摘要:

Phytomelanin in the pericarp of sunflower,Helianthus annuusL., achenes is an effective mechanism for reducing yield losses due to achene injury by larvae of the sunflower moth,Homoeosoma electellum(Hulst). In field trials, a highly significant negative correlation (r = –0.93) existed between percent injured achenes and percent achenes having phytomelanin in the pericarp. We showed in penetrometer studies that pericarps with phytomelanin harden much more quickly than pericarps lacking phytomelanin, and that there are genotypic differences for its expression among lines having the trait. We demonstrated in pericarp developmental studies that phytomelanin begins to be deposited between the hypodermis and sclerenchyma of pericarps by day 3 after ovule fertilization, and that its deposition progresses rapidly through day 13 after ovule fertilization. In laboratory feeding bioasays with whole achenes and pericarp mash incorporated in a wheat germ diet, we showed that phytomelanin exhibited both antizenosis and antiobiosis toward larvae ofH. electellumwhen eaten.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.277

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

A stochastic dynamic programming model is developed to analyze the integrated control of alfalfa weevil in central New York. The management alternatives considered include biological control by the parasitoidBathyplectes curculionis, cultural control by early harvesting, and chemical control by insecticides. The optimal policies depend upon pest and parasite densities, weather, length of planning horizon, and a number of parameters describing population dynamics. Sensitivity analysis on the parameters indicate that the policies are most sensitive to weather and weevil densities and least sensitive to parasite attack rates. The model results indicate that early harvesting is usually the most effective control procedure for alfalfa weevil management in central New York

ISSN:0046-225X    

DOI:10.1093/ee/12.2.286

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Sweep-net sampling and pitfall trapping were used to survey insects in weedy and weedfree soybean habitats. Weedy soybean habitats consisted of (1) grassy soybeans; (2) soybeans with broadleaf weeds; and (3) soybeans with broadleaf weeds and grasses. Insect species diversity was greater in weedy soybean habitats than in weed-free soybeans. Greatest diversity of species occurred in the mixed-weed soybean habitat. The most important phytophagous insect on soybeans in Indiana, the Mexican bean beetle.Epilachna varivestisMulsant, was most abundant in weed-free soybeans. Predators were most abundant in weedy soybeans.Coleomegilla maculata(DeGeer) was most abundant in weedy soybean habitats, whereasOrius insidiosus(Say) andNabisspp. were most abundant in soybean habitats with grasses and mixed weeds. In the pitfall trapping study,Harpalusspp. were more abundant in soybean habitats with grasses and mixed broadleaf and grass weeds

ISSN:0046-225X    

DOI:10.1093/ee/12.2.296

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Koa,Acacia koa, sites on the five major Hawaiian Islands were sampled during the 1978 growing season to determine the presence and damage potential of insects and diseases infesting koa seeds. Relative abundance of the most prevalent insects was 62.3% for the koa haole seed weevil,Araecerus levipennis, 20.6% for the bruchidStator limbatus, and 13.2% for the endemic koa seedworm,Cryptophlebia illepida.Other insects recovered includedStator pruininus. Cydia rufipennis, andCydiasp. The ichneumonidPristomerus hawaiiensiswas the most abundant parasite associated with seed insects.Collectotrichum gloeosporioideswas the only disease organism identified from koa seeds collected at the sample sites

ISSN:0046-225X    

DOI:10.1093/ee/12.2.299

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

A distinct distribution pattern for the Mediterranean fruit fly,Ceratitis capitata(Wiedemann), on the island of Kauai, Hawaii, was determined from trap and fruit infestation data.C. capitatawas found at upper elevations as expected. However, it was also found breeding in low-elevation localities along the coast and in major valleys of western Kauai. Traps in areas that receive little rainfall consistently caught higher numbers ofC. capitatathan those in areas that receive abundant rainfall. Hosts were generally abundant in ecotone areas between dry and wet habitats. The most important hosts were coffee,Coffea arabicaL., strawberry guava,Psidium cattleianumSabine, and peach,Prunus persica(L.) Batsch. There was evidence thatC. capitatamoved from these areas into certain dry areas. Generally, populations ofC. capitatawere absent from large areas of native forests except where the alien strawberry guava had invaded. Our study differed from previous studies by its heavy reliance on plastic fruit fly traps for delineating distributional limits ofC. capitataover large and remote areas. Once flies were detected in an area, host fruit collection data were used to establish whether flies were breeding in an area.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.303

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Pastures in southeastern Louisiana were sampled to determine percent mortality caused by a nuclear polyhedrosis virus (NPV) inSpodoptera frugiperdapopulations. Data were also collected on the host populations and environmental variables. Stepwise multiple-regression analysis indicated that overwinter NPV in the soil, but notS. frugiperdapopulation density, was an important variable relative to prevalence of the disease. Time of year was another consistently important independent variable. When time was dropped from the model, a temperature variable partially compensated for its absence. Other variables that entered the models included precipitation, presence of cattle, percent ground cover, plowing of the pasture, grass height, percent silt in the soil, and host plant species in the pasture.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.311

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Commercial apiaries were monitored with dead bee hive entrance traps in several agricultural areas of eastern Washington during 1979–1981. Low to moderate kills of honey bees occur periodically throughout much of the season in the more diversified crop areas sampled, the Yakima Valley and the Columbia Basin. Certain regions with less intensive insecticide usage, the Kittitas Valley, the Mattawa area, and the Touchet area, are much safer for summer bee pasture

ISSN:0046-225X    

DOI:10.1093/ee/12.2.317

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Bean leaf beetles,Cerotoma trifurcata(Forster) (Coleoptera:Chrysomelidae), emerging in April from an overwintering site in central Illinois were observed feeding or aggregating on four nonleguminous plants. Laboratory feeding tests indicated that three of these species,Urtica dioica. Laportea canadensis(Urticaceae), andEuonymous atropurpurea(Celastraceae), were accepted as food plants by overwintered adult beetles, butEupatoriumsp. (Compositae) was consistently rejected. These acceptable plants may serve as interim hosts for the beetles until soybean, the major host plant, is available. The implications of this finding on the dynamics of the bean leaf beetle-soybean association are discussed

ISSN:0046-225X    

DOI:10.1093/ee/12.2.321

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Interactive damage effects of stand loss and plumule abscision from seedcorn maggot,Hylemya platura(Meigen), on ‘Amsoy 71’ soybean growth and yield were investigated by using actualand simulated-damage methods. Stand reduction affected seed yield more than the presence of surviving seedlings wihtout plumules. Over all years, seed yields were greatest at 29.7 plants per 1-m row. At all plant stands, the seedlings without plumules were shorter and produced less leaf area, fewer flowers, and fewer pods than did normal plants. This retarded growth reduced leaf area index, flowers per unit area, and pods per unit area. The decrease in pods per unit area was accompanied by an increase in beans per pod. When some of the surviving seedlings lacked plumules, seed yields were reduced at poor plant stands in some years. Plant-growth characteristics were very similar for actual and simulated damage. Seed yield comparisons between actual and simulated damage suggested that seedcorn maggot injury to cotyledons had a small, negative effect on seed yield

ISSN:0046-225X    

DOI:10.1093/ee/12.2.323

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

One near-isogenic and two isogenic ‘Texas Marker-1’ (TM-1) cotton,Gossypium hirsutumL., breeder lines differing in alleles for trichome density affected ovipositional behavior and nymphal growth weight ofLygus hesperusKnight. Femalesoviposited 28 and 31% fewer eggs on the normally hirsute and Smooth leaf lines, respectively, than the Pilose line. The leaf petiole was the most preferred oviposition site, with more than 49% of the eggs deposited there on the three lines. The Pilose isoline reduced nymphal weight by 37% compared with the Smooth leaf isoline. Differences in number of eggs laid, nymphal emergence, growth, and survival were not significantly different between the Smooth leaf and normally hirsute lines. Trichome density of 33 cotton genotypes was positively correlated with nymphal emergence. A regression equation was derived to predict nymphs per female based on trichome density

ISSN:0046-225X    

DOI:10.1093/ee/12.2.331

出版商:Oxford University Press    

年代:1983

数据来源: OUP