Differences in Body Size and Egg Loads of Rhagoletis indifferens (Diptera: Tephritidae) From Introduced and Native Cherries

Abstract

The western cherry fruit fly, Rhagoletis indifferens Curran, infests introduced, domesticated sweet [Prunus avium (L.) L.], and tart cherries (Prunus cerasus L.) as well as native bitter cherry, Prunus emarginata (Douglas) Eaton. Bitter cherries are smaller than sweet and tart cherries and this could affect various life history traits of flies. The objectives of the current study were to determine 1) if body size and egg loads of flies infesting sweet, tart, and bitter cherries differ from one another; and 2) if any observed body size differences are genetically based or caused by the host fruit environment. Pupae and adults of both sexes reared from larval-infested sweet and tart cherries collected in Washington and Montana were larger than those reared from bitter cherries. In addition, flies of both sexes caught on traps in sweet and tart cherry trees were larger than those caught in bitter cherry trees and females trapped from sweet and tart cherry trees had 54.0-98.8% more eggs. The progeny of flies from naturally-infested sweet and bitter cherries reared for one generation in the laboratory on sweet cherry did not differ in size. The same also was true for progeny of sweet and bitter cherry flies reared in the field on bitter cherry. The results suggest that the larger body sizes of flies from sweet and tart cherries than bitter cherries in the field are caused by host fruit and not genetic factors.

Divergence and evolution of reproductive barriers among three allopatric populations of Rhagoletis cingulata across eastern North America and Mexico

“…Interestingly, US flies were nevertheless more fecund, laying more eggs than females from Mexican populations. The increased fecundity of US females could have been due to their development in sweet cherries, which have been found to yield more fecund R. indifferens females than bitter cherries (Yee et al., ). Alternatively, discrete fruiting periods in northern latitudes could select for short‐lived individuals that invest more heavily in reproduction early in life, a well‐known life history trade‐off (Partridge et al., ; Kirkwood & Austad, ), that has been documented for species of Drosophila along altitudinal gradients (Norry et al., ).…”

New records ofRhagoletisLoew, 1862 (Diptera: Tephritidae) and their host plants in western Montana, U.S.A.

“…Based on number of larvae per host fruit, infestation levels were higher in sweet cherry (0.534 or 0.754, except in 2012) and tart cherry (0.437-1.094) than bitter cherry (0.099-0.325). However, based on larvae per gram of fruit, infestation in bitter cherry fruit (0.331-1.082) was as high or higher than in sweet cherry and tart cherry fruit (0.076-0.364), as bitter cherry fruit are smaller (0.3 g vs. 3-7 g) (Yee et al 2011b). Three R. indifferens larvae were reared from black hawthorn in 2011, resulting in the eclosion of one adult female and representing a new host record for R. indifferens in Montana.…”

Evidence for adaptation of Rhagoletis pomonella (Diptera: Tephritidae) on large-thorn hawthorn, Crataegus macracantha, in Okanogan County, Washington State, USA

“…More work is needed to verify if fly adaptation to large-thorn hawthorn in Okanogan County has resulted in a genetically-based reduction in adult body size. This could be addressed by reciprocal crossing experiments (Yee et al 2011) where large-thorn hawthorn flies are reared from apple fruit and apple flies are reared from large-thorn hawthorn fruit. If size of flies is genetically based, then the reduction could represent a third dimension of performance- or survivorship-related changes along with eclosion life history and host choice traits along which large-thorn hawthorn flies have ecologically adapted to the host shift.…”