Fannin, Saturday, Octafcar It, Ht 2 Scientists battle European corn borer By Joan Easley NEWARK, Del. - Agricultural scientists go to great lengths to slow down a destructive insect like the European corn borer. In the 1940 s they went to Europe in search of natural controls. There they found several insects that parasitize die com borer. They brought these insects back to the United States to see if they would establish themselves and keep U.S. com borer numbers down. The one that seemed most promising was a hungry little fly called Lydella. For the next several years it did a creditable job of controlling com borer populations in Delaware and other corn-growing states in which it had been introduced. During the 19605, however, Paul Burbutis, University of Delaware Agricultural Experiment Station researcher who was heavily in volved in the Lydella project, discovered that for unknown reasons the parasite had disap peared in this country. Burbutis decided to try again. He and two researchers from the nearby U.S. Department of Agriculture Beneficial Insects Laboratory, Larry Ertle and Richard Dysart, imported thousands of European com borer larvae from Yugoslavia. They knew that about 10 percent of the borer larvae in that country carry the Lydella parasite. To find out which, though, they had to raise all the larvae to maturity and wait for the parasites to emerge. In the interest of safety, they carried out this work in the quarantine facility of the USDA lab. They released Lydella in Delaware and New Jersey in 1974, 1975, and 1976. However, winter checks of the fields during 1975 and 1977 failed to turn up any surviving Lydella. The researchers decided their attempt to reintroduce it had been a failure. During a routine com borer survey in 1978, however, a few Lydella parasites turned up. Encouraged, the researchers employed a student, Nate Erwin, to conduct a systematic search throughout the state. He found a few more surviving pockets of Lydella. Since 1979, Lydella has continued to multiply and spread throughout Delaware. Other corn-growing regions, encouraged by Delaware’s success, would like to reintroduced the parasite too. University of Delaware Agricultural Experiment Station researcher Charles Mason has agreed to try to reintroduce Lydella to lowa, Missouri, Nebraska, and possibly Minnesota. He’s working with mid-western entomologists to learn why Lydella disappeared in the first place so it won’t happen again. Past experience and a search of the literature have given Mason a few hints that may help insure the I HOG PRODUCERS! ♦ Get Top Price A, I t for Your Hogs atm 9HHB | ♦ New Holland fi | '*>£*. ■{'*,; •■ ' ! + ♦ Sold in sorted lots the auction way. See t ♦ them weighed and sold and pick up Z Z z s your check. ♦ SALE EVERY MONDAY ■ feW A.M | NEW HOLLAND SALES STABLES, INC. I Phone 717-354-4341 5 Daily market Report - Phone 717-354-7288 t Al* Diffenbach, Manager success of the midwestem reih troduction attempt. The evidence seems to indicate that Lydella is better able to survive near large bodies of water. This is probably because Lydella also parasitizes the stalk borer, an insect that feeds on grasses common to wetter areas. For that reason Mason will release the parasites near water. Whether he succeeds or fails in his initial attempt to re-establish the parasite in the Midwest, Mason will pay close attention to what happens in hopes it will help him understand the factors that led to the parasite’s first disappearance. If the parasite fails to reestablish itself, he hopes to find out why. And if it succeeds, he will want to know what factors influenced population numbers. Agricultural conditions vary from year to year. Farmers switch varieties and chemicals, and the weather changes. Any of these factors could have caused Lydella's disappearance. Mason is considering the possibility that a change in com varieties caused the problem. Lydella deposit their young as living larvae at the base of- the entrance hole to the com stalk created by the com borer. But they refuse to do this on some com varieties, perhaps because these lack certain chemical attractants that other varieties possess. Midwestern scientists are pur suing this line of research. ' There are other possible ex- planations for the parasite’s disappearance. Perhaps en vironmental conditions became less favorable to Lydella and more favorable to one of its ecological competitors such as a disease organism or another parasite of the European com borer. Even more complicated, nature has created a miniscule wasp that parasitizes the Lydella fly. A change in environment could have allowed the wasp to thrive at Lydella’s expense. To test whether a chemical may have caused Lydella’s disap pearance, University of Delaware graduate student Bob Leighty is feeding sublethal doses of in secticide to com borers in the laboratory. Some of the borers . in the experiment are parasitized by Lydella. Leighty wants to learn whether a dose of insecticide that is only slightly harmful to the borer could be fatal to the parasite. If so, entomologists will have to reconsider pest control recom mendations so as to maximize Lvdella’s chance of survival. Wherever possible scientists prefer to rely on nature’s own pest control mechanisms such as Lydell instead of chemicals. Now through the efforts of University of Delaware and USDA en tomologists, Lydella is back on the job in Delaware. With a little luck it will soon be back at work in the rest of the United States, and scientists will know what to do to keep it there. NEW JOHN DEERE “50” SERIES "RIDE AND DRIVE" DEMONSTRATIONS Tuesday, October 26 Wednesday, October 27 AT GREYSTONE MANOR FARM On Rt. 272 - Oregon Pike Approx. 5 miles North of Lancaster SPONSORED BY: ADAMSTOWN EQUIPMENT. INC. Mohnton, R.D. 2, Pa. (nearAdamstown) 215-484-4391 SHOTZBERGER'S EQUIPMENT Elm, Pa. 717-665-2141 A.B.C. GROFF, INC. New Holland, Pa. 717-354-4191 LANDIS BROS. INC. Lancaster, Pa. 717-291-1046 2550 - 2950 - 4050 - 4250 - 4450 ALL WITH THE NEW CASTER/ACTIONTM MFWD Other Equipment 1610 Chisel Plow 215 Dura Cushion Disk Harrow 225 Offset Disk Harrow 1710 A Mulch Tiller REFRESHMENTS WILL BE SERVED University of Delaware Agricultural Experiment Statioi researcher Charles Mason checks for corn borer damage ii hopes to re-introduce the corn borer parasite Lydella tothi Corn Belt. 10 AM to 3 PM Mi m PLAN NOW TO ATTEND Tuesday, November 2 Wednesday, November 3 At DEMONSTRATION SITE on Rt. 41 South. Located Vz mite South of the Rt. 10, Rt. 41 Crossing atCochranville. SPONSORED BY: OXFORD GREENLINE Oxford, Pa. 215-932-2753 215-932-2754 M.S.YEARSLEY & SONS West Chester, Pa. 215-696-2990 REGISTER FOR FREE SOUVENIR GIFT AT DEMONSTRATION SITE
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