What looks like a caterpillar chewing on a leaf or a beetle consuming fruit is likely a three-way battle that benefits most, if not all of the players involved, according to a Penn State entomologist. "Plants are subject to attack by an onslaught of microbes and herbivores, yet are able to specifically perceive the threat and mount appropriate defenses," said Gary W. Felton, Ph.D., Professor and Head of Entomology. "But, herbivores can evade plant defenses by using symbiotic bacteria that deceive the plant into perceiving a herbivore threat as microbial, suppressing the plant's defenses against herbivores." Dr. Felton's research looked at two crop pests -- tomato fruit worms and the Colorado potato beetle -- plant reactions to the pests, and the microbes that they carry. He presented his findings on February 18, 2017 at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston. This broad look at herbivore-plant interactions takes into account the entire phytobiome -- the plants, their environment, their predators, and the organisms that colonize them. Tomato fruit worms may be the most important crop pest in North and South America. According to Dr. Felton, the caterpillar enjoys eating more than 100 different agricultural crops. Unfortunately, it likes to eat what we humans eat. The Colorado potato beetle moved quickly across the U.S. from Mexico in the mid-1800s and took only 20 to 30 years to reach New York and Long Island. It strips leaves down to the veins, leaving skeletal remains. Plants have two lines of defense against these predators. One reaction, regulated by jasmonic acid, comes into play when insects chew on the plant's leaves, stems or fruit, damaging the plant and leaving insect saliva.
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