摘要:

Stress effects on a terrestrial arthropod community were evident in a study of collards grown in soil amended with chemically contaminated sewage sludge. Plant growth in the contaminated sludge was significantly reduced compared with growth in plots treated with relatively uncontaminated sludge from two small towns or with manure alone. Population densities of major arthropod taxa tended to be lower in plots of contaminated sludge than they were in uncontaminated sludge and manure plots. Species richness and diversity were also reduced in contaminated-sludge plots compared with those of uncontaminated sludge and manure treatments. In general, few differences were observed in plant growth and arthropod numbers between the uncontaminated-sludge treatment, or uncontaminated sludge treated with cadmium or with the insecticide dieldrin. Because cadmium and dieldrin were applied at dosages of cadmium and polychlorinated biphenyls (PCB's) found in the contaminated sludge, results suggested that these two toxins were not responsible for the effects on plants and arthropods observed in the contaminated-sludge treatment. Results of this study indicated the potential for sludge-borne contaminants to suppress growth in crop plants and reduce abundance of their associated arthropods.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.826

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Among 19 plant species tested for host specificity ofMegacerus discoidus(Say), a native North American seed feeder of hedge bindweed,Calystegia sepium(L.) Brown, only hedge bindweed and wild sweet potato,Ipomoea pandurata(L.), supported development to adulthood. Oviposition occurred only on seedpods of hedge bindweed and heavenly blue morning glory,Ipomoea tricolorCav., also in the same family. The latter did not support larval development. An infestation rate of fiveM. discoiduseggs per seedpod of hedge bindweed in field cages resulted in a high rate (ca. 70%) of seed infestation, but did not destroy all of the seeds. Seed consumption did not cause any change in developmental growth of hedge bindweed. Use ofM. discoidusis considered to be safe, but it must be combined with other stress factors to achieve effective control of the weed.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.834

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Responses of first-instar western corn rootworm to CO2and N2gas gradients were studied in a laboratory test arena. Number of larvae reaching the gas source, number of turns toward and away from the gas source, larval velocity, and number of turns per cm traveled were recorded. Larvae exhibited a positive chemotactic response to CO2but not N2or air. There was no indication that a kinesis of any type was involved because velocities and turning rates were not significantly different among treatments. Results indicate that newly hatched larve may use CO2to locate corn roots.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.839

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Suitability of elm varieties forXanthogaleruca luteola(Müller), the elm leaf beetle, was determined in a series of experiments. Suitability of elms was based on pupal weight, developmental time to the pupal stage, preoviposition period, and fecundity. Foliage fromUlmus pumilaL.,U. wilsoniana Schneid.,U. americanaL.,U. parvifoliaJacq., and ‘Urban’ elm, a vegetatively propagated elm hybrid, was used for interspecific comparisons.U. pumilawas the most suitable host.U. parvifoliawas the least suitable. Differences were also found inU. pumilaand ‘Urban’ elm grown in separate locations. ‘Urban’ elms grown under different fertilization and watering regimes showed differences in suitability for both larval and adultX. luteola.The differences were due to the interaction of leaf water content (%) and leaf protein content (mg/g of dry leaf).

ISSN:1754-5692    

DOI:10.1093/ee/15.4.843

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Role of host disturbance in initiation and growth of infestations of the southern pine bark beetle guild [Dendroctonus frontalisZimmermann,D. terebrans(Olivier),Ips calligraphus(Germar),I. grandicollis(Eichhoff), andI. avulses(Eichhoff)] was investigated. Host loblolly were disturbed at four intervals throughout the year and response of the bark beetle guild was monitored. Effects of the disturbance were evaluated by assessing tree mortality resulting from colonization by the bark beetle guild. Numerical responses of beetles to treatment and control trees were measured and the structure of the populations was defined in terms of proportions of the different species responding to the disturbance. All disturbed hosts were discovered and colonized by the bark beetle guild. Multiple-tree infestations developed from 10 of 20 treatment centers. Trees disturbed during the winter persisted as foci for beetle colonization for 133–150 days. The disturbance event did not have to coincide with seasonal development of the bark beetle guild for the hosts to be utilized for colonization. Trees in spring, summer, and fall treatments were colonized immediately after the disturbance. All species of the bark beetle guild were involved in the colonization process. However, structure of the populations (species composition and numbers) was different during the four seasonal treatments. Results of the experiment are interpreted in the context of the hypothesis that lightning, acting as a disturbance, is an integral component of the natural history of the bark beetle guild. The study provides experimental evidence to support the major tenets of the hypothesis.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.850

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Laboratory and field studies conducted during 1982–85 examined seasonal development ofLeptopilina boulardiBarbotin et al. and its fly hosts,Drosophila melanogasterMeigen andD. simulansSturtevant. in northern California. Both fly species overwintered as long-lived fecund adults, presumably in a state of quiescence; no diapause was detected. In contrast,L. boulardientered hibernal diapause as fifth instars within host puparia. In spring, reproductive activity ofD. melanogasterandD. simulansresumed 2–3 months before reappearance ofL. boulardi.Comparative developmental studies indicate thatD. melanogasterandD. simulanshave slightly lower thermal thresholds than their parasitoid (11.4 and 10.6°C, respectively, versus 12.8°C). and require significantly fewer degree-days (DD) to complete development from egg to adult (149 DD and 144 DD, respectively. versus 252 DD). These results indicate that the biological-control potential ofL. boulardiis limited in northern California by the parasitoid's imperfect synchrony with seasonal occurrence and developmental cycles of its hosts.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.859

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Sticky traps of various colors were used to monitor adult flea beetles in sweet corn fields. Twenty-two flea beetle species were collected; however, the corn flea beetle (CFB),Chaetocnema pulicariaMelsheimer, represented 94.4% of the total number of specimens captured. Saturn yellow and lightning yellow traps captured significantly more CFB adults than all other colors tested. Traps hung closest to the ground (0.6 m) captured significantly more CFB than traps at 1.2 or 1.8 m aboveground. Saturn yellow traps placed within the cornfield captured significantly more CFB than traps placed along the field edge or in the weedy border. The relationships between trap captures, degree-days, and the current field scouting method were investigated and resulted in tentative action thresholds for CFB management. Relationships between both adult monitoring methods (traps and field scouting) and flea beetle feeding injury were also determined.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.867

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Resting and host-seeking adult femalePsorophora columbiae(Dyar&Knab),Aedes atlanticusDyar&Knab,Aedes vexans(Meigen), andCulex salinariusCoquillett were collected. Wing length and parity of each individual were determined. Results showed that average wing lengths within the four species did not differ between the resting and host-seeking populations. ParousC. salinariusandA. vexanshad significantly longer wing lengths than did nulliparous females of the same species. Within each species, individuals were grouped in size classes of 1, 2, and 3 SD above and below the mean. In all four species, the percent parous in the larger size classes was higher than in the smaller size classes. Results indicate that large-bodied mosquitoes are more successful at blood-feeding than are smaller individuals.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.874

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Modified nesting units were field tested to determine effect on egg and larval mortality ofEumegachile pugnata(Say). Units covered with aluminum foil to reflect sunlight reduced within-nest temperatures. Mortality in foil-covered units was significantly lower (6.5%) than in uncovered ones (14.2%).

ISSN:1754-5692    

DOI:10.1093/ee/15.4.877

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A systematic survey ofBracon mellitorSay hosts was conducted from 1981 to 1985. Seven hosts other than the boll weevil,Anthonomus grandis grandisBoheman, were found. Host insects found before boll weevil infested cotton wereAnoncia leucoritis(Meyrick) on blazing-star,Mentzelia decapetala(Pursh) Urb. and Gilg.;Anthonomus fulvusLeConte on winecup,Callirhoe involucrata(Nutt.) Gray;Lema collarisSay on Ohio spiderwort,Tradescantia ohiensisRaf.;Homoeosoma electellum(Hulst) andH. stypticellumGrote on Texas thistle,Cirsium texanumBuckley; andMicrolarinus lareynii(Jacquelin du Val) on puncture vine,Tribulus terrestrisL.B. mellitorusedSchinia mortua(Grote) on gum weed,Grindellia squarrosa(Pursh) Dunal, plus host insects in puncture vine and blazing- star when the boll weevil was available in cotton. Cotton, gumweed, and puncture vine provide overwintering sites forB. mellitor.

ISSN:1754-5692    

DOI:10.1093/ee/15.4.880

出版商:Oxford University Press    

年代:1986

数据来源: OUP