Evaluating Tick Attachment, Feeding, and Reproduction in FDF-Treated Deer

Adult ticks observed and counted at day 6 and day 8 post-exposure were defined by attachment status (attached, detached) and feeding status (non-engorged, partially engorged, fully engorged), with ‘attached’ = adults which remain imbedded in the skin of deer; ‘detached’ = adults which are not imbedded in the skin of deer; ‘flat’ = non-engorged adults, showing no discernable blood meal; ‘partially engorged’ = adults with partial blood meal discernable, but not fully fed; and ‘fully engorged’ = completely bloated and darkly colored adults. Ticks were further defined by condition (dead, alive), which was determined by carefully observing and manipulating attached and detached ticks with fine-tipped forceps to elicit movement, with ‘alive’ = movement of legs, palps or mouthparts; and ‘dead’ = no movement after approximately 45 s of manipulation. The attachment status, feeding status and condition of female ticks were compared between treatment and control groups. The proportion of ticks recovered within each test group was also investigated. Differences in the proportion of ticks attached and detached for each species and differences in feeding status and condition of each species within each test group were compared using a Pearson’s χ² test for independence.
The weights of engorged females and approximate number of eggs and hatched larvae were compared between the treatment and control groups. To estimate the approximate number of eggs in each egg mass, an assumption was made that 1 g of ixodid eggs would contain approximately 20,000 individual eggs [46 (link)]. The number of hatched larvae was estimated by multiplying the approximate proportion of hatched eggs by the approximate number of eggs [46 (link)]. Differences in the weights of engorged females detaching from FDF-treated deer, relative to deer in the control group, and the subsequent numbers of eggs and larvae produced per female were estimated using a Student’s t-test.