![\"cockroach](\"https:\/\/www.purdue.edu\/fnr\/extension\/wp-content\/uploads\/2019\/07\/german-cockroach.jpg\")
<\/a>A German cockroach feeds on an insecticide in the laboratory portion of a Purdue University study that determined the insects are gaining cross-resistance to multiple insecticides at one time. (Photo by John Obermeyer\/Purdue Entomology)<\/p><\/div>\n
A Purdue University study led by\u00a0Michael Scharf<\/a>, professor and O.W. Rollins\/Orkin Chair in the\u00a0Department of Entomology<\/a>, now finds evidence that German cockroaches (Blattella<\/em>\u00a0germanica L.) are becoming more difficult to eliminate as they develop cross-resistance to exterminators\u2019 best insecticides. The problem is especially prevalent in urban areas and in low-income or federally subsidized housing where resources to effectively combat the pests aren\u2019t as available.<\/p>\n \u201cThis is a previously unrealized challenge in cockroaches,\u201d said Scharf, whose findings were published in the journal\u00a0Scientific Reports<\/a>. \u201cCockroaches developing resistance to multiple classes of insecticides at once will make controlling these pests almost impossible with chemicals alone.\u201d<\/p>\n Each class of insecticide works in a different way to kill cockroaches. Exterminators will often use insecticides that are a mixture of multiple classes or change classes from treatment to treatment. The hope is that even if a small percentage of cockroaches is resistant to one class, insecticides from other classes will eliminate them.<\/p>\n Scharf and his study co-authors set out to test those methods at multi-unit buildings in Indiana and Illinois over six months. In one treatment, three insecticides from different classes were rotated into use each month for three months and then repeated. In the second, they used a mixture of two insecticides from different classes for six months. In the third, they chose an insecticide to which cockroaches had low-level starting resistance and used it the entire time.<\/p>\n In each location, cockroaches were captured before the study and lab-tested to determine the most effective insecticides for each treatment, setting up the scientists for the best possible outcomes.<\/p>\n \u201cIf you have the ability to test the roaches first and pick an insecticide that has low resistance, that ups the odds,\u201d Scharf said. \u201cBut even then, we had trouble controlling populations.\u201d<\/p>\n For full article:<\/em> Rapid cross-resistance bringing cockroaches closer to invincibility<\/a>.<\/p>\n Resources
\n<\/strong>Report Invasive Species<\/a>, Purdue Agriculture & Indiana Invasive Species Council
\nPurdue experts encourage ‘citizen scientists’ to report invasive species<\/a>, Purdue Agriculture News
\nNew Hope for Fighting Ash Borer<\/a>, Got Nature? Blog, Purdue Forestry and Natural Resources
\nMile-a-Minute Invasive Vine Found Indiana,<\/a>\u00a0Got Nature? Blog
\nSericea Lespedeza: Plague on the Prairie,<\/a> Got Nature? Blog<\/p>\n