摘要:

Cold hardiness in a strain of laboratory-rearedFrankliniella occidentalis(Pergande) that originally came from a commercial greenhouse was examined. Lethal times (LT) at sub zero temperatures were found for second-larval instars, first and second-pupal instars, and adults. LT50at −5°C was 56.3–62.6 h for all tested instars and did not differ significantly among ins tars, At −10°C significantly different LT50values of 32.1, 24.7, and 12.1–15.4 h were found for adults, second-larval instars, and pupal instars, respectively. Supercooling points were measured for adults and second-pupal instar and were found to be significantly different at −21.3°C and −25.1°C, respectively. Supercooling points of adults reared at +25°C did not differ significantly between rearing photoperiods of 16:8 and 8: 16 (L:D) h.F. occidentaliswas found not to survive the winter of 1988–1989 in outdoor mesh cages in Denmark. Furthermore, the tolerance to total submergence in water supplied with fertilizer was investigated in four instars ofF. occidentalis. LT50values of 45.3, 32.1–39.6, and 20.7 h were found for second larval instar, pupal instars and adults, respectively.

DOI:10.1093/ee/22.3.647

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Responses of adultDiabrotica virgifera virgiferaLeConte to a nonpheromonal attractant (4-methoxycinnamaldehyde) were monitored in commercial fields of maize,Zea maysL. Plots (16 by 16 m) were treated with 4, 16, or 64 cotton dental rolls (wicks) that each contained 2.5, 10, or 40 mg of attractant or with 252 wicks at 2.5 mg each. Counts ofD. v. virgiferaon maize plants in plots were not significantly affected by any of the treatments, but unbaited yellow sticky panels in plots with 64 wicks at 40 mg each captured significantly (four times) more females than those in untreated plots. Ratios of beetles captured on sticky traps baited with attractant to those on unbaited traps were not affected significantly by the amount of attractant per wick but declined from ≈8:1 in plots with four wicks to 2:1 in plots with 64 or 252 wicks. A similar trend was observed using traps constructed from medicine vials that were or were not baited with 1.0 mg of 4-methoxycinnamaldehyde. In another study, beetles were marked and released 20 m away from either of two rows of maize that had been treated with 4-methoxycinnamaldehyde at 75 mg/m; capture in unbaited sticky traps that surrounded each release site provided no evidence that beetles were attracted toward treated rows. The attractant also did not appear to influence orientation of beetles that were observed taking flight from tops of posts 3 or 20 m from the treated rows. Given the results of these and earlier studies, nonpheromonal attractants may be of limited value in semiochemical-based broadcast baits for management ofD. v. virgiferain maize.

DOI:10.1093/ee/22.3.654

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

We measured the degree of adaptation to a xeric environment of immatures and adults of the striped earwig,Labidura riparia(Pallas). All stages of the striped earwig were moderately tolerant to heat, with critical thermal maxima ranging from 45.2 to 46.1°C for small and large nymphs, respectively. Percentage body water content ranged from 58.9% for females to 75.6% for small nymphs. Cuticular permeabilities were similar for all stages and were within the range of those reported for xeric species, ranging from 8.5 μg water lost per cm2·h·mm Hg for medium-sized nymphs to 17.0 μg water lost per cm2·h·mm Hg for females. Percentage total body water lost increased linearly with desiccation time. Lethal body water loss varied among stages and ranged from 47.6 to 52.9% for small and medium nymphs. The mean hour of death ranged from 16.8 h for small nymphs to 70.7 h for large nymphs, indicating that small nymphs were the least tolerant of desiccating conditions.

DOI:10.1093/ee/22.3.663

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Two-year-old seedlings of white oak,Quercus albaL., and red oak,Q. rubraL., were exposed to ozone (O3) fumigations in four continuously stirred tank reactor chambers in the greenhouse for 8 h/d, 3 d/wk for 6 wk. Fumigation treatments were charcoal-filtered air (CFA) and CFA + 0.15 ppm O3, Two simulated rain treatments, pH 4.2 and pH 3.0, of ≈1.25cm were applied once each week in rain-simulation chambers. Gypsy moth,Lymantria dispar(L.), third instars were allowed to feed on leaf disks from treated seedlings for 24 h. Leaf area consumed, food assimilated, weight gain, and relative growth rate (RGR) were examined. Overall, larvae fed white oak foliage consumed more foliage and gained more weight than those fed red oak foliage. Response to the fumigation and rain treatments was different for each oak species. On white oak foliage, larvae consumed significantly less foliage treated with CFA + pH 3.0 rain, but the lowest RGR occurred with the 0.15 ppm 03+ pH 4.2 rain treatment. The most food assimilated, greatest weight gain, and highest RGR occurred with the CFA + pH 4.2 rain control. Red oak foliage consumed was equivalent for all treatments, but foliage exposed to CFA + pH 3.0 rain resulted in more food assimilated, greater weight gain, and higher RGR for that species.

DOI:10.1093/ee/22.3.669

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

This study was conducted to determine the effect of the fungusZoophthora phytonomi(Arthur) on rates of parasitism byBathyplectes anurus(Thomson) andB. curculionis(Thomson). TheseBathyplectesspecies parasitized an average of 38.6 ± 1.96 and 14.0 ± 2.21% of the alfalfa weevils,Hypera postica(Gyllenhal), dissected during 1989 and 1990, respectively. However,B. curculionisparasitized only 0.15% of the 3,200 alfalfa weevil larvae reared during this study. Peak host density coincided with peak rates of parasitism byB. anurusfor reared larvae and occurred ≈3 d before the peak rate of parasitism for dissected larvae. Peak incidence of parasitism for both reared and dissected larvae occurred ≈6 d before the peak in the epizootic ofZ. phytonomi. Z. phytonomiindirectly caused high mortality ofB. anurusafter peak rates of parasitism and peak host density during 1989.B. anurusand the fungal pathogen have coexisted for 10 yr in central Kentucky with no apparent long-term reduction ofB. anurus.

DOI:10.1093/ee/22.3.674

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Fourteen parasitoid species were recovered from strawberry leafroIler,Ancylis comptana(Froelich), larvae and pupae collected in central Iowa strawberry fields in 1987 and 1989. Parasitism by the two most abundant parasitoid species,Itoplectis conquisitor(Say) (Hymenoptera: Ichneumonidae) andPediobius facialis(Giraud) (Hymenoptera: Eulophidae), was synchronous with highA. comptanapupal densities. This is the first study in North America in whichI. conquisitorandP. facialiswere the predominant parasitoids attacking immatureA. comptana. In 1987, cumulative percentage parasitism of the firstA. comptanageneration increased to 7% on 24 June. In 1989, the cumulative percentage parasitism of the first larval generation increased to 5.5% on 23 June. Because strawberries have a relatively high tolerance forA. comptanaleaf rolling and feeding activity, naturally occurring parasitoids should be conserved.

DOI:10.1093/ee/22.3.679

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Studies on the biology and host specificity ofEustenopus villosus(Boheman) were carried out in the field and laboratory in Greece and in the laboratory in Italy from 1981 to 1990. The weevil was first released in the United States for biological control of yellow starthistle,Centaurea solstitialisL. (Asteraceae: Cardueae), during 1990. In nature, overwintering adults appeared on bolting yellow starthistle plants by mid-May and were found until mid-July, south of Thessaloniki, Greece. Oviposition started at the beginning of June and the first pupae were found in early July. The first adults of the F1generation were found about mid-July in field-collected seedheads. Adults started to emerge gradually from seedheads from mid-July to the end of August and hibernated in cracks in the soil and among debris on the soil surface.E. villosusis univoltine and had three instars under laboratory conditions. Mating and feeding behavior, fecundity, and mortality are described. Adults fed on meristematic tissue and caused severe damage to the plants, and larvae fed in developing seedheads and reduced seed production up to 100% in infested seedheads. Because there is up to 97% mortality of the immature stages, the weevil does not build up dense populations in its native area.

DOI:10.1093/ee/22.3.684

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Field surveys and field-cage studies were conducted to evaluate the parasitoidMicroplitis croceipes(Cresson) as a biological control candidate for release against corn earworm,Helicoverpa zea(Boddie), in Virginia soybeans, and to gain knowledge of its diapause behavior. Corn earworm larvae were collected in 1990 and 1991 from corn and soybean fields to monitor parasitization of nativeH. zeaand to provide host material for cage experiments. Of 609H. zeacollected from corn, only one was parasitized (byCampoletissp.) indicating that field corn is not an early-season reservoir forH. zeaparasitoids. Incidence of naturalM. croceipesparasitism ofH. zeain soybean also was very low (only 10 of 717 larvae collected were parasitized). In total, 1,960 laboratory-reared and 1,060 field-collectedH. zealarvae were released with laboratory-rearedM. croceipesadult females into field cages weekly from August to October in 1990 and 1991. An average of 65% (1,975) ofH. zealarvae (over all cage releases) were recovered. Of these, 990 (50%) were parasitized byM. croceipes. M. croceipeseffectively parasitized wildH. zeaas efficiently as laboratory-reared hosts. In total, 816 (82%)M. croceipessuccessfully spun cocoons that were recovered and maintained outdoors. Adult wasps emerged from 83% (676) of the cocoons, most within 2—3 wk. The remaining 123 (15%) cocoons entered hibernal diapause. Percentages of recovered cocoons that entered diapause increased with later cage-release dates (<20% before early September to 50% by early October).

DOI:10.1093/ee/22.3.693

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

The species complex of billbugs (Sphenophorusspp.) is more complicated and may cause more damage to turfgrass than previously documented. The influence of endophyte infection on billbug feeding damage was examined in two tall fescue (Festuca arundinaceaSchreber) field trials in New Jersey. Before insect damage, endophyte infection in tall fescue had no marked influence on overall turf quality. Billbug feeding damage reduced turf cover by as much as 25% in endophyte-free tall fescue. Two billbug species,S. venatus vestitusChittenden andS. minimusHart, accounted for 94% of the adults collected from the two trials;S. venatus vestitusaccounted for 73% of the adults. Active larvae feeding during fall and early winter demonstrated that a second generation of billbug (S. venatus vestitus) occurred in New Jersey in 1991. Two additional types of turfgrass pests, sod webworms (Lepidoptera: Pyralidae) and scarabeid grubs, were observed in these two field trials. Sod webworm population was lowest in endophyte-infected tall fescue of both trials whereas grub population was only significantly lower in endophyte-infected plots of one trial. The results from this field study indicate that a species complex of insect pests, and in particular billbug, can be a serious problem in endophyte-free tall fescue turf and that endophyte infection is important for enhancing a high level of resistance to insect damage. The demonstration of serious insect feeding damage to tall fescue further emphasizes the importance of host resistance, whether through endophyte enhancement or “true” host resistance.

DOI:10.1093/ee/22.3.699

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

The bionomics ofPhrydiuchus tauWarner associated with the rangeland weed Mediterranean sage,Salvia aethiopisL. (Lamiaceae), in Idaho was evaluated. The phenology ofP. tauwas closely synchronized with that of Mediterranean sage. Adults emerged from pupation in Mayor June and fed on the rapidly growing foliage of the plant rosettes until mid-June. Estivation occurred throughout the summer when plants were dormant, and adults emerged in the autumn to feed and reproduce. Oviposition occurred from November to April with eggs oviposited singly or in groups of two to four externally in the leaf axils, on the petioles, or on the leaf or crown surfaces. Larvae developed through three instars inside the crown or leaf axil. Pupation occurred in earthen cells between May and June. Larvae often completely destroyed the crown and associated meristematic tissues, resulting in the growth of new shoots and prolonging the longevity of the plant. Larvae were found in plants ranging in size from 1.6 to 43.1 mm crown diameter. Up to 35 larvae were recovered from a Single crown. Smaller-crowned plants were attacked less frequently than larger-crowned plants.

DOI:10.1093/ee/22.3.704

出版商:Oxford University Press    

年代:1993

数据来源: OUP