摘要:

The components of productivity (offspring produced per parent) in bark beetle populations are defined as multiplication and survival. Data from the literature are used to formulate simple models relating these components to initial density in infested trees. A simple monotonic exponential decay function is proposed for describing the multiplication component, although data for validation are scarce. A humpbacked function is proposed for the survival component. This model combines 2 equations, one expressing survival as a direct function of attack density, and the other survival as an inverse function of density.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.579

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Optimum maleGrapholitha molesta(Busck) attractancy tocis-8-dodecenyl acetate (c8–12:Ac) required 6–7%transisomer, whereas maleGrapholitha prunivora(Walsh) attractancy to c8–12:Ac was best when 2.2% of thetransisomer was present. Rubber septa containing 200 μg of the attractant mixture (6.6% trans) were the most attractive forG. molestaand this could be synergized with 600 μg of dodecyl alcohol. Dodecyl acetate inhibited attractancy of bothGrapholithaspecies.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.586

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

A microencapsulated formulation of disparlure was aerially broadcast at rates of 5.0 and 15.0 g/ha onto 16-ha test plots. Laboratory-reared (lab) and field-collected (wild) gypsy moth (Porthetria disparL.) pupae were placed in these plots at densities ranging from 2 pr/ha to 32 pr in an area of ca. 700 m2. After oviposition, or at the end of a 10-11 day test period, female adults and/or their egg masses were recovered for assessment of mating success.Reduction of mating success was statistically significant in all treatments except in plots with only 2 pr wild insects/ha; mating success in control plots at this density was very low. Recovery rates of females from lab pupae were higher than those from wild pupae. In several tests with lab and wild insects, female infertility rates exceeded the 90% level previously proposed as necessary to cause population reduction in the next generation. Suppression of mating was still evident in tests initiated as long as 6 wk after pheromone application.Lab insects are suitable indicators of results to be obtained with wild gypsy moths in identical tests. Because of behavioral and physiological differences between these 2 types of insects, however, wild insects must be used for final definitive tests.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.589

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Hypera postica(Gyllenhal) larval development time was investigated for both eastern and western strains. The minimum effective developmental temperature was 8.9°C for the eastern strain and 10.6°C for the western strain. Development times were calculated for each larval instar, prepupa, and pupa of both strains. There were some differences between instars of the 2 strains. The eastern strain required 212C degree days to complete larval development while the western strain required 207C degree days.Developmental stages were subjected to temperatures below their minimum effective developmental temperatures to determine negative effects on overall development time. No significant negative effects were found where a single stage was held at 0.0° or 4.4°C for 12 h or 1 week. Some differences were found when each stage was held at the lower temperatures for 1 week.Field samples of larvae were taken at 3 different latitudes in Illinois to determine differences in larval population developmental rates.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.593

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Two indices were used to quantify the aggregation of cotton arthropods: the parameterKof the negative binomial distribution and Morisita's index of dispersionIδ. Using frequency distribution data the average values of these indices were calculated. In general there was close agreement betweenKandIδ.Cotton fleahopper,Pseudatomoscelis seriatus(Rueter), nymphs were more aggregated than fleahopper adults. A greater degree of aggregation was observed for boll weevil,Anthonomus grandisBoheman, eggs than for boll weevil adults. Bollworm,Heliothis zea(Boddie), and tobacco budworm,H. virescens(F.), eggs exhibited more aggregation thanHeliothisspp. larvae. Aggregation continued to decrease as theHeliothisspp. larvae became full grown. Among the predatory cotton arthropods, lady beetles and minute flower bugs,Oriusspp., displayed the greatest amount of aggregation. Big-eyed bugs,Geocorisspp., were less aggregated and the spatial distributions of spiders were the least aggregated of the predatory arthropods.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.598

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Individual grapevines of the variety ‘Sauvignon vert’ were sampled for 3 consecutive seasons forTetranychus pacificusMcGregor to determine its effect on grape yield. We also studied the feasibility of utilizing irrigation practices and releases of the predaceous mite,Metaseiulus occidentalis(Nesbitt), to control spider mite populations. Yield, sugar content and tartaric acid content of the grapes were measured on a vine-by-vine basis at harvest. Irrigation practices had no significant effect on quantity or quality of yield, althoughT. pacificuspopulations on sprinkler-irrigated vines were reduced by about one-half the number on control vines. Except under extreme stress conditions high spider mite densities did not reduce grape quality. Yield (weight) tended to be higher in plots where spider mites were controlled byM. occidentalis.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.601

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Intensive surveys of adult bean leaf beetles,Cerotoma trifurcata(Forster), carried out in 1971 and 1972 suggest that the species has 2 complete generations per year in east-central Illinois. Adults of the first generation start emerging in early July until the middle of August, and adults of the 2nd generation emerge starting in early September. The overwintering population is composed mainly of these 2nd generation adults. There is an apparent diel cycle of distribution with catches of adults being lowest near noon and highest about 1700 h.Dispersion of most adult populations approximated a negative binomial distribution. Dispersion was also analyzed using Morisita's index (Iδ), and Taylor's power law. We foundkc= 7.33, and Taylor'sb= 1.13, both implying a moderately contagious distribution. These 3 measures of dispersion were compared to determine the relative merits and range of applicability of each.Extensive surveys of soybean fields in 15 counties in Illinois indicated the bean leaf beetle is more abundant south of the 40° N parallel. Multiple regression analysis was used to assess the influence of chlorinated hydrocarbon residues in the soil and texture of the soil on beetle abundance. Pesticide residue levels in the soil can possibly explain the relative abundance of beetles in localized areas, but not the general patterns of distribution along north-south transects. Other latitude-related factors are probably more important in determining these patterns. Bean leaf beetle abundance was inversely correlated with clay content in the soil.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.607

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Host preference, developmental time, fecundity, adult longevity, emergence, and sex ratio ofEphedrus plagiator(Nees) at 3 constant temperatures were studied in the laboratory. The greenbug,Schizaphis graminum(Rondani), corn leaf aphid,Rhopalosiphum maidis(Fitch), oatbird cherry aphid,R. padi(L.), and English grain aphid,Macrosiphum avenae(Fabricius) were preferred over the rusty plum aphid,Hysteroneura setariaeThomas, cotton aphid,Aphis gossypiiGlover, yellow sugarcane aphid,Sipha flava(Forbes), and spotted alfalfa aphid,Therioaphis maculata(Buckton).E. plagiatorwas never observed probing or attempting to parasitize the latter 2 species. Developmental period ofE. plagiatorvaried inversely with the temperature, but was approximately the same in each aphid species at each temperature. The sex ratio averaged 30% female or below on each aphid species and at each temperature. The longevity ofE. plagiator(female and male) was greater at 16°C than at 21° or 27°C, and also decreased as temperature increased. The species of aphid host had no apparent effects on either adult longevity or development rate ofE. plagiator.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.618

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Musca domesticaL. were exposed to intense selective pressure (70–90%) from a wasp parasite (Nasonia vitripennisWalker). By the 40th generation parasite progeny produced on the resistant host race was only 57 compared with 231 progeny on the control (unexposed) hosts—a 75% reduction in progeny production. Longevity of female parasites on the resistant hosts was only about 5 days, whereas on control hosts longevity was about 9 days. Knowledge of co-evolution in parasite-host and predator-prey systems can assist entomologists in selecting effective natural enemies for biological control.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.621

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

An attempt was made to develop a modified version of the Bombosch predator model as a predictive model for field evaluation of a predator complex against the prey complex by changing a numerical census of predator species in a specific environment to a value that would measure the reductive impact of the complex against the prey species. This reductive impact was taken to be the product of predator power (predator species classified according to degree of voracity against aphids as weighted by a coefficient that proportionates all classes) multiplied by the efficacy of the predator the variable value of voracity as it is influenced by such factors as temperature, biomass of prey, and seasonal trend. It was then used to adjust the potential rate of growth of the aphid population (q) as estimated from caged plants afterqwas used to estimate the rate of increase of the population on exposed plants when no predators are present.

ISSN:1754-5692    

DOI:10.1093/ee/3.4.625

出版商:Oxford University Press    

年代:1974

数据来源: OUP