Sexier Sterile Insects for Improved Organic Pest Control
Image credit: Roi Caspi, Hebrew University
Decades after DDT and "Silent Spring," scientists are still searching for better ways to improve agricultural yields and protect desirable plants and animals (including humans) from plagues of insects. The fact that DDT is still advocated by those who argue that protecting humans from diseases carried by insects outweighs the environmental risks demonstrates how serious the issue is. Additionally, insects develop resistance to pesticides, requiring application in ever larger amounts, or development of new chemistry with the possibility of further unforeseeable effects.
One method to replace pesticides relies on release of sterilized insects. Females that breed with the sterilized fellows fail to lay eggs, and the population trends downward. This technique is currently used to combat several dozen insect species. A new breakthrough may make the so-called "sterile insect technique" more effective, by giving the sterile males more sex appeal. Sexier sterilized males is no small matter, either. Prof. Boaz Yuval at the Hebrew University of Jerusalem's Robert H. Smith Faculty of Agriculture, Food and Environment, notes that "the process of rearing millions of male insects, sterilizing them and transporting them to the release site can severely affect their sexual competitiveness."
So just what is it that a female insect is looking for in the perfect mate? Yuval's team studied the behavior and psychology of fruit flies and mosquitoes and concluded that girls like a guy with a belly full of protein and balanced bacterial symbiosis. In previous research on fruit flies and bacteria, it was found that the radiation treatment that sterilizes the insects kills off the natural bacteria. Because they are reared in industrial surroundings, the males do not re-establish the same strains of bacteria found in the wild. In addition to reducing the male sexual competitiveness, this also increases the risks that the sterile flies may carry pathogenic bacteria, like certain species of pseudomonas.
To solve this problem, Yuval's team developed a "breakfast of champions" for the sterilized flies. Before their release into the wild, the flies are fed a meal high in protein and enhanced with bacteria based on the strains found naturally. With restored energy and sexy bacterial balance, the sterilized bugs will compete more equally with their wild counterparts, improving the desired repression of birth rates.
The work is described in the ISME (International Society for Microbial Ecology) Journal.
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