Researchers have discovered a pheromone produced by female Lygus Hesperus, (also called Western Tarnished Plant Bug), that reverses the effect of an anti-aphrodisiac found in the male’s semen and signals to potential partners that the female is ready to mate again. This is the first known discovery of this type of pheromone in insects, and it helps give researchers another layer of understanding how insect reproduction signalling works.
Lygus Pest Control
Lygus Hesperus is a common, and major pest of strawberries, cotton, and other crops. Adults can move very fast and are difficult to control using only traditional chemical sprays, and when not controlled can be extremely destructive. Trap cropping systems, large vacuums, and other novel approaches have been used by growers to control populations, with varying success and cost, depending on the crop. This new discovery could lead to new methods for Lygus population control, and will likely have further application with other insects.
Lygus Reproduction Signalling
Previous studies on Lygus Hesperus have found that females that have recently mated are much less likely to be courted by males. This is due to a seminal anti-aphrodisiac that signals to potential partners that these females are not ready to mate. Using a technique called gas chromatography mass spectrometry, USDA Entomologist Colin Brent and his research team, however, have discovered that Lygus females produce a pheromone which is able to counteract this ant-aphrodisiac and signal to potential partners, that they are, in fact, ready to reproduce again after egg-laying. This type of pheromone, termed an “anti-anti-aphrodisiac” has not been yet been discovered, but they are likely very common. They have just been overlooked by researchers until now.
Potential Impact for Crop Protection
While an impact on pest control methods is not immediately apparent, this discovery does open up a whole new area of future research. Better understanding of chemical signalling systems in insect pests will allow for researchers to manipulate these systems to lower reproduction or survival rates, and this method is a potentially powerful alternative to chemical pesticides. Brent notes,
Anti-antiaphrodisiacs were not previously known to exist, but now that scientists know where to look, more are likely to be found in other species. A better understanding of how different chemicals interact to influence the mating behavior of insects could also lead to new methods of targeting pests of crops, which are safer for the environment than existing chemical pesticides.
The chemical signals emitted by insects are usually species specific, so by targeting this method in pest control, researchers (and farmers) will be able to avoid harsh chemical pesticides which can have negative consequences on non-target insect species, including beneficial insects.
“Control of western tarnished plant bug Lygus hesperus Knight (Hemiptera: Miridae) in California organic strawberries using alfalfa trap crops and tractor-mounted vacuums”. Swezey et al. Environmental Entomology. 2007