Distinction of Grapholita molesta Busck and Grapholita dimorpha Komai Larvae based on morphological feature of anal prolegs

Larvae of Grapholita molesta Busck and Grapholita dimorpha Komai, which are major moth pests that affect apples in Korea, are very difficult to identify because of their morphological similarities. In this study, we investigated how to distinguish the larvae of these two species by using specific morphological features. Between 2013 and 2014, a total of 84 specimens were collected from apples suspected of infestation in Gunwi-gun and Cheongsong-gun, Gyeongsangbuk-do, Korea, and they were observed using a stereo microscope, optical microscope, and scanning electron microscope. We found that the number of anal proleg crochets of the two species was different. PCR-RFLP results for the two species showed that G. molesta and G. dimorpha have 18-28 and 12-17 anal proleg crochets, respectively. Our findings suggest that the number of anal proleg crochets could be an excellent morphological character that could be used to identify the larvae of the two species without the need for any further experiments.