Pathophysiological effects of Neem (Azadirachta indica) derivatives to Rhipicephalus appendiculatus, the tick vector for Theileriosis (East Coast Fever)

Abstract

The effects of 2 Neem derivatives, Neem oil (NO) and Neem Seed Powder (NSP), on various physiological parameters of the brown ear tick, Rhipicephalus appendiculatus, the vector for Theileria parva. Neem oil was applied on rabbit ears using a fine brush, whereas NSP was mixed with rabbit pellets at various concentrations and fed on goats on which various instars of the tick were allowed to feed. Tick larvae smeared with Neem oil (NO) while attached to rabbit ears exhibited significant mortalities. The 10% NO induced a mortality of 40% compared to less than 1% observed in Peanut oil (PO) control. Furthermore, engorgement weights were significantly reduced (0.1 mg NO vs 4 mg PO). Their corresponding moulting percentages were 1 and 71% in NO and PO, respectively. Adult female ticks exhibited reduced engorgement weights and egg mass. Larvae able to attach on goats maintained on 100% NSP were only 11% compared to 66% for control goats fed on rabbit pellets (RP). The corresponding nymphal attachments were 24% NSP and 79% RP. The number and weights of eggs produced by adult ticks fed on goats maintained on NSP also dropped significantly. The hatchability of eggs produced by these ticks was also significantly reduced.