Genetically Modified Cotton Associated With Increased Plant Bug Attacks On Food Crops


Cotton Fleahopper - Heteroptera Miridae Image credit:Texas A&M; University

Authors of a 15-year long field study in China have reported that cotton "farms gradually become a source of mirid bug infestations, in parallel with the rise of Bt cotton. The bugs, initially regarded as occasional or minor pests, spread out to surrounding areas, "acquiring pest status" and infesting Chinese date, grape, apple peach and pear crops." I re-read the source of this information, a SciDevNet story, several times. Not being an entomologist, and never having grown a fiber of cotton in my life, I saw multiple ways to explain the observed changes with mirid plant bug. Four alternatives are listed below. Any missing?Four novice-concocted explanations are in random order. More than one could be in play at a time, of course.


  1. Mirid bugs became resistant to Bt toxin, by virtue of completing their life cycles amidst vast areas of Bt cotton growing. Hence, cotton cropland became a source of mirid bug propagation. (You would expect increased mirid damage to Bt cotton over the years if this were true. And increased use of other pesticides to compensate.)

  2. Mirid's propagate amidst the Bt cotton until late in the cotton growing cycle: at which point they leave for other nearby crops to avoid the Bt which is concentrating in plant tissue.

  3. The overall density of mirid bugs is unchanging in the region: mirids just now avoid Bt cotton and concentrate instead on contiguous food crops because they taste better.Or because Bt can be detected and avoided by them.

  4. Overall cotton acreage is slowly reducing over time, while produce acreage increases commensurately: mirids are just going for the most abundant food sources.


Dumb question.
I know that Bt use counts as an organic crop control method. Does a raising a crop with genetic capacity to generate Bt qualify as an organic practice?

Tags: Insects | Pesticides

WHAT'S HOT ON FACEBOOK