摘要:

A stratified sampling plan demonstrated that pattern of distribution of insects among nine regions of a bin (center and edge or midway in four compass directions) differed between bins of wheat. Within a bin, variation between two samples taken at a site was generally the largest, followed by variation between regions and then variation within a region between two sites 30 cm apart. The five most common species were most abundant in the center of the bin and another four species were most common along the bin wall. The negative binomial best described distribution of all species and variance increased more rapidly than the mean. Probability of detection increased with density, although progressively more slowly as density increased. Increase in number of samples with insects as a function of increasing density was apparently reduced by a disproportionate increase in number of insects per sample as density increased. Sampling effort required for detection or estimation of abundance was modeled as a function of insect density, sample-to-sample variation, and acceptable accuracy or confidence levels.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.655

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Twenty-seven common bean,Phaseolus vulgansL., cultivars were screened in the field and the greenhouse for resistance to feeding by the foliar beetle,Ootheca bennigseniWeise. They ranged from susceptible to resistant. Resistance partially resulted from nonpreference. Some cultivars also appeared tolerant toO. bennigsenifoliar damage.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.662

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Evidence indicates that the introduced parasitoidCollyria coxator(Villers) is providing adequate biological control ofCephus pygmaeus(L.) in Delaware.C. pygmaeusinfestations in wheat in 1982 and 1983 averaged ca. 2% while parasitism byC. coxatoraveraged 44% (range, 0–62%) in 1982 and 52% (range, 27–82%) in 1983. Postharvest (ca. July) sampling ofC. pygmaeuslarvae along field edges probably provides the best estimates of parasitism rates byC. coxator. There appears to be a strong density-independent parasitoid–host relationship within individual fields, regardless of field size. However, between fields, on an areawide basis, some of the data suggest a density-dependent parasitoid–host relationship.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.665

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Aspects of the outdoor activity and distribution of the smokybrown cockroach,Periplaneta fuliginosa(Serville), were studied during a 14-day period in July 1984 in Houston, Tex. Daily trapping revealed an age-class distribution of 27.2% adults (260 females : 244 males) and 72.2% nymphs (630 small : 475 medium : 214 large). Trap-catch was significantly lower following rains and correlated to the time when it rained. Rain early in the day resulted in higher trap-catches than rains occurring later in the day. The mark-recapture technique was used to estimate adult population size, movement, and home range. Of 240 females and 206 males marked and released, 12.1% and 7.3%, respectively, were recaptured at least once. A mean of 338 female and 386 maleP. fuliginosawas estimated living on the 0.23-ha study site. Of recaptured adults, 34.3% of the females and 58.8% of the males moved at least 2 m. Mean circular home ranges were 107 m2for females and 280 m2for males. Traps located near harborage sites caught>70% nymphs, whereas other traps caught<43% nymphs.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.669

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Laboratory studies were conducted to determine effects of three soybean and one lima bean cultivars on the population growth potential of the Mexican bean beetle (MBB),Epilachna varivestisMulsant. The cultivars were ‘Bonus’, ‘Williams’, and ‘Cutler 71’ soybean and ‘Henderson Bush’ lima bean. Greenhouse-grown plants were subjected to both immatures and adults. Data on development time, survival, and fecundity were used to construct MBB life tables for each cultivar. The lowest rate of population growth occurred on ‘Cutler 71’, where MBB immature development time, immature mortality, and preoviposition period were highest, and egg production was lowest. The highest rate occurred on lima bean. Adult longevity was not significantly affected by soybean cultivar, but was significantly longer on lima bean. Intrinsic rates of increase for MBB on ‘Williams’, ‘Bonus’, and ‘Cutler 71’ were 0.053, 0.043, and 0.012, respectively, compared to 0.100 on ‘Henderson Bush’.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.674

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Laboratory studies were conducted to determine host-mediated effects of plant cultivars onPediobius foveolatusCrawford. ‘Henderson Bush’ lima bean and ‘Bonus’, ‘Williams’, and ‘Cutler 71’ soybean were studied. Immature survival and longevity, and adult longevity and fecundity data were used to construct life tables forP. foveolatusparasitizing Mexican bean beetle (MBB),Epilachna varivestisMulsant, larvae on each cullivar. Fewer viable mummies and parasitoid progeny per host were produced on ‘Cutler 71’, but cultivar did not significantly affect fecundity. Consequently, relative to ‘Cutler 71’, the intrinsic rates of increase ofP. foveolatuson the other cultivars were ca. 1.3-fold higher. Relative to intrinsic rates of increase of the MBB on the same cultivars, these results indicated that population growth potentials ofP. foveolatuswere less affected. Additionally, MBB mortality caused by unsuccessful parasitoid ovipositions was higher on the more resistant cultivars. Therefore, the higher the resistance exhibited by a cultivar to MBB, the greater the relative impact of the parasitoid population, assuming that cultivars do not affect parasitoid searching.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.678

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Pollen traps that remove pollen loads from returning forager bees changed foraging patterns for hives in almond and prune orchards. Hives with traps had greater numbers of pollen foragers and higher proportions of foraging bees with pollen loads-than hives without traps. This effect was greatest before ca. 3:00 p.m. Hives with traps had less increase in capped brood and in the adult population than did hives without traps at the end of a 48-day period.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.683

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Field tests with controlled infestations of eggs ofDiabrotica virgifera virgiferaLeConte showed that larvae at higher infestation rates were stressed for food. The percentage of insects reaching the adult stage was significantly reduced at infestation rates above 600 eggs per 30.5 cm of row. Adults were significantly smaller at infestation rates above 300 eggs, they were shorter-lived at rates above 600 eggs, and they were less fecund at infestation rates above 1,200 eggs per 30.5 cm of row. These results indicate that high densities of immatures have a deleterious effect on number, size, longevity, and fecundity of adult western corn rootworms.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.687

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

Chemical treatment of a nuclear polyhedrosis virus ofAutographa californica(Speyer) was carried out initially inTrichoplusia ni(Hübner),Heliothis zea(Boddie),H. virescens(F.), andSpodoptera frugiperda(J. E. Smith), and subsequent effects of treatment on virulence of the virus were assessed in each host. No significant effects were noted in any of the four insect species after treatment with 5-bromodeoxyuridine or nitrosoguanidine. Almost a 100-fold increase in virulence was observed, however, when the virus was treated inT. niwith 3-methylcholanthrene and assayed inS. frugiperda. This isolate also maintained a high degree of pathogenicity forT. ni. Significant changes were also observed in the LT50of several virus samples, but none of these changes persisted after several serial passages. These observations support use of such low-passage virus isolates, which demonstrate a significant increase in virulence, on crops affected with a particular insect pest.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.691

出版商:Oxford University Press    

年代:1985

数据来源: OUP

摘要:

By rearingNephotettix virescens(Distant) populations on resistant ‘Pankhari 203’ and ‘IR8’ for 10 generations, colonies virulent to the resistant cultivars, as indicated by plant damage ratings,N. virescenssurvival, and population growth, were selected. Testing the colonies on cultivars that have the same major gene for resistance as the cultivar upon which they were selected indicated increased virulence on some cultivars but not on others. Minor genes play an important role in determining the degree of cross virulence ofN. virescenson different cultivars.

ISSN:0046-225X    

DOI:10.1093/ee/14.6.696

出版商:Oxford University Press    

年代:1985

数据来源: OUP