Diapause and emergence of Sitodiplosis mosellana (Diptera: Cecidomyiidae) and its parasitoid Macroglenes penetrans (Hymenoptera: Pteromalidae)

2004 ◽  
Vol 136 (1) ◽  
pp. 77-90 ◽  
Author(s):  
Ian L. Wise ◽  
Robert J. Lamb

AbstractThe requirements for successful diapause of field-collected larvae and emergence of the adult wheat midge, Sitodiplosis mosellana (Géhin), and its egg parasitoid Macroglenes penetrans (Kirby) were investigated in the laboratory. Both species showed little decline in survival for up to 5 weeks at 20 °C in dry wheat spikes and could successfully diapause in wheat spikes at 0 °C for at least 200 d, although larvae usually drop to the soil to diapause. Both species diapaused successfully in clay loam and fine quartz sand, but survival was lower in vermiculite or coarse activated clay. Diapause was completed successfully at soil temperatures of −5 to 2.5 °C, and both species survived for at least 500 d at 2.5 °C with no increase in mortality. Larval survival declined after 120 d at −10 °C. Usually more than 95% of all surviving wheat midges emerged as adults after a single diapause period of 100 d or more, but up to 5% of wheat midges and 12%−57% of parasitoids did not emerge until they were exposed to a second cold period. Postdiapausal larvae pupated and adult wheat midges emerged at constant temperatures of 16, 20, 26, and 28 °C with no differences in mortality, although none emerged at 10 °C. The timing of wheat midge emergence was temperature dependent, requiring 306 degree-days above a threshold of 9 °C. Degree-day requirements and soil temperatures from a nearby weather station accurately predicted the average timing of emergence in the field, but not the year-to-year variation in date of 50% emergence. The wheat midge and its parasitoid are well adapted to the conditions they encounter in their range in western Canada. Methods for rearing both species through diapause and adult emergence are described.

2003 ◽  
Vol 135 (2) ◽  
pp. 303-308 ◽  
Author(s):  
O. Olfert ◽  
J.F. Doane ◽  
M.P. Braun

AbstractWheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), was first detected as early as 1901 in Western Canada. The first major outbreak in Saskatchewan was recorded in 1983. In 1984, Saskatchewan wheat midge populations were found to be parasitized by the egg parasitoid Macroglenes penetrans (Kirby). Parasitism levels vary from year to year but, on average, 33% of wheat midge populations are parasitized by M. penetrans. In 1993 and 1994, Agriculture Canada and the International Institute of Biological Control in Delémont, Switzerland, collaborated to release Platygaster tuberosula Kieffer into Saskatchewan to augment biological control of wheat midge. Platygaster tuberosula individuals were recovered at low numbers in follow-up monitoring programs in each of the last 5 years. In 2001, the parasitoid population density increased fivefold at the release site and showed signs of migrating into the surrounding area.


2014 ◽  
Vol 146 (3) ◽  
pp. 335-346 ◽  
Author(s):  
M.A.H. Smith ◽  
I.L. Wise ◽  
S.L. Fox ◽  
C.L. Vera ◽  
R.M. DePauw ◽  
...  

AbstractSpring wheat varieties with the Sm1 gene for resistance to wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), were compared with susceptible wheat (Triticum Linnaeus; Poaceae) with respect to sources of yield loss and reduction in market value from wheat midge feeding damage. Four resistant varietal blends (90% Sm1 wheat plus 10% susceptible refuge) and four susceptible cultivars were grown in replicated experiments at eight locations in western Canada. Frequencies and 1000-kernel weights of undamaged and midge-damaged seeds were assessed before harvest by dissecting samples of ripe spikes, and after harvest in samples of cleaned grain. Spike data were used to estimate yield losses from reduced weight of damaged seeds and loss of severely damaged seeds (⩽8 mg) at harvest. Among midge-damaged seeds in spikes, few were severely damaged in resistant varietal blends, whereas most were severely damaged in susceptible cultivars. Cleaned, harvested grain of resistant varietal blends and susceptible cultivars had similar frequencies of midge damage and were assessed similar market grades. The primary benefit of midge-resistant wheat was reduced yield loss due to seed damage by wheat midge larvae. Resistant wheat did not protect against loss of market grade, but market value could increase due to larger yields.


2021 ◽  
pp. 1-15
Author(s):  
Amanda Jorgensen ◽  
Maya L. Evenden ◽  
Owen Olfert ◽  
Jennifer Otani

Abstract Wheat midge, Sitodiplosis mosellana Géhin (Diptera: Cecidomyiidae), is an invasive pest of wheat, Triticum spp. (Poaceae), in North America and is found in all wheat-growing regions of the world. Wheat midge biology, particularly post-diapause emergence of adults, varies with geographic region. The biology of wheat midge has not previously been examined in the northernmost area of its range in Canada – the Peace River region of Alberta. Wheat midge adult emergence was compared in situ to two phenological models of wheat midge emergence developed in other geographic regions. In-field adult emergence did not match the published phenological models. In the Peace River region, adults emerged later than are predicted by both models and precision for both models was low. With the Saskatchewan model, accumulated rainfall that was more than 110 mm in May and early June delayed emergence, whereas accumulated rainfall that was less than 43 mm during that period caused earlier than predicted emergence. Multiple peaks of wheat midge emergence, up to 20 days apart, were observed at some sites, supporting the Jacquemin model depicting “waves” of emergence. Including differences in soil temperature accumulation related to precipitation and optimising the model temperature thresholds would improve accuracy of the current Canadian phenological model in the Peace River region.


2004 ◽  
Vol 94 (6) ◽  
pp. 569-575 ◽  
Author(s):  
M.A.H. Smith ◽  
I.L. Wise ◽  
R.J. Lamb

AbstractSex ratios of populations of the wheat midge Sitodiplosis mosellana Géhin, developing on wheat Triticum aestivum L., were determined at reproduction, adult emergence, and dispersal. The patterns of sex ratio through the life cycle of S. mosellana result from: (i) a genetic mechanism that causes all or nearly all of the progeny of individual females to be a single sex, with an overall sex ratio that is slightly biased at 54–57% females; (ii) a differential mortality during diapause that increases the sex ratio to 60–65% females; (iii) mating which occurs near the emergence site followed by female dispersal which causes the post-dispersal sex ratio to rise to nearly 100% females; and (iv) oviposition which spreads eggs among different plants and assures that the next generation has a local sex ratio close to the population average. These changes in sex ratio through the life cycle have implications for using crop resistance or pheromones to manage S. mosellana, because mating takes place quickly near emergence sites, and because mated females but not males disperse from emergence sites to oviposition sites. Crop refuges used to protect resistance genes against the evolution of virulence by S. mosellana must be interspersed to prevent assortative mating that would occur in separate blocks of resistant and susceptible plants. Monitoring or mating disruption using a pheromone would be ineffective when wheat is grown in rotation with a non-host crop.


2000 ◽  
Vol 132 (2) ◽  
pp. 223-230 ◽  
Author(s):  
George W. Powell ◽  
Brian M. Wikeem ◽  
Allen Sturko

AbstractWe examined the influence of temperature and release density on the root-boring moth, Agapeta zoegana L., a biological control agent of diffuse knapweed, Centaurea diffusa Lam., and spotted knapweed, Centaurea maculosa Lam. Moths were released at six densities (1, 2, 4, 8, 16, and 32 adult male–female pairs) in each of 2 years (1992 and 1993 cohorts) into outdoor, caged plots containing spotted knapweed. Air temperature, larval establishment and mass, and adult emergence, mass, and body dimensions were measured. Larval production increased linearly with adult release density in both cohorts. Larval survival ranged from 0 to 100% and was not correlated with release density or accumulated degree-days in either year. Date of first emergence occurred earlier as both release density and larvae per plant increased, but only for the 1992 cohort. Declining resources or increased contact among the larvae may induce early pupation. Peak emergence rate increased with release density in both cohorts. First emergence was related more closely to calendar date than accumulated degree-days. In contrast, peak emergence rates were more consistent with degree-day accumulations between cohorts than calendar date. Adult production increased with parental release density in both cohorts. Females were heavier, wider, and longer than males. Optimal A. zoegana production will be achieved with releases of greater than 1.6 male–female adult pairs per spotted knapweed plant.


1999 ◽  
Vol 131 (3) ◽  
pp. 387-397 ◽  
Author(s):  
R.J. Lamb ◽  
I.L. Wise ◽  
O.O. Olfert ◽  
J. Gavloski ◽  
P.S. Barker

AbstractThe wheat midge Sitodiplosis mosellana (Géhin) occurred in all wheat-growing areas of Manitoba during 1993–1997, with 95% of spring wheat fields having some seeds infested by larvae. The level of infestation varied, but each year in excess of 20% of seeds were infested in some fields. Infestation levels in adjacent fields were more similar than in fields separated by a few kilometres. Within fields, the infestation was similar at the edge and near the centre. Wheat midge larvae also overwintered in, and adults emerged from, fields in all wheat-growing areas of Manitoba. Adults emerged from the end of June to the end of July most years, and the peak period for adult flight was mid-July, about 1 month later than in parts of Europe where winter wheat predominates. The timing of the emergence was similar from place to place and year to year. Females constituted 95% of insects caught in a flight trap. The first 10% and 50% of the flight occurred on 9 and 16 July, respectively, and the timing of the flight was not related to growing degree-days. In early August, mature larvae began dropping from wheat heads. The timing of infestation of spring wheat was variable among years because of differences in timing between midge flights and the susceptible heading stage of the crop. Nevertheless, the wheat midge flight usually coincided with the susceptible stage of the spring wheat crop.


1996 ◽  
Vol 128 (3) ◽  
pp. 367-375 ◽  
Author(s):  
R.H. Elliott ◽  
L.W. Mann

AbstractIn a 3-year field study, potted plants of ‘Katepwa’ wheat, Triticum aestivum L., were exposed to ovipositing wheat midge. Sitodiplosis mosellana (Géhin), to determine when spikes are most susceptible to damage. After exposure, plants were maintained under controlled conditions for 4 weeks and examined for wheal midge larvae and damaged kernels, ‘Katepwa’ wheat became susceptible to wheat midge damage shortly after spikes emerged from the boot leaf. Location of larvae and damaged kernels within spikes was influenced by the duration spikelets were exposed to oviposition and pattern of anthesis within spikes. In 1992, frequencies of larvae and damaged kernels were 60–90 times higher in spikes exposed to oviposition during advanced heading (stages 57–59, Zadoks’ code) than in those exposed during flowering (stages 61–69). Kernel damage in spikes exposed to oviposition during stages 57–59, 61–65, and 65–70 was 48.5, 3.2, and 0.2%, respectively, in 1993 and 21.2, 1.0, and 0.6%, respectively, in 1994. Data indicated that susceptibility to midge damage declined 15- to 25-fold between heading and early anthesis and 35- to 240-fold between heading and advanced anthesis. Potential factors contributing to these declines and concomitant reductions in larval frequencies are discussed.Commercial fields of ‘Katepwa’ wheat should be monitored for ovipositing wheat midge throughout heading (stages 51–59) when spikes are most vulnerable to damage. Larval survival and kernel damage were so low after stage 61 that monitoring during anthesis should be unnecessary. Intensive inspection of fields throughout heading would ensure that chemical treatments are applied when they are necessary and most effective.


1985 ◽  
Vol 117 (7) ◽  
pp. 811-818 ◽  
Author(s):  
G.H. Whitfield ◽  
K.W. Richards

AbstractIncidence of parasitism by Pteromalus venustus Walker in populations of the alfalfa leafcutter bee, Megachile rotundata (F.), in western Canada from 1976 to 1983 was found to average ca. 1%. An average of 17.4 parasite adults emerged from each host cocoon and the ratio of males to females was 1:1. Temperature-dependent development and survival at 8 constant temperatures are described. The range of temperatures for greatest survival of the parasite (30–32 °C) coincided with the recommended incubation temperatures for cocoons of the leafcutter bee. Development data fitted a 4-parameter development model. Linear regression of development rate versus temperature provided estimates of base temperature and development time in degree-days for the egg, larval, pupal, and combined stages.


2021 ◽  
pp. 1-9
Author(s):  
Chaminda De Silva Weeraddana ◽  
Ian Wise ◽  
Robert J. Lamb ◽  
Sheila Wolfe ◽  
Tyler Wist ◽  
...  

Abstract Orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), has been successfully reared in the laboratory for more than 20 years in Winnipeg, Manitoba, Canada. The rearing method has been developed to the point where it efficiently produces large numbers of wheat midge continuously under laboratory conditions for use in experiments on wheat midge biology and for screening wheat lines for crop resistance. Adult survival was extended by providing high humidity, and oviposition was increased by simulating natural dawn and dusk conditions and by supplying preflowering spring wheat to adults. Preventing desiccation of the wheat midge larvae in the wheat spikes before overwintering in soil and providing optimal cold conditions for a long enough period to break larval diapause enabled successful adult emergence. We provide data to facilitate the coordination of timing of wheat midge emergence from diapause with the wheat susceptible period. The method can be readily scaled up for screening many lines for resistance or scaled down for small experiments. Here, we report details of the rearing method so that others can implement it for research on the management of this internationally important pest.


2013 ◽  
Vol 93 (1) ◽  
pp. 59-66 ◽  
Author(s):  
C. L. Vera ◽  
S. L. Fox ◽  
R. M. DePauw ◽  
M. A. H. Smith ◽  
I. L. Wise ◽  
...  

Vera, C. L., Fox, S. L., DePauw, R. M., Smith, M. A. H., Wise, I. L., Clarke, F. R., Procunier, J. D. and Lukow, O. M. 2013. Relative performance of resistant wheat varietal blends and susceptible wheat cultivars exposed to wheat midge, Sitodiplosis mosellana (Géhin). Can. J. Plant Sci. 93: 59–66. Wheat midge, Sitodiplosis mosellana (Géhin), causes significant yield losses to spring wheat in western Canada. To mitigate these losses, midge-resistant wheat varietal blends, consisting of cultivars with the Sm1 midge resistance gene and containing 10% of a midge susceptible cultivar (interspersed refuge), were made available to farmers. To test their performance relative to conventional midge-susceptible cultivars, four varietal blends were grown during four consecutive growing seasons at eight locations in the provinces of Manitoba, Saskatchewan and Alberta, Canada, and compared with four conventional midge-susceptible cultivars. Midge damage varied from year to year during the 4-yr study. In general, the varietal blends, as a group, yielded more grain than the susceptible cultivars, especially when grown in environments with high (12.8%) seed damage. In environments with low (0.9%) seed damage, the varietal blend yield increases were smaller but still significant, suggesting that some of the varietal blends may be endowed with additional superior attributes, unrelated to midge resistance. The Sm1 gene was independent of time to heading and maturity, plant height, lodging and seed weight.


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