Since 1945, the European red mite, Metatetranychus ulmi (Koch) [=Paratetranychus pilosus (C. & F.)], has been one of the major pests in apple orchards in southwestern Quebec. Though it had been noted by Petch on fruit trees at Ville LaSalle, Que., in 1930 and at Lac Mégantic, Que., in 1931 it was not reported as causing serious injury to apple trees before July of 1945, when Beaulieu (1948) reported that it was responsible for the first important damage in a few orchards at Rougemont, Que. By 1946, infestations were general in the apple growing areas of southwestern Quebec and occurred as far east as the Quebec City district.
Forty-one species of spiders were found in a Quebec apple orchard. The most abundant species were Theridion murarium, Araniella displicata, and Philodromus rufus. Spiders in general were rather low in population density throughout the study, and they declined by two-thirds in the final year, owing probably to several factors including the use of broad spectrum insecticides for the control of particular orchard pests.
LXXXVIIIT H E CANADIAN ENTOMOLOGIST 487 sometimes base. In one specimen apex of postpetiole yellow. N o annulus. Otherwise like female. Length 16 mm. FemaleTemple profile narrowed in straight line behind eyes, cheek profile strongly and in a straight line narrowed towards mandibles. The latter normal, the upper tooth but little longer than the lower.Flagellum long, slender, srrongly attenuated, with 40 joints, not broadened but distincd~ flattened below beyond middle, first joint 2.7 times longer than wide at the ipex, seen from the side about 12th joint as long as broad, the broadest joint seen from the flat side about as broad as long.Mesonotum very densely and strongly punctured, opaque. Scutellum short, abruptly and deeply sloping down t o the postscutellum.Area superomedia great, subquadrate. Postpetiole with sharply defined aciculated middle field, at the knee raised.
Can. Ent. 99: 771-778 (1967) Ecological studies, undertaken to determine the fluctuations of phytophagous mites and predators in apple orchards, were conducted in 1955, 1956, and 1957 at Rougemont, Que., in two plots sprayed only with fungicides for the control of apple scab, Venturia inaeqmlis (Cke) Wint., and in a third one sprayed, in addition to fungicides, with all insecticides needed for the control of destructive insects. Phytophagous mites \\rere more numerous in the plot sprayed with insecticides than in plots sprayed only with fungicides, and cfensities of rhe mites in the latter plots were inresely proportional to densities of predatorq. 1A similar relationship existed in the insecticide plot between the amount nf chemicals used and numbers of predators present. The principl mite predators were T Y P~~U~T O~R I S rhenmzzu (Oudmc,), mmt effccti~-c against the two-spotted spider mite. Tersanycb?ls zrrrione Koch, and ,Cleciiolntu rrrnli (F,\'.wing), most effective against the European red mice, Pnnrmy char tll?)fi (Koch) . Des ktt~des Pcologiques furent poursuivies en 1955, 1956 et 1957 i Rougemont, Qu6., en w e de dCtem1iner l e~ tluctuations des populationc de tktranpques phyto-phage< et dc leurs pr6dstenrs dans les vergers. Le travail fut effectue dans trnis parcelles expCrimentales dont d e w braicnt rrairkes exclusivemcnt avec des fongicides pour Ia rfpressioti de Ir tavel~~re du pclmmier, Ve~rtrtria intreqnnlir (Cltc) Wint., ec une troisii.me, avec tous les pesticides ndcessaircs B 11 r6prer;sion des maladies et ties insectes nuisil~les. Les t6tranyques pl~ytopluges Ctaient bcaucwp plus nomk~reux dans la psrcelle trait& avec insccticides et fongicides que dans les parcelles n'ayant r e p que deq fongicidcc;. Les densit& des populations de predateurs et celles des tPtranyques phytophages dtaienr inrerscment pr{lportionnelles, et fa m6mc relation c~israit cntre les traiternents insecticides et les populations de prkdateurs. Les principaux acariens prkdateurs Ctaient Typhlodremzcs rhenanus (Oudms.), particuli6rement efficace contre le tktranyque h deux points, Tetranychus urticae Kooh, et Mediolata mali (Ewing), qui prkfkrait le tktranyque rouge du pommier, Panonychus ulmi (Koch).
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