Project Number: 3620-22410-014-02
Project Type: Nonfunded Cooperative Agreement

Start Date: Mar 22, 2011
End Date: Dec 31, 2012

Objective:
1) Demonstrate that microsclerotia of Metarhizium anisopliae (Ma) have the ability to control this soil pest; 2) compare efficacy experimental formulations for beetle control; and 3) acquire information to support submission for larger grant opportunity to develop biological control tactics as part of an integrated control program that reduces dependence on chemical insecticides.

Approach:
Samples of Metarhizium anisopliae (Ma) formulations will be prepared at USDA-ARS-NCAUR and provided to the University of California Desert Research and Extension Center near Holtville, CA, for field application and evaluation. The formulations supplied by NCAUR will include (at least) a granule formulation and a hyphal matt formulation containing microsclerotia of Ma. The field study will be conducted at the University of California Desert Research and Extension Center near Holtville, CA. Treatments will be applied to field grown cantaloupe plots, replicated four times in a randomized complete block design. Experimental treatments will all contain microsclerotia of Ma. Treatments may be applied three times during the growing season. Treatments will be evaluated based on 1) beetle counts form 20 melons per plot, 2) beetle counts on potato pieces placed in the plots after application, and 3) by evaluations of damage to melons at harvest. Additionally, laboratory Petri dish assays will be conducted to evaluate darkling ground beetle infection and mortality by Ma treatments listed below. Additional laboratory bioassays to determine insect infection will be conducted at the University of California Desert Research and Extension Center near Holtville, CA. Treatments will be applied to adult Darkling Ground beetles in a completely randomized design with 40 replications. Forty beetles will be placed into individual sterilized glass vials with bait, granule, and Ma matt treatments. Treatments will be incubated in the dark at 25° C in a growth chamber. Insect mortality will be assessed on a daily basis. Spore production will be assayed to determine fungal reproduction on beetle hosts, by randomly selecting 5 beetles (out of 40) within each treatment for which there was spore production. Each beetle will be washed with 5 ml of sterile distilled water with 0.1% Triton X-100. Spore production will be determined by hemacytometers counts of dilute solutions. Spore viability will be detemined by plating on 2.5% Noble agar (Becton Dickinson Sparks, MD). Germination will be assessed at 24 h by microscopic observation for spores with germ tubes longer than half the size of the spores.