Swede Midge on Two Northumberland Farms, 1959–61

Patterns of diapause frequency and emergence in swede midges of southern Ontario

“…Swede midge emergence peaks in mid‐June and early July were in agreement with previous observations from bare soil in Markham, Ontario, and Stouffville, Ontario, in 2003 and 2004 (Hallett et al , ), and emergence data validate the 7‐day rainfall threshold used in the midgemerge model (Hallett et al , ). Late summer emergence of diapausing swede midge was observed in Northumberland, U.K. (Rogerson, ). However, two large peaks of late‐summer (August) emergence observed from pheromone traps in the field were absent within cages, indicating that most of the August emergence can be attributed to subsequent swede midge generations (i.e.…”

“…Late emergence in the swede midge may be a means of avoiding adverse spring conditions such as cold snaps or heavy rains (Diarisso et al , ; Hopper, ; Yukawa, ; Lalonde & Roitberg, ). Early emergence phenotypes would be maintained through increased reproductive success (early mating can allow for additional subsequent summer generations under favourable conditions) (Rogerson, ; Rygg & Braekke, ). Early or late emergence timing allows some insects to avoid peaks of parasitoid emergence or predator activity (Thireau & Régnière, ; Stoks et al , ); however, this may be an unlikely strategy for the swede midge because few natural enemies of swede midge are found in Europe or North America (Corlay et al , ; Abram et al , ).…”

“…Pesticide applications that target adult emergence from diapause (i.e. before late July depending on climatic conditions) should provide the most efficient means of population control for two reasons: eliminating the majority of adults emerging from diapause will (i) diminish the potential for population expansion later in the season and (ii) prevent damage to early, often more susceptible, plant stages by first larval generation feeding (Rogerson, ; Bardner et al , ). We encourage additional multi‐year field studies of swede midge population dynamics and factors controlling diapause entry and emergence to enable the development of appropriate pest management programmes for this invasive pest.…”

“…In both its native and North American ranges, swede midges of a single overwintering cohort exhibit bimodal, and possibly trimodal, emergence patterns (Rogerson, ; Goodfellow, ; Hallett et al , ). In southern Ontario, a small initial emergence of swede midge typically occurs in late May, with a larger, second peak occurring in early to mid‐June (Hallett et al , ).…”

Swede Midge (Diptera: Cecidomyiidae), Ten Years of Invasion of Crucifer Crops in North America

“…In Europe, its region of origin, Swede midge larvae are parasitized by Pirene eximia Haliday (Hymenoptera: Chalcididae) (Bovien and Knudsen 1950), Synopeas sp. (Hymenoptera: Platygasteridae) (Rogerson 1963, Readshaw 1966, 1968, and Platygaster sp. (Hymenoptera: Platygasteridae) (Readshaw 1966).…”