Influence of intertree distance on foraging behaviour of Rhagoletis pomonella in the field

Abstract. 1. We tested a prediction from contemporary foraging theory that animals should decrease their allocation of energy to the searching of individual patches when interpatch travel costs decrease. 2. We used individual Rhagoletis pomonella Walsh (Diptera: Tephritidae) females foraging for oviposition sites (= Crataegus fruit) in a host tree which was surrounded by four other trees at varying distances. 3. We found that flies generally invested less search, measured as time spent searching a tree or number of leaves visited on a tree, when neighbouring trees were nearby than when farther away. 4. Under our test conditions, flies appeared to have difficulty locating neighbouring trees at a distance of more than 1.6 m. 5. Our study calls into question the interpretation of search effort by insects within resource patches in the absence of information on interpatch distances.