摘要:

Pollen foraging as determined from nest provision analysis of sevenOsmiaspecies from one area for 2 yr indicated two specialist and five generalist species.Osmia coloradensisCresson andO. californicaCresson were Asteraceae specialists.Osmiageneralists showed significant pollen preferences.Osmia bakeriCresson,O. indeprensaSandhouse,O. kincaidiiCresson, andO. lignariaSay preferred Hydrophillaceae (Phacelia) pollen.Osmia pikeiCresson preferred Saxifragaceae (Ribes) and Ericaceae (Arctostaphylos) pollen. For aging parameters of flowering species collected, dominant pollen, number of cells with 100% one pollen, and niche breadths were not significantly different between specialists and generalists. The wide use of Asteraceae genera by the specialists and the preferences shown by the generalists reduced the foraging differences between the groups.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.133

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The spatial dispersion and sampling methodology of the southern green stink bug (SGSB),Nezara viridula(L.), were studied on fresh market tomatoes,Lycopersicum esculentumMill. A visual count was used to sample SGSB populations from horizontal plant strata. More SGSB individuals were sampled from fruit clusters than from vegetative structures and samples from fruit clusters had the lowest coefficients of variation (CV) and the highest mean SGSB counts. Values of mean SGSB, CV, relative variation, and relative net precision indicated that the penultimate fruit cluster was the most efficient sampling unit among plant strata. Time consumed in counting SGSB on each stratum ranged from 3 to 10 s and showed little variation in mean or CV values. Regression equations estimating wholeplant populations of SGSB from individual fruit clusters were developed. The between-plant dispersion of SGSB fitted a negative binomial distribution with a moderate aggregation. A sequential sampling plan using the penultimate fruit cluster as a sample unit was developed to classify SGSB populations into light, moderate, and severe damage levels.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.139

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The Pherocon lC trap baited with a rubber septum impregnated with 2.5 mg pheromone captured the greatest number ofPlatynota flavedanaClemens moths. Traps hung at 2.1 and 3.0 m captured the greatest number ofP. flavedana. Trap heights of 1.2, 2.1, and 3.0 m caught the greatest number ofP. idaeusalis(Walker) moths. The outsidethe-canopy trap position captured moreP. flavedanamoths, whereas the within-canopy trap location caught the greatest number ofP. idaeusalismoths. Traps placed in the west portion of the tree captured the greatest number ofP. flavedanamoths.P. idaeusalismoth catches were not influenced by compass quadrants.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.145

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The within-field and within-panicle distributions ofHeliothts zea(Boddie) andCelama sorghiella(Riley) eggs were studied in Arkansas grain sorghum during 1985 and 1986. The distribution of eggs parasitized byTrichogrammaspp. was also evaluated. None of the three insect species showed a consistent preference for any portion of a grain sorghum panicle based on either location (upper, middle, or lower third) or flowering stage (⅓, ⅔, or full bloom).H. zeaexhibited a clumped within-field spatial pattern for total and parasitized eggs as based on Taylor's indices of aggregation (a= 1.24,b= 1.31, anda= 1.85,b= 1.18, respectively). Total and parasitizedC. sorghiellaeggs were decidedly more aggregated than those ofH. zeawith Taylor's indices ofa= 2.56,b= 1.46, anda= 3.28,b= 1.34, respectively. Required sample sizes needed to estimate population densities of both species are provided.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.150

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

By integrating the dynamics of cotton fruit production with insect pests and their natural enemies, the TEXCIM model predicted the timing and magnitude of pest and injured fruit pulses 7–14 d into the future. Biofixes from field counts of fruit, pests, and natural enemies provided a self-correcting feature for improving these predictions. Based on current economic thresholds, serious Type I and Type II errors occurred only 1.7% of the time forHeliothisspecies and 5.2% of the time for cotton fleahoppers. Thus, TEXCIM has considerable potential for developing dynamic decision rules for guilds of pests that feed on cotton and as a decision aid in pest management.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.157

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Hydrellia pakistanaeDeonier, a leaf-mining ephydrid fly, has been reported only from hydrilla,Hydrilla verticillata(L.f.) Royle, in the Punjab region of Pakistan and Karnataka State in southern India. Host range studies were conducted in a quarantine laboratory in Florida with a fly colony from India. Females tested on 29 plant species in choice tests oviposited on all, but preferred hydrilla. Fifty-one plant species were included in larval no-choice tests, resulting in small numbers of adults being produced on six species. Curly leaf pondweed,Potamogeton crispusL., an associate of hydrilla in Asia and an introduced weed in the United States, produced the most adults. No more than 4% of the larvae developed to adults on two native pondweeds, and none developed on four others. Only 4% of the larvae developed to adults onP. crispuswhen hydrilla was present in choice tests. A dramatically declining fly population was maintained onP. crispusuntil the seventh generation, when it died out. These studies indicated thatH. pakistanaewas safe to release in the United States for biological control of hydrilla.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.164

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Chrysoperla carnea(Stephens) larvae fedNosema pyrausta(Paillot)-infectedOstrinia nubilalis(Hübner) eggs developed normally and produced adults with unimpaired fecundity, fertility, and longevity. The microsporidium evidently failed to cause any infection inC. carnea. The ingested spores remained in the midgut throughout the larval feeding period and were eliminated in meconium during imaginal eclosion. These spores, which had been withinC. carneafor at least 7 d, remained infective in bioassays againstO. nubilalislarvae. In nature, this general insect predator may suppressO. nubilalisnot only by predation but also by dispersing microsporidian spores. Furthermore,C. carneaandN. pyraustaare compatible entities to be utilized in a pest management program.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.172

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Natural sunlight is the most significant environmental factor affecting the stability of microbial insecticides formulated from occluded entomopathogenic viruses. Theoretically the crystalline protein matrix that occludes and surrounds each virion containing DNA should provide some protection against inactivation by sunlight-UV. No significant differences, however, were obtained in either the extent or rate of inactivation when nonoccluded, polyhedra derived virions (PDV) and tissue culture derived virions (TCNOV), or virions occluded in polyhedral inclusion bodies (PIBOV) of the Singly-enveloped nuclear polyhedrosis virus ofHeliothis species(HzSNPV) were exposed to a simulated sunlight-UV source (SUV). The residual half-life of PDV, TCNOV, and PIBOV, as measured by bioassay against susceptible larvae ofHeliothis virescens, was 6.3, 6.3, and 5.8 h, respectively. There was smearing of the EcoRI restriction enzyme (REN) patterns and an increase in lower molecular-weight species after exposure to SUV of both naked viral DNA and DNA of virions occluded in polyhedral inclusion bodies (PIB). Production of higher molecular-weight species of DNA, however, only was detected in DNA from PIBOV exposed to SUV. Changes in REN patterns of viral DNA were never detected with shielded-exposed HzSNPV.

ISSN:1754-5692    

DOI:10.1093/ee/18.1.177

出版商:Oxford University Press    

年代:1989

数据来源: OUP

ISSN:1754-5692    

DOI:10.1093/ee/18.1.184

出版商:Oxford University Press    

年代:1989

数据来源: OUP