The Kingdom of Saudi Arabia includes fauna from three zoogeographic regions: the Afrotropical, Oriental, and Palaearctic regions. To study the mosquito (Diptera: Culicidae) fauna of these regions in Saudi Arabia, larval collections were made at 15 sites during 2005-2006. Thirty-three species representing nine genera were found. Six species, Anopheles culicifacies Giles s.l., Anopheles subpictus Grassi s.l., Culex arbieeni Salem, Culex simpsoni Theobald, Culex univittatus Theobald, and Ochlerotatus detritus Haliday are reported for the first time for Saudi Arabia. An annotated checklist and an illustrated key to the fourth-instar larvae of the 33 species are presented, along with some remarks about problematic species. Eleven species of genus Anopheles Meigen, five species of tribe Aedini, 13 species of genus Culex L., two species of genus Culiseta Felt, one species of genus Lutzia Theobald, and one species of genus Uranotaenia Lynch Arribátlzaga were recorded during the study.

The cardiac glycoside, digitoxin, from Digitalis purpurea L (Scrophulariaceae), a cardiac glycosidal (cardenolide) extract from Calotropis procera (Ait) R Br (Asclepiadaceae), azadirachtin and neem oil from Azadirachta indica A Juss (Meliaceae) were tested for their effects against larvae and adult stages of the camel tick, Hyalomma dromedarii Koch (Acari: Ixodidae). The contact LC50 values of the first three materials against adults were 4.08, 9.63 and >40.7 microg cm(-2), respectively, whereas the dipping LC50 values of the four materials were 409.9, 1096, >5000 and >5000 mg litre(-1), respectively. Contact and dipping LC50 values of the extract and azadirachtin against larvae were 6.16, >20.3 microg cm(-2) and 587.7 and >2500 mg litre(-1), respectively. Azadirachtin had no effects on egg production or feeding of adults up to 5000 mg litre(-1); however at 2500 mg litre(-1), it caused significant reduction in feeding activity of larve, prolonged the period for moulting to nymphal stage, and caused 60% reduction in moultability. Results of the two cardiac glycoside materials are comparable with those of several commercial acaricides. The risks and benefits associated with the use of cardiac glycosides are considered.

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The life cycle of Hyalomma dromedarii Koch (Acari:Ixodidae) on rabbits at 25 and 32ºC was compared at 85% R.H. At these temperatures, it behaved as a two-host tick and completed its life cycle in 108-146 and 80-115 days, respectively. The preoviposition, incubation and moulting periods varied significantly and were influenced by temperature. The survival periods of different developmental stages of Hyalomma dromedarii at 25ºC, 32, 38, 43, and 48ºC at 85% R.H. were investigated. The eggs, engorged nymphs and engorged females died at 38ºC, and the unfed larvae died at 43ºC. The longevity of the unfed adults decreased from 90-120 days at 25ºC to7-15 days at 43ºC. They died at 48ºC. These results suggest that the survival periods of eggs, engorged nymphs and engorged females were significantly decreased with an increase in temperature. They were more susceptible to high temperature than unfed adults. The role of unfed adult in the continuity of the life cycle of the tick throughout the year is discussed.Keywords: Hyalomma dromedarii, life cycle, survival, laboratory conditions. he camel tick, Hyalomma dromedarii Koch (Acari: Ixodidae) is the most important tick infesting camels in Saudi Arabia (Badawi, 1994). The ecology and the biology of the camel tick has not been fully investigated. The availability of information on the effect of temperature and humidity on the rate of development and survival of the camel tick is essential for a rational control program. The current study was carried out to assess the life cycle of H. dromedarii and its survival at different temperatures under laboratory conditions. Materials and MethodsFully engorged females of H. dromedarii were obtained from a camel in Muzahmyia area (50 Km South of Riyadh City) and identified as H. dromedarii according to Hoogstraal (1956). They were put in an incubator at 28°C and 85% R.H. to oviposit. The emerged larvae, nymphs and adults were fed on white New Zealand tick-native rabbits.Five white New Zealand tick-native rabbits were infested with approximately 200 larvae of H. dromedarii.

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