Effect of Artificial Control Practices on the Parasites and Predators of the Codling Moth H. A. JAYNES and P. Eo MAI\UCCI, a.S.D.A., Agr. Res. Adm.., Bureau of Entomology and Plant Q1~arantinel Although the codling moth, Carpocapsa thereafter the orchard was pruned and p01nonella (L.), is the major insect pest thoroughly scraped. On April 6, 1936, of apples in this country, very little work sodium nitrate was applied at the rate of has been done on its control by biological 7 pounds per tree. This was the first com- measures. In 1936 a biological-mechanical mercial fertilizer that the orchard had codling moth control project was started ever received. The same amount of so- by the Bureau of Entomology and Plant dium nitrate was applied the next spring. Quarantine in cooperation with the West In April 1937 the orchard was thoroughly Virginia Agricultural Experiment Station, disked and seeded to yellow and white to determine whether, under conditions sweetclover and winter hairy vetch. A prevailing in West Virginia, it was prac- 4-12-4 fertilizer was used at the rate of 300 pounds per acre. The orchard was ticable from the commercial point of view Downloaded from to reduce or eliminate the spray schedules kept in sod with clean cultivation beneath but to continue all other control measures. the trees, and weed growth being care- In West Virginia a high degree of control fully removed by hand. of the codling moth is not usually at- The trunks and all main scaffold tained, even when 4 to 7 c~)Versprays are branches were banded with untreated 2- applied. Fruit infestation is not limited to inch corrugated-cardboard bands. These http://jee.oxfordjournals.org/ 5 per cent or less, as it is in some other bands were removed at 7- to lO-day inter- sections of the country when this number vals throughout the season and replaced of sprays, or even fewer, are used. In 1938 with new bands. Care was taken to remove the work was extended to include a study all larvae on the tree under the bands. The of the relative value of various natural- infested bands were placed in a screen control factors and the effect of the arti- cage, centrally located in the orchard, ficial-control practices on these enemies of where the moths and parasites were al- the codling moth, and to develop methods lowed to emerge but only the parasites could escape into the orchard. A few of of sampling for parasite, predator, and by guest on June 9, 2016 host populations and of evaluating and the larger species of parasites, which were comparing natural-control values in unable to escape through the 12-mesh sprayed and unsprayed orchards. The re- wire screening, were captured in vials and sults of the Bureau's studies in two liberated. orchards in 1938, 1939,' and 1940 are A commercially sprayed orchard lo- re1;>,0rtedin this paper. cated just north of the biological-control THE EXPERIMENTALORCHARDS.-An orchard and separated from it by 21 18-acre orchard about 30 years old, lo- rows of apple trees was selected for com- cated 12 miles west of Kearneysville, was parison. This orchard was comparable to utilized for the biological-control experi- the biological-control orchard and con- ment. It contained 574 trees, including 255 tained 148 York Imperial and 196 Ben York Imperial and 96 Ben Davis (Ga- Davis trees. The commercial orchard was noes), the varieties chosen for this study. pruned each winter, and some of the The orchard is located on deep, fertile roughest bark was scraped. Commercial soil, which is well drained for both air fertilizer was applied each spring. All and water! bearing trees were banded with chemically In the \vinter of 1935-36 and each year treated bands, except the count trees, the trunk and main scaffold branches of which 1 The writers are indebted to C. P. Clausen. in char((e of tbe were thoroughly scraped and then banded Division of Foreign Parasite Introduction, for suggestIOns and criticism during the experiments here reportcd and in the prepa- with 2-inch strips of corrugated card- ration of the manuscript. They wish to express their gratitude board. to Edwin Gould, of the West Virginia Agricu]tural Experiment Station, and E. O. Hamstead. of the Division of FrUIt Inseet Since the end product by which codling Investigations and J. H. Gei9S1~ formerly of that Division for their full cooperation; also to w. G. Cushwa and W. Gatrell, moth control is adjudged is the amount of uwners of the orchards used in these experiments. Acknowledg- injury to the fruit, it seems advisable to ment is due members of the Division of Insect Identification for tletenuinntion of the parasites and predators. indicate the infestation records of the two 9 10 JOURNALOFECONOMICENTO:\!OLOGY Vol. 40, No.1 orchards before discussing the biological- calcium arsenate, lime, and copper sul- control factors that were in operation. fate; and the fourth of a commercial According to unpublished data of Mr. summer spray oil containing nicotine. Gould and Mr. Geissler, the commercial In 1940 the commercial orchard re- orchard had higher percentages of total ceived a dormant oil spray with tar oil sound fruit (harvest and drop fruit) in all added; a pink spray of lime-sulfur; and a three years. The percentages of sound petal-fall spray of lime-sulfur, lime, and fruit in the commercial orchard were 56.0, lead arsenate. The first cover spray con- 69.9, and 75.0, as compared with 37.5, sisted of copper sulfate, lime, and lead 38.3, and ~8.0 in the biological-control arsenate, with nicotine added for three- orchard for the years 1938, 1939, and fourths of the trees; the second of copper 1940, respectively. sulfate, lime, and lead arsenate; and the In the commercial orchard 7~ per cent third of·nicotine, lime, and summer oil. of the harvested fruit was sound during NATURALCONTRoL.-The natural ene- the three years, and in the biological- mies found attacking the codling moth in control orchard 50 per cent was sound. the apple orchards of West Virginia con- In all three years, at the beginning of sisted of parasitic and predaceous insects Downloaded from the second brood, the biological-control 'and a fungus disease. orchard had a much higher p'opulation of EGGPARASITES.-Todetermine the ex- worms than did the commercial orchard. tent of parasitization by Trichogramma However, despite the fact that the com- minutum (Riley), search was started on mercial orchard carried on with a typical May 13, 1938, and continued until June commercial spray program at the begin- 14, for codling moth eggs on the foliage http://jee.oxfordjournals.org/ ning of the second brood, and consid.ering and fruit in both the biological-control the comparative population, the number and the commercial orchards. It soon be- of injured fruits while this brood was came evident that not enough eggs could present was proportionately much higher be found to give a satisfactory comparison than in the biological-control orchard. of the parasitization in the two orchards. SPRAYSCHEDULEs.-Forthe five years Methods were then developed-to induce 1936 to 1940, inclusive, the biological- the codling moth to deposit eggs on cello- control orchard was given a dormant or phane paper in cages. The cellophane delayed-dormant oil spray, followed by a paper bearing freshly laid eggs was cut by guest on June 9, 2016 pink spray of lime-sulfur and a petal-fall into small sections containing 1 to 3 eggs spray of lime-sulfur, lime, and lead ar- each, and the sections were pinned to the senate. No cover sprays were applied to leaves on 6 to 1~ trees, from 5 to II being this orchard. placed on each, throughout the two or- The sprays applied to the commercial chards. These sections were gathered be- orchard, especially the cover sprays, fore the eggs hatched, and records were varied considerably during the three taken of the number of cggs parasitiz€d seasons. In 1938 this orchard received a and the number of sections on which par- late delayed-dormant oil spray, a pink asitized eggs were found. spray of lime-sulfur, and a petal-fall The parasitization recorded for codling spray of lime-sulfur, lime, and lead ar- moth eggs placed in the two orchards senate. The first cover spray consisted of while the first and second broods were lime-sulfur, lime, and lead arsenate; the present is summarized in table 1. The second of nicotine, summer oil, lime, and greatest difference occurred in 1938,when lead arsenate; the third and fourth of com- parasitization was considerably higher in mercial nicotine bentonite and summer the biological-control orchard. In only oil; and a fifth of a commercial nicotine- one set of eggs exposed in the commercial summer oil preparation. orchard did the parasitization exceed 10 In 1939 the commercial orchard re- per cent. These eggs were exposed from ceived a dormant oil spray with tar oil August 1 to 4, and 35.3 per cent were par- added for aphid control; a pink spray of asitized, as compared with ~8.8 per cent lime-sulfur; and a petal-fall spray of lime- in the biological-control orchard. On sulfur, lime, and lead arsenate. The first August 17 another set of eggs, placed on cover spray consisted of lime-sulfur, liIpe, the same trees and left until August 20, and lead arsenate; the second of lime and gave 2.1 and ~8.7 per cent parasitization, lead arsenate; ·the third of lead arsenate, respectively.