Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2012
Publication Date: 1/15/2013
Citation: Behle, R.W., Jackson, M.A., Flor-Weiler, L.B. 2013. Efficacy of a granular formulation containing Metarhizium brunneum F52 (Hypocreales: Clavicipitaceae) microsclerotia against nymphs of Ixodes scapularis (Acari: Ixoididae). Journal of Economic Entomology. 106(1):57-63.
Interpretive Summary: Control of soil inhabiting arthropod pests such as ticks and grubs with applications of pathogenic fungal spores has been relatively costly with unacceptable variability. New fermentation technology produces microsclerotia of insect pathogenic fungi, a fungal structure with a high potential for improving biological control of ticks inhabiting urban landscapes because the microsclerotia produce the infective spores after application. Laboratory evaluations of a prototype granular formulation containing microsclerotia of Metarhizium brunneum and applied to potting soil successfully produced infective spores that infected both fed and unfed nymphs of black-legged ticks. Successful development of biopesticide formulations containing microscloteria have the potential to provide a more economical and environmentally safe control of ticks, while reducing the potential for transmission of tick-borne human disease without the risks associated with conventional chemical insecticide applications.
Technical Abstract: Technical improvements in the production and formulation of microbial agents will increase the potential for development of biological pesticides able to compete with chemical insecticides in the marketplace. Here we report the efficacy of a simple granule formulation containing microsclerotia of Metarhizium brunneum (Petch) F52 (Hypocreales: Clavicipitaceae) for control of unfed and fed nymphs of Ixodes scpaularis Say (Acari: Ixoididae). Granules applied to moist potting soil produce infective conidia within 2 wks and conidia remained viable for up to 8 wks after application. Microsclerotia produced from 3.05 × 109 to 1.24 × 1010 conidia/g granules in potting soil. Both unfed and fed nymphs were susceptible to infection when exposed to treated potting-soil with up to 56% mortality and 74% mortality, respectively. The fungus demonstrated a transtadial transmission on fed nymphs exposed to treated soil with signs of a fungal infection becoming apparent only after molting into adults. Conidial production rates from these granules made with microsclerotia combined with tick mortality support the need for additional research on the efficacy of this treatment technology as a biopesticide option for control of ticks.