Sex ratios of Sitodiplosis mosellana (Diptera: Cecidomyiidae): implications for pest management in wheat (Poaceae)

2004 ◽  
Vol 94 (6) ◽  
pp. 569-575 ◽  
Author(s):  
M.A.H. Smith ◽  
I.L. Wise ◽  
R.J. Lamb
Keyword(s):  
Life Cycle ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Adult Emergence ◽  
Differential Mortality ◽  
Sitodiplosis Mosellana ◽  
Single Sex ◽  
Crop Resistance ◽  
Wheat Midge ◽  
Population Average

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.

A laboratory method for mass rearing the orange wheat blossom midge, Sitodiplosis mosellana (Diptera: Cecidomyiidae)

2021 ◽  
pp. 1-9
Author(s):  
Chaminda De Silva Weeraddana ◽  
Ian Wise ◽  
Robert J. Lamb ◽  
Sheila Wolfe ◽  
Tyler Wist ◽  
...  
Keyword(s):  
Adult Emergence ◽  
Mass Rearing ◽  
Laboratory Method ◽  
Adult Survival ◽  
Sitodiplosis Mosellana ◽  
Rearing Method ◽  
Crop Resistance ◽  
Wheat Midge ◽  
Important Pest ◽  
Wheat Blossom Midge

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.

Seasonal emergence patterns of Sitodiplosis mosellana (Diptera: Cecidomyiidae) in the Peace River region, Alberta, Canada

2021 ◽  
pp. 1-15
Author(s):  
Amanda Jorgensen ◽  
Maya L. Evenden ◽  
Owen Olfert ◽  
Jennifer Otani
Keyword(s):  
Adult Emergence ◽  
Geographic Region ◽  
Invasive Pest ◽  
Phenological Model ◽  
Sitodiplosis Mosellana ◽  
Peace River ◽  
Wheat Midge ◽  
Emergence Patterns ◽  
River Region ◽  
Accumulated Rainfall

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.

Factors influencing oviposition by Sitodiplosis mosellana (Diptera: Cecidomyiidae) on wheat spikes (Gramineae)

2001 ◽  
Vol 133 (4) ◽  
pp. 533-548 ◽  
Author(s):  
M.A.H. Smith ◽  
R.J. Lamb
Keyword(s):  
Flag Leaf ◽  
Growth Stages ◽  
Secondary Importance ◽  
Sitodiplosis Mosellana ◽  
Crop Resistance ◽  
Wheat Midge ◽  
Single Spike ◽  
Egg Density ◽  
As Effects ◽  
Different Growth Stages

AbstractFactors that might contribute to variability in the densities of wheat midge eggs, Sitodiplosis mosellana (Géhin), on common and durum wheats, Triticum aestivum L. and Triticum durum Desf., were investigated to improve the quantification of oviposition preferences in relation to crop resistance. Egg densities on wheat spikes were highly variable, with a similar contagious distribution in the laboratory and field, although variance was highest in the laboratory. Females laid eggs in small groups, usually of one to six eggs; most infested spikes had more than one egg group. Females showed no preference for ovipositing on different parts of a spike, although spikelets on one side and at the base often received fewer eggs because these spikelets were covered by the flag leaf and inaccessible for longer than others. Oviposition rates varied from night to night, probably related to the weather. Females showed no preference for spikes at different growth stages, from the time spikes began to emerge until at least flowering. Spike size did not affect egg density, and spike height was a factor only for spikes deep within or protruding above the canopy. Sources of environmental variation such as effects of weather on oviposition rates in the field or spatial phenomena in cages were measurable but of secondary importance. In the field, comparisons among spikes which emerged on the same day could reduce variation in egg density. In the laboratory, variation in egg density could be reduced by using arrays of excised spikes arranged at the same height, leaving the central portion of the array empty. The primary cause of high variability in egg density among spikes was variation in egg-group size and the presence of multiple egg groups on a single spike, factors which cannot be experimentally controlled because they are the result of oviposition behaviour rather than environmental heterogeneity.

Unexpected offspring sex ratios in response to habitat quality in a size-dimorphic bark beetle

1999 ◽  
Vol 77 (4) ◽  
pp. 524-529 ◽  
Author(s):  
Risa D Sargent ◽  
Mary L Reid
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Habitat Quality ◽  
Bark Beetle ◽  
Sex Ratios ◽  
Diploid Species ◽  
Differential Mortality ◽  
Male Reproductive Success ◽  
Offspring Sex

Facultative sex ratio manipulation has been examined in a limited number of diploid species, mainly vertebrates. We tested the prediction that mothers would preferentially place males in conditions conducive to large size in the diploid pine engraver bark beetle, Ips pini. In this species, males are the larger sex and therefore male reproductive success was expected to be more dependent on body size than female reproductive success. Because body size is largely environmentally determined in bark beetles, mothers were expected to alter sex ratios in response to habitat quality. Contrary to predictions, offspring sex ratios tended to be more female biased in situations conducive to large offspring size than in situations producing offspring of small size. We were able to rule out nonadaptive explanations such as differential mortality or development times of males and females, suggesting that the observed pattern is adaptive. This study provides a rare example of sex ratio manipulation in diploid insects. However, the unexpected direction of sex ratio biases suggests that daughters gain a yet unknown benefit from being reared in high-quality conditions that surpasses the fitness that would be gained from producing relatively larger sons.

Male-biased adult sex ratios in a red squirrel population

1987 ◽  
Vol 65 (5) ◽  
pp. 1284-1286 ◽  
Author(s):  
T. Andrew Hurly
Keyword(s):  
Sex Ratio ◽  
Habitat Use ◽  
Sex Ratios ◽  
Sexual Differences ◽  
Differential Mortality ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Male Mortality ◽  
Adult Sex Ratio ◽  
Sampling Biases

A 3-year study of a red squirrel population revealed that the adult sex ratio was biased towards males. There is no evidence that the skewed sex ratio was prejudiced by sampling biases due to sexual differences in mobility, observability, trappability, or habitat use. The tertiary juvenile sex ratio was even and therefore not the cause of the biased adult sex ratio. The data suggest that the skewed sex ratio may be the result of differential mortality. This is consistent with other reports of higher female than male mortality in red squirrels.

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
Keyword(s):  
Adult Emergence ◽  
Larval Survival ◽  
Egg Parasitoid ◽  
Western Canada ◽  
Degree Days ◽  
Temperature Dependent ◽  
Sitodiplosis Mosellana ◽  
Wheat Midge ◽  
Soil Temperatures ◽  
Fine Quartz

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.

scholarly journals Adult sex ratio influences mate choice in Darwin’s finches

2019 ◽  
Vol 116 (25) ◽  
pp. 12373-12382 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant
Keyword(s):  
Mate Choice ◽  
Sex Ratio ◽  
Phylogenetic Analyses ◽  
Sex Ratios ◽  
Differential Mortality ◽  
Sexual Imprinting ◽  
Darwin's Finches ◽  
Darwin’S Finches ◽  
Adult Sex Ratio ◽  
Geospiza Fortis

The adult sex ratio (ASR) is an important property of populations. Comparative phylogenetic analyses have shown that unequal sex ratios are associated with the frequency of changing mates, extrapair mating (EPM), mating system and parental care, sex-specific survival, and population dynamics. Comparative demographic analyses are needed to validate the inferences, and to identify the causes and consequences of sex ratio inequalities in changing environments. We tested expected consequences of biased sex ratios in two species of Darwin’s finches in the Galápagos, where annual variation in rainfall, food supply, and survival is pronounced. Environmental perturbations cause sex ratios to become strongly male-biased, and when this happens, females have increased opportunities to choose high-quality males. The choice of a mate is influenced by early experience of parental morphology (sexual imprinting), and since morphological traits are highly heritable, mate choice is expressed as a positive correlation between mates. The expected assortative mating was demonstrated when theGeospiza scandenspopulation was strongly male-biased, and not present in the contemporaryGeospiza fortispopulation with an equal sex ratio. Initial effects of parental imprinting were subsequently overridden by other factors when females changed mates, some repeatedly. Females of both species were more frequently polyandrous in male-biased populations, and fledged more offspring by changing mates. The ASR ratio indirectly affected the frequency of EPM (and hybridization), but this did not lead to social mate choice. The study provides a strong demonstration of how mating patterns change when environmental fluctuations lead to altered sex ratios through differential mortality.

scholarly journals In-Culture Selection and the Potential Effects of Changing Sex Ratios on the Reproductive Success of Multiannual Delayed Gametophytes of Saccharina latissima and Alaria esculenta

2021 ◽  
Vol 9 (11) ◽  
pp. 1250
Author(s):  
Alexander P. J. Ebbing ◽  
Gregory S. Fivash ◽  
Nuria B. Martin ◽  
Ronald Pierik ◽  
Tjeerd J. Bouma ◽  
...  
Keyword(s):  
Life Cycle ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Female Gametophyte ◽  
Sex Ratios ◽  
Saccharina Latissima ◽  
Male And Female ◽  
Alaria Esculenta

Multiannual delayed gametophyte cultures can stay vegetative for years, while also having the ability to grow. This study aims to investigate whether male and female multiannual delayed gametophyte strains of the species Saccharina latissima and Alaria esculenta grow at different rates in culture. We furthermore assessed how changing sex ratios can affect the reproductive yields of these cultures. The results indicate that the reproductive yield of cultures declines with decreasing male:female ratios, a correlation that becomes especially apparent at higher culture densities for both species. Female gametophyte densities in particular affected the observed reproductive yield of the cultures, with S. latissima cultures showing a clear reproductive optimum (sporophytes·mL−1) at 0.013 mg·mL−1 DW female gametophyte biomass, while the reproductive success of A. esculenta peaked at a density of 0.025 mg·mL−1 DW of female gametophyte biomass, after which the reproductive yield started to decline in both species. The results show that the sex ratio of a gametophyte culture is an important biotic life cycle control, with higher amounts of female gametophyte biomass halting gametophyte reproduction. Understanding how these changing sex ratios in gametophyte cultures affect reproduction is especially important in the aquaculture of kelp, where reliable preforming cultures are key to long-term success.

scholarly journals Sex Ratio Bias at Hatching and Fledging in the Roseate Tern

The Condor ◽  
2001 ◽  
Vol 103 (2) ◽  
pp. 385-389 ◽  
Author(s):  
Patricia Szczys ◽  
Ian C. T. Nisbet ◽  
Jeremy J. Hatch ◽  
Richard V. Kesseli
Keyword(s):  
Molecular Markers ◽  
Life Cycle ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Ratio Bias ◽  
Sex Ratio Bias ◽  
Sterna Dougallii ◽  
Roseate Tern ◽  
Existing Data

Abstract Several hypotheses have been proposed to explain facultative manipulation of sex ratios in birds, but existing data are inconsistent within and among species, and do not clearly support any one of the hypotheses. The sex ratio among breeding Roseate Terns (Sterna dougallii) at Bird Island, Massachusetts is female-biased (56%). We sought to determine at what stage of the life cycle this sex ratio bias is established. We monitored 461 eggs from 252 nests and, using molecular markers, we sexed 342 chicks at hatching and followed them to a stage when survival (or non-survival) to fledging could be inferred. We found that the sex ratio at hatching (and, by inference, at fertilization) was biased toward females (55%). This bias was significant in chicks from first-laid eggs (58%) but not second-laid eggs (48%). We also found that the overall bias increased (to 56.6%) during the chick stage through differential loss of male chicks.

Sexual differences in development and behaviour of larval Ischnura verticalis (Odonata: Coenagrionidae)

1992 ◽  
Vol 70 (6) ◽  
pp. 1161-1165 ◽  
Author(s):  
Robert L. Baker ◽  
Mark R. L. Forbes ◽  
Heather C. Proctor
Keyword(s):  
Life Cycle ◽  
Sex Ratio ◽  
Larval Development ◽  
Sex Ratios ◽  
Sexual Differences ◽  
Emergence Period ◽  
Southern Ontario ◽  
Male And Female ◽  
Ischnura Verticalis

The emergence period of Ischnura verticalis from a pond in southern Ontario lasted at least 97 days; the sex ratio of emerging larvae was not significantly different from 1:1. A 17-month study on larvae from the same pond indicated that the life cycle was univoltine and that male larvae tended to develop faster than female larvae. Analysis of instar distributions of larval I. verticalis collected from a series of ponds also indicated that males were in more advanced instars than females. In the laboratory, male I. verticalis larvae in the final instar developed faster than female larvae in the final instar but male and female larvae in the penultimate instar developed at approximately the same rate. Male larvae in the antepenultimate instar consistently spent more time moving and crawled farther than female larvae in the antepenultimate instar. Sexual differences in larval development and behaviour could help explain sexual differences in instar distributions and altered sex ratios at emergence.

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