| Summary: | 碩士 === 國立臺灣大學 === 昆蟲學研究所 === 101 === Cannibalism, defined as killing and consuming conspecifics for energy gain, tends to be size or age dependent, and is common in many creatures including cat fleas, Ctenocephalides felis (Bouche). Since the flea larvae normally live in habitat with limited resource, their conspecifics might be an accessible choice for additional energy. In my laboratory experiment, cat flea larvae are found to consume conspecific eggs, smaller larvae or naked pupae by their chewing mouthparts. Although cat flea displayed cannibalistic behavior in all three larval instars, differences are still showed in their preference or successful rate. Eggs were under higher risk of being attacked by late instar larvae while the age did not affect larvae to cannibalize the naked pupa. The pupa can be protected by cocoon which keeps the larvae from consuming them. Environment factor can influence the cannibalistic tendency, flea larvae consume more eggs under high density or lack of food. However, high larval density reduces the egg consumed of each larva when no porcine blood curd powder is provided as additional food. The interaction between these two factors should be further considered. The non-viable eggs produced by mated females also influence the cannibalistic behavior. The viable eggs are round and may be relatively difficult for the larvae, especially the first instar, to consume. Since the non-viable eggs are flat and it may be easier for larvae to feed on them, more non-viable eggs were consumed by larvae when both eggs were available. Although I did not calculate a credibly optimal ratio of viable egg among all eggs laid, the protective and nutrition providing function might trigger the female flea to produce non-viable eggs to reduce egg cannibalism. It can be seen as a kind of parental care which plays an important role in cat flea population sustaining.
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