Cotton arthropod pests reduced overall U.S. cotton yields by 2.91 percent in 2006, reflecting one of the lowest damage ratings since reporting began in 1979.

According to a preliminary report, Cotton Insect Loss Estimates — 2006, the bollworm-budworm complex retained top ranking as the No. 1 cotton pest by reducing yields 0.874 percent.

The report pegged lygus as the No. 2 pest with a 0.64 percent yield loss, followed by stink bugs, 0.418 percent; thrips, 0.374 percent; and spider mites, 0.197 percent.

The report, presented at the 2007 Beltwide Cotton Conferences by Mississippi State University Extension entomologist Michael Williams, is a collection of estimates from cotton entomologists in each cotton-growing state.

According to the report, total cost and loss to insects in 2006 was $1.018 billion.

Direct management costs totaled $48.13 per acre. Costs plus loss were $68.46 per acre in 2006, noted Williams.

The percent loss is significantly less than the 4.47 percent damage caused by arthropod pests in 2005, which caused $1.256 billion in total costs and loss to insects, or $88 per acre. Direct management costs were approximately $57 per acre in 2005.

Williams noted that losses below 5 percent “reflect the outstanding contribution technology has made to managing pest complexes which have long plagued cotton growers.

“The boll weevil and tobacco budworm remain a threat, but are no longer the major factors in production they once were. The emergence of new pest complexes has been much slower than many anticipated.”

The last year that losses to arthropods exceeded 5 percent was in 2000, when 9.26 percent of the crop was lost. At that time, the boll weevil was still the No. 1 pest in the United States, causing yield losses of 2.86 percent and accounting for losses in Texas alone of nearly 730,000 bales.

Bollworms and budworms are again the undisputed top cotton pests for 2006, and once more bollworm was the dominant species, comprising around 92 percent of the complex, according to the estimate.

Heliothine damage resulted in the loss of 315,418 bales, with Tennessee taking the biggest hit at 61,417 bales. North Carolina, with a 2.08 percent yield loss, Virginia, 1.79 percent, Louisiana, 1.51 percent and Georgia, 1.35 percent, rounded out the top five. Only California reported no losses to heliothines.

Bt cotton acreage increased to 8.472 million acres in 2006. Heliothines were sprayed on 3.964 million Bt cotton acres. Bt technology is used on about 57 percent of the total U.S. crop, noted Williams.

Lygus was the second-most damaging pest in U.S. cotton last year, reducing yield by 0.649 percent, or 234,150 bales. The estimate included the western species, lygus hesperus, and the eastern species, lygus lineolaris.

Louisiana, 2.57 percent, California, 2.54 percent, Arkansas, 2 percent, Mississippi, 1.82 percent and Alabama, 1.44 percent, reported the highest losses. The pest infested about 50 percent of the U.S. crop.

Stink bugs were the third-most damaging pest in the United States last year, reducing the crop by 0.418 percent or 150,600 bales. South Carolina reported major problems with the pest with 3.3 percent of its crop lost.

Early-season thrips infested 77 percent of U.S. cotton acreage in 2006 and cost farmers $5.92 per acre in management. There were 134,814 bales of U.S. cotton lost to this pest in 2006. Alabama reported the highest losses, at 2.7 percent, or 41,000 bales lost. California reported no losses from early-season thrips.

Spider mites ranked fifth in losses in U.S. cotton, with around 70,965 bales lost. The pest can be somewhat inconsistent in its impact. But this marks the third straight year the pest has been a significant problem. It infested about 4.242 million acres of cotton in 2006. Ten states, however, reported no losses to the pest.

While aphids are the sixth-most damaging pest in U.S. cotton, only Alabama, 1.08 percent, reported 1 percent or greater losses. Seven states, Arkansas, Kansas, Missouri, North Carolina, South Carolina and Virginia reported no losses to aphids. Kansas reported no acres infested. Aphids reduced U.S. production by 62,987 bales.

The fall armyworm comes in as the seventh-most damaging pest, with yield losses of 24,992 bales. Nine states reported losses to the pest — Tennessee, Mississippi, Arkansas, Louisiana, Alabama, Georgia, Texas, Florida and New Mexico. Eight states reported no losses to fall armyworm, while three states reported no acres infested.

Cotton fleahopper ranked eighth in damage, destroying 21,013 bales of cotton on 5.6 million acres. Oklahoma, Kansas, Texas and Arizona reported losses to fleahopper. All other states reported no losses.

The silverleaf whitefly comes in as the ninth-most damaging pests, with yield losses of 18,040 bales of cotton reported in Texas alone. Two states, Arizona and Georgia, reported infestations, while California and South Carolina reported infestations, but no losses.

Other insects, including darkling beetles, yellow-striped armyworms, clouded plant bugs and western flower thrips, combined to reduce cotton yields by 0.03 percent last year. European cornborers, beet armyworms, cutworms and loopers, banded-winged whiteflies, cotton leaf-perforator, grasshoppers, saltmarsh caterpillars and southern armyworms also contributed to losses from arthropod pests in 2006.

Only three states, Arkansas, Oklahoma and Texas, reported acres infested by boll weevil in 2006. Texas reported 1,637 bales lost, while Oklahoma lost two bales. Boll weevil eradication costs for U.S. cotton producers averaged $7.88 per acre, according to Williams.

Alabama had the largest overall percent reduction in yield due to insects at 7.74 percent, followed by Tennessee, 6.29 percent, South Carolina, 5.94 percent, North Carolina, 5.06 percent, and Louisiana, 4.81 percent.