摘要:

Diapause of the horn fly,Haematobia irritans(L.), was investigated for 4 yr in central Missouri. The earliest diapause detected was 18 August. Diapause occurred during August, September, and October. Most (91%) diapausing pupae were produced from eggs laid during September. Generally, in the fall, the incidence of horn fly diapause increased as both temperature and photophase decreased.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1092

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Phidippus audaxHentz of varying ages were field-collected and observed for feeding on a range of commonly occurring insects. Insects offered to the spiders included crop pests, economically unimportant species, and insect predators. Twenty insect species previously unreported as prey ofP. audaxwere found to be consumed by spiders of various ages. In addition, late-instar and adultP. audaxwere presented with a series of paired insect prey choices and their feeding behavior was observed. The spiders were found to attack prey selectively, with some species being attacked and consumed readily, whereas others were avoided and still others were only taken occasionally. The coccinellids,Hippodamia convergensGuérin-Méneville andColeomagilla maculata(DeGeer), were generally avoided, butGeocoris punctipes(Say) was readily attacked and consumed by the spiders. Similarly, bollworm,Heliothis zea(Boddie), larvae were attacked and consumed significantly more often by the spiders than adults of the boll weevil,Anthonomus grandisBoheman.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1098

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Crepuscular movement of the leafhopper vector of X-disease,Paraphlepsius irroratus(Say), between orchard groundcover and fruit tree foliage and back was monitored by light-trapping and sweeping within a sour cherry orchard. The adult leafhoppers spent the day within orchard groundcover, and at twilight they moved into fruit tree foliage. There was no significant difference in this diurnal behavior between the two adult generations. Leafhopper density found in several within-orchard subhabitats (i.e., groundcover, sour cherry foliage, sweet cherry foliage) changed significantly over a 24-h period. The active crepuscular mass flight into the trees in the evening was contrasted to the passive movement back into the orchard groundcover the following morning.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1103

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The response of laboratory-reared and wild horn flies,Haematobia irritans(L.), to three temperature regimes was studied with an olfactometer. Response comparisons were made between average temperatures of 26 and 31°C (regime 1), 27 and 36°C (regime 2), and 31 and 36.5°C (regime 3). With 2.5 liters/min airflow and a light behind the test cage, 88–97% of older laboratory flies responded to the warmer side of the olfactometer with regimes 1 and 2, but with regime 3 only 66–68% responded to the warmer side. With the light in front, 70–76% responded to the warmer side with regime 2. Both sexes of young horn flies (6–15 h old) or newly emerged females (<6 h old) tested at 2.5 liters/min and with a light behind during regime 1 preferred (73–78%) the warmer side; 92% of newly emerged (<6 h old) male flies preferred the warmer side. With both sexes of wild flies of mixed ages 68–70% preferred the warmer side of the olfactometer. Flight activity of laboratory flies of all ages was less after heat application; wild fly activity was unchanged. Probing response to heat was greatest by newly emerged and young horn flies. Probing response of wild flies was slightly less than that of newly emerged or young flies.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1107

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Predation by the striped lynx spider,Oxyopes salticusHentz, on cotton arthropods was studied in an unsprayed field in east Texas.O. salticuswas the most abundant spider species in cotton (68% of all spiders collected by D-Vac), with population densities of<0.1 spiders per m2in June gradually increasing to 7.2 per m2in September. This diurnally and nocturnally feeding spider captured prey ranging between 0.1 and 1.1 of its own size. Most prey were small (average body length = 2.61 ± 0.16 mm [SEM]). The natural diet ofO. salticus, a generalist predator, wasdiverse, and consisted (by number) mainly ofSolenopsis invictaBuren (21.9%), leafhoppers (17.2%), dipterans (15.6%), aphids (14.1%), and spiders (14.1%). Predaceous arthropods, includingGeocorisbugs, and larvae ofChrysopaand Syrphidae, composed 42% of the spiders' diet. The proportion ofO. salticusfeeding at any one time was<5% throughout the 1985 season. Asubadult/adult spider captured about one prey daily in the middle of the growing season. Based on population density counts and the assessment of the prey capture rate we estimated that in the middle of the growing season ca. 0.12 million prey may have been killed byO. salticusper ha cotton land per wk (weekly kill ca. 4.5% of the average arthropod density).

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1114

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

It was demonstrated in laboratory transmission tests that corn stalks inhabited by European corn borer (ECB),Ostrinia nubilalis(Hübner), larvae that are infected withNosema pyrausta(Paillot), become readily contaminated, via spores in larval excrement and that contaminated feeding cavities provide a major source of infection for the healthy inhabitants of the stalk. Exposure of uninfected ECB larvae to damaged plant cavities that harbored actively feeding infected ECB larvae leads to higher frequencies of transmission than cavities that have been abandoned or are inhabited by uninfected individuals. Results also indicate that in each generation, there is a time lag following ECB oviposition before effective transmission takes place in the field, and in the second generation, ECB larvae continue to contaminate plant tissues with infectious spores until they enter diapause. This mechanism of transmission, along with larval feeding behavior and intraplant movement, contribute significantly to the horizontal spread and annual build-up ofN. pyraustawithin the ECB population.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1124

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

N-alkylmaleimides having 2 to 12 carbon atoms in the alkyl group were evaluated as blocking agents of sex pheromone perception by cabbage looper,Trichoplusia ni(Hübner), males. Compounds containing two to six carbons in the alkyl group were the most active. Complete blockage of antennal response, as measured by electroantennogram procedures, was obtained by exposure of males to a dose of 37.5μg/liter of theN-butylmaleimide for 1 hr. Blockage, presumably reaction with essential sulfhydryl groups, was irreversible, and pheromone offered no protection to maleimide-sensitive sites. Major reduction of male antennal response was necessary to disrupt the insects' ability to locate pheromone in a wind tunnel. Males' interest in mating was apparently destroyed, but females appeared to mate normally following exposure of moths to blocking doses of the chemical.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1130

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Comparisons were made of beetles collected at various times after deposition from the dung of cattle treated with fenvalerate-impregnated ear tags for horn flies,Haematobia irritans(L.), and untreated cattle. The study was conducted on cattle pastured in two different range types, sandhills prairie and a combination of mixed and sandsage prairie. The horn fly larvae present in dung from treated cattle were significantly fewer (P<0.05) than in dung from untreated cattle. However, consideration of beetles by a coefficient of community index and species evenness index indicated that lack of horn fly eggs and larvae did not create much difference in either numbers of species or of individuals within a species. There was a greater difference in beetles between the two rangeland types than between the treatments within each rangeland type.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1135

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A temperature-dependent model was developed to predict spring emergence of bagworm,Thyridopteryx ephemeraeformis(Haworth), larvae. Rearing of eggs collected weekly from October through May and then incubated at 26.1°C showed that embryonic synchrony occurred by late January, when variation in larval emergence periods reached a minimum. There was a linear relationship (r2= 0.989) between development rate and temperature between 16.7 and 26.1°C for eggs collected in late January and early February. Larvae required heat accumulations of approximately 380 degree-days (DD) for first median day emergence and 572 DD for last emergence. The average deviation between predicted and observed dates of first emergence was less than one day, but the predicted time for last emergence was greater than the observed time by 5 days or more.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1141

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Eucosma sonomanaKearfott, the western pine shoot borer, damages terminal shoots of pines by mining the pith and stunting growth of infested leaders. A study in central Oregon in a young ponderosa pine plantation showed that those trees with the largest terminal buds also produced the longest leaders. The larger buds were also favored for attack by the shoot borer. As a result, the potentially largest leaders in the plantation are most likely to be infested.

ISSN:0046-225X    

DOI:10.1093/ee/16.5.1145

出版商:Oxford University Press    

年代:1987

数据来源: OUP