The impact of Ixodiphagus hookeri, a tick parasitoid, on Ambl yomma variegatum (Acari: Ixodidae) in a field trial in Kenya

Abstract

In an experiment to investigate the effect of the tick parasitoid, Ixodiphagus hookeri, on tick numbers on cattle, 150000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. Amblyomma variegatum was reduced from 44 to two ticks per animal while Rhipicephalus appendiculatus increased over the time of parasitoid release. During the time of release 51% of the nymphs of A. variegatum collected from the animals were parasitized. The recovery of the parasitoids after the releases were stopped was only 9%. The total numbers of A. variegatum remained low up to 1 year after the parasitoid release was stopped. This study gives an insight into how I. hookeri could be used strategically for the management of A. variegatum on small-scale farms.

Feasibility of Controlling <I>Ixodes scapularis</I> Ticks (Acari: Ixodidae), the Vector of Lyme Disease, by Parasitoid Augmentation

“…Perhaps of equal importance, the theoretical results obtained against the blacklegged tick are in close agreement with the results obtained in a Þeld release experiment conducted by Mwangi et al (1997) in Africa against Amblyomma variegatum (F). Their experiment is the only effort that has been reported that has tested the feasibility of controlling tick populations by the parasitoid release technique.…”

“…In the experiment conducted by Mwangi et al (1997) the parasitoids had no effect on Rhipicephalus appendiculatus (Newmann) ticks on the experimental animals. This tick species, therefore, is probably not a suitable host for the parasitoid used in their experiment.…”

“…They may be incapable of readily getting on large hosts such as deer and cattle. In the investigations conducted by Shastri (1984) and Mwangi et al (1997) the implications are that engorging nymphs are parasitized while on the cattle. This, however, would be inconsistent with the known parasitism behavior involving the larval and unengorged nymphal stages.…”

“…The feasibility of controlling ticks by releasing large numbers of parasitoids in tick habitats has received little consideration by researchers. However, Mwangi et al (1997) undertook a small augmentation experiment in Africa that yielded encouraging results. The results of that important experiment will be discussed in more detail later.…”

Occurrence of Ixodiphagus hookeri (Hymenoptera: Encyrtidae) in Ixodes ricinus (Acari: Ixodidae) in Southern Italy

“…Wasp females insert their ovipositors inside the tick and lays eggs (Hu et al, 1998); subsequently, the larval stage of the wasp consumes the entire internal of the engorged tick, and the adult wasp emerges from the tick host 30-57 days following oviposition (Wood, 1911). This wasp was first described parasitizing Rhipicephalus sanguineus in TX, USA (Howard, 1908), as well as other species belonging to the genera Dermacentor (Wood, 1911), Amblyomma (Mwangi et al, 1997), Hyalomma (Cooley, 1930), Haemaphysalis (Doube and Heath, 1975) and Ixodes (Wood, 1911;Boucek and Verny, 1954;Costa-Lima, 1915). Given the wide geographical distribution of these wasps, it is possible that allopatric populations of I. hookeri belong to different taxa (Collatz et al, 2011) and are characterized by different biological behaviors.…”