correlation between the number of victims consumed and development rate under conditions of low food availability. On balance, cannibalism appears to be costly; alternative explanations for its occurrence in this speciesa re discussed. Key words: cannibalism, fall armyworm, food availability, larval development, spooopterfaru giperda, survival. |
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