摘要:

Vegetative patterns appear to influence foraging ofHeterotermes aureus(Snyder). Termite attack on toilet-paper baits was greatest at sites having the most vegetative cover. However, continued foraging at an already occupied toilet-paper bait was unrelated to vegetative cover. A new statistical model was developed to analyze the effect of distance between food items on termite foraging behavior. In plots 6 by 6 m, the pattern of attack by termites was generally consistent with the null hypothesis that termites forage randomly with respect to distance between potential food sources. Seasonal variations in the numbers of foragers were consistent with previously reported data.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.791

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Laboratory studies demonstrated that temperatures down to −15°C had little effect on mortality of adult viviparous, parthenogeneticMyzus persicae(Sulzer) collected from overwintered spinach,Spinacia oleraceaL. The LT50and LT95values at −15°C were 68.61 and 87.07 h, respectively. Aphid survival at −17°C, however, was significantly reduced. The LT50and LT95values were 7.53 and 9.31 h, respectively. Additional temperature reductions in laboratory tests reduced aphid survival further. Field samples collected from overwintered spinach in 1985 revealed significant reductions in aphid abundance and survival following extremely low temperatures (−20.6 and −21.7°C). Furthermore, aphid survival was significantly greater on sheltered plant locations. Significant reductions inMyzus persicaeabundance and survival were not detected during the mild winter of 1986 when the lowest temperature was −12.8°C. At the 1986 harvest, the mean number of live aphids per plant was 37-fold greater than in 1985.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.796

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Foraging activity of the red imported fire ant,Solenopsis invictaBuren, was monitored at bait traps for 1 yr to determine how weather and season affected foraging. Soil temperature at 2 cm was the best individual predictor of foraging rates at our study site (R2= 59%); workers foraged from 15 to 43°C, with maximal rates between 22 and 36°C. Season explained another 19% of sample variation in a multiple regression with soil temperature; this was because foraging was unusually low in late fall. Rain reduced foraging rates by ca. 40% and explained an additional 3% of the variation. Workers did not exhibit a tendency to forage more at night because neither time of day nor night/day were significantly correlated with foraging rates. Relative humidity, saturation deficits, soil moisture, and wind were also unrelated to foraging. Average weight of individual foragers increased ca. 30% with increasing soil temperature and decreased 15% with the advancing season. Soil-temperature data were used to calculate periods of foraging activity for an open pasture, a nearby shaded woodlot, and seven additional locations in the southeastern United States. Activity periods were distinctly shorter in shady habitats and higher latitudes. Low temperatures limited activity much more frequently than high temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.802

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Investigations concerning the influence of four weevil densities, three oviposition/feeding periods, two maize genotypes (susceptible and resistant), and three kernel densities on the aggregation of maize weevil (MW),Sitophilus zeamaisMotschulsky, eggs indicated that each had a significant impact on egg distribution. Results showed that egg aggregation generally increased with increasing MW density and duration of oviposition/feeding period, but the specific response depended on kernel density and maize genotype. These findings serve to illustrate the influence of four environmental factors on the biology and ecology of the MW, as quantified by changes in egg distribution, and may aid in the identification of factors (such as resistant varieties) that can be manipulated to the detriment of the insect pest in a pest management program on stored grains.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.809

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Impact of arthropod predators on mortality of early instars of the range caterpillar,Hemileuca oliviaeCockerell, was assessed in three field experiments. In the first two experiments, first instars ofH. oliviaewere introduced into experimental units; predators were excluded from half of the units insecticidally and with cages. Results showed no effect on larval survivorship from the initial level of larvae, indicating density-independent mortality, and a significant effect resulting from exclusion of potential predators. Evidence from sweep-net samples, pitfall traps, and general observations suggested an important role for generalist predators, especially the antCrematogaster punctulataEmery. Possible impact of spiders, cicindelids, mantids, and gryllacridids is considered. In the third experiment,C. punctulatawas shown to be a predator ofH. oliviae. Implications for importance of arthropod predators in saving rangeland forage are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.814

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Corn earworms,Heliothis zea(Boddie), are a major pest in the major sweet corn seed-growing area of the United States. In an effort to predict corn earworm infestations, populations per 100 ears were recorded over a period of 8 yr, 1971–78. Growing degree-days (GDD) were calculated (thresholds of 13 and 35°C) for 1970–78. Chronological dates for photoperiod necessary for diapause induction were also determined. Correlations of peak corn earworm populations with GDD during the previous year were calculated. Highest degree of correlation occurred between GDD on 23 September and the peak population the following year. A theory is presented to explain the relationship of accumulated GDD on 23 September and the peak corn earworm population the following year.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.821

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Anagrus mutansWalker andAnagrus silwoodensisWalker overwinter as late second instars inside eggs ofCicadella viridisL. (Homoptera: Cicadellidae).Dicranotopis hamata(Boheman) (Homoptera: Delphacidae) is a summer host of both parasitoid species. Parasitoid size and fecundity were greater in females reared fromC. viridis(the larger host) than in those reared fromD. hamata.SmallA. mutansfemales failed to produce progeny onC. viridis.Progeny reared fromC. viridiswere larger than those fromD. hamata. A. mutansdeveloped faster inD. hamataeggs, whereasA. silwoodensisdeveloped faster inC. viridiseggs.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.825

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

In Oconee County, S.C., a dump fly,Ophyra aenescens(Wiedemann), displaced the house fly,Musca domesticaL., as the predominant muscoid fly present in the pits of two enclosed environmental poultry houses. During an 18-wk period (June–October 1983), these flies were allowed to breed without restriction. Twenty-eight sticky-tape monitoring stations at distances of 0–1,500 m from the poultry farm provided evidence that flies did not migrate to sensitive areas such as nearby residences in sufficient numbers to be considered a nuisance. Habits of this muscoid fly differ from those of the house fly in thatO. aenescensapparently is more attracted to the dark pit area of poultry houses, shaded woodlands, and similar areas rather than human habitations. Because it does not appear to be a problem at human habitations,O. aenescensmay be useful as an alternative biological strategy for suppressing house-fly breeding on poultry farms.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.828

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Control ofLiriomyza trifolii(Burgess) in commercially grown chrysanthemums in greenhouse trials was evaluated using three strategies: pesticide application two times per week (grower); an insect growth regulator (IGR) application; and biological control (BC) with no chemical applications until late in the crop. In the BC and IGR greenhouses, considerable migration of natural parasite fauna (Diglyphusspp.) occurred, butChrysacham parksiCrawford, which was released, failed to become established. Populations of adultL. trifoliiwere highest in the BC greenhouse, followed by the IGR and grower greenhouses, although percentage of parasitism exceeded 95% in the IGR and BC greenhouses. Parasitism increased, moving from the top to bottom strata of the chrysanthemum plant. Potential of parasites and IGR applications for control ofL. trifoliion commercially grown chrysanthemums is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.832

出版商:Oxford University Press    

年代:1987

数据来源: OUP