摘要:

In New York state, there are three races of European corn borer moths, which are characterized principally by differences in voltinism and the sex pheromone communication system. One race is bivoltine, with females producing and males responding to a 99:1E/Zisomeric ratio of ∆11-14:0Ac's as the sex pheromone. Two races, one univoltine and one bivoltine, produce and respond to a 3:97E/Zblend of ∆11-14:OAc's. The races are referred to as BE, UZ, and BZ to denote these differences. Analyses by gas chromatography of field-collected females indicate that there is significant hybridization between the Z and E races when in sympatry, with hybrid females producing a 68:32 ratio ofE/Z11-14:OAc. Gene flow among the races was investigated using differences in triose phosphate isomerase (TPI) allozyme frequencies of moths from sites sampled across the state. The fixed nature of theTpi-1allele in the BE race and increases in theTpi-1allele frequencies in UZ populations in sympatry with the BE race support the hypothesis that gene flow following hybridization is unidirectional from BE populations into the Z populations. In addition, the TPI genotypes of the 10 hybrid females analyzed were consistent with hybridization occurring by E males mating with Z females.

DOI:10.1093/ee/20.5.1356

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A three-generation bioassay was developed to determine the response curves of the western spruce budworm,Choristoneura occidentalisFreeman, to compounds that occur in the foliage of Douglas-fir,Pseudotsuga menziesii(Mirb.) Franco, one of its principal hosts. Insects from a nondiapausing laboratory colony ofC. occidentaliswere reared on artificial diets containing defined levels of various nutrients and allelochemicals. An experimental base diet (nutritionally similar to Douglas-fir foliage in concentrations of nitrogen, sugars, and minerals) was modified to test responses. Insects spent their entire larval period, for three consecutive generations, feeding on the treatment diets. Responses measured include survival rates for all life stages, pupal masses, and larval development times and growth rates. Data on survival and fecundity (predicted from female pupal masses) were used to estimate population growth over three generations for the levels of the compound(s) tested. The tremendous variation in the survival and reproduction ofC. occidentalisamong 29 replications of the bioassay on the experimental base diet emphasizes the importance of replicating whole experiments for this type of bioassay. The great variability that occurred in these feeding studies underscores the critical importance of using large sample sizes and proper controls on each experiment to ensure that conclusions made from feeding bioassays are reliable. Average performance on the base diet was: 68% of the first instars survived to the late larval stage, 57% of the initial cohort survived to the pupal stage, 40% of the cohort survived to the moth stage, 45% of the egg masses produced had viable eggs, mean fresh pupal mass was 97 mg for females and 66 mg for males, mean larval development time was 44 d for females and 40 d for males, and larval growth rate was 2.3 mg/d for females and 1.7 mg/d for males.

DOI:10.1093/ee/20.5.1363

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The departure of winged aphids from a plant by flying or walking to neighboring plants may, in theory, be affected by wind speed or the density of leaf bridges between plants. This study explored the effects of these two factors on the departure rate of wingedUroleucon ambrosiae(Thomas) from bean plants,Phaseolus vulgarisL., in monocultures and in mixtures with maize,Zea maysL., in Costa Rica. Residence half-time, herein defined as the length of time required for half the winged aphids placed on a plant to depart, was shorter in mixed crops than in bean monocultures and was negatively correlated with wind speed at bean canopy level. Residence half-time had no detectable correlation with the number of inter plant leaf bridges. Departure by flight, based on these findings, may have been more common than walking from plant to plant via leaf bridges. Maize in mixed crops formed barriers that reduced wind speed at bean canopy level, leadingU. ambrosiaealatae to depart more readily from bean plants in bean–maize mixtures than in bean monocultures.

DOI:10.1093/ee/20.5.1375

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A simulation model of a major mite pest of stored grain,Acarus siroL., was developed to predict the maximum rate of its population growth and survival by interpolating daily rates of growth of its population derived from published studies. The model simulates the population dynamics at −10 to 40°C and 20–90% RH without resource limitation or natural enemies. The model's predictions were in reasonable agreement with naturally occurring mite populations in bulk stored wheat in granaries in Manitoba, England, and Czechoslovakia.

DOI:10.1093/ee/20.5.1381

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

In a 3-yr study, adult tarnished plant bugs,Lygus lineolaris(Palisot de Beauvois), were collected in sampling plots of mustard (Brassica juncea crispifolia(L.)) by sweep net. Sticky traps placed around these plots were used to sample flying bugs. Each year, four of eight mustard plots were treated regularly with insecticide. Thus, treated plots contained immigrant populations, and untreated plots contained immigrants and residents. A greater percentage of tarnished plant bugs in treated plots were female than in untreated plots. Immigrant adults, collected from treated plots, were younger than adults in untreated plots. Bugs caught on traps were younger than those collected from sweep net samples; on average, females were older than males. Within treatments, there was no difference in the vertical distribution of males and females on traps. The average age of females decreased with capture height. whereas male age was unaffected by capture height. The age and reproductive status of captured bugs indicate that young, parous females are most likely to colonize new host patches. Differences between the sexes in flight behavior and advantages of dispersal by parous females were discussed.

DOI:10.1093/ee/20.5.1387

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Nineteen sorghum,Sorghum bicolor(L.) Moench, accessions were compared with the standard commercial cultivar ‘Northrup King Savanna 5’ for hard-dough stage panicle resistance to feeding by larvae of the fall armyworm,Spodoptera frugiperda(J. E. Smith). The biological variables measured to determine the differential development ofS. frugiperdaon diets containing florets of the sorghum genotypes were larval and pupal weight, duration of the larval stage, time to adult emergence, survivorship, fecundity, net reproductive rate, intrinsic rate of increase, and relative fitness. The plant introductions IS1340C, IS2246C, IS2403C, IS2553C, IS2569C, IS2825C, IS3477C, IS6911C, IS7007C, IS7498C, IS8337C, IS12219C, IS12592C, IS12612C, IS12617C, IS12662C, IS12664C, IS12666C, and IS12683C were all found more resistant than ‘Northrup King Savanna 5’, which is the most resistant commercial genotype available. Resistance in IS1340C, IS2246C, IS2403C, IS2553C, IS3477C, IS6911C, IS7007C, IS7498C, IS12612C, IS12662C, IS12664C, and IS12666C was primarily due to factors in the glumes (including lemmas and paleas). Chemical components in the seed were mainly responsible for resistance in IS2825C, IS12617C, and IS12683C, whereas factors in both seed and glumes were responsible for the resistance shown by IS12219C and IS12592G. Resistance was significantly correlated (r2>0.50,P<0.05,n= 16) with the concentration of acid detergent fiber and tannin in the seed.

DOI:10.1093/ee/20.5.1393

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A linear regression model for predicting pheromone trap catch of male European pine shoot moth,Rhyacionia buoliana(Denis&Schiffermüller), based on accumulated heat units is presented. The model was developed from 3 yr of maximum–minimum air temperature and pheromone trap data collected in western Oregon during 1986–1988. Data collected the following years, 1989–1990, were used to evaluate the model. A lower threshold (base) temperature of −2.2°C was used in calculating daily degree-days since 1 January. The model successfully predicted accumulated male moth catch to within 1–3 d during 1989. Predicted degree-day requirements (above −2.2°C) are 1,712 for 10% catch, 1,958 for 50% catch, and 2,205 for 90% catch.

DOI:10.1093/ee/20.5.1403

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Among-sample spatial variation in gypsy moth egg mass population density was quantified from four databases: the Melrose Highlands data (104 plots [0.0405 ha] sampled throughout coastal New England over a 20-yr period in the early 1900s; maximum point separation of ≍250 km), Massachusetts state survey data (150 plots of 20 banded trees located throughout Massachusetts and sampled from 1985 to 1987; maximum point separation ≍300 km), Fox Chapel Survey Data (517 plots [0.0101 ha]sampled throughout Fox Chapel Borough, Pennsylvania from 1988 to 1990; maximum point separation ≍8 km) and Cape Cod within-stand data (groups of 169 plots [0.008 ha] located in a 25-m grid; maximum point separation ≍1 km). Sample semivariograms were calculated that quantified spatial dependency in density at a variety of spatial scales. Both the Melrose and Massachusetts data showed evidence of spatial contagion in density at distances ranging from 20 to 100 km. The range and magnitude of this spatial dependence varied considerably from year to year. The extent of small-scale (<200 m) spatial contagion of egg mass densities in the Cape Cod data was also quite variable. Some of the sites in some years showed evidence of spatial dependence at various distances, whereas data from other years and other sites showed no spatial contagion. In contrast, semivariograms from the Fox Chapel plots were quite similar: in each of the 3 yr the maximum distance of spatial dependence (“range”) was ≍1 km. In summary, we quantified spatial dependency in egg mass densities at scales ranging from 25 m to 100 km. There was little evidence of spatial dependency at greater distances. The ordinary kriging procedure can use these semivariograms to generate maps of interpolated estimates of egg mass densities. These maps may be valuable in area-wide gypsy moth management programs. Specific recommendations were developed for the spacing of spatially stratified egg mass samples in area-wide management systems.

DOI:10.1093/ee/20.5.1407

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The population dynamics of four parasites of house fly,Musca domesticaL., pupae,Spalangia endiusWalker,S. cameroniPerkins,Muscidifurax raptorGirault&Sanders, andM. zaraptorKogan&Legner, and their host were simulated in a computer model written in the C language. The model incorporates nonlinear temperature-dependent development, effects of host–parasite ratio on host mortality and parasitism, competition between adult parasites, and options for various insecticide, manure removal, and parasite release strategies for fly control. Examples of the results of simulating parasite releases and pesticide applications are presented.

DOI:10.1093/ee/20.5.1418

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Natural oak regeneration is poor in Missouri's forests. The potential of the Asiatic oak weevil to affect Missouri's oak resource was addressed by determining the weevil's host plant preference for 10 common Missouri tree species. Host plant preference was assessed in two-choice feeding experiments and no-choice longevity and oviposition experiments. Changes in host plant preference because of previous feeding experience also was investigated. Black oak, red oak, white oak, and sugar maple were acceptable hosts for adult weevils because measurable feeding occurred on these species during two-choice preference tests. In 1985, significantly more leaf was consumed from each oak species than from sugar maple. Leaf consumption for sugar maple and black oak did not differ in 1986. Adults fed red oak and black oak in no-choice tests lived significantly longer and laid significantly more eggs than weevils fed white oak or sugar maple, indicating that red and black oaks were preferred hosts. Of the other species tested, ash, basswood, dogwood, elm, hickory, and sassafras were considered nonhosts because adults did not feed or oviposit when restricted to these tree species. Sugar maple and white oak were acceptable but not preferred hosts because longevity and egg production were reduced when weevils fed on these species. A feeding preference for white oak and sugar maple could not be induced in adults by an earlier feeding experience on these hosts.

DOI:10.1093/ee/20.5.1427

出版商:Oxford University Press    

年代:1991

数据来源: OUP