Improvement of Arthropod Biological Control Systems For Organic Greenhouse Production

Graduate Student Final Report – Ceres Trust Research Grant

Graduate Student: Emily Pochubray, Michigan State University Department of Entomology

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

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Objective 1. Determine the preference of Atheta coriaria for breeder piles (with mites) vs. bran piles (without mites).

Objective 2. Determine whether the use of Amblyseius cucumeris hanging sachets will prevent A. coriaria from entering bran mixture.

An experiment that addressed both objectives was conducted at Elzinga and Hoeksema Greenhouses (Portage, MI) in spring 2011 to determine the compatibility of A. cucumeris mites and A. coriaria rove beetles for greenhouse biological control, and to explore an alternative application method of A. cucumeris to reduce potential negative interactions between the predators. Barley seed was planted into beds on five greenhouse benches (5.5x16ft) with each bench considered a separate experimental replicate. After two weeks of growth four treatments: 1) sawdust, 2) bran, 3) breeder piles, and 4) hanging sachets were equally spaced in a randomized complete block design on the benches.There were 50 1.5g piles of each sawdust, bran, and breeder piles, respectively, placed onto the soil surface of the barley beds, and 50 hanging sachets that were hung on cardstakes. A.coriaria were released from two containers of 100-Atheta-System (BioBest, Ontario, CA) (~200 adult beetles) onto greenhouse benches. At weekly intervals for 9 weeks 5 piles of sawdust, bran, and breeder piles, and 5 hanging sachets were randomly selected and destructively sampled using Berlese funnel heat extraction. The 10th week of samples were not collected due to low mite densities extracted in previous weeks. Data collection for this trial has been completed. A second trial using similar methods is currently underway.