摘要:

The close affiliation between the honey bee industry and commercial pollination of U.S. crops is described, followed by a literature review that demonstrates why insufficient numbers of honey bees may be available to support adequate crop pollination services in the near future. Recent recommendations offering different methods to increase numbers of crop pollinators (continued honey bee research, establishment of management habitats, and development of additional non-honey bee pollinators) are described, and the positive and negative characteristics of each proposal are discussed. The status of crop pollination is then reviewed in some detail, followed by a recommendation to combine pollinator studies into one collaborative pollination program focused on producing the maximum number of efficient crop pollinators in the shortest possible time frame.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1649

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The influence of temperature and substrate quality on the hibernation of the polyphagous predatorColeomegilla maculata lengiTimberlake was examined. Survival rate and lipid content were periodically evaluated at six temperatures (20, 10, 4, −0.5, −4, and −10°C) on two substrates (fallen leaves and wood chips). Rapid total mortality was observed at −10, 10, and 20°C. At −4 and −0.5°C, survival extended until May, but only at −0.5°C was the survival rate higher than that observed at natural hibernation sites. Fallen leaves were a better substrate than wood chips except in situations of sudden warming and subsequent snow melt. The rate of lipid consumption increased with temperature, and no significant variation was found between substrates.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1657

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Apentacyclic triterpenoid, boehmeryl acetate, was identified as the dominant peak in gas chromatographic profiles of the periderm of susceptible sweet potato cultivars. Boehmeryl acetate, present in the methylene chloride-hexane (1:3) fraction of methylene chloride surface extracts, induced significantly (P<0.05) higher oviposition by female sweetpotato weevils on sweet potato cores in laboratory bioassays. Dose-response studies showed significant linear and quadratic log dose effects, with peak oviposition stimulating activity for this compound at about 0.01 potato equivalents (0.04μg/core). Results indicate that boehmeryl acetate is an oviposition stimulant of the sweetpotato weevil,Cylas formicarlus elegantulus(Summers).

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1663

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Survival ofCeratitis capitata(Wiedemann) larval and pupal stages was determined in several soil types at three levels of water saturation at 15 and 25°C, as well as in water. Survival was negatively correlated with the soil bulk density but positively, with percentage of porous space and percentage of water saturation. Temperature and soil texture both interacted with moisture to give the lowest emergence from dry soils with high bulk density at 15°C. Larvae submerged under water survived up to 4 d and pupae, 3 d. When submerged intermittently for 9 and 12 h daily, 65% of 3rd instar larvae and 17% of pupae, respectively, survived to emerge as adults. The pupal stage lasted 45–56 d at 15°C for survivors. Mortality in wet soils was not caused by pathogenic organisms. We conclude that water loss during a lengthy pupal period at low temperature in soils with low water holding capacity during the dry season is the probable cause of pupal mortality. Anoxia, on the other hand, may be the cause of death during the rainy season in soils with high bulk densities.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1666

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Laboratory bioassays of southern pine beetle,Dendroctonus frontalisZimmermann, showed that beetles exhibited regional differences in response to pheromones. Bioassays of crude pheromone extracts from billets infested with beetles collected from Georgia, Texas, and Virginia showed that beetles from each region had significantly higher positive responses to pheromones from their own region. Beetles from Texas showed the strongest response to a standard of frontalin, trans-verbenol, and loblolly pine turpentine, followed by beetles from Georgia and Virginia.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1671

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The prior arrival of red sunflower seed weevil (Smicronyx fulvusLeConte) males on early season sunflowers and on greenhouse-grown sunflowers appeared to have been the stimulus for female weevils to settle on plants. There were no observations in which females discovered an anthesis stage sunflower before males had been established. Anthesis stage sunflower alone was more attractive to males than was anthesis stage sunflower infested with females. Sunflowers artificially infested with males attracted four times more females than males and attracted nearly five times more weevils than sunflowers alone. When hexane extractions were made of either sex, male extract attracted 40 times more females than males, and female extracts attracted no insects at all. An aggregation pheromone produced by males was established to have a role in the discovery of host sunflowers by female weevils.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1675

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A laboratory culture method for the benthic invertebrateChironomus decorusJohannsen is described in detail. The culture requires minimal maintenance and produces an abundant supply of midge larvae throughout the year for many types of bioassays. Appropriate food, substrate, space, photoperiod, and temperature are important aspects of successful midge culture. The life history ofC. decorusis described, and the effects of varying temperature on the time to hatching, larval growth rate, and time to adult emergence were evaluated. Increasing the temperature over the experimental range (10–28°C) decreased the the time to hatch and the time to adult emergence. Larval growth rates increased from 10 to 20°C and declined at higher culture temperatures. Midges cultured at 28°C were half the size of those cultured at lower temperatures. A length/weight regression forC. decoruslarvae cultured at 20°C was calculated.C. decorusis an excellent bioassay organism for both acute and chronic tests because of its relatively short life cycle, wide distribution, ecological importance, and ease of culture in the laboratory. The recommended culture and bioassay temperature forC. decorusis 20°C.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1681

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Developmental rates of western grapeleaf skeletonizer.Harrisina brilliansBarnes and MacDunnough. life stages were determined under constant temperatures ranging from 12.4 to 39°C. and linear and nonlinear developmental rate functions were fitted to the data.H. brilliansdevelopment under fluctuating temperatures also was investigated. with emphasis on high-temperature regimes. Degree-day and nonlinear methods for simulating larval development were validated by comparing predictedH. brilliansdevelopment with actual field observations. Assuming linear development, the lower development thresholds for egg, total larval, and pupal stages were 9.0, 8.8, and 9.2°C, respectively. Linear (degree-day) predictions of larval development in the field were more accurate than predictions derived by the nonlinear method. The linear model underestimated larval development at low temperatures and overestimated development at high temperatures by as much as 8.6%. The nonlinear model consistently underestimated larval development by as much as 17.3%. We suggest that error involved in nonlinear, temperature-dependent development models may relate to the critical assumption that enzyme systems respond almost instantaneously to temperature changes.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1689

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Experiments were conducted to determine the effect of Hessian fly,Mayetiola destructor(Say), larval feeding on one susceptible and two resistant wheat,Triticum aestivumL. em Thell., cultivars. The stem number, plant and crown weights, and soluble crown carbohydrates were measured in susceptible ‘Monon’ (with the H3gene) and resistant ‘Abe’ (H5gene) and ‘Caldwell’ (H6gene) wheat infested with biotype E Hessian fly larvae. All plant variables were significantly different between infested and control ‘Monon’ wheat, and no significant difference in plant variables was detected in the resistant wheats 4 wk after infestation. Of the four carbohydrates analyzed, only fructan in ‘Monon,’ and fructose in ‘Abe’ differed significantly between the two treatments. These data support the use of resistant genes in plants to control the Hessian fly, in that essentially no damage was observed in the resistant wheat, whereas susceptible ‘Monon’ was damaged severely.

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1698

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Disruption ofEpiphyas postvittanamating behavior using synthetic pheromone was investigated in field cages and in replicated small-plot trials in a pinePinus radiata(D. Don) plantation. Polyethylene tubing dispensers releasing two formulations were tested: 70% (E)-11-tetradecenyl acetate and 30% (Z)-11-tetradecenyl acetate (monoene) or 92.6% (E)-11-tetradecenyl acetate, 2.8% (Z)-11-tetradecenyl acetate, and 4.6% (E,E)-(9,11)-tetradecadien-1yl acetate (monoene/diene). Field cage tests suggested that the second blend was the more effective disruptant, probably because of the presence of the diene. The concentration–response of males to the monoene/diene blend showed greater disruption of their normal response to caged females than the monoene alone (P500/ha of monoene in 100-m2plots (P<0.01). The percentage of tethered virgin females that were mated also was significantly reduced in all monoene treatments (P<0.01) compared with untreated controls. In larger plots (900 m2), the highest rate of monoene (1,000 dispensers/ha) resulted in 17% mating of tethered females (n= 64) compared with 93% mating in controls (n= 57). However, the second blend containing monoene/diene applied at 1,000 dispensers/ha reduced the percentage of mated females to 0 (n= 35), at an average pheromone release rate of 9.8 mg/ha per h. In a similar trial of the monoene/diene blend (900 m2plots), 73% of females mated in control plots (n= 80), compared with 1% (n= 90) in plot treated with 1,000 dispensers/ha (9.5 mg/ha per h).

ISSN:1754-5692    

DOI:10.1093/ee/19.6.1702

出版商:Oxford University Press    

年代:1990

数据来源: OUP