摘要:

Adult femaleLiriomyza trifolii(Burgess) lived significantly longer when confined on tomato leaves than when confined on glass plates and starved. Males survived similar numbers of days on both substrates. Continuous exposure of adults to aphid honeydew on tomato leaflets resulted in increased longevity for both sexes and increased fecundity of females relative to adults exposed to tomato foliage without honeydew. When adults were exposed initially to aphid honeydew on leaflets for 24 h and transferred to leaflets without honeydew, fecundity was still increased, but longevity was not.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1001

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The influence of host plant on the susceptibility of the fall armyworm (FAW),Spodoptera frugiperda(J. E. Smith), to a nuclear polyhedrosis virus (NPV) was investigated. Median lethal concentrations (LC50's) of NPV were determined in third-instar FAW by a leaf-disk feeding bioassay. LC50's for FAW on signalgrass/corn (88 polyhedral inclusion bodies [PIB] per mm2), corn (l05 PIB per mm2), brown-top millet (111 PIB per mm2), and signalgrass (142 PIB per mm2) were significantly higher than the LC50's for FAW on soybeans (13 PIB per mm2), bermudagrass (17 PIB per mm2), ryegrass (24 PIB per mm2), and sorghum (32 PIB per mm2), based on the lack of overlap of the 95% FL.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1004

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

In this study reasons are suggested why virulent biotypes ofSchizaphis graminum(Rondani) (the greenbug) are severely injurious to winter wheat (Triticum aestivumL.) Biotype C greenbugs (GBC) were compared with biotype E greenbugs (GBE)on a winter wheat selection with ‘Amigo’-type resistance (resistant to GBC, susceptible to GBE). Superior growth and reproduction of GBE was associated with feeding damage (chlorosis and necrosis) and greatly increased concentrations of free amino acids in the wheat leaves at the infestation sites. GBC did not elicit this type of damage during the course of the experiment. When GBC fed on tissue previously damaged by GBE, it reproduced and grew as if feeding on a susceptible host. The nitrogen concentration of these aphids and their honeydew was also greater than that of GBC fed from GBC-damaged tissue. Thus, ‘Amigo’-type resistance was apparently not solely dependent upon secondary metabolites or other substances that may render the plant unpalatable or toxic. Rather, it appeared to be related to a chemical interaction between the susceptible host and the greenbug which resulted in a localized modification of the plant's metabolism similar to senescence. By inducing chlorosis, virulent greenbugs appear to enhance the nutritional quality of their hosts.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1007

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Permethrin has been recommended for use in predator exclusion studies ofAmblyseius limonicusGarman&McGregor (formerly inTyphlodromalus), an important predator of tetranychid cassava (Manihot esculentaCrantz) pests: green mite,Mononychellus progresivusDoreste, and twospotted spider mite,Tetranychus urticaeKoch. Among criteria for a chemical exclusion agent are selective toxicity and lack of side effects such as enhanced pest fecundity, stimluation of plant growth, or improvement of host plant nutritional quality. Laboratory and field tests provided no evidence for phytostimulation, change in cassava nutritional quality, or increased spider mite fecundity; however, abundance of nontarget arthropods was significantly reduced in permethrin-treated field plots. A possible repellency effect of permethrin onM. progresivuswas suggested under laboratory conditions. Implications of repellency and lowered abundance of nontarget species for field use of permethrin as a predator exclusion agent are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1012

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Effects of host density and plant species diversity on populations of Colorado potato beetle,Leptinotarsa decemlineata(Say), were studied in experimental field plots. Hosts were grown at two densities and four levels of plant diversity: potato monoculture, potato/bean biculture, potato/bean/weed triculture, and potatoes grown in fallow plots. All life stages of the beetle were affected by both host density and plant diversity. Numbers of beetles per plant were highest in low-diversity cultures of low host density; higher host density or plant diversity was accompanied by a reduction in numbers of beetles per plant. Differences in host-plant size among treatments were partially responsible for these trends. When beetle densities were expressed as numbers per unit leaf area, treatment effects were lessened or lost. Changes in beetle density among treatments were accompanied by differences in fecundity among treatments, but not by differences in survival. Fecundity, calculated as numbers of eggs deposited per adult, was lower in high-diversity than in low-diversity plots. Survival rates (egg to late instar) and predation on eggs were not affected by plant species diversity.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1019

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Although case-bearing leafmining larvae ofColeophora klimeschiellaToll were released on Russian thistles,Salsola australisR. Brown (Chenopodiaceae), at 13 locations in southern California during 1977–85, this biological control agent remained tenuously established at only one site by late 1986. Neither insectary-reared or field-collected stocks released in field cages or in the open in numbers of 100–600 per site appeared to foster colony establishment. Poor host-plant adaptation as well as predation and parasitism by indigenous natural enemies are identified as possible sources of biotic resistance to the establishment of this imported insect. The predator,Phylobacnus atriplexus(Foster) (Coleoptera: Cleridae), and the primary parasite,Macroneurasp. (Hymenoptera: Eupelmidae), found attackingC. klimeschiella, also are known from gall-midge hosts on native saltbushes (Atriplexspp., also Chenopodiaceae).

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1027

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

(Z)-5-decen-l-ol acetate was isolated from extracts of abdominal tips of femaleArgyrogramma verruca(Fabricius) and was identified by gas chromatography and mass spectrometry. In a flight-tunnel bioassay, this compound elicited upwind anemotactic flight by males to the pheromone dispenser at dosages equivalent to amounts extracted from one female abdominal tip. (Z)-5-decen-l-ol acetate was also attractive to maleA. verrucain the field, as indicated by catches in traps baited with this chemical. (Z)-7-dodecen-l-ol acetate, the major component of the female sex pheromone of numerous other Plusiinae, was not detected inA. verrucafemale abdominal-tip extracts.

ISSN:1754-5692    

DOI:10.1093/ee/16.4.1030

出版商:Oxford University Press    

年代:1987

数据来源: OUP