摘要:

Skellam's model of random dispersal, fitted to the rate of spread of larch casebearer (Coleophora laricella) since its discovery in the Northern Rocky Mountains in 1957, suggests that the avg female casebearer oviposits its eggs 4.8 mi. (7700 m) from its point of emergence. Less than 4 of the female progeny survive to reproductive maturity.A discrete-time version of the Verhulst-Pearl-Reed Logistic equation, fitted to the observed growth of 10 casebearer populations in Montana, indicates an avg net reproductive rate of 4.6/year. The upper density asymptote, or carrying capacity, appears to be inversely related to stand tree density.A random-walk model, fitted to observed occurrence of the braconid parasite,Agathis pumila, along transects intersecting 2 parasite-release sites, suggests that the avgAgathisfemale produces about 12 reproductive female progeny. Eggs are laid at intervals of approximately 300 ft (90 m).A parasite-host model, developed for theAgathis-Coleophorainteraction and extended to include dispersal terms, predicts that these reproductive and dispersal rates would allow control ofColeophorabyAgathisover a 50-square mile (108square meters) area within 8 years.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.843

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

A “sticky”-trap bioassay system for the pheromones of the western corn rootworm (WCR),Diabrotica virgiferaLeConte, and northern corn rootworm (NCR),Diabrotica longicornis(Say), is described. Living female beetles of both species and WCR pheromone extract were tested. Males of both species were strongly attracted to virgin females of either species, as well as to this extract. Male WCR and NCR responded to pheromone sources at different times of day. The NCR were most active around midnight, with virtually none coming to traps during daylight hours. Male WCR had a bimodal pattern, being more active before sunset and again after sunrise, but the pattern was less rigid than that of the NCR. The study could not demonstrate comparable emission patterns in female beetles. Relationships between trap catch and temperature, wind speed, dew point depression, solar radiation intensity, and male population are discussed.The virgin female beetles were, on the average, 3 or 4 days old before becoming attractive but then retained the ability to attract males for at least a month unless mating occurred. Mated females were not generally attractive.Males of both species appeared most active within a meter of the ground, and neither species was responsive to traps baited with WCR pheromone extract set at 2 m. Several considerations for using pheromone traps to survey populations are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.853

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Eggs of western corn rootworm,Diabrotica virgiferaLeConte, in different embryonic stages separated according to their sp. gr. were exposed to 4 temperatures and their viability was determined. Results indicated that, in developing eggs, survival was adversely affected by a chill period of 12 wk. The effect was more pronounced at more advanced stages of development and at lower chill temperatures. Overall % hatch means for 20°, 10°, 5°, and 0°C were 81.7, 63.3, 45.7, and 31.0, respectively. Results also showed that time to hatch was delayed and the duration of hatching was shortened following chill. Thus, if eggs developed in the field during the fall they would not survive and hatch in the spring, and the species would not adapt to produce 2 generations per season.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.862

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Survival of instar IV–VI gypsy moths,Lymantria dispar(L.), in a sparse and numerically stable population near Eastford, Conn., was inversely correlated with larval density. Larvae that rested in bark flaps during the day were more likely to survive than those that rested in the forest litter. Since few of these insects were killed by parasites or disease, we believe that most of them were eaten by density-dependent predators that can forage in the litter.The results also suggest that predator densities in this particular area were always sufficient to remove most of these larvae, and that resting locations, coupled with prey density per se, were most important in determining this survival rate. In contrast to Eastford, predators were ineffective in containing equally sparse subpopulations at innocuous levels in a general outbreak area near Glenville, N.Y.; apparently, most of the attacks by these predators were absorbed by the prey insects in nearby, more dense subpopulations.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.865

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Reduviolus roseipennis(Reuter) spatial location and searching activity on cotton, and effectiveness in reducing numbers of 1st-instarHeliothis zea(Boddie) larvae on cotton were studied in the greenhouse and laboratory. Spatial location of adults on plants was mainly confined to the upper ⅓ of the plant on the lower surface of leaves. Predator activity, which suggests searching on plants, was crepuscular and peaked at 7:00 p.m. (CDST).First, 3rd, and 5th instar nymphs consumed 1.9, 7.9, and 38.2 larvae per day, respectively. Feeding by adults decreased with age; females consumed more hosts than males.Feeding effectiveness decreased significantly (P= 0.05) (as indicated by percent available prey consumed per predator) with an increase in number of predators. However, effectiveness was not significantly affected by an increase in number of prey. Individual predator effectiveness decreased with increased plant age and size.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.872

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Volatilization of disparlure (cis-7,8-epoxy-2-methyloctadecane) applied in gelatin microcapsules (2%-NCR and 10%-NCR formulations) to 1-ha plots at 500 g/ha was measured intermittently for 2 mo by a micrometeorological technique. The formulations differed in rates and duration of disparlure release. Vapor fluxes initially decreased, later increased with increasing air temperature. Estimated season-long vaporization of the pheromone from the 2 and 10% formulations was only 2.3 and 12.2% of that applied, respectively. Results, which were consistent with laboratory measurements of release rates, showed need for improvement in controlled-release technology.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.877

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Eggs of a species ofHemisarcoptesnearcocophagusMeyer (Acarina: Hemisarcoptidae), consisting of 1–18 per batch, are laid on the body of the host,Parlatoria blanchardiTargioni (Hemiptera:Coccidae), and take 10 days or more to hatch. Upon eclosion, larvae seek hosts, feed on their blood, and become adults after 2 nymphal stages. The entire life cycle, except when seeking hosts, is spent within the scale-cover ofP. blanchardi. At least a few engorgements involving a few individual scales seem necessary for a female to lay all her eggs. No mating has been observed.The mite population is density-dependent, attacking mostly mature female scales. The population, based upon numbers of eggs, is large in the cold season (Nov.–Feb.), decreases in the hottest period (Apr.–June), but recovers quickly during the rains (July–Aug.). Breeding continues throughout the year, producing some 15 generations per annum. Advantages of utilizing this organism for the biological control ofP. blanchardiand the method of its artificial re-distribution are described.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.882

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Laboratory studies of carbaryl metabolism after piperonyl butoxide application to alfalfa leafcutting bees,Megachile pacifica(Panzer), suggested that synergist differences were more useful than synergist ratios in estimating levels of mixed function oxidases in vivo in insects.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.885

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Synthetic pheromone evaporated from controlled-release applicators substantially reduced the ability of male Douglas-fir tussock moths,Orgyia pseudotsugata(McDunnough), to locate females and mate in the field. Dosages of 0.05–5.0 mg/ha/day were tested; the 2 strongest treatments of 1.0 and 5.0 mg/ha/day were the most effective. The disruption effect was relatively greater with traps baited with live females than with traps baited with synthetic pheromone. Catches of males in traps increased with increased height of traps above the 1.5 m treatment level up to 18.3 m.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.889

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

The toxicities of residues of carbofuran (Furadan®), methyl parathion, methoxychlor, and methidathion (Supracide®) were evaluated in the laboratory againstMicroctonus aethiopoidesLoan, an alfalfa weevil parasite. Adult parasites were exposed at different time intervals to alfalfa plants previously treated with insecticides. Applied dosages approximated field application rates. Carbofuran was the most toxic insecticide through day 7 but induced only 10% mortality by the 10th day. Methidathion was highly toxic to the parasites 2 days postspray and almost totally dissipated after 1 wk. Methoxychlor residue was the least toxic initially but most persistent, inducing ca. 10% mortality 2 wk later. Methyl parathion residues, although causing 100% mortality immediately postspray, declined sharply 24 h later and caused 0% mortality by day 5.

ISSN:0046-225X    

DOI:10.1093/ee/6.6.893

出版商:Oxford University Press    

年代:1977

数据来源: OUP