摘要:

Vertical movement of commercially formulated conidia ofBeauveria bassiana(Balsamo) Vuillimen in four soil types was measured in 30.6-cm columns of soil. Tifton and Greenville series soils were more restrictive to vertical movement of the conidia than either Cecil or Townley series soils. When applied as an aqueous suspension to the soil surface,>90% of the viable colony-forming units (CFU's) were recovered in the upper 15.2 cm of columns containing Tifton or Greenville soils. Approximately 12.5% of the CFU's moved through the 30.6-cm columns of Cecil and Townley series soils and were collected in the effluent. Formulated conidia are not restricted only to the surfaces of these soils.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.178

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Laboratory experiments were conducted to quantify the influence of weed plant species common to soybean fields in north Florida on rates of predation and oviposition byGeocoris punctipes(Say). Predation rates were affected by plant species and prey abundance when weed species were presented alone and when soybeans were presented with each weed in a paired free-choice arena. Rates of predation were comparatively low on weeds such as sicklepod, crotalaria, and Florida beggarweed. Interactions between soybeans and certain weed plants appeared to alter overall predation rates in free-choice arenas, resulting in reduced rates of attack on prey on soybeans. Changes in plant leaf area were shown to have a significant influence on the searching behavior of the predator. As plant leaf area increased, the predator responded by searching a bigger area, thereby maintaining a fairly constant rate of attack. Alterations in predator searching behavior as a result of plant species and species interactions were most important at the lower range of prey densities (prey per square centimeter leaf area) examined. Oviposition rates were influenced by plant species but not by prey abundance. Soybeans appeared to be a highly suitable plant oviposition site although oviposition on plants in general was very low

ISSN:0046-225X    

DOI:10.1093/ee/16.1.182

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Four sticky-trap designs were evaluated for their effectiveness in capturing the face fly,Musca autumnalisDe Geer, from three different locations in an irrigated pasture. The trap site where most flies were collected (67%) was near resting cattle. Fly collections from open pasture and areas bordered by trees represented 20 and 13%, respectively, of the season total. Pyramid traps, when placed at each of the three locations, captured significantly more male and female flies per unit time than did a cylinder, square panel, or blood board. Catches on the cylinder and square panel were not significantly different. The blood board captured the fewest flies of either sex. The pyramid also captured significantly more female flies per unit surface area when placed near areas where cattle rested. Physiological age of trapped female flies was determined for each location and trap design. Nearly equal numbers of nulliparous and uniparous flies were captured on both pyramid and square-panel traps placed where cattle rested. At that site, uniparous flies outnumbered nulliparous flies by nearly 2:1 when captured on the cylinder design. Pyramid traps captured 80% (117 of 146) of gravid flies (nulliparous, uniparous, and biparous+) trapped during the study. The pyramid trap was also useful in assessing incidence of the nematode,Heterotylenchus autumnalisNickle, and reproductive diapausing face fly females.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.190

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

We tested two diploid (M. glandulosaDavid andM. prostrataJacquin) and one tetraploid (M. glutinosaMarshall von Bieberstein) glandular-haired perennialMedicagaspecies for resistance to oviposition by the alfalfa weevil,Hypera postica(Gyllenhal). The control plants were perennialM. sativaL. (susceptible) and annualsM. scutellata(L.) Mill. andM. disciformisDC. (resistant).M. prostrataandM. glandulosawere highly resistant to oviposition in both the free-choice and the no-choice test. Both entries ofM. glutinosawere not statistically less preferred than the controls in the free-choice test. In the no-choice test, the twoM. glutinosaentries were significantly less preferred thanM. sativa.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.195

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Galls ofRhopalomyia californicaFelt contain from 1 to>50 larvae per gall and can be viewed as discrete host patches in space and time. Analysis of>1,800 galls from three adjacent field sites in northern California revealed thatTorymus koebelei(Huber) parasitized hosts in a sufficient number of galls to permit an analysis of spatial density dependence for 10 sample dates. Average parasitization per exploited gall was consistently low (<25%), and response to spatial variation in host density was either density independent (five cases) or inversely density dependent (five cases). For all galls combined (exploited + nonexploited), average parasitization never exceeded 12%; response to spatial variation in host density was density independent in six cases and directly density dependent in four. Virtually all responses to spatial variation in host density (both data sets) qualified as “density vague.” Results indicate thatT. koebeleiis relatively inefficient in exploiting host patches and that it is not capable of consistently regulating or controlling the midge population. It is suggested that patch-exploitation patterns may be of some value in selecting parasites for use in biological control, particularly in augmentative release programs.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.198

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Within heavily defoliated areas, gypsy moth,Lymantria dispar(L.), larvae develop 1–3 wk faster than they do in lightly defoliated sites. On sunny days, we found that larvae in an outbreak population were 2–6°C warmer than those in a nearby low-density population. This temperature difference appears to result largely from density-related shifts in the microhabitat of the larvae. Data from a subsequent laboratory rearing study indicate that this temperature difference is sufficient to account for the relatively rapid larval development that occurs during outbreaks.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.202

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The effects of repeating or switching, generation by generation, all possible combinations of three larva diets for four generations on the biomass production (grams per female per day) of the corn earworm,Heliothis zea(Boddie), were investigated. The diets were whole-kernel sweet corn (C), green tomato fruits (T), and an alfalfa-meal-based artificial diet (A). Biomass production of the fourth generation was calculated by dividing the total biomass production (eggs per female × pupal weight × percentage survival) by the days required for that generation (duration of preoviposition, egg, larva, and pupa stages). Treatments were replicated 20 times throughout the study. The entire experiment was repeated once. Significant differences (P<0.05) in biomass production were found among diet regimes AAAA, CCCC, and TTTT. Many other diet regimes consisting of switched diets also exhibited significant differences. The number of times that A appeared in a diet regime was positively correlated (P<0.01) with biomass production, whereas the opposite occurred with T. No correlation between C and biomass production occurred (P<0.05). Finally, no significant differences occurred in biomass production related to the number of times the diet was switched, although the results suggested a reduced biomass production as the number of diet switches increased. The results also indicate that the positive influence of A in the diet, or the negative influence of T, would be exerted for three generations after its use in the diet regime.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.206

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Flight range, dispersal activity, and habitat preference were determined for the horse fly,Tabanus abactorPhilip, in north central Oklahoma, using a mark/recapture technique. In 1982 and 1983, engorged and nonengorgedT. abactorwere marked and released at the same release site. Horse flies were recaptured in 12 dry-ice-baited Malaise traps located 0.4 and 0.8 km from the central release site in 1982, and in 20 traps located 0.4–2.4 km from the release site in 1983. A total of 45,153T. abactorwere marked and released, with a mean recapture rate of 6.12%. Recapture rates of ca. 9 and 4% were achieved for the engorged and nonengorged flies, respectively. Engorged flies were recaptured in greatest numbers on days 3 and 4 after release, whereas nonengorged flies were recaptured primarily on days 1 and 2 after release. Dispersal of the engorged flies was the same as that of the nonengorged flies once digestion of the blood meal had occurred. Marked flies were recaptured at all distances from the release site, but over 85% of those recaptured were collected within 8 d after release.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.211

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Median lethal doses (LD50's) were determined for geographical isolates of nuclear polyhedrosis virus (NPV) in fall armyworms (FAW),Spodoptera frugiperda,from several locations in the Western Hemisphere. LD50's ranged from 1.36 to 16.05 and from 0.85 to 11.93 polyhedra per insect in 1983 and 1984, respectively. LD50's for NPV from Louisiana were significantly lower than for other isolates in 1983, and in 1984 LD50's were higher in FAW from Brazil than from other locations. Two methods of cluster analysis of the results indicated that FAW populations in Louisiana were most similar in NPV susceptibility to FAW from Texas, and that populations from around the Gulf of Mexico and Puerto Rico were more similar to one another than to FAW from Brazil. In 1984 the geographical distance between the NPV isolate and FAW colony was significantly (P<0.01) and positively correlated with the LD50, but similar analyses were not significant (P<0.05) for 1983 or the combined data.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.218

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Studies were conducted in Connecticut from 1983 to 1986 to determine the ease with which the Asian coccinellid,Harmonia axyridisPallas, can be reared in the laboratory, its ability to controlMatsucoccus resinosaeBean and Godwin onPinus resinosaAiton, and its ability to overwinter outdoors. The beetle was reared on a diet of pea aphids,Acyrthosiphon pisum(Harris), grown onVicia fabaL. at 27°C and a photoperiod of 16:8 (L:D). Mean development time from oviposition to adult eclosion was 18.6 ± 1.3 d and the average female produced 718.7 ± 93.6 offspring during her adulthood of 83.6 ± 18.7 d. Percentage of predation was high (>80%) if scale-infested pine branches were caged with different densities ofH. axyridislarvae when the conspicuous eggs, cysts, and adults ofM. resinosaewere present. Percentage of predation was significantly lower when scales were predominantly first instars concealed beneath pine bark. Cannibalism was common (>50%) amongH. axyridislarvae at all experimental densities. Most of 905 paint-marked adult beetles released uncaged onto infested pines dispersed within the first few days after release. However, before departure, some adults laid eggs on the pines and established a resident population ofH. axyridis.Less than 10% of the adult beetles (n= 762) placed in overwintering cages in the field survived from November through March, a period during which weather conditions were normal for Connecticut.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.224

出版商:Oxford University Press    

年代:1987

数据来源: OUP