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Title: Field Applications of Entomopathogenic Fungi Beauveria bassiana (Hypocreales: Clavicipitaceae) and Metarhizium anisopliae F52 (Hypocreales: Nectriaceae) for the Control of Ixodes scapularis (Acari: Ixodidae)

Author
item STAFFORD III, KIRBY - Connecticut Agricultural Experiment Station
item Allan, Sandra - Sandy

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2010
Publication Date: 7/23/2010
Citation: Stafford Iii, K.C., Allan, S.A. 2010. Field Applications of Entomopathogenic Fungi Beauveria bassiana (Hypocreales: Clavicipitaceae) and Metarhizium anisopliae F52 (Hypocreales: Nectriaceae) for the Control of Ixodes scapularis (Acari: Ixodidae). Journal of Medical Entomology. 47(6):1107-1115.

Interpretive Summary: The black legged tick, Ixodes scapularis, is the primary vector of tick-borne diseases, including Lyme disease, in the United States. Most cases of Lyme disease are acquired in residential yards, however, tick control using conventional pesticides raises environmental and health concerns. In this study conducted collaboratively with a scientist at USDA’s Center for Medical, Agricultural and Veterinary Entomology (CMAVE) in Gainesville (FL), the use of fungi that specifically target arthropods, not mammals, was evaluated for tick control in residential areas in Connecticut. Field trials for two years demonstrated that application of Metarhizium fungi provided control as effective as synthetic chemicals. This approach provides a clear alternative to conventional pesticides for area-wide control of I. scapularis.

Technical Abstract: Two commercial formulations of Beauveria bassiana (Balsamo-Crivelli) Vuillemin were applied to residential sites in Old Lyme, Connecticut for the control of nymphs of the blacklegged tick, Ixodes scapularis in 1999 and 2000. The pyrethroid bifenthrin was applied to other homes for comparison with B. bassiana. A wood chip barrier was installed and maintained at 5 of the treated properties. In 1999, control of I. scapularis nymphs ranged from 74.5 to 83.0% on lawns without woodchips and from 88.9 to 90% on lawns with wood chip barriers. Of a sample of nymphs collected from the lawns after treatment (n = 18), all died and 79-83% developed mycoses. No ticks (n= 23) collected at pretreatment or control sites developed mycoses. Control of I. scapularis on the lawns in 2000 with the two B. bassiana products was lower; 38.0 and 58.7% without the barrier and 56.9 and 55.1% with the wood chip barrier. Postreatment differences in nymphal numbers between treatments and control were significant (P = 0.005 and P = 0.039, 1999 & 2000, respectively). The bifenthrin provided 86 and 87% control each year, respectively. The application of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 to 9 residential sites in Westport and Weston, CT in 2002 provided significant reductions (P = 0.015; P = 0.004) with 81.6 and 85.0% reductions in nymphal tick abundance on lawn and woodland plots, respectively. Lower levels of control (17.8%) were observed with late season applications to 9 lawns at Old Lyme. These results suggest the application of entomopathogenic fungi could provide an effective alternative to synthetic chemicals for area-wide control of I. scapularis, but timing, frequency of application, dosage, and formulation for foliar persistence of fungal conidia need further study.