FALL ARMYWORM TASTE TEST
Studies have shown that certain turfgrasses are more prone to insect damage than others. While we know that certain turfgrass species are more resistant to damage, few have studied the mechanism of their resistance. What is it that makes some turfgrasses more tasty to insects than others? Researchers at Clemson University set out to find the answer.
Researchers focused on the chemical makeup of leaves of four turfgrass species (zoysiagrass, bermudagrass, centipedegrass and St. Augustinegrass). Fall armyworms were the taste-testers in their studies. Each turfgrass had a characteristic leaf chemistry profile that allowed it to be differentiated from the other grasses. Fall armyworms were divided into groups, and each group was fed leaves of one particular turfgrass for seven days. At the end of that time, researchers weighed the larvae. Using bermudagrass-fed larvae as the control (0 percent=bermudagrass-fed larvae weight loss), larval weight loss was 90, 79, and 29 percent for those fed only zoysiagrass, centipedegrass, and St. Augustinegrass, respectively. Chlorogenic acid, luteolin, and the flavonoid-glycosides rutin, maysin, and isoorientin were highly active in a laboratory bioassay in reducing fall armyworm larval weights; however, no correlations could be made between fall armyworm resistance and the levels of chlorogenic acid, flavonoids, or total phenolics extractable from the grasses evaluated. There is still more work to be done to better define the leaf chemicals that fall armyworms and other insect pests prefer, but it is a step in the right direction for breeding insect-resistant turfgrasses.
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