NATURAL CONTROL of the EUROPEAN PEA MOTH LASPEYRESIA NIGRICANA on SUMAS PRAIRIE, B.C. (Lepidoptera Olethreutidae). H
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ENTO~lOLOGICAr. Soc. OF BBITISH COLU :\WU: PHO!'. (1946 J. VOL. 43, FnL 4, 194 7 25 NATURAL CONTROL OF THE EUROPEAN PEA MOTH LASPEYRESIA NIGRICANA ON SUMAS PRAIRIE, B.C. (Lepidoptera Olethreutidae). H . G. FULTON Dominion Entomological Laboratory, Agassiz, B.C. HISTORY OF AREA INVOLVED. The area and practical, but this was not adopted by now known as Sumas Prairie was a lake the growers. before the reclamation scheme, sponsored PARASITE INTRODUCTIO N. Since this by the Provincial Department of Agricul pest had several natural enemies in Eng ture, was completed in the year 1924. This land, a study of the situation there was area, approximately ten miles long and suggested by the Dominion Parasite La four miles wide was at one time covered horatory at Belleville, Ontario. Ewen with water f or the greater portion of the Cameron of the Imperial Parasite Service year. made a study of the situation in England When dyking, draining and land clear during the years 1936-37 and reported that ing operations were completed and agricul A scogastrr quadridentatus W esm., an egg ture took over, it was soon learned that parasite, was found in as hign as 48 per clove r and peas were among the crops cent of the pea moth larvae and GiJ,pta which cou ld be grown most successf~lly on haesitator Grav. and a species of A ngitia, the sandy clay soil of th e old lake bed. larval paraiites, were attacking as high as INTRODUCTION OF THE PEA MOTH. It 24 per cent. Parasi te material was collect became the common prac tice to use peas ed in England and sent to Canada f rom as a nurse crop, seeded down with clover, 1936 to 193.9, when the ou tbreak of war or quite often peas were grown two and. ca used this work to stop. three years in succession on the sa me field. Before any imported· European material Soon large areas were devoted to pea grow was available the Belleville Laboratory ing. This procedure proved very suitable propagated and made three shipments of for the multiplication 0 f the pea moth, the parasi tes, Ascogaster carpocapsae Vier. Laspeyresia nigric{ma Stephens, whi ch was and Macrocentrus ancyLivorus Roh., which apparently present in a nearbv pea growing had been reared success fully on the orien district snuth 0 f the International Boun tal fruit moth, Laspeyresia molesta Busck., dary. a close relati ve of the pea moth. Total lib By 1933, when 3,000 acres or more eratiGn of all parasi tes is shown in T ahle 1. were devoted to pea growing in th e Sumas METHOD OF TRANSPORT. Until 1938 area, in festation by the pea moth had be parasites were shipped in refrigerated cages come very heavy and severe losses were hy railway express requiring four days to suffered by the growers. make the trip from Bellevi ll e to Agassiz. In 1934, officers of the Agassiz Labora Only one shipment was received in which .. tory began a study of the conditions. Ac undue mortality had occurred by this cording to literature Laspeyresia nigricana method. Time, however, became an im was accidentally introduced into Canada portant factor, especially with shipments of from Europe sometime before 1893, and egg parasite A. quadridentatus, as some became established without any of its na were recei ved too late to be liberated dur tural enemies. Since then it has spread to ing the maximum egg laying period of the most of the pea growing areas on this con pea moth, which occurs about the end of tinent. Under conditions similar to those June. By using non-refrigerated cages and found on Sumas Prairie the pest soon be ~ i r express, parasites could be picked up in comes epidemic. By experiments a rotation Vancouver twelve hours after leaving the control was demonstrated to be effecti ve east, and delivery from Vancouver to Agassiz required an additional twenty 1 Contribution No. 24:~8, Division of Entomology, Scien ce Service, Dej)art ment 01 Agriculture, Ottawa, h~Irs. This method was used for all ship Ont. ments made in 1939 withou t undue mor- 26 E:,\To ~r OLOGICAL SOl". OF BRITISH COIX1im .\ , PHOC. (1946 ) , VOl.. 43, FEB. 4 , 1947 TABLE I Liberations of Parasites Made in the Chilliwack and Sumas Areas Liberations of the North American Species 'Year A. ca'rp()capsa(' M . ancylivorus Liberation P oi nt 1936 1!! G6 ]229 Chilliwack and Samas 19 :~ 7 50 Sumas Total 1316 1229 Liberations of Imported European Species A.S(" ogllst er Glypta Angi t-ia 81). Year ~iberatioll Point quad·r idell tatus haesitator 1937 34 14 Sumas 1938 88 0 735 5 Sumas and Chilliwack 1939 23 67 2:l 44 Chilliwack 1939 2010 662 Sumas 1939 124 Ni comen l sI a nd Total 5291 1544 63 tality occurring. In eight shipments mor nection with the cultivation control experi tality varied from 5 to 65 per cent with an ments. A second specimen of the same average of only 12 per cent. The follow genus was captured in a field on Sumas ing table shows the mortality by species. Prairie in early July. These recoveries TABLE II were rather surprising as only fourteen in Mortality of Parasites During Shipment dividuals of A ngitia had been liberated the Species Ran ~e in % Average % prevIous year. A. quadridentatus 5·19 10 In 1939, six specimens of C. haesitator G. haesitator 19·45 25 and a few doubtful specimens of Angitia Angitia sp. 36 ·65 57 were obtained from 8,000 cocoons used in One shipment of C. haesitator was pick the experiments. ed up in Vancouver thus saving 20 hours In 1940, one specimen of A. quadriden from a total of 32 hours en route. Only tatus was obtained from 6,000 cocoons at 13 per cent of this shipment had died at Agassiz; and from 10,500 cocoons sent to the time of liberation as compared to the Belleville, 1 A. quadridentatus, 4 G. haesi average of 25 per cent in the other ship tator and 92 Phanerotoma species emerged. m ents of the same species. Phanerotoma is apparently a native hymen RECOVE RIES OF PARASITES. Large num opteron which occasionally attacks the pea bers of pea moth cocoons were collected moth. The record of A. quadridentatus each year to be used in the cultivation con and C . haesitator was most encouraging as trol experiments and some were also sent these species are largely responsible for the to Belleville for the purpose of parasite control of the pea moth in England. recovery checks. In the cultural experi In 1941, 6,000 cocoons at Agassiz, ments cages of cheesecloth were used; con yielded 1 Clypta haesitator and 4 Phaner structed over plots of soi l twelve feet by otoma, and from 3,360 cocoons sent to three feet, artificially stocked with pea Belleville, 1 C. haesitator and 5 Phaner moth cocoons to test the effect of various otoma were obtained. soil cultivation practices on moth emer In 1942, 2,000 cocoons at Agassiz gave gence. A check was also kept of the para 1 A. quadridentatus,.2 C. haesitator and sites that emerged. 3 Phanerotoma; and from 3,350 cocoons First signs of parasifism were observed se nt to Belleville, 7 A. quadridentatw, 3 in 1938 when one speciment of Angitia C. haesitator and 25 Phanerotoma em was taken on June 25 from the experi erged. mental cages at Agassiz, in which 10,000 In 1943 no further cage experiments pea moth cocoons were being used in con- were carried on at Agassiz, but 4 A. quad- EXTO»WLOGICAL Soc. OF BIIITlSH COLl'~IBlA , P1WL (1946), VOL. 43, FEll. 4, 1947 27 ridentatus and 6 G. haesitator emerged might not hold for the entire Sumas Prairie from 706 cocoons sent to Belleville. area. Nevertheless the outlook is very fa In 1944, 3,000 cocoons were sent to vourable. Tn 1946 it is probable that one Belleville and these showed approximately of the most destructi ve insect pests of peas 7 per cent parasitism, an appreciable in will have been checked by its natural ene crease. mies, which were originally imported from During the summer months of 1944, England during the years 1937, 1938 and specimens of A scogaster and Glypta were 1939. occasionally caught in the net when sweep We note that no recoveries were made ing pea fields and roadside patches of of parasites of the oriental fruit moth, lib vetch. In the fall 3,800 pea moth cocoons erated in 1936 and 1937. Apparently the were sent to Belleville and it was reported pea moth was not suitable as a host. It is that 6 per cent of these were parasitized also interesting to note that Phanerotom(l by A. quadridentatus and 3 per cent by G. was not recovered until after 1942. haesitator. The foregoing data in tabular form, In the pea flowering season of 1945 the show the gradual increase in percentage of presence of A. quadridentatus was quite parasitism. noticeable, many specimens being captured SUMMARY.-l. The pea moth was in in net sweeping in several different pea troduced into the lower Fraser valley of TABLE III Percentage of Parasitism of the Pea Moth on Sumas Prairie Ascogaster Glypta Angitia Phanel'otoma No. of Total Year quadridentatus haesitator species .,·pedes Cocoons Per cent No. % No. % No. % No. 70 1937 10,000 0 0 0 0 1 .01 0 () .0] 1938 8,000 0 0 6 .07 ? ? 0 0 .1 1939 6,000 1 .02 0 0 0 0 0 1 .6 10,500 1 .01 4 .04 0 0 92 .88 J 1940 6,000 0 0 1 .02 0 0 4 .071 .12 3, 360 0 () 1 .0 3 0 0 5 .14 J 1941 2, 000 1 .05 2 .1 0 0 3 .151 .76 3,350 7 .2 3 .09 0 0 25 .HJ 1942 706 4 .56 6 .85 0 0 0 0 1.4 ] 943 3, 000 0 0 0 0 0 0 0 0 7.