摘要:

Previous reviews have criticized the use of significance tests in general and of unplanned pairwise multiple comparisons in particular. In this paper, it is argued that these tests are nonetheless useful. Significance tests compare treatment variation to error variation, which complements interval estimation. Unplanned pairwise multiple comparisons play a unique and valid role in separating treatment means. These tests are in no way invalidated by the previous authors' examples of misuse, nor wholly replaceable by the methods that they suggest as alternatives, which often have different purposes. Additional research questions are suggested.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.901

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Analyses of four dispersion indices ofHeliothis zea(Boddie) egg from O.31-m row samples of soybeans (Glycine max(L.) Merrill) indicated aggregated patterns for most data sets taken during 1980–1982 when mean density was>2.00 eggs/O.31-m row. Coefficients from regression equations of mean crowding on mean density and log variance on log mean also indicated aggregated patterns. Coefficients from regressions of mean crowding on mean density were used to develop sequential precision level sampling plans.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.908

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The influence of four tillage systems and two crop rotations on populations of first- and second-generation European corn borer,Ostrinia nubilalis(Hübner), was determined. In six of the eight years, populations of European corn borer were influenced by either crop rotation or tillage. It is suspected that population dynamics were directly affected by crop maturity at time of egg deposition and early larval establishment and development.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.917

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The potential for resistance toRhopalosiphum padi(L.) was evaluated in seedlings ofAgropyron elongatum(Host.) Beauv.,Agropyron intermedium(Host.) Beauv.,Agropyron repensL. Beauv.,Elymus angustusTrin., and hybrids obtained from crosses between these perennial Gramineae and cultivated wheat,Triticum aestivumL. Binary choice tests designed to detect antixenosis showed thatA. repensand the hybrid wheat ×A. repenswere less attractive than the two parental wheat varieties used to produce the hybrid (P<0.05). Parameters of aphid performance, including reproductive rate, duration of prereproductive period, adult fresh weight, and aphid biomass, also allowed the detection of various levels of antibiosis in the four perennial grasses and hybrids tested. Results showed that natural resistance found inAgropyronandElymusspp. can be successfully transmitted to hybrids produced from their crosses with cultivated wheat.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.921

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Responses of male velvetbean caterpillar moths,Anticarsia gemmatalisHübner, were examined in field tests of cone-type traps baited with the female sex pheromone compounds, (Z,Z,Z)-3,6,9-eicosatriene (C20) and (Z,Z,Z)-3,6,9, heneicosatriene (C21). Various blends, formulated on rubber septa, were quantified in the laboratory for release rate and release ratio of the C20 and C21 components; the optimum release ratio (C20:C21) and rate for the capture of males were 78:22 and 10 ng/h, respectively. This specificity was not apparent unless both parameters of release rate and ratio were tested. The number of males observed flying in a viewing area in the field was increased significantly by the presence of C20:C21 blends; however, the close approach of males and sustained hovering at baits were more blend sensitive than other behaviors. Three species of the genusMocisalso responded to the velvetbean caterpillar pheromone components:disseverans(Walker),latipes(Guénée), andmarcida(Guénée).M. disseveranswas captured in large numbers and responded preferentially to baits that released about 50% or more C21. The mostM. disseveranswere captured at traps containing only C21.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.933

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Cumulative catches of brood I tufted apple bud moth,Platynota idaeusalis(Walker), males in sex pheromone traps early in the season (before 28 May) provided a significant predictor of total-season fruit injury for the apple cultivars ‘Yorking’ and ‘Delicious’ but not for ‘Golden Delicious’ during 1986 and 1987. Early-season pheromone trap catches were also significant predictors of brood I injury for ‘Yorking’ in 1986 and ‘Delicious’ in 1987. Incorporating a measure of tree size with these cumulative trap catches improved the prediction of total fruit injury for the cultivars ‘Delicious’ and ‘Yorking’ in 1987. Significant regressions of total fruit injury with first-brood injury also were found for each cultivar except ‘Golden Delicious’ in 1987. The potential use of these early-season measures of population densities to more effectively manage tufted apple bud moth on apple is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.939

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Introduction of desirable legume species into old fields for improvement of forage production allows survival of much of the natural old-field fauna. This study used covered pitfall traps at four field locations of minimum-tillage tests to examine the responses of the spider community to physical and chemical disturbances of the habitat. Management involved the introduction of three legume species, herbicide treatment, mowing and raking, insecticide application, and mollusk control treatments. Although spider activity appeared to be lower in the no-till plots than in previous old-field studies or in mature alfalfa field studies, 19 spider species were repeatedly trapped. Carbofuran spray for insect control caused a reduction in the capture rate for the most common species in the treated plots but did not cause permanent extinction. Plots treated with methiocarb for mollusk control did not differ from controls for spider trapping rate. Analysis was complicated by clumped distributions of spiders that could not be associated with any of the pesticide treatments or management practices. This study demonstrated that a diverse spider population survives and is active during the establishment phase of minimum-tillage pasture improvement. For late summer and early fall samples, the numbers of spiders trapped were considerably lower than numbers encountered in other studies for mature legume stands.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.945

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Feeding damage by Pacific spider mite,Tetranychus pacificus(McGregor), or Willamette mite,Eotetranychus willametti(McGregor), was shown to reduce grape leaf photosynthesis and stomatal conductance. Negative linear regressions between feeding damage and grape leaf gas exchange were developed for both species of mites (P<0.01). Both mite species appear to have comparable effects on field photosynthetic rates and stomatal conductance of grapevines. Photosynthetic rates of undamaged adjacent leaves were not affected by mite feeding damage, whereas stomatal conductance appears to increase in undamaged adjacent leaves. In greenhouse trials, significant interaction effects were observed between cultivar type and stomatal conductance, but not between cultivar type and photosynthesis. Four insecticides did not affect grape leaf photosynthesis or stomatal conductance.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.953

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The relationship of selected herbivores and herbivore complexes to the incidence of winter and summer annual weeds associated with alfalfa was evaluated over a 3-yr period. Winter annual weed populations in the first cutting, second production year, were associated with aphid stress imposed during the previous fall and exacerbated by a severe infestation 6–8 wk before harvest. A significant (P<0.05) interaction between Egyptian alfalfa weevil and aphids affected winter annual weed percentages in the first harvest of the third production year. Summer annual grass populations did not develop until the third year. Egyptian alfalfa weevil had a significant effect on grass percentages in three of the four cuttings in which grasses were present.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.958

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Since first being discovered in Oklahoma during 1983,Erynia phytonomi(Arthur) has been found in 35 counties. Seasonal incidence of the pathogen and the percentage of mortality in populations of the alfalfa weevil,Hypera postica(Gyllenhal), were determined at two locations in Oklahoma from 1983 to 1987. The first infections were usually detected in weevils after accumulation of 200–250 degree-days (base temperature l0°c) from 1 January, coinciding closely with occurrence of peak larval densities. During each year except 1987, rainfall and temperature conditions were favorable to the pathogen, and disease incidence in host larvae exceeded 60% on one or more sampling dates. Incidence of infection in prepupae frequently exceeded 80% and up to 52% of pupae were infected. The pathogen appears to be important as a natural control agent and often reduces the number of insecticide applications required.

ISSN:1754-5692    

DOI:10.1093/ee/18.6.964

出版商:Oxford University Press    

年代:1989

数据来源: OUP