Management of lowbush blueberry insect pest (blueberry maggot) with biopesticides

Project Code BPI09-010

Project lead

Chris Cutler - Nova Scotia Agricultural College

Objective

To evaluate the efficacy of Beauveria bassiana (BotaniGard) in a pest management strategy for the management of blueberry maggot (Rhagoletis mendax), blueberry spanworm (Itame argillacearia), and blueberry flea beetle (Altica sylvia)

Summary of Results

Background

The Pesticide Risk Reduction Program and U.S. IR4 program consider biopesticides an important tool for replacement of problematic organophosphorus pesticides in the management of insect pests of wild (syn. ‘lowbush’) blueberry. Projects that evaluated the efficacy of biopesticides for the management of these pests were initiated as a joint Canadian-U.S. priority.

This project evaluated the efficacy of Botanigard, a formulation of the entomopathogenic fungus Beauveria bassiana, as a biocontrol agent for the management of blueberry maggot (Rhagoletis mendax), blueberry spanworm (Itame argillacearia) and blueberry flea beetle (Altica sylvia).

Approaches

Blueberry maggot: One experiment assessed impacts of Botanigard applications on non-target arthropod fauna in crop and pruned plots. Another large-scale field experiment aimed to quantify berry infestations following applications of Botanigard, alone or in combination with GF-120 Naturalyte, the only biopesticide currently registered in Canada for blueberry maggot control. Experiments were conducted in 2009 in a commercial wild blueberry field and at the Wild Blueberry Research Institute in Nova Scotia.

Blueberry spanworm and flea beetle: To investigate the efficacy of Botanigard against blueberry spanworm and blueberry flea beetle, laboratory bioassays were done with field-collected insects. Small-plot field experiments were conducted in New Brunswick and Nova Scotia. For the laboratory bioassays, mid-instar spanworm and flea beetle larvae were collected in the field and exposed to different doses of Botanigard or to an industry standard. Percent larval mortality was recorded after nine days. Field trials compared infestation rates following application of two different concentrations of Botanigard versus industry standards. Both experiments were conducted in 2009.

Results

Overall, results with Botanigard in 2009 were not promising. No control of blueberry maggot, spanworm or flea beetle was observed in the field, although laboratory experiments with spanworm and flea beetle revealed some fungal infection and good insect mortality. A follow-up experiment was conducted to ascertain that the lack of activity of Botanigard against blueberry insect pests was not due to poor batch quality.

No adverse effects of Botanigard on non-target arthropods were observed in both pruned and vegetative blueberry plots, regardless of rate, plot type (pruned vs. vegetative) or exposure duration.

Overall, this study suggests limited potential of Botanigard for control of blueberry maggot, spanworm and flea beetle in wild blueberry.

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