An analysis of the pattern of feeding in the Costa Rican weevil, Exophthalmus jekelianus, on the tropical tree, Cedrela odorata
1999
Wright, G.A. | Raubenheimer, D. | Simpson, S.J.
Feeding patterns were recorded and analyzed for adult female weevils, Exophthalmus jekelianus (White) (Coleoptera: Curculionidae), feeding on Central American mahogany, Cedrela odorata L., in the field in Costa Rica. The study forms part of a investigation into the relationship between feeding patterns and the fine-scale variation in leaf chemistry occurring within the host plant. The weevils' feeding patterns were the simplest in temporal structure of any reported to date for an insect herbivore. Weevils spent an average of only 3% of their time feeding during the 10-h observation periods. Meals lasted and average of 2.8 min and occurred at a mean interval of 84 min. The feeding patterns gave the appearance of a short-term rhythm underlying the onset of feeding (as has been found in locusts and caterpillars), although there were insufficient meals taken by individuals over the 10-h period to test this suggestion. Meals were notable in apparently lacking intrameal pauses and also commencing without preliminary sampling behaviors, such as palpating or biting. Whether the combination of short, infrequent meals, ingested without pauses and not preceded by sampling behavior, represents an adaptation reducing apparency to natural enemies, or else simply reflects low nutritional needs, is discussed. Correlations between meal durations and following and preceding intermeal intervals suggested that variation in intermeal intervals stemmed largely from variation in meal duration, not vice versa, with variation in meal duration resulting from an external influence such as leaf nutritional and/or allelo-chemistry. The latter suggestion is currently being tested.
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