摘要:

Seasonal patterns of abundance of tarnished plant bug (TPB),Lygus lineolaris(Palisot de Beauvois), on uncultivated roadside hosts near large cotton fields were determined in two physiographic provinces, the Highland Rim (HR) and the Coastal Plain (CP) of Alabama. Sequence of hosts utilized was similar between years in both provinces, but time that hosts harbored populations shifted in the HR, probably in response to rainfall.Erigeron annuus(L.) Persoon andErigeron strigosusMuhlenberg ex Willdenow, in the HR and CP, respectively, held the densest populations during the time cotton was in an early square growth stage. In both provinces, diversity and density of hosts, and frequency of most hosts, declined while cotton was entering this growth stage. The predatorsGeocorisspp.,Oriusspp., and Coccinellidae shared the same hosts in early spring, but were much less dense than TPB on late spring-early summer hosts.Polymerus basalis(Reuter) shared some of the same hosts in the CP. Heavy rainfall in the spring along with an increased frequency and diversity of uncultivated weedy hosts of TPB coincided with low estimates of cotton yield loss from plant-bug feeding. Potential for area-wide management via host manipulation and potential effects on predator populations are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.379

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Interactions during colonization among the southern pine bark beetle guild membersDendroctonus frontalisZimmermann,Ips avulsus(Eichhoff), andIps calligraphus(Germar) were investigated in nine loblolly pines,Pinus taedaL. This study examined host colonization and the manner by which competition is reduced among members of a guild. Two components of colonization were used for this analysis: accumulation of attacking adults and gallery construction. Attack and gallery construction were examined in individual trees and as an average process for all trees. Vertical arrangements ofD. frontalisattack and gallery were similar among trees, but the arrangement differed for eachIpsspecies.I. avulsusshowed the most rapid accumulation of attacking adults and gallery followed byD. frontalisandI. calligraphus.D. frontalisandI. calligraphusproduced less gallery per adult at high adult densities, suggesting presence of a density-dependent compensatory feedback mechanism that regulates their egg densities.I. avulsusdid not show this relationship. The species studied are members of a guild that is partially maintained through reduction or avoidance of competition. We found that differences in attributes of attack patterns among guild members served to separate breeding areas and, therefore, reduce competition for oviposition sites among the species. The density-dependent compensatory feedback mechanism reduced competition within and among brood species.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.390

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

In the presence of ample food and water, host-deprived seedcorn fly,Delia platura(Meigen), females laid half as many eggs during their lifetimes as did flies exposed to germinating lima beans, which provide strong ovipositional stimuli for seedcorn flies. In addition, host-deprivedD. platuramatured eggs at about half the rate of undeprived flies and took twice as long to begin ovipositing. We conclude that germinating lima beans acted as a strong reproductive “primer” for seedcorn fly females. Seedcorn flies exposed to beans until 2 d after first oviposition and then offered only moist sand as ovipositional sites deposited eggs at half the rate of their undeprived counterparts for 4 d; for the remaining 6 d of the experiment, egg deposition for the host-deprived group rebounded to 22 eggs per d. Although compensations in release rates for well-primedD. platuracan occur in a few days, the cumulative effects of deprivingD. platuraof highly suitable ovipositional sites are pronounced over a lifetime, giving credence to the notion that highly unpreferred host plants might exhibit partial resistance in a no-choice situation.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.400

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A 2-yr study evaluated changes in life-history parameters, electrophoretic characteristics, reproductive behavior, and mating competitiveness that occurred whenCulex tarsaliswas colonized in constant or variable rearing environments. The ability to reproduce and to demonstrate mating competitiveness under laboratory conditions developed more rapidly in colonies held under constant conditions than in those held under variable conditions. Genetically, colonies reared under variable conditions remained more like the parental strain than those reared under constant conditions. Assortative mating occurred regardless of colonization regime.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.405

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Dispersal behavior of the histerid predator,Carcinops pumilio(Erichson), was examined from the standpoint of life-history parameters and nutritional background. No significant differences were found between dispersing and nondispersing populations with respect to sex ratios, mating condition, parity, ovarian development, or morphometric characters. Flight and phototactic behaviors of dispersing beetles were reversed following administration of a dipteran prey meal. Withholding prey from beetles that had previously fed on many prey induced a delayed flight response which began on day 4 after deprivation, peaked on days 5 and 6, and returned to initial levels by day 9.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.415

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Field and laboratory studies were conducted to quantify impact of nectariless cotton on parasitism of bollworm,Heliothis zea(Boddie), eggs by egg parasiteTrichogramma pretiosumRiley. Results from a small-plot field test of a single cohort ofT. pretiosumshowed a 3.3-fold decline in percentage ofH. zeaegg parasitism during a 2-d period on a nectariless cotton (72.3% on day 0 to 22.0% on day 2), whereas the decline was only 1.5- fold during the same period on nectaried cotton (74.7%on day 0 to 48.3% on day 2). In a large-plot field study, seasonalH. zeaegg parasitism by naturally occurringTrichogrammaspp. was ca. 16%lower on a nectariless cotton compared with a nectaried cultivar. A laboratory bioassay showed thatT. pretiosumfemales given a honey/nectar mixture lived 3-fold longer than parasites held without the mixture, regardless of presence or absence of host eggs.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.420

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Diurnal and nocturnal feeding patterns ofHeliothis zea(Boddie) on pigeonpea nectar were studied in South Carolina. Feeding rhythms of males and females over time were statistically similar; feeding was most intense before and during sunset. Feeding on pigeonpea nectar was correlated positively with sugar concentration, nectar volume, total sugar, and ambient temperature, and inversely with relative humidity and percentage of flowers without reward. Nearly 17% of sugar feeding in pigeonpeas was on sap flows from buds damaged by larval feeding. Foraging patterns are considered adaptive in relation to reward, time available for mating, and breadth of diet.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.424

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Ips calligraphus(Germar) spatial attack pattern, reproduction, and development were studied in 55-cm-long bolts of slash pine (Pinus elliottiiEngelm. var.elliottii) with thick (3–4 mm) or thin (1–2 mm) phloem. Bolts, artificially infested with two male beetles each, were placed in the field to allow colonization by wild populations. Quadrat and distance sampling methods indicated that the spatial pattern of male attacks (nuptial chambers) was uniform (ca. 9 cm apart) on bolts of both phloem classes. Males attacked predominantly (93%) through bark crevices. Attack, gallery, egg, and brood adult densities were all positively correlated with phloem thickness. Averages of 3.3 and 3.0 parent females per attacking male were found in thick and thin phloem, respectively. Gallery systems of introduced males tended to have more total gallery length and more eggs than those of wild males in both phloem classes. Brood adults from thick phloem emerged earlier and were larger than those from thin phloem. The sex ratios of brood adults reared from thick and thin phloem were similar (ca. 45% males). Results of this field study agreed with previous laboratory studies.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.428

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Eucelatoria bryaniSabrosky adults fed water and sucrose were subjected to various repeated treatments at 6, 8, 10, and 12 d in the laboratory. There was no difference in fecundity for 10-d-old flies exposed either to liveHeliothis zea(Boddie) larvae, hemolymph, or to the control, sucrose and water. Fecundity of 12-d-old flies exposed either to host larvae or host hemolymph was 4.1- to 7.5-fold greater than that of 12-d-old flies exposed only to sucrose and water. From 10 to 12 d, fecundity decreased only for flies fed sucrose and water. Host hemolymph, which was both a nutrient and an arrestant, increased fecundity. Host frass was an arrestant and did not affect fecundity. This probably is the first report to demonstrate conclusively that feeding on hosts affects fecundity of a species of Tachinidae.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.437

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Corn earworm,Heliothis zea(Boddie), larval survival and development on determinate cultivar soybeans,Glycine max(L.) Merrill, at plant growth stages from prebloom to bean maturation stage were tested. Larvae confined to plants established on all stages tested, although fewer established on plants at more mature stages. Mortality of later instars was low in all treatments. Larvae feeding on prebloom stage plants weighed more after 12 d than those feeding on bloom or podfill stage plants. However, larvae from podfill stages had higher pupal weights. Development rates of larvae were not significantly different for the cultivars of soybean and plant stages tested from field-grown plants, except for one ‘Forrest’ prebloom growth stage.

ISSN:1754-5692    

DOI:10.1093/ee/16.2.441

出版商:Oxford University Press    

年代:1987

数据来源: OUP