摘要:

Elevated atmospheric carbon dioxide (CO2) levels of 1,000 parts per million (ppm) significantly increased consumption of foliage byTrichoplusia ni(Hübner) and significantly enhanced growth ofPhaseolus lunataL. when compared with ambient levels of 340 ppm. Mean pupal weight was less under treatments with elevated atmospheric CO2under a high fertilization regime, but larval survival and percent nitrogen content of pupae were not affected by level of CO2treatments at high, medium, or low fertilizer rates. Regardless of CO2concentration, larval survival and pupal weight were reduced in absence of fertilizer. Nitrogen and protein consumption increased with fertilization rate. Because percent leaf area of plants consumed byT. nilarvae was not affected by CO2concentration, this study suggests that increased plant growth resulting from elevated atmospheric CO2may benefit the plant proportionately more than the insect.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.639

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

This research was conducted to determine host plant specificity and oviposition behavior ofBangasternus orientalisCapiomont andBangasternus fausti(Reitter) in a freechoice field experiment. Labeled adultBangasternusspp. were exposed equally to eight selected plant species and cultivars in a field experiment in Greece. Weevil/plant associations were quantified and weevils were reared and identified from randomized flower head samples from all blocks. AdultB. orientalisshowed overwhelming preference forCentaurea solstitialisL., although some attraction and oviposition occurred onCentaurea diffusaLam. andCentaurea calcitrapaL. AdultB. faustishowed strong preference forC. diffusa, but some attraction and oviposition occurred onC. calcitrapaandC. solstitialis. The evidence suggests that theseBangasternusspp. have a very restricted host-plant range, feeding only on a small number of plants in the genusCentaurea, and are potential candidates for biological control programs againstCentaureain California.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.645

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Annual counts of eastern yellowjacket,Vespula maculifrons(Buysson), colonies in a Delaware woodlot in 1965–82 exhibited a statistically significant, 2-yr cycle of abundance. In 1976–80 the mean size of queen cells also exhibited an apparent 2-yr cycle. When queen cell size was up, colony abundance was down and vice versa. This is the first quantitative evidence of variation in a queen characteristic that may be linked to the familiar cycles of yellowjacket abundance.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.649

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Rates of parasitization of the pea weevil,Bruchus pisorumL., byEupteromulus leguminisGahan were studied on nine genotypes of peas,Pisum sativumL. There were significant differences in percentages of weevils parasitized among the different pea genotypes. A small, though highly significant, negative correlation between susceptibility to weevil infestation and percentage of parasitized weevils was found. Adult parasites emerged from pea seeds through exit holes made by pea weevil larvae. Those parasites that killed weevil larvae before completion of the exit hole (4.9%) were trapped within the seed.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.653

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Piperidine alkaloids in poison hemlock,Conium maculatumL. (Umbelliferae), are responsible for the plant's acute toxicity toward mammals and other vertebrates. Because of this property, these compounds are often assumed to be toxic to insect herbivores as well. One of these alkaloids, coniine, was bioassayed for toxicity, growth inhibition, and feeding deterrency in the polyphagous speciesHeliothis zea(Boddie) (Lepidoptera: Noctuidae). Contrary to expectations, coniine showed no biological activity towardH. zeaat the concentrations tested.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.656

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The peach silver mite (PSM),Aculus cornutus(Banks), was monitored on leaves of peach,Prunus persicaL. Batsch, ‘Flordaking’ and ‘June Gold’, from 6 May to 5 August 1985. PSM first appeared in significant numbers on 21 May on unsprayed trees, peaked on 11 June, and disappeared by 8 July. Between 50 and 3,400 peach silver mite-d (PSMD) per leaf accumulated per tree. Percentage of leaf damage varied between 0 and 88% of the adaxial leaf surface. Net CO2assimilation rate (A), leaf conductance (gl), and transpiration (E) were inversely related to PSMD and percentage leaf damage. Predicted reductions inAat 3,000 PSMD and 80% leaf damage were ca. 20 and 22%, respectively. More PSM occurred on ‘June Gold’ than ‘Flordaking’ but interactions between PSMD and cultivar or percentage leaf damage and cultivar were not significant forA, gl, E, or chlorophyll concentration. The percentage of decline inglwas similar to the decline inAand leaf chlorophyll concentration was not affected by PSM. These data suggest that PSM is primarily an epidermal feeder, and that PSM feeding may inhibit leaf gas exchange by affecting stomatal function. PSM were at least 10-fold less debilitating to leaf gas exchange of peach thanTetranychus urticaeKoch in a previous study, and may not ordinarily need to be controlled by chemical sprays.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.660

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A population ofOsmia cornutaLatr. was trapped in northern Spain during 1984, transported to the United States, quarantined, exposed to various temperature regimes through summer months, and placed in California almond orchards through winter months. Results of this study demonstrated that bees overwintered in commercial almond orchards emerged in synchrony with almond bloom; gregarious nesting was expressed; immatures developed normally on provisions composed mostly of almond pollen and nectar resources; prewintering temperatures affected winter survival of parent bees; and populations that had the highest rates of winter mortality produced the fewest number of cells per emerged female.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.664

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Pinuspollen was found in pollen loads of 12 of 13 species ofOsmiabees and in the cell provisions of 6 of 7 species.Pinuspollen averaged 5.8% by volume in pollen loads of Pinus-carrying individuals and 3.0% in the cells of nests withPinuspollen. There was no difference in larval survival between cells with and withoutPinuspollen.Pinuspollen collection was fortuitous; bees became contaminated with pine pollen that was on their normal pollen and nectar hosts.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.668

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The fall armyworm,Spodoptera frugiperda(J. E. Smith), a polyphagous pest of grasses and legumes, showed higher rates of cannibalism when feeding on red kidney bean seedlings than on corn seedlings. These differences are related to behavioral preferences. In choice tests, the larvae showed a strong preference for corn. To see if these differences in cannibalism rates could be attributed to host chemistry alone, these tests were repeated using detached corn and bean leaf disks. No differences in cannibalism rates were observed under these conditions, although cannibalism on corn was higher than in earlier experiments. In no-choice tests, the efficiency of conversion of ingested food (ECI) was higher on corn seedling foliage than on bean seedling foliage. The ECI of cannibalizing larvae that were limited to other larvae as a food source was equivalent to that on corn. Larvae were able to offset these differences in food quality to some degree by increasing relative consumption rates on beans. The relative growth rate was highest on corn, second highest on other larvae, and lowest on beans. These data provide the first nutritional indices for a normally herbivorous species on a carnivorous diet, and so are useful for ecological studies of between-species comparisons relating growth to food-source differences.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.672

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Greenbug,Schizaphis graminum(Rondani), biotypes were studied by comparing biological data to total esterase activity levels measured by fluorescent microscopy. Also, total esterase activity was evaluated in relation to host plants and insecticide resistance. The intensity of fluorescence was measured from tarsi of large embryos after staining with fluorescein diacetate. Biotypes on susceptible ‘Wheatland’ sorghum produced significantly more and larger progeny than those on resistant KS 30 or PI 264453. Furthermore, there was a carryover effect of the previous host plant on progeny production. Greenbugs reared on resistant plants had a higher level of fluorescence compared with those on susceptible plants. Increased fluorescence was also found in separate insecticide-resistant colonies of greenbugs. However, no significant differences in esterase activity as measured by fluorescence were found among biotypes reared on the same cultivar.

ISSN:1754-5692    

DOI:10.1093/ee/16.3.676

出版商:Oxford University Press    

年代:1987

数据来源: OUP