Predation on Aedes aegypti (Diptera: Culicidae) by Theridion rufipes (Araneae: Theridiidae) in Puerto Rico.

Theridion rufipes Lucas was found in rearing cages of Aedes aegypti (L.) in the School of Medicine, San Juan, PR. From the 1970s to the 1990s, the spiders had a continuous existence in the cages and in the room outside the cages. A single spider eventually could eliminate all the mosquitoes in a cage. The behavior of the mosquitoes in the web was observed by isolating spiders individually in glass or plastic flasks. When a mosquito comes in contact with the beads of sticky silk on the web, it is immediately paralyzed before the spider approaches it. The instant immobilization without a struggle as well as other aspects of prey behavior suggest that there is a compound in the sticky webs that causes the paralysis. Analysis of this material might lead to the discovery of a new insecticide. Efforts to control dengue in Puerto Rico should not interfere with the natural enemies of the vector.