|Erwin, Terry - SMITHSONIAN NAT'L MUSEUM|
Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2009
Publication Date: April 20, 2009
Citation: White, W.H., Erwin, T.L. 2009. Leptotrachelus dorsalis (F.) (Coleoptera: Carabidae): The Prodigal Son Returns [abstract]. Proceedings of the 7th International Society of Sugar Cane Technologists Entomologist Workshop, Tucuman, Argentina. April 20 - 24, 2009. Technical Abstract: In Louisiana, beneficial arthropods provide a significant proportion of the season long control of the sugarcane borer, Diatraea saccharalis (Frabricius). However, most of that control comes from predation by the red imported fire ant, Solinopsis invicta Buren. The balance of bio-control comes from a wide array of species representing numerous arthropod taxa. As in many agroecosystems, insecticide use patterns have a profound impact on beneficial species presence and abundance. Insecticide chemistry used in Louisiana sugarcane production has progressed from botanicals, through the organochlorines and organophosphates, into and beyond the pyrethroids, and now to the insect growth regulators (IGR). The IGR tebufenozide has ushered in an era of environmentally friendly chemistry to the Louisiana agroecosystem that has had a profound impact on the presence and abundance of arthropod predators. One species that we hypothesize has benefitted from this new chemistry is the carabid beetle Leptotrachelus dorsalis Frabricius. The larva of this beetle, once killed by broad spectrum contact insecticides, is now able to exploit the sugarcane ecosystem and has the potential to become an important predator of larvae of the sugarcane borer. Research is underway to describe the immature stages; to understand how the insect exploits the sugarcane habitat; and to quantify predation during the critically important time of June through September when the sugarcane borer is considered an economic pest. Our research shows that L. dorsalis moves into cane when the first above-ground internodes are present (mid-June) and increases in numbers thereafter. While considered a ground beetle it has never been caught in pit-fall traps and although thought to be univoltine, all three larval instars are present throughout the growing season. Our population surveys indicate that L. dorsalis can increase in numbers sufficient to significantly impact sugarcane borer numbers.