Population structure of Argas arboreus (Acari: Argasidae) ticks associated with seasonally abandoned mixed heronries, dominated by cattle egrets (Bubulcus ibis), in South Africa.

H.J.B. Butler,V.N. Belozerov,D.J. Van Niekerk

doi:10.4102/ojvr.v70i4.297

Abstract

During winter populations of Argas arboreus from heronries of the cattle egret, Bubulcus ibis, in South Africa are composed of adults, with some predominance of males, and II-IV instar nymphs, in a state of diapause. The period of tick activity, including reproduction and development of eggs, larvae and N1 nymphs, is synchronized with the nesting and breeding season of their avian hosts. It begins during spring with the return of birds to the heronry, and ceases in autumn through induction of reproductive diapause in engorged females, and behavioural diapause in unfed nymphs and adult ticks. Many ticks showed morphological anomalies and malformations, the study of which could possibly be used for monitoring of environmental pollution.

Highlights

In southern Africa the cattle egret (Bubulcus ibis) is a partial migrant, especially in the highveld and the drier northwest, that disperses during winter after breeding activities in spring and summer (Martin 1997)
Heronries are usually abandoned after the breeding season, but the birds may use the same site for breeding year
The proportion of adult and N2–4 nymphs is similar for the samples from Wolwekop Farm (WF) (Fig. 1A), Soetdoring Nature Reserve (SNR) (Fig. 1D) as well as the Eucalyptus tree sample from Willem Pretorius Game Reserve (WPGR) (Fig. 1E)

Summary

Introduction

In southern Africa the cattle egret (Bubulcus ibis) is a partial migrant, especially in the highveld and the drier northwest, that disperses during winter after breeding activities in spring and summer (Martin 1997). They are highly colonial breeders, often breeding in large numbers in mixed-species heronries (Maclean 1993; Martin 1997; Steyn 1996), and there is usually a high degree of breeding synchrony throughout the heronry (Steyn 1996). The dormant state of the adult ticks is related to reproductive diapause controlled by photoperiod and

Methods

Results

Conclusion