Aspects of the development of Ixodes anatis under different environmental conditions in the laboratory and in the field
Abstract Background Numerous laboratory and few field-based studies have explored the influence of microclimates on developmental times of different stages of various species of ixodid ticks and found that most of these species develop quicker and survive better at temperatures between 18 and 26°C and relative humidity between 75% and 94%. Ixodes anatis Chilton, 1904, or kiwi tick, is an endophilic, nidicolous species endemic to North Island brown kiwi (Apteryx mantelli, NIBK) and the tokoeka (Apteryx australis). Little is known about the environmental conditions that are ideal for the development of the kiwi tick. Our aims in this study were to determine and compare the conditions of temperature and RH that ensured the best survival, and the shortest interstadial periods for the kiwi tick, in the laboratory and outdoors inside artificial kiwi burrows.Methods We collected free walking engorged ticks off wild kiwi hosts and placed them in the laboratory at various fixed temperature and humidity regimes. We also placed sets of different stages of these ticks in artificial kiwi burrows and in both cases, recorded the times taken for the ticks to moult to the next stage.Results We found that larvae and nymphs both showed optimum development between 10-20°C, which is lower than many other species of ixodid ticks. However, larvae moulted quicker and survived better when saturation deficits were <1-2 mmHg (RH>94%) while for nymphs the optimum saturation deficits were 1-10 mmHg.Conclusions We believe that the kiwi tick has adapted to stable, but relatively cool and humid conditions in the burrows reflecting the evolutionary consequences of its association with the kiwi.