A Predator From East Africa That Chooses Malaria Vectors As Preferred Prey

Main Category: Tropical Diseases
Also Included In: Veterinary;  Biology / Biochemistry
Article Date: 02 Jan 2007 - 0:00 PDT

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In choice tests using live prey as well as dead prey mounted in a life-like posture on cork discs, we found an East African jumping spider, Evarcha culicivora, to choose blood-fed female mosquitoes in the genus Anopheles as its preferred prey. Mosquitoes in the genus Anopheles are best known as the vectors of malaria and E. culicivora is the first predator that has been found to single out Anopheles as prey. In a sated condition, E. culicivora´s preference held regardless of the sex or age of the spider. When fasted, larger spiders chose both mosquito choices (sympatric mosquitoes of different genera) in equal numbers, but the smaller E. culicivora maintained their preference for Anopheles.

Anopheles holds its body at a 45 degree angle relative to the substrate when resting, whereas other mosquitoes rest with their bodies parallel to the surface of the substrate. We investigated whether the characteristic resting posture of Anopheles was a cue E. culicivora uses to distinguish these mosquitoes from others. To do this we drew 3D virtual mosquitoes whose movement was based on frame-by-frame copying of digital video footage of grooming Anopheles. The use of virtual mosquitoes eliminated variables except the variable in question. We found the single most important visual cue used to distinguish Anopheles mosquitoes is its resting position. Finding a predator that chooses Anopheles as its preferred prey shows that we should not abandon efforts to search for avenues for the biological control of malaria.

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