摘要:

Despite the apparent commonness of parasitoid aggregation in areas of high host density, positive spatial correlations between host density and the intensity of parasitism appear to be uncommon in nature. Negative correlations, and lack of any correlation, have been reported more frequently. Much remains to be learned of these important spatial relationships. They presently lack an unequivocal theoretical explanation, and empirical investigations designed to clarify relationships between searching behavior and spatial variations in the intensity of parasitism have not yet been carried out.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.149

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Contamination of seedlings with a formulation containing an entomopathogenic virus at the time of transplanting was found to be a technically feasible method of introducing an insect virus into an agroecosystem. Cabbage so treated with the highly infectious, single-embedded nucleopolyhedrosis virus of the cabbage looper,Trichoplusia ni(Hübner), maintained a high concentration of the virus thoughout the season. In bioassays, larval mortality on treated plants averaged 97.2% during the 1st-week posttreatment and 95.0% throughout the 84 days of sampling. Larval mortality on untreated plants averaged 4.5% during the 1st-week posttreatment and increased to 89% by 84-day posttreatment due to spread of virus from treated plots.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.153

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Obscure root weevil(Sciopithes obscurusHorn) feeding stimulants can be obtained from leaf tissue of theRhododendroncv. Cynthia(R. catawbienseMichaux ×R. griffithianumWight). Exhaustive ethanolic extraction, followed by solvent partitioning against hexanes and thin-layer chromatography of the ethanolic and hexanes fractions, yields three components with phagostimulatory activity in a membrane filter insect feeding bioassay. Sucrose, one of the obscure root weevil feeding stimulants present in the leaves of ‘Cynthia’, is more potent in the insect feeding bioassay than several other simple carbohydrates.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.155

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

The results from 2 orchard experiments are combined to derive a method for determining minimum sample sizes for surveying the European red mite,Panonychus ulmi(Koch), in apple orchards. Both the required number of trees and number of leaves per tree are considered. Also given is a method for estimating mite density from an estimate of the percent mite-infested leaves.The negative binomial distribution with common K parameter accurately described mite aggregation among the leaves of a single apple tree. This enabled the functional form of the distribution to be estimated from the sample mean mite density. The spatial distribution of mites among trees was described by the variance of individual tree means. This statistic was highly dependent on the orchard wide average mite density.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.159

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Following simulated operational spraying of trees with one % lindane emulsion, applied to run-off, soil residues were ca. 30 ppm in the top 76 mm of the soil, with very little residue below the top 12 mm.Directly sprayed plots were treated so that residues were at a base rate (29 ppm in the top 76 mm), and 10× the base rate. Soil arthropods were extracted with Berlese funnels. Surface samples were taken before the plots were treated and 3, 9, 21, 45, 93 and 141 days posttreatment. Subsurface samples were taken 30 and 155 days post-treatment.Fourteen of 17 cryptostigmatid species showed a significant effect during at least one sampling period, most at the high dosage rate. Nine of 12 prostigmatid families showed a change in numbers. The mesostigmatid mites were generally not reduced in numbers. The Collembola families were all affected, one strikingly, three others less so.Seasonal differences in lindane effect (some delayed) were found in the Cryptostigmata and Prostigmata. The Cryptostigmata demonstrated a reduction in heterogeneity and a change in community structure of 10× the base rate.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.164

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

A comprehensive 12-mo. survey of indigenous house fly parasites was conducted in the 3 geographic regions of North Carolina. Eight parasite species,Muscidifurax raptorGirault and Sanders,Spalangia cameroniPerkins,S. endiusWalker,S. nigraLatreille,S. nigroaeneaCurtis,S. n. sp. neardrosophilae, Pachycrepoideus vindemiae(Rondani), andNasonia vitripennisWalker were found.M. raptorwas the most abundant parasite collected and the only species active throughout the year.S. cameroni,S. endiusandS. nigroaenea, active from June through Nov., were the prevalentSpalangiaspecies. A discussion of collection techniques is included.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.175

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Over 250 diseased or unwanted elm trees (Ulmus americana) were killed with the herbicides cacodylic acid (Silvisar 510®) or MSMA (Silvisar 550®), applied either to axe-frills or by pressure injection. Elms thus poisoned and baited with the pheromone “multilure,” were mass-attacked by elm bark beetles but more than 87% of the potential brood was effectively eliminated. A decline in the Dutch elm disease rate accompanied brood elimination. We suggest that this trap tree technique will make a positive contribution to Dutch elm disease control programs by enhancing existing sanitation procedures and allowing tree removal to proceed in an orderly manner, rather than on the urgent schedule now necessary to prevent new infections vectored by emerging beetles.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.181

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

The variance-mean relationship of 92 cereal leaf beetle (CLB) egg and larval samples was represented by a 2nd order log-log model. Maximum likelihood estimates of sample negative binomial k's were found to be independent of sample mean density and mean instar. Common k's were estimated to be 2.56 for eggs and 1.44 for larvae. Of four variance stabilizing transforms, z=log (x+c) was recommended as best.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.186

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Response of male San Jose scale,Quadraspidiotus perniciosus(Comstock), to female produced and synthetic sex pheromones was studied in Washington and California. Males responded equally well to two isomers of pheromone at rates of 33–900 μg/trap. Pheromone cap loads of 100 μg were more attractive than 300 virgin female scales on gourds. Simplified trap designs were evaluated with synthetic pheromone caps, and were comparable in male collections to the standard 473-ml carton traps normally used with virgin females. Observations of males in the field indicated a lower flight threshold temperature of ca. 17°C, and active flight at wind velocities of less than 1.8 m/sec (4.0 mph). In greenhouse tests, most males responded to pheromones at light values between 4.6 and 32.5 lux.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.190

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

The effects of companionate planting on insect pests of snap bean,Phaseolus vulgarisL., were investigated in Chesterfield Co., VA, during 1977 and 1978.Significantly fewer Mexican bean beetles,Epilachna varivestisMulsant, occurred on beans bordered by French marigold than on nonbordered controls (P<0.01). However, this effect was overshadowed by the allelopathic response of French marigold to beans (P<0.01). No such effect was observed on beans bordered by pot marigold, garden petunia, summer savory, Dalmatian pyrethrum, apple-of-Peru and garden nasturtium.The corn earworm,Heliothis zea(Boddie) occurred significantly more on beans bordered by pot marigold and summer savory (P<0.05). The apple-of-Peru was completely defoliated by the threelined potato beetle,Lema trilineata(Olivier). Companionate planting described in this study does not appear to be a useful control strategy for insect pests ofP. vulgarisin home garden plots.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.195

出版商:Oxford University Press    

年代:1980

数据来源: OUP