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United States Department of Agriculture

Agricultural Research Service

Research Project: Biological Control for Soil Dwelling Insect Pests of Melon Crops

Location: Crop Bioprotection Research

2011 Annual Report

1a. Objectives (from AD-416)
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.

1b. Approach (from AD-416)
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.

3. Progress Report
Research is conducted under a new cooperative agreement with the University of California and supports a grant funded by the California Melon Board to the University of California. Under this agreement, we are developing formulations of fungal-based biological insecticides for control of soil dwelling insect pests in melons. University of California scientists are conducting field trials with these biocontrol formulations in field plots within the major melon producing region of the South Western United States. Results from these studies will direct future research on the development and use of fungal bioinsecticides for control of insect pests in melons. Research activity under this new agreement is being monitored through phone calls and informal reports. The final results will be presented to the California Melon Board as a formal annual report.

4. Accomplishments

Last Modified: 06/28/2017
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