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United States Department of Agriculture

Agricultural Research Service

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Location: Emerging Pests and Pathogens Research

2011 Annual Report

1a. Objectives (from AD-416)
1: Characterize fungal strains associated with insects (including insect pathogens and symbionts and plant pathogens vectored by insects) and develop methods to enable their rapid identification and tracking. 1a. Develop molecular assays to detect and quantify plant pathogenic oomycetes vectored by insects to verify transmission. 1b. Identify the primary fungal symbiont associated with Asian ambrosia beetles and assess the genetic diversity of these fungi from beetles in the eastern United States. 1c. Evaluate fungal delivery, establishment and persistence in target populations of invasive wood-boring beetles. 2: Determine and improve the effectiveness of fungi for use within integrated management systems for greenhouse, horticultural and landscape pests, including but not restricted to thrips, whiteflies, ambrosia beetles and emerald ash borer. 2a. Develop a biologically-based IPM program for western flower thrips infesting greenhouse crops. 2b. Compare the efficacy of Beauveria bassiana and Metarhizium anisopliae against the Q biotype of Bemesia tabaci. 2c. Develop available microbial control agents for management of Asian ambrosia beetles and their symbiotic fungi. 2d. Integrate pathogenic fungi with other biocontrol agents for emerald ash borer and evaluate non-target impacts.

1b. Approach (from AD-416)
The goals of this project are to integrate entomopathogenic fungi into management systems for selected insect pests of horticultural, nursery and landscape plants and to track fungal strains in these environments. The work comprises fundamental laboratory studies as well as applied greenhouse and field research. This project will develop basic information on the biology of fungal and oomycete pathogens associated with insects, their genetic and phenotypic variability, and their survival and transmission in greenhouse and field environments. Integration of fungal pathogens will be accomplished for management of key pests: a biologically based program will combine use of pathogens and predators for control of western flower thrips infesting greenhouse crops; efficacy of fungal pathogens will be determined for Bemisia whiteflies (B. tabaci Q biotype); microbial control agents will be developed for management of Asian ambrosia beetles; and a fungal mycoinsecticide will be integrated with other biocontrol agents used against emerald ash borer. Fungi used in the ways developed in this project will provide safe, effective biological alternatives to synthetic chemical insecticides and/or rotational partners for insecticide resistance management.

3. Progress Report
A robust and easily maintained laboratory colony of western flower thrips (Frankliniella occidentalis) was established on excised bean leaves. Insects from this colony were used in an extensive screening effort to identify fungal pathogens from the USDA-ARS collection of Entomopathogenic Fungal Cultures (ARSEF) with high virulence against key pests of greenhouse crops (see report of activities under Cooperative Research and Development Agreement project 1907-22000-019-12T). Thrips from the lab colony were also used to infest greenhouse research plots of potted impatiens for research aimed at development of a biologically based IPM program for western flower thrips. A number of greenhouse tests aimed at assessing efficacy of fungal pathogens (Beauveria and Metarhizium isolates) against western flower thrips and predatory midges (Aphidoletes aphidimyza) against green peach and foxglove aphids were conducted in 2011. Tests of promising fungal pathogens against thrips during summer were unsuccessful due to extraordinarily high thrips pressure from unknown sources (movements of migrating thrips into our greenhouses). We are currently in the process of sealing the research compartments against future invasions before resuming testing. A series of experiments were done to assess the impact of insect pathogenic fungi on Asian ambrosia beetles in the field. Small logs were attached to stakes in infested woodlots and then sprayed with a strain of Metarhizium brunneum. Survival of this fungus was high for 3 weeks. Beetle attack rate, survival, and reproduction were all significantly reduced versus controls. Emergence of adult progeny and establishment of M. brunneum within beetle galleries are currently being analyzed. Newly discovered infestations of the emerald ash borer in New York are being characterized so that an integrated plan for their management can be developed and implemented. Clusters of girdled trees serve as ‘sinks’ for concentrating beetle attack. Individual girdled trees used across a larger area help delimit the population. All trees used in 2010 have been felled and beetles quantified. For 2011, new clusters of girdled trees also serve as foci for release of hymenopterous parasitoids. In addition, predation, parasitism and disease incidence are being quantified at several sites. This work is being done in cooperation with researchers at several institutions.

4. Accomplishments

Review Publications
Castrillo, L., Griggs, M., Ranger, C.M., Reding, M.E., Vandenberg, J.D. 2011. Virulence of Beauveria bassiana and Metarhizium anisopliae (Ascomycota: Hypocreales) commercial strains against adult Xylosandrus germanus (Coleoptera: Scolytidae) and impact on brood. Biological Control. 58(2):121-126.

Faria, M., Hajek, A.E., Wraight, S.P. 2009. Imbibitional damage in conidia of the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, and Metarhizium acridum. Biological Control. 51:346-354.

Faria, M., Hotchkiss, J.H., Hajek, A.E., Wraight, S.P. 2010. Debilitation in conidia of the entomopathogenic fungi Beauveria and Metarhizium anisopliae and implications with respect to viability determinations and mycopesticide quality assessments. Journal of Invertebrate Pathology. 105(1):74-83.

Last Modified: 10/16/2017
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