摘要:

In the northeastern United States, forest stands on xeric sites, such as ridgetops and steep upper slopes, generally experience more gypsy moth,Lymantria dispar(L.), defoliation than those on mesic lowland sites. To address whether foliage quality from a site could contribute to forest stand susceptibility, we reared gypsy moth larvae on chestnut oak,Quercus prinus(L.), and northern red oak,Quercus rubra(L.), foliage collected from two xeric and two mesic forest sites. Food quality of foliage was measured as protein and phenolics (hydrolyzable and condensed tannins, total phenolics and protein binding capacity) and was related to measures of gypsy moth success. Chestnut oak foliage had greater measures of phenolics than red oak and produced heavier male and female pupae and more fecund females. Foliage from xeric sites was likely to have greater measures of phenolics, but only male pupal weights were greater for larvae reared on xeric site foliage. Larval development times (days to pupation) were shorter on chestnut oak foliage than on red oak foliage for females and shorter on foliage from mesic sites than from xeric sites for males. Female pupal weights and fecundities were negatively correlated with measures of red oak hydrolyzable tannins, but there was no relationship between chestnut oak phenolics and gypsy moth success. The greater frequency of gypsy moth outbreaks on xeric sites may be more a function of tree species composition than site induced differences in foliage quality.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.699

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Seasonal synchrony of phytophagous insects, especiallyHeterothrips azaleaeHood, and the predaceous miridsDicyphus rhododendriDolling andRhinocapsus vanduzeeiUhler, was determined on five species of native deciduous azaleas (Rhododendronspp.) during 1990–1993. Florida, Alabama, Piedmont, and Flame azaleas supported populations ofH. azaleae; Plumleaf azalea did not. Peak adult and larval activity of this species of thrips varied with sequence of flowering during April and May. WhileR. vanduzeeiwas present on all azalea species, except Plumleaf,D. rhododendriwas found to be abundant only on Florida azalea and occurred more rarely on Alabama azalea.Dicyphus rhododendrinymphs emerged in late March or early April, 2–3 wk beforeR. vanduzeeinymphs emerged from overwintering eggs, which were inserted into the woody plant tissue. AdultD. rhododendribecame scarce after mid-May.Rhinocapsus vanduzeeiadults were present until the last week of June. Although both species are known to be pollen feeders, scavengers, or both, they were observed to be active effective predators of thrips and other small insects in the field and in laboratory tests. Additional thrips species collected were Terebrantia:Frankliniella tritici(Fitch),Anaphothrips obscurus(Muller),Chaetanaphothrips orchidii(Moulton),Thrips nigropilosusUzel, and Tubulifera:Leptothrips mali(Fitch). Seasonal occurrence of additional phytophagous Hymenoptera, Lepidoptera, and Homoptera are given.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.712

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

We studied the effects of temperature on growth, consumption, assimilation, conversion efficiencies, and molt ofNematus calaisKirby (Hymenoptera: Tenthredinidae), a willow sawfly, in interior Alaska. Growth rate of fourth instars increased across the full range of naturally encountered temperatures (biomass doubling time of 6.1 d at 6°C versus 0.85 d at 30°C). Growth rate of fifth instars also increased from 6 to 24°C, but had generally lowerQ10Sthan fourth instars, and actually decreased from 24 to 30°C. Patterns in growth rate across temperatures were almost entirely a function of patterns in consumption rate; relative consumption rate increased sixfold from 6 to 24°C, whereas conversion efficiencies were constant across temperatures (approximate digestibility = 0.41 to 0.45, efficiency of converting digested matter = 0.24 to 0.31). The duration of the fourth molt decreased from 1.32 d at 6°C to 0.17 d at 24°C and then increased to 0.40 d at 30°C. Compared with more southerly distributed insects, growth rates ofN. calaistended to be less temperature sensitive and to peak at lower temperatures. Similarities betweenN. calaisandDineura virididorsata(Retzius), a sawfly from northern Europe, suggest that the Tenthredinidae may be fundamentally different in their molting physiology from the Lepidoptera and Coleoptera; the ability of tenthredinids to molt rapidly at low temperatures may contribute to their ecological success in high-latitude environments.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.719

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The effect of concentration, insect age, time of day, and length of previous exposure on the response of olive fruit fly,Bactrocera (Dacus) oleae(Gmelin), males to pheromones was studied under laboratory conditions. Concentrations of 0.05, 0.08, 0.1, 0.5, 1.0, 10, 50, 100, 200, 500, and 1,000 μg on Whatman no. 1 filter paper were tested. Male response increased with concentrations from 0.05 to 10 μg and decreased with those higher than 10 μg up to 1,000 μg. The log of concentrations and the corresponding insect responses had a positive linear relationship for the first range of concentrations and a negative linear relationship for the second range of concentrations. Response to the concentration with maximum male response (10 μg) appeared on the third day after adult emergence, increased gradually up to the sixth day, and dropped gradually thereafter. At the age of 35 d, a low response was still present in the flies. Males responded to pheromone during the last 4 h of the light period at a photoperiod of 14:10 (L:D) h. Response increased toward the end of this 4-h period. Response to the concentration of 10 μg decreased significantly after 1 min of continuous exposure to the pheromone, but increase of concentration did not increase the response of these insects.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.726

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Responses of the ragwort Ilea beetle,Longitarsus jacobaeae(Waterhouse), to cues associated with conspecific beetles were examined using two-choice tests in the laboratory and in the field. In the laboratory test, a male or female flea beetle was allowed to choose between two tansy ragwort (Senecio jacobaeaL.) leaves, one that had been previously exposed to five male or female beetles for 1 d, and the other without any previous exposure to conspecific beetles. Male beetles were found more often on leaves that had been previously exposed to female beetles than on the clean leaves without female-associated cues, but were randomly distributed when the treated leaves were previously exposed to male beetles. Female beetles were randomly distributed between the two leaves, regardless of whether one leaf was previously exposed to male beetles or female beetles. Similar tests using filter paper as substrate instead of leaves showed similar results, suggesting that male beetles responded to cues associated with female beetles rather than to plants. In a field experiment, ragwort leaves that had been previously exposed to female beetles attracted more male beetles than leaves without female-associated cues. The evidence suggests thatL. jacobaeaefemales emit a sex pheromone that is attractive to male beetles. Attraction of male beetles to leaves exposed to females may be one of the mechanisms underlying the clumped distribution of flea beetles within plants.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.732

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The light-activated toxic effect of erythrosin B on apple maggot fly was studied in the laboratory. Flies were allowed to feed in the dark on an aqueous solution of erythrosin B in 10% sucrose and were then exposed to light. Mortality, observed at the end of a 6-h exposure period, increased with dose of erythrosin B over the range 500–2,000 ppm but leveled off at higher doses. Mortality also increased with exposure time at 1,000 and 2,000 ppm. Data on survival versus exposure time were analyzed using a logarithmic model previously proposed, but apparently never used, to describe the process by which insects succumb to dye-sensitized photooxidation. With the addition of a parameter representing an exposure-time threshold, this model fit our observations on apple maggot better than the pro bit model, which is usually but we believe inappropriately, applied to data in studies of this type. Insects continued to die after they were returned to the dark following exposure to light, suggesting the existence of a residual effect of the light exposure. This calls into question the standard practice of assessing mortality immediately following the period of light exposure in studies of dye-sensitized photooxidation.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.738

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Adult response of face flies,Musca autumnalisDe Geer, to diapause-inducing stimuli was tested. Treatment of larvae and pupae with four temperature and photoperiod combinations had statistically significant effects on subsequent diapause in the adults. Larvae reared in a cool, short-day regime (15°C, 10:14 [L:D]), yielded some flies that showed arrested ovarian development and high levels of hypertrophied fat body even when placed in a warm, long-day regime (24°C, 14:10 [L:D]), which normally favors ovarian development. Diapause induction in adult face flies depended largely on environment, but our data showed that the larval and pupal environments also had significant effects on subsequent reproductive or diapause development.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.744

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Two isolates ofMetarhizium anisopliae(Metschnikoff) Sorokin were tested against the sugarcane pestInopus rubriceps(Macquart) in separate field trials. Conidia were mixed with attapulgite and applied to soil at two rates by four different procedures. When conidia were applied in the planting drill at 8.5–13 × 1014per ha, concentrations of conidia exceeded 1 × 106g−1in soil soon after application and were maintained above the background level for at least 34 mo. Residual concentrations were not significantly greater than background level when the same amount of conidia was broadcast over the whole plot. Bioassays indicated that the isolate FI 161 was more effective than FI 203. In the trial using FI 161, soil samples after drill application at 8.5 × 1014conidia per ha showed infectivity against larvae ofI. rubricepsfor up to 4 mo in bioassays. Rates of infection and mortality were significantly related to concentrations of conidia in the corresponding samples. However, numbers of larvae in the field 1 and 2 yr after planting were not affected by treatment in either trial. Larval densities were not high, andM. anisopliaemay be more effective under other circumstances.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.749

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Two-way factorial experiments were set up to compare the fecundity and longevity ofTrichogramma minutumRiley and the percentage emergence and sex ratio of their offspring when reared from the eggs ofEphestia kuehniellaZeller,Sitotroga cerealella(Olivier),Choristoneura fumiferana(Clemens),Manduca sexta(L.) orLambdina fiscellaria(Guenée) (rearing host species) and attacking the eggs ofE. kuehniella, S. cerealellaorC. fumiferana(host species attacked). Data were combined across all host species attacked when analyzing the effects of rearing host species and vice versa. There was no significant difference in any of the measured parameters for femaleT. minutumreared from eitherE. kuehniellaorS. cerealella, but greater fecundity and longevity were recorded for females attacking eggs ofE. kuehniellarelative to those attacking eggs ofS. cerealella. Females reared fromE. kuehniellahad lower fecundity than those reared fromL. fiscellaria, M. sextaorC. fumiferana. Parasitoids had significantly lower fecundity and longevity when attacking eggs ofC. fumiferanathan when attacking eggs of eitherE. kuehniellaorS. cerealella, and the percentage emergence of the offspring was significantly higher from the latter two host species. Parasitoids reared from eggs ofC. fumiferanaproduced more offspring on eggs ofE. kuehniellathan on eggs ofC. fumiferana. Results from these studies highlight the need to separate the effects of the host species from which the parasitoid is reared from the effects of the host species which the parasitoid attacks. They also illustrate the need to examine reproductive performance against the target species before a comprehensive cost-benefit analysis of a mass-rearing system is made.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.755

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Laboratory and field experiments were conducted to determine the suitability of the oriental fruit fly,Bactrocera dorsalis(Hendel), for the development ofDiachasmimorpha tryoni(Cameron). In the laboratory, parasitism of individualB. dorsalislarvae by 6–10D. tryonieggs killed and prevented the pupation of 8.0 ± 3.7% of the parasitized hosts and the emergence of 50.0 ± 7.1% of the puparia. Mortality of immatureB. dorsalisincreased significantly as the rate of superparasitism increased. A mean of 68.0 ± 6.6% ofB. dorsalisthat received 1–5D. tryonieggs per larva pupated and eclosed to morphologically normal flies. These flies contained melanized eggs of the parasitoid in their abdomens. In uneclosed hosts which received 6–10 parasitoid eggs per larva, melanized eggs along with 1–6 melanized first-instar parasitoids were recorded. Parasitism ofB. dorsalisbyD. tryonialone never results in parasitoid development beyond the first instar. However, in a heterospecific parasitism test involvingD. tryoniandDiachasmimorpha longicaudata(Ashmead), ≈1/10 of the parasitized puparia eclosed to adultD. tryoni. Average percentage ofD. tryonifemales emerging from suchneutralized B. dorsalis(parasitized byD. longicaudatabefore or after exposure toD. tryonito block host immunity) was 81 to 92%. Emergence ofD. tryonifrom field collectedB. dorsaliswas also very low (0.35% emergence; 8D. tryoniadults out of 2,279B. dorsalispuparia). We conclude that contrary to the published host-range lists, neither laboratory-reared nor wildB. dorsalisare natural hosts for the opiine parasitoidD. tryoni.

ISSN:0046-225X    

DOI:10.1093/ee/23.3.761

出版商:Oxford University Press    

年代:1994

数据来源: OUP