Observations on the Biology of Ixodidae

Extract

Rhipicephalus appendiculatus requires three hosts upon which to feed in its larval, nymphal and adult stages. The larvae remain upon the host 3–7 days in most cases; when they remain considerably longer they either do not imbibe blood freely or they may not actually attach themselves on the day on which they were placed on the host; gorged larvae have dropped off the host up to 15 days after the unfed larvae were placed on the host. Nymphs remained upon the host 5–11 days and fertilized replete females abandoned the host after 6–14 days. The males may stay on longer. Unfertilized females may remain upon the host up to 24 days. The temperature at which the host is maintained, within the limits observed, exerts no apparent influence upon the time that the different stages of the tick remain attached. Metamorphosis takes place: from egg to larva in 32–65 days at 17–19° C.; from larva to nymph in 4–6 days at 30° C., in 21–41 days at 15–17° C., in 60–75 days at 13–14° C.; from nymph to adult in 10 days at 37° C., in 21–28 days at 20° C., in 64 days at 14° C. Temperature therefore markedly influences the rate of development. Oviposition commences 6–23 days at 17–19° C. to 50–61 days at 12° C. after the female abandons the host, the process lasting 15–56 days, during which period the female lays 3000–5770 eggs. Unfed larvae and nymphs were still lively after 333 days and 164 days respectively in a tightly corked bottle maintained at room temperature in a darkened cupboard in the laboratory. Unfed adults were lively after 181 days on moistened earth in a gauze covered jar kept in the cupboard; we have one lot of which a few individuals were living (unfed) after 630 days, a single male being still alive after 682 days (21. iii. 13).