Evaluation of apple flea weevil dispersal and the potential of Kaolin Clay-based management in organic apples

Graduate Student:  John Pote, Michigan State University Department of Entomology

Major Professor:  Dr. Matthew Grieshop, Assistant Professor, Michigan State University Department of Entomology

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Objective 1.Determine the dispersal capability of Apple Flea Weevil (AFW) within orchard landscapes Objective one was addressed through a large-scale mark-release-recapture experiment, performed at Clarksville Horticulture Experiment Station (CHES) in Clarksville, MI. Mature apple flea weevil (AFW) were collected from various organic orchards across Mid-Michigan and marked with fluorescent powder. Once marked, the weevils were released in the center of four 12-row plots, each measuring

165’ x 130’ in area. Two releases of roughly 300 weevils per plot occurred on 6/28/11 and 7/1/11. To measure the dispersal ability of AFW, yellow sticky cards were deployed in a 5 by 6 grid centered around the point of release. These traps were checked every two weeks and changed after one month. In an attempt to recapture marked weevils after over-wintering, yellow sticky cards were deployed again in the late spring of 2012. Weevils were determined as having been marked by exposure to a blacklight hand lamp which caused the marking powder to fluoresce brightly.

Of the thousands of released weevils at all four plots, only five marked weevils were recaptured: three from the Spring of 2012 and two from Summer 2011 (Fig. 1). No marked weevils were recovered from the cards deployed in the Spring of 2011. The longest distance traveled by any marked weevil was 81 ft, recaptured in the Spring of 2012 and the longest distance traveled by a marked weevil captured in 2011 was 62 ft. The average distance traveled by recaptured weevils was 64.5 ft (Table 1).

Given the low number of recaptured weevils, it is difficult to infer useful information from this data. However, it was shown that weevils are capable of moving at least 81 ft. and that, on average, the may move significantly farther than previously expected, given the observed aggregate nature of AFW damage. It is possible that few weevils travel very far but the vast majority remain so long as conditions are favorable. If this experiment is to be repeated, a larger quantity of weevils will need to be released to obtain more tangible results.

Objective 2. Determine the efficacy of Surround on AFW in lab and field trials Significant Revisions: Due to the unforeseen and sporadic weather of the Spring of 2012, AFW adults were not present in the field in large enough quantities to allow for lab testing to occur. In lieu of this,we modified the focus of Objective two to include more extensive field insecticide testing including exploration of Entrust (Spinosad), a compound shown to be promising in other studies, as well as an assessment of the effect of various insecticides (including Surround and Entrust) on the AFW parasitoid community.

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