摘要:

The potentially devastating impact of the oriental chestnut gall wasp,Dryocosmus kuriphilus(Yasumatsu), on nut productivity of Chinese chestnut,Castanea mollissima(Bl.), prompted an assessment of the role of endogenous phytohormone-like growth regulators in gall development. Enzyme immunoassays for several growth regulators associated with developing galls indicated the probable presence of t-zeatin (Z), t-zeatin riboside (ZR), dihydrozeatin (DHZ), dihydrozeatin riboside (DHZR), indoleacetic acid (IAA), and abscisic acid (ABA) in gall tissues. Levels of these regulators were similar in amount and seasonal abundance to that in nongalled shoots; however, ABA- and DHZR-like substances were much higher in developing stem galls. All of these regulators (except ABA-like substances) were detected in developing gall wasps within the stem gall; however, levels within the insect were much lower than in stem-gall tissue. This indicates that these particular regulators may not be the growth controlling factor(s) that initiate gall development. Gall wasp pupae contained high levels of IAA- and DHZR-like substances, whereas larvae contained only high levels of a DHZR-like factor, indicating these substances may exhibit a role in insect morphogenesis.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.915

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Pheromone was collected from the air surrounding cultured boll weevils,Anthonomus grandisBoheman, as they fed on flower buds from seven cotton genotypes,Gossypium hirsutumL., grown in two field environments. An effluvial method was used to collect the pheromone, and capillary column gas chromatography was used to quantify it. Significantly more pheromone was collected when boll weevils fed on flower buds from some glanded genotypes than when they fed on flower buds from glandless genotypes (i.e., genotypes without epidermal glands containing terpenoid aldehydes). Boll weevils feeding on flower buds of some glanded genotypes produced significantly more pheromone than those boll weevils feeding on flower buds of other glanded genotypes depending upon the environment where the cotton was grown. The amounts and ratios of the four pheromone components also were affected by genotype and the environment where they were grown. These results suggest that boll weevil pheromone quantity and quality is dynamic in time and space depending upon host-plant genotype, environment, and insect age.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.921

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Development of the squash bug,Anasa tristisDeGeer, was observed at 12 constant temperatures between 20.0 and 40.0°C. Times required for development of all life stages at the different temperatures followed the classic “backwards-J” shape. A nonlinear biophysical model was fit to data representing each individual life stage as well as to several combinations of life stages. Generally a four-parameter model was selected with high-temperature inhibition of development.R2values for the individual models ranged from 0.901 to 0.994. The models indicate that the use of heat-unit accumulation techniques to predict development times is valid within the linear response range ofA. tristisand may be used in the development of management strategies.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.926

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Centrifuged and filter-sterilized salivary homogenates of male and female cotton fleahoppers (CFH),Pseudatomoscelis seriatus(Reuter), were found to contain a polygalacturonase (pectinase), an enzyme capable of breaking down pectic materials in the middle lamella of plants. Salivary preparations from male CFH had more enzyme activity than homogenates from female salivary glands. Salivary extracts were strong elicitors of stress ethylene production when injected into excised cotton shoot tips. Excised cotton buds injected with male salivary preparations produced ethylene at higher rates than those buds injected with female preparations. Enzyme activity and ethylene-inducing capacity of these salivary homogenates were destroyed by boiling and reduced by long-term storage. Ethylene production by cotton buds also was induced by solutions of commercial pectic enzymes.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.930

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Ooencyrtus kuvanae(Howard) parasitism of gypsy moth,Lymantria dispar(L.), egg masses (EMs) laid on different host species and substrates was studied in newly infested areas in Virginia. Parasitization rates of gypsy moth EMs byO. kuvanaewere highest on red maple and inanimate objects and lowest on oaks. The effect of host plant species on parasitism was independent of the number of eggs per mass and may be due to the effects of bark texture on egg mass geometry and searching behavior ofO. kuvanae. Percent parasitization was also inversely related to eggs per mass; the latter is a function of host suitability and gypsy moth population density.O. kuvanaeappears to be incapable of maintaining gypsy moth populations at low densities but may be an additional factor mediating against the reproductive success of individuals feeding on nonpreferred host plant species.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.936

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Field studies showed thatEdovum puttleriGrissell, an egg parasitoid of the Colorado potato beetle,Leptinotarsa decemlineata(Say), did not visit and feed on nectar of flowers commonly found near potato fields in the northeastern United States. Field cage observations and laboratory tests determined thatE. puttleriuses aphid honeydew on potato as a source of nutrition. Because aphids do not usually colonize potato crops until early July in the Northeast, honeydew scarcity may prevent early-season establishment of this parasitoid in potato.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.941

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Eggs of the bigeyed bugs,Geocoris punctipes(Say) andGeocoris uliginosus(Say), were collected in cotton fields in east-central and northern Alabama from 1983 to 1985 to determine seasonal levels of parasitism byTelenomus reynoldsiGordh and Coker andTrichogramma pretiosumRiley. Total host density fluctuated from<0.1–3.6 eggs per plant from June to September with maximum densities occurring in late August and early September. The density of eggs parasitized byT. reynoldsiwas linearly correlated with host density in 1984 and 1985. Parasitism byT. reynoldsivaried between 10% and 60%. In 1985,Geocoriseggs were deposited about equally on leaves and terminals before mid-June but primarily on leaves thereafter. Rates of parasitism were higher in terminals than on leaves during June. Rates of parasitism up to 58, 77, 27, and 31% were recorded in soybeans, corn, wild mustard, and crimson clover, respectively.T. pretiosumparasitized<1% of theGeocoriseggs in east-central Alabama and 0% in northern Alabama.Geocorisis newly recorded as a host forT. pretiosum.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.945

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The susceptibility of gypsy moth,Lymantria disparL., larvae to the gypsy moth nuclear polyhedrosis virus was significantly altered when larvae were fed different host plants in conjunction with the virus. Larvae consuming the virus on the foliage of oak species suffered lower mortality rates than did larvae consuming the virus-contaminated foliage of aspen species. Decreased viral pathogenicity was correlated with increased acidity and hydrolyzable tannin content of the leaf material.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.952

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Mortality ofDendroctonus simplexLeConte was investigated near St. John's, Newfoundland, in 1983, where two broods were produced. The fourth larval instar had the highest mortality at 18.9% and pupae the lowest at 2.9%. Percent mortality of the third and fourth larval instars was significantly less in the lower meter of the bole than at 2.5–3.5 m and 5.0–6.0 m above ground. Egg mortality within the second brood was 69% higher than within the first brood. Total mortality was 79% and 82% for first and second broods, respectively. Generally, pathogens caused the highest mortality among eggs, second-instar larvae, and pupae; resinosis among first-instar larvae; and parasitoids among third- and fourth-instar larvae. Prewinter mortality among new brood adults was 6.4% and 8.7% for the first and second broods, respectively.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.959

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

In greenhouse studies, four nitrogen (N) rates were applied to potted grape plants. Foliar N increased significantly as applied N increased, and there were significant differences in N content between leaves taken from lower, middle, and upper node locations on the vines. In leaf cages,Tetranychus pacificus(McGregor) responded to increasing foliar N with significantly (P<0.05) increased fecundity and shorter immature developmental time only during the second year of the study. There appeared to be no relationship between foliar N and immature survivorship, ovipositional duration, or female longevity.

ISSN:1754-5692    

DOI:10.1093/ee/17.6.964

出版商:Oxford University Press    

年代:1988

数据来源: OUP