Efficacy of spot-spray application of Metarhizium anisopliae formulated in emulsifiable extract of Calpurnia aurea in attracting and infecting adult Rhipicephalus appendiculatus ticks in semi-field experiments

Abstract

The efficacy of spot-spray application of conidia of Metarhizium anisopliae (Metsch.) Sorok. conidia formulated in an emulsifiable extract of Calpurnia aurea (Ait.) Benth in attracting and infecting Rhipicephalus appendiculatus Neumann, 1901 ticks was evaluated in semi-field experiments. Formulation was applied on a 900-cm² spot and ticks released from various distances. Attracted ticks were individually placed in glass vials to determine the number of M. anisopliae conidia picked by a single tick. Infected ticks were either transferred in glass vials or maintained in the laboratory until death or exposed to rabbits in order to investigate the effects of fungal infection on feeding and potential reproduction parameters. Data showed that individual ticks picked between 3.2 and 4.1 × 105 conidia. Mortality of 83 % was observed among ticks maintained in the laboratory conditions. The engorgement period of fungus-infected ticks significantly increased by 16 % compared to the control. A significant reduction (P < 0.0001) was recorded in body weight, egg-mass and egg hatchability from fungus-infected females. It is therefore possible to use M. anisopliae formulated in C. aurea extract for an integrated pest management approach. This study showed that conidia of M. anisopliae formulated in C. aurea extract are effective in attracting, infecting and causing mortalities of R. appendiculatus ticks. Moreover, the reproduction performance of fungus-infected females was significantly reduced.