SPATIAL PATTERN OF THE IMMATURE STAGES OF HYLEMYA BRASSICAE ON CABBAGE

1970 ◽  
Vol 102 (10) ◽  
pp. 1216-1222 ◽  
Author(s):  
M. K. Mukerji ◽  
D. G. Harcourt

AbstractCounts of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage did not conform to the Poisson distribution, there being an excess of uninfested and highly infested plants over the expected number. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. The negative binomial parameter k tended to increase with density. Using a common k, the distribution of the various stages may be described by expansion of (q − p)−k, when values of k are as follows: egg 0.78, larva 0.71, pupa 0.84. Three different transformations are offered for stabilizing the variance of field counts.

1970 ◽  
Vol 102 (11) ◽  
pp. 1354-1359 ◽  
Author(s):  
J. C. Guppy ◽  
D. G. Harcourt

Abstract Random counts of the white grubs, Phyllophaga fusca Froelich and P. anxia LeConte, in a permanent meadow did not conform to the Poisson distribution, there being an excess of uninfested and highly infested sample units over the expected number. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. Using a common k, the distribution of the various stages may be described by expansion of (q-p)−k, when values of k are as follows: egg 0.15, first instar 0.41, second instar 1.30, third instar 2.00, pupa 1.62, teneral adult 1.30. Aggregation resulted from the clumping of eggs at oviposition, and randomness increased with dispersal of the larvae. For all stages, the variance was proportional to a fractional power of the mean. Three transformations are offered for stabilizing the variance of field counts.


1972 ◽  
Vol 104 (12) ◽  
pp. 1995-1999 ◽  
Author(s):  
C. D. F. Miller ◽  
M. K. Mukerji ◽  
J. C. Guppy

AbstractThe Poisson and the negative binomial series, Taylor’s power law, and Morisita’s Iδ-index were used to interpret the dispersion of field counts of the immature stages of Hypera postica (Gyll.) on alfalfa. The data conformed consistently to an overdispersed distribution. Transformations are offered for stabilizing the variance of field counts.


1967 ◽  
Vol 47 (5) ◽  
pp. 461-467 ◽  
Author(s):  
D. G. Harcourt

Counts of eggs of Hylemya brassicae (Bouché) in cabbage did not conform to the Poisson distribution owing to a preponderance of uninfested and highly infested plants. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. The spatial pattern may be described by expansion of (q—px)−k with a common k of 0.95.Three methods of transformation stabilized the variance of field counts. A sequential sampling plan based on the negative binomial distribution and providing for two infestation classes was drawn up for use in control of the insect in the stem brassicas.


1953 ◽  
Vol 85 (1) ◽  
pp. 1-8 ◽  
Author(s):  
E. H. Colhoun

During investigations on the natural enemies of root maggots attacking Cruciferae, the beetle Baryodma ontarionis Casey was reared from puparia of the cabbage maggot, Hylemya brassicae (Bouché). This was not unexpected, for Gibson and Treherne (1916) had reported a similar occurrence; the staphylinid beetles reared at that time were identified by Casey (1916), who decided that they belonged to the verna group of Baryodma and assigned the name Baryodma ontarionis. Casey (loc. cit.) considered the species rather common and stated that it did not seem to resemble any European species; but Mr. W. J. Brown (in litt.), Systematic Entomology, Division of Entomology, Ottawa, who identified the beetles collected in 1950, is of the opinion that B. ontarionis is synonymous with Aleochara bilineata Gyll., tvhich attaclrs the cabbage maggot in Europe. Wadsworth (1915) dealt with the biology of A. bilineata, giving detailed descriptions of the immature stages. A study of the biology of B. ontarionis was carried out at the Belleville laboratory as part of n program of parasite introduction with the purpose in view of using the information to evaluate the beetle as a factor in the control of root maggots that are severe pests of cabbage, cauliflower, turnip, and radish.


1970 ◽  
Vol 102 (12) ◽  
pp. 1513-1518 ◽  
Author(s):  
M. K. Mukerji ◽  
D. G. Harcourt

AbstractA study of sampling variation in field populations of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage in Ontario, revealed that inter-plant and block differences were rarely significant. For the immature stages, the most appropriate sample unit was the plant root together with a 4- to 6-in. diameter core of soil. The number of samples required was inversely proportional to population density; this relationship was graphed for three levels of sampling precision.The insect is bivoltine in eastern Ontario but has three generations in the southwestern part of the province.


1963 ◽  
Vol 95 (8) ◽  
pp. 813-820 ◽  
Author(s):  
D. G. Harcourt

AbstractCounts of the Colorado potato beetle on potato did not conform to the Poisson distribution, there being an excess of uninfested and highly infested hills over the expected numbers. However, when observed distributions were fitted to the negative binomial series, the discrepancies were not significant when tested by chi-square. The negative binomial parameterktended to increase with density. Using a commonk, the distribution of the various stages may be described by expansion of (q−px)−k, when values ofkare as follows: adult, 1.95; egg mass, 4.10; first instar, 0.68; second instar, 0.78; third instar, 1.04; fourth instar, 1.07.For all stages, the variance was proportional to a fractional power of the mean. Use of the individual potato stalk as a sample unit had little effect on the skewness of the distribution. Four transformations are offered for stabilizing the variance of field counts.


1967 ◽  
Vol 99 (8) ◽  
pp. 890-893 ◽  
Author(s):  
D. G. R. McLeod ◽  
G. R. Driscoll

AbstractThe cabbage maggot, Hylemya brassicae, has a facultative diapause induced by the appropriate conditions of light and temperature: 16 hours of light per 24 hours at 20 °C produce nondiapause pupae while 12 hours of light per 24 hours at 20 °C produce diapause pupae. Diapause can be terminated if the pupae are exposed to temperatures from 0 to 5 °C for 4–5 months. Discrepancies in the literature with regard to the foregoing facts are explained.


Author(s):  
Ian Hamilton ◽  
Scott Himes ◽  
R. J. Porter ◽  
Eric Donnell

Design consistency in the context of highway and street design refers to the conformance of highway geometry to driver expectancy. Existing design policies provide guidance related to horizontal alignment design consistency. While design consistency has safety implications and is intuitively linked to roadway departure crashes, the authors are only aware of a few studies that sought to link measures of design consistency to safety performance. This study explores relationships between alternative measures of horizontal alignment design consistency and the expected number of roadway departure crashes along horizontal curves on rural, two-lane, two-way roads. The authors analyzed 854 horizontal curves on rural two-lane highways in Indiana and Pennsylvania using data obtained from the SHRP 2 Roadway Information Database (RID) 2.0. Relationships between measures of design consistency and the expected number of roadway departure crashes were explored using a negative binomial regression modeling approach. The results indicate a relationship between the frequency of roadway departure crashes on a study curve and the radii of upstream and downstream curves. The ratio of the length of upstream and downstream tangents relative to a study curve radius was also statistically significant in Pennsylvania. Such findings are intuitive given the concept of design consistency and represent an advancement to existing predictive methods in the AASHTO Highway Safety Manual, which estimate the expected number of crashes on a segment as a function of the characteristics of only that segment.


Sign in / Sign up

Export Citation Format

Share Document