摘要:

In studying the relationship between insect dispersion and population density, we need an index which allows us to separate statistical artifacts from biologically significant effects. I used a simulation model to generate patterns of egg dispersion and tested several dispersion indices as predictors of these patterns. Green's coefficient and standardized Morisita's coefficient were not influenced by population density and are good measures of dispersion. Variance/mean was only weakly correlated with density and has the advantage of being easy to compute and readily understandable. Dispersion indices related to k of the negative binomial are not appropriate for data either more or less clumped than the negative binomial and should only be used with caution.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.619

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

It is not uncommon to find that newly introduced, pest resistant crop varieties soon lose their resistance. This study examines some possible problems in present resistance screening programs which may lead to development of such temporarily resistant varieties. A procedure is suggested which may improve our ability to predict whether a variety's resistance will be more or less permanent in the field. This procedure is used to predict future resistance in a model system involving resistant ‘Marketmore 70’ cucumber and the twospotted spider mite,Tetranychus urticae.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.622

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Rationale are presented for the careful introduction of pyrethroid insecticides into decidous fruit pest control programs and more specifically apple IPM systems. Factors emphasized are the cost-benefits of current IPM programs, the stabilization of resistance development among pests and the adaptation to chemical stresses of several beneficial natural enemy species relative to currently used, organophosphorus-based insecticide programs.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.627

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

A rate of 5 mg/h/ha of (Z)-11-tetradecenyl acetate either alone or combined with other chemicals, completely disrupted the orientation ofArgyrotaenia velutinanamales to pheromone baited traps in small plots, but was not very effective withChoristoneura rosaceanamales. A mixture of (Z)-11- and (E)-11-tetradecenyl acetate and (Z)-11- and (E)-11-tetradecenyl alcohol at a rate of 5 mg/h/ha for each chemical was the most effective againstC. rosaceanamales although it was not significantly better than a mixture of just the 2 isomers. Z11-14:OH and Z11–14:formate tested individually at rates of 5 mg/h/ha poorly disrupted the orientation of males of either species.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.631

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Cold acclimation and cold tolerance were studied in laboratory-reared diapausing pink bollworms,Pectinophora gossypiella(Saunders), conditioned at 5°, 10°, and 15° C for 2, 4, and 8 wk. Larval mortality, abnormal pupation and total mortality from 2-h exposure to sub-zero temperatures increased similarly as the temperature decreased from −6° to −15° C. Exposure to −9° C and above had little effect.The effect of cold conditioning on cold tolerance was most important at the −12° C exposure. Conditioning at 5°, 10°, and 15° C reduced total mortality after exposure to −12° C, compared to unconditioned larvae. Conditioning of larvae at 10° C for 8 wk resulted in the least mortality of all treatments.Water content decreased as duration of conditioning increased, with no significant differences between conditioning temperatures. Decreased water content did not correlate well with observed changes in cold tolerance.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.633

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Non-linear and linear models were compared to determine how well they described the within-tree distribution of egg gallery constructed by the southern pine beetle attacking short leaf pine. The model which resulted in the best description, i.e., smallest root mean squared error and highest R2, was y = a + bx + cx2+ d1IBTm+ d2R + d3A, where y is the gallery length per 100 cm2, x is the height of infestation, IBTmis the innerbark thickness at mid-bole, R is the ratio of infested bole length to tree height and A is representative of infested area computed by multiplying infested bole length by diam at breast height.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.636

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Recent studies led to the hypothesis that North American populations of the gypsy moth,Lymantria dispar(L.), are regulated by processes that tend to produce a numerically bimodal population system. We postulated that this system has 4 distinct features—2 major and relatively stable modes (outbreak and innocuous) and 2 transient phases (release and decline). First, the system can apparently be contained indefinitely within a sparse density range, though the processes that result in numerical stability at innocuous levels tend to be least effective near the advancing front of the generally infested area. Second, processes must exist through which sparse populations can expand numerically to outbreak levels. These processes are found most commonly within outbreak foci. Third, there are processes that can maintain the outbreak for several years (up to a decade), on an area-wide basis, as a quasi-stable feature. Such processes tend to be most effective were a mixture of dense and sparse subpopulations is represented. Fourth, there are processes that ultimately cause outbreaks to collapse; these include disease, starvation, and reduced fecundity. Our results support this hypothesis; we conclude that this population system is now, and has been, numerically bimodal in North America.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.641

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Certain organisms such asT. politum(Hymenoptera: Sphecoidea) offer unique opportunities for the calorimetric measurement of energy budget components under natural conditions. Natural kinds, quantities, and rates of food input are easily obtained, as are total egestion and production.The positive growth phase of the wasp's life cycle is short, its entire mean consumption of spiders (1046 cal) occurring in a mean time of 4.5 days with a mean consumption rate of 233 cal/day. Despite this high consumption rate, its maximum assimilation efficiency of 76% is similar to those reported for other invertebrate predators. This is probably due to prolonged gut retention time whereby feces are retained between 4 and 8.5 days.Secretions used in the building of the cocoon required 99 cal and mean total egestion was 244 cal.Maximum gross (45%) and net (59%) efficiencies of growth ofT. politumgenerally agree with those reported for other invertebrate predators. On the whole these statistics for the latter are lower than those given for vertebrate poikilotherm predators.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.647

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Observations of predatory behavior of a carabid beetle,Calosoma sayiDejean, and the striped earwig,Labidura riparia(Pallas), were carried out in soybean fields and the functional responses of adult females of each species to noctuid prey were studied in laboratory and field experiments. EachC. sayifemale consumed ca. 1–3 noctuid pupae each day regardless of numbers available, but consumed more small pupae than large ones.C. sayipreyed upon 0.95±0.23 to 15.20±3.67Anticarsia gemmatalisHübner larvae daily when 1–20 hosts were available, respectively. Pupae on the soil surface and in the soybean canopy were attacked without bias. AdultC. sayiwere crepuscular in their locomotor activity and their larvae were active only during daylight.L. ripariaconsumed ca. 2 noctuid pupae/day and were not inhibited by the presence of the silk cocoon covering the pupae of soybean loopers (Pseudoplusia includens(Walker)). When from 5–100 soybean looper larvae were available daily,L. ripariaattacked 4.51±0.96 to 37.93±16.68, respectively.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.653

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Synthesis of DNA in lymphocytes isolated from adult human peripheral blood was detected by measuring incorporation of tritiated thymidine after cell cultures were exposed to polyhedra of a nuclear polyhedrosis virus ofAutographa californica. Similar results obtained with lymphocytes isolated from human umbilical cord blood suggests that this mitogenic activity is nonspecific. No DNA synthesis was evident when lymphocyte cultures were treated with enveloped or unenveloped nucleocapsids. Observation of lymphocytes cultured over a 3D-day period, in the presence of baculovirus, provided no evidence of permanently transformed cells.

ISSN:1754-5692    

DOI:10.1093/ee/7.5.657

出版商:Oxford University Press    

年代:1978

数据来源: OUP