Abstract
Apple flea weevil, Orchestes pallicornis (Say) was a sporadic pest in the early 1900s and has reemerged as a severe pest of cultivated apple ( Malus domestica Borkh.) in Michigan. Organic apple orchards in Michigan have had outbreak population levels of apple flea weevil since 2008 and damage has resulted in up to 90% losses. Apple flea weevil is a small, 2–3-mm black weevil with enlarged high legs for jumping. The adults feed on bud and leaf tissue and heavy pressure causes bud termination. Leaf tissue is removed in multiple small circles, with the net result of the large removal of photosynthetic material. Larvae are leaf miners, developing between the upper and lower leaf cuticles while migrating from the midrib to the leaf margin where pupation occurs. Pupae develop inside a blister, an air-filled space that turns brown. Low populations of apple flea weevil are missed easily or misdiagnosed as either frost damaged from bud feeding or sulfur burn from pupal cases. Apple flea weevil is likely secondarily managed by broad-spectrum insecticides used in conventional programs. However, there are currently no proven management options for use in organic production. As broad-spectrum materials are replaced by reduced-risk compounds, it is possible that apple flea weevil will become an important pest in apple production.
Highlights
Orchestes pallicornis (Say) (Coleoptera: Curculionidae), the apple flea weevil, has rapidly become a serious pest in Michigan organic apple (Malus domestica Borkh.) orchards—with some growers experiencing Ͼ90% crop loss (Grieshop et al 2010)
It was not attributed to apple flea weevil until 2010 by which time over half of the organic apple acreage in Michigan was reporting high damage and populations
One hypothesis for the recent reemergence of this pest in relatively newly certified organic, but not conventional orchards, is that the recently organic orchards are relying on narrow spectrum pesticides
Summary
Orchestes pallicornis (Say) (formerly Rhynchaneus pallicornis) (Coleoptera: Curculionidae), the apple flea weevil, has rapidly become a serious pest in Michigan organic apple (Malus domestica Borkh.) orchards—with some growers experiencing Ͼ90% crop loss (Grieshop et al 2010). It was not attributed to apple flea weevil until 2010 by which time over half of the organic apple acreage in Michigan was reporting high damage and populations. Orchestes pallicornis adults begin emerging from their overwintering sites in the orchard floor early in the apple growing season.
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