Identification of resistance in Malus to codling moth and leafroller

A whole-leaf bioassay method was developed that provided apple-leaf quality over time. Data on the development and mortality of obliquebanded leafroller, Choristoneura rosaceana, larvae reared on an artificial diet (pinto bean) provided a timeline on which to evaluate larval performance on leaves. Delicious and Granny Smith represented standard control apple varieties. Larvae feeding on Viking, Yellow Transparent, Liberty, Virginiagold, Antonovka and Poeltsamaa had the longest development time, while those on Florina (males) and Cox Orange Pippen (females) had the shortest, and were similar to those on Granny Smith, Delicious, and pinto bean. Larvae reared on pinto bean weighed more than those on any apple variety. Males had lower pupal weight and developed faster than females. Female pupae varied more in weight than males. Pupal weight was inversely correlated with development time. No female larvae survived on Lady or Northern Spy, and males survived least on Lady and Northern Spy. Male larvae survived best on Cox Orange Pippen and pinto bean. Overall, there was about 10% or less survivorship of male and female larvae feeding on Lady, Northern Spy, Viking, Yellow Transparent, and Antonovka. Moreover, larvae that fed on Antonovka had developmental abnormalities suggestive of juvenile hormone effects. Adult emergence was positively correlated with pupation day. The reproductive assessment of adults showed that when reared on some varieties fecundity was significantly reduced. Apple varieties that negatively impacted larval survival and development showed both negative and positive impacts on fecundity.