Location: Crop Bioprotection Research2013 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:
Under Objective 1 of this non-funded agreement, laboratory experiments demonstrated the ability of the fungal bioinsecticide Metarhizium anisopliae (Ma) successfully infected and killed the target insect pest, Blapstinus beetles. Under Objective 2, experimental formulations have demonstrated efficacy in laboratory assays although field experiments have been inconclusive due to unusually low natural beetle densities. Under Objective 3, the information generated as a result of this cooperation has contributed to the success of the University of California to receive funding from the California Melon Board to evaluate field treatments for control of this insect pest. This non-funded cooperative agreement was established in 2011 with ARS Crop Bioprotection Research Unit scientists at the National Center for Agricultural Utilization Research, Peoria, Illinois, to evaluate Ma microsclerotia formulations for the control of Blapstinus beetles, a pest of melon production in the Southwest United States. This research project was extended in 2013 and directly supports the development of the Ma microsclerotia technology as a biological insecticide. Results of field experiments from 2012, which showed no differences among treatments due to low insect pressure, were reported to the California Melon Board in December. Currently, sample formulations based on laboratory research have been provided to cooperators at the University of California for evaluation under field application conditions. Data collections to evaluate crop protection by these treatments are underway for 2013 and preliminary evaluations indicate damaging pest pressure in the field experiment. In addition to these field evaluations, field collected and laboratory colony beetles will be assayed for susceptibility to treatments that are identical to field treatments.