SURICATA 5 (2017) 677 CULICIDAE 31 (Mosquitoes) Maureen Coetzee Fig. 31.1. Female of Toxorhynchites (Toxorhynchites) brevipalpis Theobald (Tanzania) (photograph © S.A. Marshall). Diagnosis usually with numerous scales on body, legs and wing veins, of varying colours, including white, silvery, yellowish, brown, Small- to medium-sized (body length: 4–13 mm), slender- black and bluish, some with metallic sheen; posterior margin bodied nematoceran flies (Fig. 1); head with proboscis of of wing with fringe of scales (Jupp 1996: 1; Service 1980: male and female conspicuous, scaly, forwardly-projecting; 22, 1990: 3) (Figs 3, 9–24); males usually distinguished from Kirk-Spriggs, A.H. & Sinclair, B.J. (eds). 2017. Manual of Afrotropical Diptera. Volume 2. Nematocerous Diptera and lower Brachycera. Suricata 5. South African National Biodiversity Institute, Pretoria; pp. 677–692. CHAPTER TITLE 678 SURICATA 5 (2017) females by the highly plumose antennae (Figs 2, 27), while attract females by the formation of swarms around dusk, us- living adults of the two subfamilies Anophelinae and Culicinae ing various markers on the ground or above, e.g., around tree can be recognised by their resting positions (Figs 4, 5). branches, and swarm for approximately 20 minutes. The ma- jority of swarms are single-species males (Assogba et al. 2013; Head globular, with prominent compound eye (Fig. 2); Dabire et al. 2013a), but in the Anopheles (Cellia) gambiae occiput with erect scales posteriorly, vertex with broad, and/ Giles, 1902 complex, mixed swarms of An. coluzzii Coetzee or narrow, decumbent scales; antenna multi-segmented, & Wilkerson, 2013 and An. gambiae may be found (Dabire et plumose in males in most genera, giving feathery appearance al. 2013b), but mating remains assortative within species. In (Figs 2, 27), in females delicate, with 5–7 short setae arising general, larger males are more successful in mating than their from base of each flagellomere (Figs 3, 26); palpus scaly, arising smaller counterparts (Sawadogo et al. 2013). from below clypeus, either short, or as long as proboscis (Figs 2, 26, 27); proboscis scaly, forwardly-projecting. Female mosquitoes can oviposit from 30–300 eggs at a time, depending on the species. Some species (e.g., Culex L. and Thorax clothed in scales dorsally, sometimes bearing rows of Anopheles Meigen), deposit their eggs directly onto the sur- setae; lateral pleural sclerites with or without scales and setae. face of the water, while others, such as Aedes Meigen spp., lay Scutellum usually trilobed in subfamily Culicinae (Figs 31, 35), their eggs above the water level on damp substrates. Such eggs evenly rounded in Anophelinae (Fig. 28), with scales or setae. can usually withstand desiccation. Eggs are normally blackish Wing (Figs 3, 9–25) long, narrow, veins with scales dorsally and in colour and ovoid (Fig. 7), but there is considerable variation, ventrally, posterior margin of wing with fringe of outstanding for example, Toxorhynchites Theobald eggs do not turn black narrow scales. Legs long and slender (Figs 1, 3). following oviposition (Muspratt 1951), while some species of Abdomen long and slender (Fig. 3); tergites and sternites Mansonia Blanchard have skittle-shaped eggs, that are glued 1–8 well-developed; female terminalia with paired cerci that onto the under-surface of floating vegetation (Jupp 1996: 23; may be withdrawn into terminal segments; male terminalia Service 1980: 61). The eggs of the subfamily Anophelinae are with jointed claspers; paramere heavily-sclerotised, positioned characterised by air sacks that allow these to float on the sur- ventral to claspers; female terminalia of limited use in differen- face of the water (Figs 41, 42). tiating species, but male terminalia often of taxonomic value. Mosquito larvae occur in a wide range of aquatic habitats, Adult Culicidae superficially resemble midges of the families including temporary rainwater pools, artificial water contain- Chaoboridae (see Chapter 30), Chironomidae (see Chapter 35) ers, tree holes, crab holes, leaf axils, impoundments, swamps and Dixidae (see Chapter 28), but are easily distinguishable by and slow-moving streams. They are mostly filter-feeders, feed- the prominent forwardly-projecting, elongated mouthparts. ing on algae, yeasts, bacteria, protozoans and other micro- organisms, but some are predaceous. Larvae go through four moulting stages and development from first-instar larva to Biology and immature stages pupa may last from 7–30 days, depending on the species and on temperature. Larvae of Anopheles can be recognised by The aquatic larval stages (Figs 6, 43, 44) have a well- their feeding and breathing positions, lying parallel with the developed head, a pair of antennae, stemmata, a bulbous tho- meniscus of the water (Fig. 44). Culicine larvae usually browse rax, absence of prolegs and only one pair of dorsal spiracles on over the substratum in search of food and only come to the the last segment of the abdomen (Anophelinae) (Fig. 44), or sit- surface of the water to breathe through a respiratory siphon uated at the end of a respiratory siphon (Culicinae) (Figs 6, 43). (Figs 6, 43). Species of the genera Mansonia and Coquillettidia Anopheline larvae lie parallel with the meniscus of the water, Dyer have highly specialised siphons that pierce roots, or stems feeding on surface debris (Fig. 44), while all other mosquitoes of aquatic vegetation, to obtain oxygen from air cells in the hang head down and are mostly bottom-feeders (e.g., Figs 6, aerenchyma tissue of plants. 43), but some are predaceous. Pupae of all mosquitoes are comma-shaped (e.g., Fig. 8) and Only female mosquitoes take blood, as they require a pro- are capable of brisk movement, using the paddles at the tip of tein meal for egg development. Not all species require blood, the abdomen. They do not feed during this stage. They breathe however, and indeed all females of the tribe Toxorhynchit- through respiratory organs on the cephalothorax (Fig. 8), with ini require only the nectar of flowers in order to develop egg pupae of Mansonia and Coquillettidia having modified trum- batches. Male mosquitoes lack mouthparts adapted for pierc- pets for breathing through plant stems. The pupal stage usually ing skin and, therefore, do not suck blood. Some species of lasts 2–3 days before adult eclosion. culicines can survive for extended periods without laying eggs, e.g., when over-wintering. An occasional blood meal will be taken, but the female will only venture out of her refuge once Economic significance environmental conditions are conducive for oviposition. Some species of mosquitoes can lay their first batch of eggs without Mosquitoes play an important role in the transmission of hu- taking a blood-meal, but thereafter require a blood-meal for man and animal diseases, such as malaria, filariasis and various every subsequent gonotrophic cycle (Service 1980: 26). arboviruses (Jupp 1996: 4; Service 1980: 46). Hence, they are one of the best-studied families within the Diptera (see Chap- Male mosquitoes usually eclose from their pupal cases be- ter 6). fore females and are only ready for mating once the apical seg- ments of the abdomen have rotated 180˚, which takes about The most significant mosquito-borne disease is malar- 24 hours (Dahan & Koekemoer 2013). In many species, males ia. Parasites of the genus Plasmodium Marchiafava & Celli MANUAL OF AFROTROPICAL DIPTERA – VOLUME 2 SURICATA 5 (2017) 679 Figs 31.2–8. Life stages of Aedes (Stegomyia) aegypti L. and resting positions of adult Culicinae and Anophelinae (Culicidae): (2) head of adult Ae. aegypti, lateral view ♂; (3) same, habitus, dorsal view ♀; (4) Culicinae adult resting position, lateral view; (5) same, Anophelinae; (6) larva of Ae. aegypti, dorsal view; (7) same, egg, dorsal view; (8) same, pupa, lateral view. Figs 2–8 (after Coetzee et al. 2009, original paintings by N. Lighton). Abbreviations: ant – antenna; plp – palpus; prbs – proboscis; resp o – respiratory organ; resp siph – respiratory siphon; stm – stemmata; th – thorax. CULICIDAE (MOSQUITOES) 31 680 SURICATA 5 (2017) Figs 31.9–18. Wings of Culicidae (dorsal view): (9) Aedeomyia (Lepiothauma) africana Neveu-Lemaire; (10) Aedes (Stegomyia) aegypti (L.); (11) Ae. (Mucidus) sudanensis Edwards; (12) Anopheles (Cellia) gambiae Giles; (13) Coquillettidia (Coquillettidia) aurites (Theobald); (14) Culex (Culex) annulioris Theobald; (15) Culiseta (Allotheobaldia) longiareolata (Macquart); (16) Eretma- podites chrysogaster Graham; (17) Ficalbia nigra (Theobald); (18) Hodgesia sanguinae Theobald. Photographs A.H. Kirk-Spriggs. Abbreviations: CuA – anterior branch of cubital vein; Cu-fork – cubital vein fork; CuP – posterior branch of cubital vein; M1 – first branch of media; M2 – second branch of media; M4 – fourth branch of media; R1 – anterior branch of radius; R2 – upper branch of second branch of radius; R3 – lower branch of second branch of radius; R4+5 – third branch of radius; Sc – subcostal vein. MANUAL OF AFROTROPICAL DIPTERA – VOLUME 2 SURICATA 5 (2017) 681 (Plasmodiidae) are transmitted to humans only by Anopheles coastal West Africa (An. (Cellia) melas (Theobald, 1903)) and mosquitoes, but other species of plasmodia that affect non- East/southern Africa (An. (Cellia) merus Dönitz, 1902) (Sinka humans, e.g., primates, birds and reptiles (Garnham 1966: et al. 2010). 11), may be transmitted by culicine mosquitoes. In the Afro- tropical Region, malaria remains the number one killer of preg- The causative agent of Bancroftian filariasis, commonly nant women and children under five years of age (WHO 2015: known as “elephantiasis”, is a nematode transmitted by both x) and plays a major role in contributing to poverty in many anopheline (An. gambiae and An. funestus Giles, 1900) and cu- African countries. In the Afrotropical Region malaria parasites licine mosquitoes (Culex (Culex) quinquefasciatus Say, 1823), are transmitted chiefly by species in the An. gambiae complex in the Afrotropical Region (Service 1980: 49). and the An. (Cellia) funestus-group, with other species playing minor roles in restricted parts of Central Africa (e.g., An. (Cellia) At least 13 arboviruses have been isolated from Culicidae moucheti Evans, 1925 and An.