Early-season host plant fruit impacts on reproductive parameters of the oriental fruit moth (Lepidoptera: Tortricidae)

Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), a cosmopolitan pest of tree fruits, has been a significant pest in the United States since its introduction in the early 20th Century. Grapholita molesta historically has been a major pest of stone fruit. However, since the mid to late 1990s, outbreaks in commercial apple orchards in the eastern United States have become common place. This study examined the effects of larval host (e.g., apple vs. peach) on G. molesta reproduction, as a means to better understand the increased importance of G. molesta as an apple pest in the midAtlantic region. In laboratory investigations, G. molesta adults reared on apple fruit had approximately 2-fold higher fecundity than those reared on peach (F = 10.98; df = 3,101; P < 0.001). In two separate studies, when larvae were reared under either crowded or noncrowded feeding conditions, female adult longevity and oviposition period were significantly greater among moths reared as larvae on apple than those reared on peach (2001: P = 0.019 and 0.009, respectively; 2002: P = 0.031 and 0.001, respectively). Female pupal weight was significantly higher in individuals reared on apple than those reared on peach, in both studies (2001 and 2002: P < 0.001). Similar host-influenced impacts on G. molesta reproductive phenomena could affect population dynamics of G. molesta, especially late in the season when apple fruit are a preferred feeding site.