Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/21/2013
Publication Date: 8/1/2013
Citation: Davis, T.S., Garczynski, S.F., Stevens-Rumann, C., Landolt, P.J. 2013. A test of fruit varieties on entry rate and development by neonate larvae of the codling moth, Cydia pomonella. Entomologia Experimentalis et Applicata. 148:259-266. Interpretive Summary: Codling moth is a damaging insect pest of fruit orchards, and larval feeding causes substantial economic losses for growers by reducing commercial value of fruit crops. Although this insect is a serious management concern for orchardists, there is surprisingly little information available regarding basic fruit preferences of codling moth larvae. Researchers at the USDA-ARS laboratory in Wapato, Washington are seeking to determine how larval feeding and development on fruit is affected by fruit species, variety, and nutritional content. They discovered that larvae preferentially feed on apples and pears, and that larvae were less likely to feed and develop in quince and walnut fruits. Similarly, they found that larval entry rates and subsequent development was best in Golden Delicious apples, and that larvae were less likely to feed and develop into large adults when colonizing Red Delicious or Granny Smith apple varieties. Finally, sugar content of apple pulp was found to be positively correlated with larval entry and performance, and Golden Delicious apples had the highest average sugar content. Their studies provide new insight into the factors important for management of codling moth larvae, and suggest that assessments fruit species and variety have important behavioral and developmental effects on moth larvae and pulp sugar content of fruit.
Technical Abstract: The rate of entry by neonate larvae of the frugivorous codling moth, Cydia pomonella (L.), into fruit material was investigated. Larval entry was assayed across several host plant species and several genetic varieties within a host species (apple). Effects of apple varieties on adult moth size, larval development time, and pulp sucrose concentration were also determined. Four important findings emerged: (1) neonate larvae had the highest frequency of entry (86% of larvae) into apple fruits, compared with pear (78%), quince (56%), and walnut (32%); (2) the frequency of larval entry into immature apples varied by apple variety, and larval entry rate was highest in var Golden Delicious apples (72%), compared to Granny Smith (46%) and Red Delicious (64%); (3) on average, adult moths were larger and development times were shorter on the variety with the highest entry frequency (Golden Delicious); and (4) sucrose concentrations were higher for the Golden Delicious variety (17.5 µg/mg) than either Granny Smith (15.9 µg/mg) or Red Delicious (15.1 µg/mg) varieties—which positively correlates with entry and development data. In summary, host plant species and varietals within a species have consequences for the entry success and development of neonate codling moth larvae in fruits, and that larval performance is correlated with the mean sucrose concentration of host material. Future studies should seek to directly link host fruit varieties and sugar concentrations to aspects of moth population dynamics with manipulative experiments in a field setting.