摘要:

In four trials conducted in 1986 and 1987, inundative releases of the parasitic waspDiglyphus begini(Ashmead) reducedLiriomyza trifolii(Burgess) populations in greenhouse marigolds grown for seed to approximately zero within 8 wk of the first release, and they remained at that level for the duration of the crop. The parasitoid populations within the greenhouses were a direct result of the releases and subsequent reproduction and not because of migration. Releases ofEncarsia formosaGahan andChrysoperla carneaStephens may have been responsible for the maintenance ofTrialeurodes vaporariorumWestwood,Aphis gossypiiGlover, andMyzus persicaeSulzer at acceptable levels in three of four trials. Spot applications ofBacillus thuringiensissuccessfully controlled Lepidoptera species. Under successful biological control conditions, the upper foliage of the plants at the end of the trials sustained leafminer damage of 0–1.2 mines per leaf.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.825

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Laboratory-reared carrot weevil,Listronotus oregonensis(LeConte), adults were exposed to various temperature-photoperiod regimens (TPRs) to determine their effects on reproductive activity. The occurrence of reproductive diapause in females was regulated by interaction of photoperiod and temperature. Adults not sexually mature when placed at test regimens did not oviposit at certain TPRs, whereas reproductive diapause was induced in sexually mature females after periods of exposure to similar TPRs. Threshold photophases for oviposition were between 16 and 18 h at 16°C, between 14 and 16 h at 20°C, about 14.5 h at 24–25°C, and between 10 and 12 h at 28–30°C. Oviposition also occurred at short photophases (0 to 8 h), again modulated by temperature. Oviposition in the laboratory by field-collected adults that had overwintered was not influenced by photoperiod. Sexually mature adults mated at a TPR unfavorable to oviposition.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.836

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

This research was designed to test the hypotheses that 1) phenolic glycosides can account for differential performance of gypsy moth (Lymantria disparL.) on quaking aspen (Populus tremuloidesMichaux) and otherPopulusspecies, and 2) midgut esterases are involved in detoxication of phenolic glycosides by gypsy moth larvae. We bioassayed tremulacin, a phenolic glycoside, with and without S,S,S,-tributylphosphorotrithioate (DEF), an esterase inhibitor, against first and fourth instars. We also measured activities of β-glucosidase, esterase, and glutathione transferase enzymes from larval midguts. Tremulacin did not alter first instar survival but greatly prolonged duration of the first larval stadium. Tremulacin at the 2% level did not alter performance of fourth instars, but at the 3% level it reduced growth through effects on approximate digestibility and food conversion efficiency. DEF strongly potentiated the effects of tremulacin, suggesting that esterases are important for detoxication of phenolic glycosides by gypsy moth larvae. Enzyme assays revealed moderately high esterase activities, which were not induced by larval consumption of tremulacin. We suggest that high levels of tremulacin and related compounds in somePopulusfoliage may overload the detoxication capacity of gypsy moth larvae, leading to impaired performance.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.842

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A degree-day model forCalocoris norvegicus(Gmelin) has been developed that uses the first-observed, first-instar nymph as a biofix and predicts the time of development to each stage. This model is useful for timing control tactics in pistachios beforeCalocorisdisperses from surrounding host plants. Based on laboratory studies at five different temperatures, the lower developmental threshold was estimated at 6.39°C. Development from newly emerged nymph to the fourth instar required a mean of 142 degree-days (DO). Seasonal phenology data from a pistachio orchard in the Sacramento Valley in 1987 and 1988 indicated that the degree-day interval to peak levels of fourth-instar nymphs was 122 and 159 DD after the first instar. Before field implementation, final validation of the degree-day model will require extensive phenology data in multiple locations. Timing of insecticide applications before the dispersal ofCalocorisin the ground cover bordering the pistachio orchard significantly reduced the level of epicarp lesion damage.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.848

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The influence of ozone (O3) on induced resistance in soybean,Glycine max(L.) Merr., cv. Williams 82, was investigated. Feeding by larval soybean looper,Pseudoplusia includens(Walker), was used to induce resistance, and the feeding preference of the Mexican bean beetle,Epilachna varivestisMulsant, was used to indicate induced resistance. Greenhouse grown soybean plants at the V9 growth stage (eight open trifoliolates) were used in all experiments. One day following feeding injury by the soybean looper, the injured plants and the uninjured controls were exposed to three concentrations of ozone in transparent mylar chambers: level in ambient air (about 0.025 ppm), 0.06 ppm, or 0.1 ppm. Plants were exposed for 5 h a day for a period of 2–4 d. Ozone exposure at the levels used in this study produced no visible injuries to leaves. Low doses (up to 4-d-exposure to 0.06 ppm or 2-d exposure to 0.1 ppm) of ozone overrode the resistance in soybean that had been induced by the feeding of soybean looper larvae. Higher doses (3- or 4-d exposure to 0.1 ppm) of ozone actually resulted in a greater acceptability by the Mexican bean beetle of plants injured by the soybean looper than of uninjured plants. Doses of ozone used in these experiments did not significantly alter the feeding preference of the Mexican bean beetle for the uninjured plants. Because ozone pollution and herbivore injury are commonly experienced by plants in nature, the results of this study add another perspective to insect–plant interactions.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.854

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Temperature-dependent developmental rate curves for larvae and pupae ofCotesia melanoscela(Ratzeberg), a parasitoid of the gypsy moth,Lymantria dispar(L,), were developed using linear and nonlinear models. There were small but statistically significant differences among developmental rates of parasitoids reared in first, second, and third host instars when the hosts fed on oak foliage. Differences in developmental rate between parasitoid larvae developing in first-instar hosts feeding on foliage versus artificial diet and between male versus female parasitoid pupae were more substantial. Although ther2values for the linear model were high, the deviations from regression were significant. Two nonlinear models fit well (highr2) for all treatments of parasitoid larvae and pupae, and the deviations from regression were not significant. Cumulative Weibull functions were fit to the data from all treatments to model the distribution of developmental time. Applications of these models are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.859

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A computer-controlled system of eight environmental chambers was constructed. The system allows independent control of up to 10 photoperiods and smooth daily thermoperiods for each chamber. Within- and between-chamber temperature differences were small enough for estimation of population variance in development time and detection of small thermoperiodic effects on development time in pupae ofPseudaletia unipuncta(Haworth).

ISSN:1754-5692    

DOI:10.1093/ee/19.4.866

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The effect of temperature on the rate of development ofBiprorulus bibax(Breddin) was determined by rearing individuals under a range of constant temperatures (15–37.5°C). Rates of development changed in a linear fashion over a wide range of temperatures. Estimates of lower developmental thresholds were obtained for all stages of development and for egg–adult (14.3°C). Fastest rates of nymphal and egg development occurred at 32.5 and 35.0°C, respectively. A requirement of 455.4 DD (degree-days) was estimated for development from egg to adult. Nymphal survivorship was highest at 25, 27.5, and 30°C; 41–63% survived from the first stadium to the adult stage at these temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.874

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Critical thermal (CT) maxima (CTMAX)and critical thermal minima (CTMIN) were determined for minor caste workers of the red imported fire ant,Solenopsis invictaBuren. Ants were tested from polygynous colonies collected from northwestern Texas. Mean CTMAX is lower than that reported for the upper lethal temperature for short exposures and higher than that reported for the upper foraging limit. Mean CTMIN was, likewise, lower than the reported lower foraging limit. The CT values obtained at weekly intervals as colony maintenance temperatures were reduced from 29 to 9°C showed significant reductions in both CTMAX and CTMIN. The CT values averaged 40.7 (MAX) and 3.6°C (MIN). Differences between critical thermal values and those reported in previous studies of lethal and foraging temperatures are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.878

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Adult western corn rootworm,Diabrotica virgifera virgiferaLeConte, and northern corn rootworm,D. barberiSmith and Lawrence, were captured at white and yellow sticky traps and at traps made from plastic vials that contained a mixture of a toxicant and a feeding stimulant. Over 18 d, capture of western corn rootworm was up to 100 times greater at traps baited with estragole orp-methoxycinnamonitrile (p-MCN) than at unbaited traps; baits of eugenol produced 3- to 50-fold increases in capture of northern corn rootworm. Addition of indole to baits containing estragole orp-MCN had little effect on capture at sticky traps but reduced numbers of both species caught in vials. Daily temperature-activity indices, based on bi-hourly temperatures and on actograph data from a previously published study, explained 26% (female) and 50% (male) of day-to-day variation in capture for western corn rootworm but only about 8% for northern corn rootworm. Lesser proportions of daily variation in capture were explained by raw temperature data and by measurements of wind, humidity, and numbers of beetles on plants. When traps were baited with 5, 50, or 500 mg of the attractants, catch of northern corn rootworm on sticky traps increased with the amount of eugenol, but catch of western corn rootworm in vials declined with increases in amount of attractant. Dose of attractant had relatively little effect on capture of western corn rootworm on sticky traps or northern corn rootworm in vials. Both species were captured primarily around midday, except that large numbers of northern corn rootworm (particularly males) were also captured on warm nights.

ISSN:1754-5692    

DOI:10.1093/ee/19.4.882

出版商:Oxford University Press    

年代:1990

数据来源: OUP