摘要:

Life table data were collected for seven generations ofLaplatcris disparRehn. Variation in hatching between generations was negatively correlated with rainfall during fall and winter. Both unrealized natality and mortality during the egg stage were density independent. Nymphal mortality, the key factor related to variation in total mortality, was considered to be largely caused by polyphagous spiders, and was density independent. Adult mortality, mainly caused by parasites and predators, was density dependent, compensatory with the previous mortalities, and important as a regulating factor in population density.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.775

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Differences in larval coloration of velvetbean caterpillars,Anticarsia gemmatalisHübner, reared on two soybean cultivars under two crowding regimes and two photoperiodic regimes were associated with crowding andsex.Forty-seven percent of crowded and 6% of uncrowded larvae were black. Crowding was associated with a significant decrease in pupal and adult weights. Time from egg hatch to pupation increased when larvae were fed the resistant cultivar ‘Tracy’ and reared under the 14:10 (L:D) photoperiod. Differences in larval coloration were also obtained when larvae were reared on black locust and kudzu foliage and under crowded regimes. Sixty-seven percent of uncrowded larvae were green and 24% of crowded larvae were green. Sixty-one percent of total larvae reared on black locust were black and 21% of total larvae reared on kudzu were black. Larvae took less time to pupate when reared on black locust than on kudzu.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.779

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Velvetbean caterpillars,Anticarsia gemmatalisHübner, were reared at different densities on ‘Davis’ soybean. The degree of dark pigmentation was found to be density dependent under field and laboratory conditions. No significant effect on the degree of dark pigmentation was observed when the soybean plant, ages R2–R4, R4–R6, and R6–R7, were tested under laboratory conditions. Larval development was delayed and 1-day-old adult weight decreased as the population density and plant age increased. The highest degree of dark pigmentation was expressed in the last instar when larvae were crowded throughout development.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.784

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Phytoseiulus persimilisandAmblyseius californicuswere released into commercial field corn in the Texas High Plains in 1982 and 1983. Both predators significantly reduced spider mite infestations and maintained these infestations below economically damaging levels. Timing of releases was critical to the efficacy of the phytoseiids. Plots treated withP. persimilisgenerally had lower spider mite densities than did plots treated withA. californicus, though statistically significant differences were detected on only one occasion.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.790

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Stage-specific growth rates, mortality rates, energy intake, and energy expenditures are incorporated into an empirical model of energy budgeting for a population of eastern tent caterpillars,Malacosoma americanum(F.), Maryland. Of the 3,460 kJ of energy ingested by a hypothetical population of 1,000 larvae, 50.2% was egested, 34.5% was respired, 1.2%was lost as exuviae, 12.5%went into biomass production, 1.5%was used for silk production, and 0.3% went into egg production. Mortality losses at each stage were incorporated into the model. Population assimilation and growth efficiencies based on energy were as follows: assimilation (100 × assimilation/ingestion) = 49.8%, gross growth (100 × production/ingestion) = 15.3%, and net growth (100 × production/assimilation) = 30.7%.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.795

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Adult longevity, duration of development from hatching to adult emergence from the pupae, numbers of eggs laid, and prey consumed byChilomenes sexmaculataF. were evaluated at constant temperatures ranging from 26 to 34°C. Adult survival varied from 6.1% at 34°C to 65.7% at 30°C. Maximum oviposition rate was attained at 32°C, but fecundity was highest at 30°C. Low oviposition rate and fecundity at 26 and 34°C indicated that these temperatures were near the threshold of activity for the adult.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.800

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Continuous high-intensity (24:0 [L:D] photoperiod) light-induced susceptibility in PI 227687 soybean plants previously resistant to cabbage looper,Trichoplusia ni(Hübner), was evidenced by insect feeding assays and the biology of the insect on diet supplemented with leaf powder from such plants. Ethyl acetate and hexane extractables from leaves of these susceptible PI 227687 plants did not show antifeedant activity againstT. nilarvae. However, when such plants were subsequently placed under a 16:8 photoperiod for 2 weeks they regained their resistance against the pest, as shown by leaf-disk feeding assays and presence of antifeedant activity in the ethyl acetate and hexane fractions. Thinlayer chromatography demonstrated that only one of the resolved components in ethyl acetate and hexane extractables is present in resistant PI 227687 but is missing in susceptible PI 227687, ‘Clark’, and ‘Davis’.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.803

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A velvetbean caterpillar (VBC),Anticarsia gemmatalisHübner, population model was developed for use in a pest management program. The processes of oviposition, development, mortality, and immigration are modeled. Temperature effects on oviposition and development rates are included, as well as differences in individual response to temperature. Information in the literature and field data were used to set the parameters of the model, with simulated larval populations compared with field larval populations for 1 year. Early season population dynamics were well described by the model for an additional 2 years. Late-season population dynamics were well described in only 1 of the other 2 years, due to an outbreak 1 year of the entomogenous fungusNomuraea rileyiFarlow (Sampson), which caused the VBC population to crash.A Nomuraeamodel is needed to improve predictions when weather conditions are favorable for the disease. Sensitivity analyses indicated that accurate estimates of adult influx into the field are important to predict population dynamics of VBC within the field.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.809

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Impact of egg-mass detrition of European corn borer,Ostrinia nubilalis(Hübner), on estimation of egg-mass density in a cornfield was investigated. Both an average and worst-case detrition rate curve were estimated from field egg-mass counts. At 50% completion of a 20-day symmetric oviposition period, 1.14 and 1.46% of egg masses deposited were predicted missing using these curves. Of 20 cornfields observed between 1982 and 1983, the management decision was never changed as a result of correcting for egg-mass detrition.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.817

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Larvae and adult females of the western flower thrips,Frankliniella occidentalis(Pergande), showed a functional predatory response to increases in density of spider mite eggs. Female flower thrips showed a faster rate of egg discovery than did larvae, but larval thrips had a higher upper limit for predation than did adult females, which was exhibited by a shorter egg handling time for larvae. Spider mite webbing on the eggs and leaf surface significantly inhibited predation by thrips larvae. Flower thrips are omnivorous opportunists, because they can resort to herbivory when mite eggs are absent or scarce. Thrips are important as herbivores, predators, and prey for other predators. Information on predation by flower thrips will lead to a better understanding of their impact on spider mite populations in the field.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.821

出版商:Oxford University Press    

年代:1986

数据来源: OUP