Bioassay Techniques of Insecticidal Plant - Extracts on Tropical Cattle Ticks (Boophilus microplus)

Abstract

The engorge female of tropical cattle ticks survived in vitro more than 72h and began laying at 70-75h after taking from cattles. The larvae were hatches 14-23 days after laying. The unfed larvae survived more than 2 months in humid bottle. The leg contact method was used for larvicidal bioassay. The larvae were left to contact with the dry film of plant-extract. The mortality of larvae in empty, evaporated ethanol-and ethyl acetate- coated bottles as control were considerably low and no significant difference were found among them. In insecticidal bioassay of adult ticks, both body dip0ing and leg contact methods could be applied. The dipping method was rapid and easy procedure for screening bioassay. The leg contact methods was used for bioassay in the fractionation of compounds dissolved in non polar organic solvents. The mortality of engorge female ticks was very low at 48 h after dipping with water, methanol, ethanol, acetone and 2% polyoxyethylene sorbitan mono – oleate. After dipping with ethyl acetate and toluene the mortality were high. The survival checks of larvae was observed on its leg movement after exposing to fresh air. The treated engorge female tick was observed in its leg and body movement after exposing to warm-air, 100w lamp’s light sunshine and direct press to the body. The non survival ticks were confirmed by its non laying. This study demonstrated that the cattle ticks can be bioaassayed for larvicidal and insecticidal activities in vitro before further application in vivo