Amid the recent technological advances in cotton insect control, some pests, including stink bugs, have fallen through the cracks.
"In many areas of the Cotton Belt, successful eradication of the boll weevil, expanding use of transgenic Bt cotton and advances in lepidopteran-specific insecticide chemistry all have contributed to our changing pest complex in cotton," said Jeremy Greene, University of Georgia entomologist, speaking at the 2000 Georgia Cotton Production Workshop held recently in Savannah.
As a result of these changes, growers have reduced their use of broad-spectrum insecticides, allowing stink bugs to avoid a "coincidental demise," says Greene.
Three species of stink bugs are found in Southeastern cotton, notes the entomologist, and they include the green stink bug, the Southern green stink bug and the brown stink bug.
"Organophosphorus insecticides such as dicrotophos (Bidrin) and methyl parathion provide excellent control of stink bugs in cotton," says Greene. "Pyrethroid insecticides also will offer control - apparently differing between species - and are useful when populations of lepidopterous pests and stink bugs are present concurrently."
The choice of an insecticide, he says, will depend on the cotton variety, insect pressure and species of stink bug present in the field.
For growers to understand how to better manage stink bugs, they must have an understanding of the biology of the pest and how they relate to their environment, he adds.
"We should strive to know what stink bugs are capable of and not capable of, what their weaknesses and strengths are, and how their surroundings and our manipulations can affect them," he says.
As stink bugs age, he explains, they can cause increasing damage to bolls in terms of visible symptoms of feeding and yield loss.
"Late instars - the fourth and fifth - of the Southern green stink bug can cause damage comparable to that caused by adults. Also, we've found that bolls younger than three weeks from white bloom remain susceptible to damage from stink bugs but decrease in susceptibility with age," notes Greene.