An analysis of the pattern of feeding in the Costa Rican weevil, Exopthalmus jekelianus, on the tropical tree, Cedrela odorata

Feeding patterns were recorded and analysed for adult female weevils, Exopt halmus jekelianus (White) (Coleoptera: Curculionidae), feeding on Central A merican mahogany, Cedrela odorata L., in the field in Costa Rica. The study forms part of an investigation into the relationship between feeding patte rns and the fine-scale variation in leaf chemistry occurring within the hos t plant. The weevils' feeding patterns were the simplest in temporal struct ure of any reported to date for an insect herbivore. Weevils spent an avera ge of only 3% of their time feeding during the 10-h observation periods. Me als lasted an average of 2.8 min and occurred at a mean intermeal 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 caterpill ars), although there were insufficient meals taken by individuals over the 10-h period to test this suggestion. Meals were notable in apparently lacki ng intrameal pauses and also commencing without preliminary sampling behavi ours, such as palpating or biting. Whether the combination of short, infreq uent meals, ingested without pauses and not preceded by sampling behaviour, represents an adaptation reducing apparency to natural enemies, or else si mply reflects low nutritional needs, is discussed. Correlations between mea l durations and following and preceding intermeal intervals suggested that variation in intermeal intervals stemmed largely from variation in meal dur ation, not vice versa, with variation in meal duration resulting from an ex ternal influence such as leaf nutritional and/or allelo-chemistry. The latt er suggestion is currently being tested.