摘要:

A linear deterministic simulation model was developed to examine the historical rate of movement of the boll weevil,Anthonomus grandis grandisBoheman, across the southeastern United States. This manuscript addresses the hypotheses proposed during the initial invasion of the boll weevil that cotton production and prevailing winds were the primary factors regulating movement of this pest. A modification of the historical model was used to predict defensive strategies required to maintain boll weevil-free areas resulting from the current program efforts.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.195

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A laboratory investigation examined the effects of temperature on development ofGraminella nigrifrons(Forbes) using seedling johnsongrass as the host. Daily development for each life stage was calculated. Results indicate no significant differences between developmental rates of male and femaleG. nigrifronseggs at the temperatures studied. Male nymphs, however, exhibited significantly faster developmental rates than female nymphs. Using estimated thresholds of development of eggs and female nymphs, it was determined that three generations of the leafhopper per year were likely in central Kentucky.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.209

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Iodoacetic acid, a classical sulfhydryl reagent, elicited increased and decreased soybean preference by cabbage looper,Trichoplusia ni(Hübner), depending on dose, method of application, specific leaf assayed, and time after treatment. Elicitation was achieved by treating only a minor portion of the plant surface area. LarvalT. nifeeding preference for soybean leaf tissues was inversely correlated with the combined amount of the major isoflavanoids daidzein and coumestrol. These compounds have demonstrated antifeedant and antibiotic activities inT. nilarvae.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.215

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The behavior ofAphidius nigripesAshmead was studied when searching for its host, the potato aphidMacrosiphum euphorbiae(Thomas), in the complex foraging environment of a mature potato plant. The presence of hosts and host honeydew on the foliage was manipulated experimentally to identify determinants of foraging behavior. Parasitoid residence and searching times on a plant were longest with aphids present, but honeydew alone doubled the effect on these parameters compared with clean control plants. In the presence of honeydew, percentage of available leaves searched, time spent per leaf, and leaf surface area covered increased above control values. Parasitoids searched the lower leaf surface with greater intensity than the upper surface; the latter apparently was sampled solely for the presence of honeydew residues. On honeydew-contaminated plants, searching time was allocated preferentially to the upper half of plants where honeydew contamination was abundant, compared with a more evenly distributed search of clean plants. Parasitoids tended to follow horizontal sampling paths on the foliage of clean plants but horizontal and vertical search paths on honeydew-contaminated plants. These observations are discussed with reference to patch definition for aphid parasitoids and the potential for manipulation of aphid parasitoid behavior in pest control.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.222

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Development and survival of threecornered alfalfa hopper,Spissistilus festinus(Say), nymphs were assessed at 10 constant temperatures from 12.8 to 35.0°C. Relationships between temperature and development rate of individual instars and the nymphal stage were described by either two- or four-parameter biophysical models. The occurrence of high-temperature inhibition of development was variable among instars. Development of the nymphal stage was described by a model with no inhibition and a model with high-temperature inhibition. Mortality of nymphs was 100% at 12.8, 19.7, and 35.0°C. Nymphal survival was>50% only at 26.7 and 29.4°C.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.229

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Aqueous suspensions produced by grinding leaf tissue of tansy, sage, basil, catnip, dill, and rue in water deterred feeding of adult and larval Colorado potato beetles,Leptinotarsa decemlineata(Say), when tested on eggplant leaf disks in laboratory choice tests. Tansy showed the most potent antifeedant effect. Adult beetles refused to feed on leaf disks dipped in a 10% (2 g in 20 ml) suspension of tansy tissue, even after 22 h in either a choice or no-choice situation. Beetles kept for 22 h on leaf disks treated with a 1% (0.2 g in 20 ml) tansy suspension subsequently rejected the treatment to the same extent as naive beetles. Tansy treatments caused substantial mortality to beetle larvae that fed on them from egg hatching. These effects could have been caused by starvation or physiological toxicity. Tansy and other herbs show potential for use in integrated pest management programs aimed at the Colorado potato beetle.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.234

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Chestnut blight fungus,Cryphonectria (Endothia) parasitica, causes bark and wood deformity to the lower bole of scarlet oak,Quercus coccineaL., but does not kill the tree. We tested the hypothesis thatC. parasiticainfection stresses the tree and predisposes it to attack by the twolined chestnut borer,Agrilus bilineatus(Weber). Scarlet oaks with obvious disease symptoms attracted significantly moreA. bilineatus, cerambycids, and scolytids than did apparently healthy trees. However, only 9 of 21 diseased trees were successfully colonized. Total nitrogen and tannin concentrations of the phloem did not differ significantly between diseased and control trees; however, phenolic concentrations were significantly higher in the phloem of diseased trees that were colonized by borers. Total carbohydrate concentrations of xylem and phloem in July did not differ significantly between diseased and control trees, even in those diseased trees that were colonized. However, starch concentrations of the outer sapwood were slightly lower in all diseased trees. This tree decline complex is unusual in that the apparent predisposing stress,C. parasitica, did not reduce radial growth or total carbohydrates, which are generally regarded as indicators of tree vigor.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.239

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Sap-feeding and predaceous arthropod faunas of forage bunchgrasses in reseeded rangeland vegetation were examined. Four major species of sap feeders were found; the major predators were spiders. Grass monoculture had very high densities of sap feeders compared with grass biculture, shrub-grass, tree-grass, and native areas; this was reflective of the large contribution from the miridsIrbisia brachyceraUhler andConostethus americanus(Knight). They were present during the leaf stages of crested wheatgrass when it had its lowest carbohydrate root reserves. Homoptera and predator densities were not significantly related to the pattern of vegetation. The lowest number of sap-feeder species occurred in the grass monoculture, and sap-feeder faunas in this plot were dissimilar to those of all other plots. One-season dispersal experiments did not support the hypothesis that grass density caused the differences between arthropod faunas in different vegetation, whereas big sagebrush, common in reseeded pastures, repelledI. brachyceraduring short-term dispersal. The data indicate that reseeding to monocultures may result in high densities of Miridae during the leaf stages compared with moderate densities of Homoptera during the flower and seed stages in bicultures. The implications for pest management are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.244

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Transmission ofHeliothisnuclear polyhedrosis virus (NPV) by the parasitoidMicroplitis croceipes(Cresson) toHeliothis virescens(F.) larvae was examined. Mortality from NPV occurred in larvae exposed to Heliothis NPV-contaminated female parasitoids in the laboratory and on soybean in the field. In single-plant and large-cage field tests, mortality fromHeliothisNPV in larvae exposed to virus-contaminated parasitoids was higher when the parasitoid's entire body surface had been artificially contaminated with virus than when only the parasitoid's ovipositor and surrounding area were artificially contaminated or when the parasitoid was previously allowed to oviposit inHeliothisNPV-infected larvae. The level of mortality fromHeliothisNPV in caged larvae also increased as the parasitoid density in the cage increased from 0.25 to 3.0 per meter of row.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.251

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Regression equations were constructed relating spruce budworm,Choristoneura fumiferana(Clemens), egg mass dimensions to number of eggs per egg mass on black spruce,Picea mariana(Miller) B.S.P., in northern Maine. Comparison of the results from the current study and from previously published studies suggest that the relationship between egg mass dimensions and number of eggs per egg mass is relatively constant over a broad range of conditions.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.257

出版商:Oxford University Press    

年代:1990

数据来源: OUP