Behavior And Ecology

FIGURE 12.16 Resting and feeding positions of mosquito larvae. (A) Anopheles, showing horizontal position at the water surface, dorsal side up; larva has rotated its head 180° so that the ventral side of the head is uppermost and the mouthparts are applied to the water surface for filter feeding on floating detritus; (B) Culex, showing typical diagonal position while suspended from water surface; (C) Ma-nsonia, attached to submerged part of aquatic plant (stem or root) by its siphon. (A and B, from Ross, 1947; C, from Gordon and Lavoipierre, 1962.)

FIGURE 12.16 Resting and feeding positions of mosquito larvae. (A) Anopheles, showing horizontal position at the water surface, dorsal side up; larva has rotated its head 180° so that the ventral side of the head is uppermost and the mouthparts are applied to the water surface for filter feeding on floating detritus; (B) Culex, showing typical diagonal position while suspended from water surface; (C) Ma-nsonia, attached to submerged part of aquatic plant (stem or root) by its siphon. (A and B, from Ross, 1947; C, from Gordon and Lavoipierre, 1962.)

than one of the above techniques. Anopheles primarily filter-feed at the water surface by rotating their heads 180° so that the oral opening becomes dorsal. Many Aedes, Ochlerotatus, and Culex, on the other hand, filter-feed near the surface but also gather, scrape, or shred organic matter at the bottom, depending on food availability. Coquillettidia and Mansonia, which are anchored to submerged vegetation, employ a combination of filterfeeding, gathering, and scraping techniques within their immediate surroundings. Larval feeding has been reviewed by Merritt et al. (1992).

Mosquito pupae normally remain motionless at the water surface with the tips of their thoracic air trumpets

FIGURE 12,17 Toxorhynchites amboinsnsis larva feeding on larva of Culex pipiens. This predaceous species has been used in biological control trials and naturally exerts a damping effect on populations of pest and vector mosquitoes. (Photo by W. A. Foster.)

in contact with the air. Like larvae, they dive when disturbed, propelling themselves with their caudal paddles by extending the abdomen, then snapping it back inward toward the céphalothorax. Pupae of most species are buoyant, due to the ventral airspace beneath the céphalothorax, and rise to the surface without swimming. They remain submerged by repeatedly swimming downward or by wedging or lodging themselves under debris. After sufficient submergence time, they lose their buoyancy as their air supply dwindles, and they must swim actively to the surface. Pupae of a few mosquitoes (e.g., Limatusspp.) are never buoyant and can. keep from sinking only by clinging to the surface film, much as most mosquito larvae do. The plant-piercing pupae of Mansonia, and Coquillettidia species do not rise to the water surface until they release their attachment to plants when ready for adult emergence,

Upon emergence from the pupal stage, adults typically seek shelter in vegetation, cavities, and other resting sites, where they remain except during periods of activity When resting, they typically are positioned head-up on vertical surfaces, with forelegs and midlegs on the substrate and hindlegs raised (Fig. 12.18). Culicines and toxorhynchitines hold the abdomen in various positions, but the proboscis is always at an angle to it (Fig. 12.18A).

Allergy Relief

Allergy Relief

Have you ever wondered how to fight allergies? Here are some useful information on allergies and how to relief its effects. This is the most comprehensive report on allergy relief you will ever read.

Get My Free Ebook


Post a comment