摘要:

Improvements are reported on a model of cotton harvesting economics that has been used to make recommendations about insect pest management in cotton (Gossypium hirsutumL.). Simulations show that the effects of time of crop maturity on yield and revenue are not as great as those in the original model. We found a 0.7% increase in gross revenue with a 1-wk advance in maturity and a 0.3% decrease in gross revenue with a 1-wk delay in maturity. Simulated commercial yield did not change significantly with a 1-wk advance or delay in maturity, indicating that the differences in gross revenue arose from changes in lint quality. Until quantitative estimates are available for the effects of early season insects on the relation between yield and harvest date, the influence of early season insect control on time of maturity cannot be incorporated in models of harvesting economics. However, the small differences in gross revenue found in the simulations suggest that early season insects must have a very large effect on time of maturity to warrant automatic insecticide applications to advance maturity.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.755

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

More male gypsy moths,Lymantria disparL., were captured in traps at the perimeter compared with traps at the center of a 6- x -6 grid of pheromone traps spaced every 80 m. Additional tests demonstrated suppression of catch at the center of hexagonal arrays of traps with intertrap distances ranging from 2.5 to 40 m. In a hexagonal array of traps spaced every 20 m and monitored every 1–3 h, more males were captured in upwind and downwind traps than in crosswind or central traps.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.764

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The trace substance selenium is known to influence several systems exhibiting a high rate of cellular proliferation. Data are reported on survival patterns and times in various developmental stages ofTribolium confusumDuval reared in a defined medium supplemented with sodium selenite. Insects reared from eggs hatching in a selenium medium (Se medium) show a prolonged time in the larval period and marked larval mortality compared with those reared on unsupplemented medium. Adults emerging in an Se medium show reduced survival compared with adults transferred to such medium 1 wk after emergence. Larval survival patterns mimic those of the adult, whereby younger larvae that are transferred to Se medium appear to be more sensitive than those exposed to Se medium later in the larval stage. Transfer of Se medium-reared adults to unsupplemented medium as pupae has a beneficial effect on survival compared with adults that emerged in Se medium 1 wk before transfer.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.770

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Water content and percentage of total body water (TBW) lost as a function of time was determined for four common predators in the peanut agroecosystem that may feed on the lesser cornstalk borer,Elasmopalpus lignosellus(Zeller) (Insecta: Lepidoptera: Pyralidae). TBW loss byGeocoris punctipes(Say) (Hemiptera: Lygaeidae),Reduviolus roseipennisReuter (Hemiptera: Nabidae), andOxyopes salticusHentz (Aranae: Oxyopidae) increased linearly with desiccation time, but for workers ofSolenopsis invictaBuren (Hymenoptera: Formicidae), it increased as a curvilinear function of desiccation time. Mortality of insects in a 24-h period was 69.4 and 80.6% for nymphal and adultG. punetipes, 16.7 and 58.1% for nymphal and adultR. roseipennis, 100% forS. invietaworkers, and 14.7 and 13.0% for nymphal and adultO. saltieus.These high mortalities suggest that the lesser cornstalk borer is better able to survive xeric conditions than some of its common predators.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.778

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Artificial augmentation of soybean leaves with reduced glutathione (GSH) elicited all of the same responses from Mexican bean beetle (MBB),Epilachna varivestisMulsant, as did fumigation with the air pollutant sulfur dioxide. Larval growth, rate of development, and survivorship as well as adult fecundity and longevity were all significantly greater on excised leaves that had been allowed to imbibe a solution of the tripeptide. In addition, adults showed a strong preference for feeding on the treated leaves over nontreated leaves. Increased fecundity after feeding on treated leaves was a consequence of the earlier and longer period of egg laying rather than a change in the rate of egg production. The effects of GSH treatment were even more distinct than those produced by exposure of plants to the pollutant. These results establish the very close correlation between changes in foliar glutathione and alteration of MBB success on this plant in response to air pollution.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.782

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Field studies were conducted to evaluate the acute effects of spring applications of 2,4-D ((2,4-dichlorophenoxy) acetic acid), picloram (4-amino-3,5,6-trichloro-2- pyridinecarboxylic acid), and a 2,4-D + picloram mixture on overwintering larvae ofUrophora affinis(Frauenfeld) andU. quadrifasciata(Meigen) (Diptera: Tephritidae) associated with spotted knapweed,Centaurea maculosaLamarck (Compositae: Cynareae). Also, the chronic effects of picloram on the re-establishment of the flies into previously treated spotted knapweed sites were evaluated. Spring applications of 2,4-D, picloram, or their combination did not significantly affect larval-pupal mortality rates ofU. affinis.Picloram and a picloram- 2,4-D mixture did not significantly affectU. quadrifasciatamortality. There were significant differences, albeit conflicting, between the high and low rates of 2,4-D in the two plots studied. Flies from one plot exhibited a higher rate of mortality with the high rate of 2,4-D, whereas flies from the second plot displayed higher mortality with the lower rate of 2,4-D. No long-term impacts of picloram on the re-establishment ofUrophoraspp. into previously treated sites were found. Infestation rates (number of galls per capitulum and percent capitula infested) for the two fly species in treated plots were not significantly different from those in control plots. Larval-pupal mortality rates for both species were also not significantly affected. The results of these studies suggest that applications of 2,4-D and picloram are generally compatible with the utilization of these two biological control agents for the management of spotted knapweed in northern Idaho.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.785

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Efficient pollination of male-sterile (MS) cotton,Gossypium hirsutumL., remains a key factor for the commercial production of hybrid cotton seed. A study was conducted to investigate the importance and potential use ofBombusspecies as cotton pollen vectors on the Texas High Plains. A survey of 13 counties showed thatBombus pennsylvanicus(DeGeer) was the predominant species. Bumble bees visited cotton flowers throughout the blooming season, and they foraged for both nectar and pollen. More foragers were present on MS than isoline male-fertile (MF) flowers, but visitation to the MS flowers was restricted primarily to morning hours. Nectar and pollen foragers collected in MF flowers carried large amounts of cotton pollen on their body (5,586 to 16,235 grains per forager). Both types of foragers also visited MS flowers, although the quantity of pollen they carried was significantly less (82 to 4,138 grains per forager). Bumble bees carried more cotton pollen than honey bees on MS and MF lines. Wooden domiciles provided an acceptable means for moving bumble bee nests into an area needing pollination, but subsequent visitation to the target fields by the imported bees was low. All colonies in domiciles were parasitized byPsithyrus variabilis(Cresson) during the season. In a cage study, cotton bolls harvested on MS lines had more seeds per boll whenBombuswas used as pollinators than when honey bees,Apis melliferaL., were used. This indicates that nests ofBombusspecies could be used effectively to pollinate small crossing blocks of MS cotton isolated under cages. It also suggests that, on an individual basis, bumble bees are more efficient pollinators of MS cotton than honey bees, which is consistent with the greater cotton pollen load found onBombus.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.789

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Telenomus podisiAshmead andTrissolcus euschisti(Ashmead)are sympatric parasitoids of stink bug eggs. In field experiments,T. podisiparasitized significantly more egg masses on alfalfa,Medicago sativaL., than onhackberry,Celtis occidentalisL., andT. euschistiparasitized egg masses only on hackberry. There was no significant difference in the number of host egg masses parasitized 0–1 and 3–4.2 m above the ground byT. euschistiin black cherry,Prunus serotinaEhrhart, and hackberry trees. This is one of the few examples where sympatric solitary Hymenoptera that share a host resource subdivide their environment by host plant type. We suggest that the host plant type be considered when importing scelionids for stink bug control in classical biological control programs.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.795

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The life histories of three darkling beetle populations were studied using pitfall traps and ovarian development in females from field samples and laboratory rearing during three years in typical Mediterranean grassland and pinewood study areas. One population presented a “one-year life cycle, overwintering as larvae”(Micrositus ulyssiponensisGermar), characterized by high adult fecundity and egg viability, emergence of new beetles in spring, ovarian maturation at the beginning of summer, and egg laying toward the end of summer and in autumn. A second group of populations was characterized by a “two-year life cycle, larvae and adult overwintering”(Pimelia costataWaltl andTentyria platycepsStevens). In this case, darkling beetles are maxithermics because they seek out particular thermal microhabitats that allow them to stabilize body temperatures at high levels (newly emerged beetles occurred in midsummer, reproductive periods from spring to the end of the summer of the following year, and high adult fecundity and egg viability were observed only in summer.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.799

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

A variety of diffusion and convection-diffusion models were fit to field mark-recapture data for female cabbage root flies(Delia brassicaeBouchè). Hawkes' hypothesis that anemotaxis is key toDelia'sdiscovery ofBrassicacrops was tested by comparing the performance of different models. Whereas models lacking a convection term totally failed, models with a convection term explained 39–44%of the observed variance inDeliarecapture density. The direction of the best-fit convection vector was towardBrassicaand in almost perfect opposition to the prevailing winds. This suggests thatDeliafly upwind in the presence ofBrassicaodors. The application of diffusion-convection models to insect dispersal is discussed in general, with special emphasis on parameter identification methods. These methods (new to the biological literature) allow one to find realistic dispersal models that describe field mark-recapture data.

ISSN:1754-5692    

DOI:10.1093/ee/17.5.815

出版商:Oxford University Press    

年代:1988

数据来源: OUP