Effects of entomopathogenic nematodes on evolution of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac

The evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from Bacillus thuringiensis (Bt). However, fitness costs may act to delay pest resistance to Bt toxins. Meta-analysis of results from four previous studies revealed that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) imposed a 20% fitness cost for larvae of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), that were homozygous for resistance to Bt toxin Cry1Ac, but no significant fitness cost was detected for heterozygotes. We conducted greenhouse and laboratory selection experiments to determine whether S. riobrave would delay the evolution of pink bollworm resistance to Cry1Ac. We mimicked the high dose/refuge scenario in the greenhouse with Bt cotton (Gossypium hirsutum L.) plants and refuges of non-Bt cotton plants, and in the laboratory with diet containing Cry1Ac and refuges of untreated diet. In both experiments, half of the replicates were exposed to S. riobrave and half were not. In the greenhouse, S. riobrave did not delay resistance. In the laboratory, S. riobrave delayed resistance after two generations but not after four generations. Simulation modeling showed that an initial resistance allele frequency \u3e0.015 and population bottlenecks can diminish or eliminate the resistance-delaying effects of fitness costs. We hypothesize that these factors may have reduced the resistance-delaying effects of S. riobrave in the selection experiments. The experimental and modeling results suggest that entomopathogenic nematodes could slow the evolution of pest resistance to Bt crops, but only under some conditions

Effects of four nematode species on fitness costs of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac

Evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt). In conjunction with refuges of non-Bt host plants, fitness costs can delay the evolution of resistance. Furthermore, fitness costs often vary with ecological conditions, suggesting that agricultural landscapes can be manipulated to magnify fitness costs and thereby prolong the efficacy of Bt crops. In the current study, we tested the effects of four species of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) on the magnitude and dominance of fitness costs of resistance to Bt toxin CrylAc in pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae). For more than a decade, field populations of pink bollworm in the United States have remained susceptible to Bt cotton Gossypium hirsutum L. producing CrylAc; however, we used laboratory strains that had a mixture of susceptible and resistant individuals. In laboratory experiments, dominant fitness costs were imposed by the nematodeSteinernema riobrave Cabanillas, Poinar, and Raulston but no fitness costs were imposed bySteinernema carpocapsae Weiser, Steinernema sp. (ML18 strain), or Heterorhabditis sonorensis Stock, Rivera-Orduño, and Flores-Lara. In computer simulations, evolution of resistance to CrylAc by pink bollworm was substantially delayed by treating some non-Bt cotton refuge fields with nematodes that imposed a dominant fitness cost, similar to the cost observed in laboratory experiments with S. riobrave. Based on the results here and in related studies, we conclude that entomopathogenic nematodes could bolster insect resistance management, but the success of this approach will depend on selecting the appropriate species of nematode and environment, as fitness costs were magnified by only two of five species evaluated and also depended on environmental factors

Effects of Pink Bollworm Resistance to Bacillus thuringiensis on Phenoloxidase Activity and Susceptibility to Entomopathogenic Nematodes

Widespread planting of crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on many key agricultural pests to evolve resistance to Bt. Fitness costs can slow the evolution of Bt resistance. We examined effects of entomopathogenic nematodes on fitness costs of Bt resistance in the pink bollworm,Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), a major pest of cotton,Gossypium hirsutum L., in the southwestern United States that is currently controlled by transgenic cotton that produces Bt toxin Cry1Ac. We tested whether the entomopathogenic nematodes Steinernema riobrave Cabanillas, Poinar, and Raulston (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) affected fitness costs of resistance to Cry1Ac in two laboratory-selected hybrid strains of pink bollworm reared on non-Bt cotton bolls. The nematode S. riobrave imposed a recessive fitness cost for one strain, and H. bacteriophora imposed a fitness cost affecting heterozygous resistant individuals for the other strain. Activity of phenoloxidase, an important component of insects\u27 immune response, did not differ between Bt-resistant and Bt-susceptible families. This suggests phenoloxidase does not affect susceptibility to entomopathogenic nematodes in Bt-resistant pink bollworm. Additionally, phenoloxidase activity does not contribute to Bt resistance, as has been found in some species. We conclude that other mechanisms cause higher nematode-imposed mortality for pink bollworm with Bt resistance genes. Incorporation of nematode-imposed fitness costs into a spatially explicit simulation model suggests that entomopathogenic nematodes in non-Bt refuges could delay resistance by pink bollworm to Bt cotton

Older drivers in British Columbia : predicting future patterns and assessing strategies for prevention of accidents. A Report for the Insurance Corporation of British Columbia\u27s SMART Program

This report provides a comprehensive review of literature to patterns, behaviors, and policies related to older drivers in BC

A systematic review of causes of recent increases in ages of labor market exit in OECD countries.

Ages of labor market exit have increased steadily since the late 1990s in OECD countries, but with continuing population aging, there are calls for further stimulation of labor force participation at older ages. Social scientists have extensively studied causes of variation in retirement timing between individuals and across countries, but have paid less attention to causes of variation over time. This study systematically reviews evidence of causes of increases in ages of labor market exit over the past 30 years in OECD countries. Two goals are pursued: first, to provide an overview of the retirement domains that have been subject to investigation; second to compare studies with respect to the magnitude of change in retirement behavior that they attributed to different causes, in different contexts. Nineteen studies were reviewed. Available evidence articulates itself around four domains: inter-cohort changes in labor force participation of women (3 studies), educational attainment (3 studies) and lifetime wealth (1 study), and changes to social security systems (16 studies). Determinants in all domains explain a significant amount of past increases in ages of labor market exit, though figures attributable to similar determinants vary between studies and across countries. Evidence suggests that further postponement of labor market exit may depend on further increases to normal retirement ages and more limited access to early retirement programs, but also on further increases in educational attainment and the continued integration of women in the labor market. However, a large share of the past increases in ages of labor market exit remains unexplained; therefore, other factors such as those related to work and organizational characteristics deserve further research

Fact book on aging in British Columbia, 3rd Edition

Table of ContentsForeword; 1. Size of the Elderly Population; 1.1 Past Trends and Future Growth; 1.2 Population Aging Within the Older Population Itself; 1.3 Median Age of the Population; 2. Sex Ratio; 3. Mortality; 3.1 Trends in Life Expectancy; 3.2 Deaths and Mortality Rates; 3.3 Causes of Death; 3.4 Cancer; 4. Marital Status; 5. Geographic Distribution and Mobility; 5.1 The Older Population of B.C. in Relation to Other Provinces; 5.2 Rural-Urban Distribution; 5.3 Geographic Distribution Within British Columbia; 5.3.1 Geographic Distribution Within the Greater Vancouver Regional District; 5.3.2 Geographic Distribution Within the Capital Regional District; 5.4 Mobility; 5.4.1 Total Population and Population Aged 65+;5.4.2 Distance Moved; 6. Ethnic Composition; 6.1 Predominant Groups; 6.2 Proportion of Ethnic Origin Groups Aged 65+; 6.3 Visible Minorities; 6.4 Mother Tongue; 6.5 Immigrants; 6.6 Aboriginal Peoples; 7. Living Arrangements; 7.1 Persons by Type; 7.2 Types of Household; 8. Housing; 8.1 Home Ownership 8.2 Housing Costs; 8.3 Preferred Structural Type; 9. Education 9.1 Educational Attainment; 9.2 Educational Attendance; 10. Labour Force; 10.1 Labour Force Participation Trends; 10.2 Full and Part-time Employment; 11. Unpaid Activities; 11.1 Unpaid Housework; 11.2 Unpaid Caregiving to Seniors; 11.3 Unpaid Childcare; 12. Income; 12.1 Median Income of Individuals; 12.2 Poverty Rate; 12.3 Incidence of Low Income Among Economic Families; 13. Disabilities; 13.1 Disability Rates;13.2 Seniors with Disabilities in Private Households and Institutions; 13.3 Nature of Disabilities; 13.4 Severity of Disabilities; 14. Health Service Utilization; 14.1 Hospitals; 14.2 Continuing Care; 14.3 Health Service Expenditure

Réorganisation de l’annonce des crues en France

Inauguré en septembre 2003 par la ministre de l’écologie et du développement durable, le SCHAPI, Service Central d’Hydrométéorologie et d’Appui à la Prévision des Inondations, est un nouveau service technique central de l’Etat chargé d’assurer un soutien méthodologique aux Services de Prévision des Crues et de développer la prévision des crues et des inondations. Il a également pour mission d’assurer à toute heure un soutien aux services confrontés à des crues torrentielles afin de les aider à établir un diagnostic de prévision en période de crues, et il est responsable de la publication quotidienne d’une carte de vigilance inondations nationale actuellement en période de test. Elément fondamental d’une stratégie globale de lutte contre les inondations comprenant également des volets relatifs à la prévention et à la protection contre les crues, le SCHAPI est rapidement devenu le promoteur d’une politique de recherche et développement pour améliorer les logiciels de prévision des inondations en même temps qu’un interlocuteur national des services de sécurité civile

Effects of entomopathogenic nematodes on evolution of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac

The evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from Bacillus thuringiensis (Bt). However, fitness costs may act to delay pest resistance to Bt toxins. Meta-analysis of results from four previous studies revealed that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) imposed a 20% fitness cost for larvae of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), that were homozygous for resistance to Bt toxin Cry1Ac, but no significant fitness cost was detected for heterozygotes. We conducted greenhouse and laboratory selection experiments to determine whether S. riobrave would delay the evolution of pink bollworm resistance to Cry1Ac. We mimicked the high dose/refuge scenario in the greenhouse with Bt cotton (Gossypium hirsutum L.) plants and refuges of non-Bt cotton plants, and in the laboratory with diet containing Cry1Ac and refuges of untreated diet. In both experiments, half of the replicates were exposed to S. riobrave and half were not. In the greenhouse, S. riobrave did not delay resistance. In the laboratory, S. riobrave delayed resistance after two generations but not after four generations. Simulation modeling showed that an initial resistance allele frequency >0.015 and population bottlenecks can diminish or eliminate the resistance-delaying effects of fitness costs. We hypothesize that these factors may have reduced the resistance-delaying effects of S. riobrave in the selection experiments. The experimental and modeling results suggest that entomopathogenic nematodes could slow the evolution of pest resistance to Bt crops, but only under some conditions.This article is from Journal of Economic Entomology, 105 (2012): 994, doi:10.1603/EC11376.</p