Temperature Effects on Oviposition by Rhagoletis indifferens (Diptera: Tephritidae) Vary in Different Developmental Stages of Sweet Cherry.

Fruit developmental stage affects oviposition responses by tephritid fruit flies, but the role temperature plays in these responses to different fruit stages remains largely unknown. Here, temperature effects on oviposition rates of western cherry fruit fly, Rhagoletis indifferens Curran, in different stages of Bing sweet cherry (Prunus avium L.) were determined in no-choice experiments. Stage 1 (green), stage 2 (green-yellow to orange red), stage 3 (yellow-orange to red), and stage 4 cherries (red to burgundy) were exposed to flies at 15.6, 21.1, 26.7, and 32.2°C for 3 h and oviposition recorded. Oviposition was lower at 15.6°C than at all other test temperatures within all four cherry stages. Regression analysis using the three higher temperatures indicated there were significant cherry stage and temperature effects and a significant cherry stage × temperature interaction. The oviposition-temperature relationship was best explained by linear or curvilinear equations, depending on cherry stage. Oviposition in stage 1 cherries was lowest of the four stages and was not or linearly related to temperature. Oviposition in stage 2 cherries was greater and was related to temperature in a linear or curvilinear response. Oviposition was greatest in stage 3 and 4 cherries, with curvilinear and linear equations, respectively, best explaining oviposition-temperature relationships. Results suggest that temperatures and cherry stage together rather than cherry stage alone may have selected for behaviors leading to oviposition responses in R. indifferens.