摘要:

A common phenomenon of yellowjacket (Vespula) population dynamics is the occurence of “wasp years” or years of extreme abundance contrasted with other years of extremely low populations. The number of flying workers per square meter aids in defining wasp outbreaks in the Pacific Northwest. In addition to this estimate, public reaction and colony collections provide qualitative evidence for establishing 1973, 1977, and 1979 as outbreak years ofV. vulgarisorV. pensylvanicaor both throughout most of this region. Spring (April to June) weather conditions during the critical stage of colony founding appear to be the major factor determining outbreak populations. Wasp years have not occurred in the Pacific Northwest since 1971 unless this spring period was warm and dry. Several meteorological factors during this April-through-June period from 1973 through 1979 substantiate this hypothesis. Although these weather factors are possibly the most important ones determining wasp years, they are not necessarily the factors regulating wasp cycles; however, they may prove to be valuable tools in predicting yellowjacket outbreaks in the Pacific Northwest.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.267

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Adult and larval population fluctuation of the South American fruit flyAnastrepha fraterculus(Wiedemann) (Diptera: Tephritidae) has been determined and related to host availability. A peak in the adult population on each host occurred five weeks after the peak in larval population. The average number of larvae per fruit is between 1–5 in large hosts (guava, peach and loquat) and it is smaller than one for small fruit (surinam cherry).

ISSN:1754-5692    

DOI:10.1093/ee/10.3.275

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The thermal requirements for development ofMicroctonus aethiopoidesLoan were studied under laboratory and field conditions. Laboratory studies indicated that the threshold temperature for development ofM. aethiopoideslarval and pupal stages was 8.4°C (47.2°F). The relationship between temperature and duration in days for development was linear within the range of temperatures supporting complete development (r2= 0.97). Averages of 222 and 240 Fahrenheit degree days (F°D) were required for development of the larval and pupal stages, respectively. Larval plus pupal development required an average of 469 F°D.Degree days in the field were accumulated beginning 1 January, and based on a threshold for development of 47.2°F. During 2 years of study, 50% of the first and second generations emerged when means of 463 and 484 F°D, respectively, had accumulated. These data validated the use of °D, as computed in the laboratory, to forecast periodicity ofM. aethiopoidesadults in the field.The ability to predict parasite development would be helpful for collecting, rearing, and further releases of this insect in the field. This information would also be useful in timing of insecticide sprays to avoid the demise of the parasites.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.279

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Insect colonization of collards in contiguous weedy and weed-free plots was monitored in 1978 and 1979. Green peach aphids,Myzus persicae(Sulzer) preferentially invaded weed-free collards and developed higher densities thereon. Numbers ofChrysopa oculata(Say), Coccinellidae, and Syrphidae were higher in plots in which weeds were uncut, despite lower aphid densities. When weeds were trimmed to 10 cm maximum height, predators became more numerous on weedless collards. Predator response were generally inefficient, especially when overall aphid densities were low.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.285

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The temperature-dependent development of the immature stages of the Japanese beetle is described. The effect of temperature on the development of overwintered 3rd-instar grubs and the reproductive maturation period of the adults are quantified. Emergence of adults was not affected by soil moisture. Data from simulations of immature development and adult emergence compared favorably with field data.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.290

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The seasonal occurrence of the various life stages of the Japanese beetle in the Piedmont and Coastal Plain areas of North Carolina was observed during the period from 1977 through 1979. Data on emergence, period of activity, and population and sex ratio trends of adults caught in attractant traps during the summer were obtained. The importance of other Scarabaeidae found in association withPopillia japonicaas potential competitors is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.297

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Caryophyllene compounds were tested as attractants forCollops vittatus(Say), a predacious beetle found in Arizona cotton fields. Caryophyllene alcohol was 10 × more attractive than caryophyllene oxide, a compound previously found to be attractive. Caryophyllene alcohol attracted only male beetles and these oriented to the source from a downwind direction. Cotton dental rolls containing 0.1 g of caryophyllene alcohol were attractive for 4 weeks under field conditions. The dental roll baits in delta traps were used to monitor populations ofC. vittatusin cotton and alfalfa fields near Phoenix. Caryophyllene alcohol is a useful attractant for survey and ecological studies ofC. vittatus.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.301

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Alfalfa weevil larvae,Hypera postica(Gyllenhal), infected with the fungus,Entomophthora phytonomiArthur, were subjected to different photoperiods and timing of conidial showers was not affected. Treatment of healthy larvae with conidia showed that the shower technique was more effective than the contact. Regardless of the technique used, all infected 2nd instar larvae produced conidia while infected 3rd instar larvae produced resting spores. High humidity conditions were necessary to initiate sporulation ofE. phytonomiin alfalfa weevil.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.305

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Populations of the green peach aphid,Myzus persicae(Sulzer), and associated weed hosts were monitored continuously from April 1978 to March 1979 on the floor of three peach orchards and the bank of a drainage ditch. Aphid populations at all sites peaked in spring and declined in summer. Although natural enemies were most active during the period of peak aphid abundance, they were not numerous enough to account for population declines at all locations. In 2 orchards, significant positive correlations were found between green peach aphid populations and the abundance of preferred host plants. No such correlation was found in the third orchard, where aphids were less abundant and patchily distributed, or in the ditch bank, where pathogens and climatic factors may have limited the aphid population.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.307

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Dispersal of the predatory phytoseiid miteAmblyseius fallacis(Garman) within the ground cover, the air beneath the tree canopy, on the tree trunk and on tree foliage of commercial apple orchards during a growing season is described in relation to environmental factors and densities ofA. fallacisand its preyPanonychus ulmi(Koch),Tetranychus urticaeKoch, andAculus schlechtendali(Nalepa) in the aforenamed habitats. Ambulatory and aerial means of dispersal were involved in initial colonization of trees byA. fallaciscoming from the orchard ground cover. A mean total of 261°0 (base 12.2°C) since January 1 plus the presence of predators in the ground cover and prey in excess of oneP. ulmiequivalent/apple leaf, i.e., the number ofP. ulmi+T. urticae+ (A. schlechtendali/15) on an apple leaf, were prerequisites for tree colonization byA. fallacis. Aspects of density independent and dependent dispersal byA. fallacisfrom trees to sites within and beyond an orchard in response to prey are also reported.

ISSN:1754-5692    

DOI:10.1093/ee/10.3.313

出版商:Oxford University Press    

年代:1981

数据来源: OUP