摘要:

A field experiment was conducted during 1984–85 to evaluate the influence of six ground covers on white grub (Coleoptera: Scarabaeidae) densities and feeding damage to roots of young Fraser fir (Abies fraseri(Pursh) Poir.) Christmas trees in the southern Appalachians. The three dominant grub species werePhyllophaga anxia(LeConte) Glasgow,Phyllophaga fusca(Froelich) Glasgow, andPolyphylla comesCasey. Ground covers were fescue (Festuca elatiorL. cv. Kentucky-31), orchardgrass (Dactylis glomerataL.), Kentucky bluegrass (Poa pratensisL.), red clover (Trifolium pratenseL.), subterranean clover (Trifolium subterraneumL. cv. Mt. Barker), and dead sod–entire plot herbicide. Mowed grass plots supported the densest grub populations ($\bar x$= 32.3 to 43.0 grubs per m2) when compared with clover and dead sod plots (x¯= 13.3 to 16.1 grubs per m2), and contained fir trees with the most severe feeding damage to roots, poorest health, and lowest wood volumes.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.63

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Seasonal abundance of adultCulicoidesspp. in coastal Georgia was examined during a 20-mo period (September 1983–May 1985) by carbon dioxide-baited CDC miniature light traps and sticky cylinder traps. A total of 215,269 adult biting midges was collected, composed of 18 species and including the first report ofC. loughnaniEdwards in Georgia. Two possible undescribed species were collected.Culicoides furens(Poey),C. hollensis(Melander&Brues), andC. melleus(Coquillett) comprised 99% of the collection.Culicoides furenswas abundant from early spring to late fall.Culicoides hollensisandC. melleuswere bimodal with spring and fall abundance, butC. melleusappeared later in the spring and disappeared sooner in the fall. Significant differences were found among numbers ofC. furens, C. hollensis, andC. melleuscollected at three heights with sticky cylinder traps. Adult light trap catches were statistically significant for temperature but not for rainfall, wind velocity, or moon phase.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.67

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

A degree-day model was developed to predict flights ofRhyacionia frustrana(Comstock) in southern California using daily temperatures and number of male moths captured in traps baited withR. frustranapheromone lures. The model utilized upper and lower thresholds of 37.25°C and 5.50°C, respectively, and was based on a total of 575.15 degree days accumulated from first moth captured to peak flight. The model's predictive capability proved exceptional, predicting all flight peaks within 1 Julian d. This model was used in conjunction with pheromone trap data to accurately schedule insecticide applications for early-instar tip moth larvae with excellent results.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.75

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Most diapause eggs ofHydraecia immanisGuenée stored in environmental chambers at 1.7 and 4.4°C terminated diapause after ca. 2 or 3 mo. After diapause was completed, mean egg hatch occurred in ca. 12 or 13 d at 21.1°C. About 0.1% of eggs held continuously at 21.1°C hatched without exposure to cold storage, which indicates that low temperatures are not required to terminate diapause for all eggs. Diapause eggs laid between 16 August and 4 September 1985 in a greenhouse under conditions of natural daylight and placed in an outdoor weather shelter in Champaign, Ill., on 4 September, generally terminated diapause by the end of the year, although some eggs did not complete diapause until later in winter. To achieve 50% hatch under field conditions, 119.5 degree days above a threshold temperature of 9.43°C were required by eggs that had completed diapause.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.80

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Virgin female pink bollworm,Pectinophora gossypiella(Saunders), were paired individually with a 2- to 3-d-old virgin male for one night at ages<1, 1, 5, 10, and 15 d from eclosion in lots of 25. Virgin females served as controls. Records were kept on numbers of eggs deposited daily, percentage hatch, and day of adult death. All dead females were dissected to determine mating status. When total females of each age group were considered, mating at the age of 5, 10, and 15 d resulted in significantly less mating, fewer eggs, less hatch, and fewer first-instar larvae than when mating occurred at the age of<1 and 1 d. Virgins lived significantly longer than females mated at<1, 1, and 5 d of age. Mating delays of 10 and 15 d resulted in longevities similar to that of virgins. Differences in mating and oviposition between treatments for mated and total females were statistically similar, and there were no significant differences in percentage hatch of eggs produced by mated females regardless of the female's age. These results suggest that one mating provided adequate sperm to fertilize available eggs. Mated females showed a marked oviposition response on the second night after mating. Generation increases established from previously reported field populations and compared with reproduction in the current study show that mating delays of 5 d or more could result in a 5-fold decrease in population density over four generations.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.86

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Parasitoids and pathogens of green cloverworm,Plathypena scabra(F.), were studied during the spring on a wild host (vetch,Viciaspp.) and during the summer on a cultivated host (soybean,Glycine max(L.) Merrill) at four locations in Louisiana during 1984 and 1985. Six species of primary parasitoids and one species of hyperparasitoid representing a total of four families were encountered during the study.Cotesia marginiventris(Cresson) was the most abundant parasitoid collected during the spring of 1984, whileRogas nolophanaeAshmead was the most common in the spring of 1985. Parasitism during the spring of 1984 and 1985 totaled 12.8 and 36.4%, respectively, whereas parasitism rates during the summer of those years were 10.4 and 6.0%, respectively.Cotesia marginiventriswas the prevalant parasitoid during the summer in both years of the study. Two entomopathogens were collected from green cloverworm—Nomuraea rileyiSamson and a granulosis virus were collected in the spring, while onlyN. rileyiwas collected during the summer.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.90

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

A method is proposed for modeling development of an insect population that passes through a series of discrete developmental stages. This model, including a temperature-dependent development rate, can be estimated directly from field data or can be estimated from laboratory data taken at constant or fluctuating temperatures. The temperature-dependent development rate can have a nonlinear form, and effects on development by environmental factors other than temperature can also be estimated and included. In addition, the method allows for variability among individuals of the population in terms of life-stage duration and allows for correlations among various stage durations. Survival is assumed to be a function of time, but need not be estimated. The proposed method for estimating development of an insect population was applied to spruce budworm,Choristoneura fumiferana(Clemens), field data collected from 23 various location/year combinations in New Brunswick and Maine. The estimated phenology model that best fit the field data included effects of region, host species, calendar date, a linear effect of temperature in New Brunswick, and a nonlinear temperature effect in Maine. The nonlinear development rate estimated for the Maine data set was found to be comparable with development rates in the laboratory. On both the regression data set and an independent data set, the selected model performed better than either a model in which time was measured in calendar-days and better than a model in which time was measured in degree-days.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.97

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The impact on arthropods when using a rye cover crop in a soybean,Glycine maxMerrill, production system was studied. Soybean was planted in plots that did not have a rye cover crop, plots that had rye plowed and disked into the soil, plots that had rye disked only, and plots that had rye left on the soil surface. Green cloverworm,Plathypena scabra(F.), populations varied during the two years, with numbers in the rye-notill being highest the first year but lowest the second. Potato leafhopper,Empoasca fabae(Harris), numbers were consistently lowest in the rye-notill plots, whereas bean leaf beetle,Cerotoma trifurcata(Forster), and Japanese beetle,Papillia japonicaNewman, adults were highest in the rye-notill treatments. Striped flea beetles,Phyllotretaspp., were consistently higher in the conventional tillage and rye-plow plots where rye was completely buried or was absent. The study indicates that the use of a rye cover crop has a variable impact on arthropods, depending on the species and also on the management of the cover crop. Knowing the influence that a cover crop might have on arthropods can assist growers in better managing their crop.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.109

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Genetic differences in the responses ofTribolium confusum(duVal) andTribolium castaneum(Herbst) to antibiotics are reported. The antibiotics erythromycin, tetracycline, and spectinomycin were tested for their effect on productivity of each of three strains ofT. confusumandT. castaneum. The results of two experiments examining productivity of populations in environments containing antibiotics are presented. The first experiment examines strain and species sensitivity to low dosages (0.005% by weight) of three antibiotics. ForT. castaneum, the antibiotics significantly affect productivity in only one of the three strains examined. InT. confusum, there is a significant genotype-environment interaction; that is, the different strains react in different ways to the antibiotics. The second experiment examines the effects of different dosages (0.0625–0.25% by weight) of tetracycline on the three strains ofT. confusum, and demonstrates genetic differences among strains in sensitivity to dosage of antibiotic. Differences in antibiotic sensitivity are of general interest because antibiotics are often used in laboratory insect diets.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.115

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Bacillus thuringiensisBerliner was encapsulated within a starch matrix and assayed for biological activity against neonate and second-instar larvae of the European corn borer,Ostrinia nubilalis(Hübner). When larvae ingested encapsulatedB. thuringiensis, they digested the starch matrix and released into their gutsB. thuringiensiscrystals and spores, which initiated infection. Nearly 100% mortality occurred at all dosages and concentrations tested whenever the starch granules were hydrated and high relative humidity conditions (>80%) were maintained during the 24-h exposure period of the assay. EncapsulatedB. thuringiensisstored in the laboratory for 4 mo exhibited no detectable decrease in pathological activity.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.120

出版商:Oxford University Press    

年代:1988

数据来源: OUP