Field Applications of Entomopathogenic Fungi <i>Beauveria bassiana</i> and <i>Metarhizium anisopliae</i> F52 (Hypocreales: Clavicipitaceae) for the Control of <i>Ixodes scapularis</i> (Acari: Ixodidae)

Twocommercial formulations ofBeauveria bassiana(Balsamo-Crivelli)Vuilleminwere applied to residential sites in Old Lyme, CT, for the control of nymphs of the blacklegged tick, Ixodes scapularis, in 1999 and 2000. The pyrethroid bifenthrin was applied to other premises for comparison with B. bassiana. A wood chip barrier was installed and maintained at six of the treated properties. In 1999, control of I. scapularis nymphs ranged from 74.5 to 83.0% on lawnswithout wood chips and from 88.9 to 90% on lawns with wood chip barriers. As a control check, no ticks (n 23) collected at pretreatment or control sites died from B. bassiana, although 15 of 18 nymphs from treated lawns developed mycoses. Control of I. scapularis on the lawns in 2000 with the two B. bassiana products was lower, as follows: 38.0 and58.7%without thebarrier and56.9 and55.1%with thewoodchipbarrier. Posttreatment differences in nymphal numbers between treatments and control were signiÞcant (P 0.005 and P 0.039, 1999 and 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 signiÞcant (P 0.034; P 0.039) reductions in nymphal tick abundance with 55.6 and 84.6% fewer ticks on lawn and woodland plots, respectively. These results suggest the application of entomopathogenic fungi could provide another approach for the control of I. scapularis nymphs in residential or similar landscapes.