DESIGN OF A SAMPLING PLAN FOR STUDIES ON THE POPULATION DYNAMICS OF THE CABBAGE MAGGOT, HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE)

1970 ◽  
Vol 102 (12) ◽  
pp. 1513-1518 ◽  
Author(s):  
M. K. Mukerji ◽  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Plant Root ◽  
Immature Stages ◽  
Southwestern Part ◽  
Sample Unit ◽  
Diameter Core ◽  
Sampling Variation ◽  
Hylemya Brassicae ◽  
Cabbage Maggot

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.

A SAMPLING PLAN FOR STUDIES ON THE POPULATION DYNAMICS OF WHITE GRUBS, PHYLLOPHAGA SPP. (COLEOPTERA: SCARABAEIDAE)

1973 ◽  
Vol 105 (3) ◽  
pp. 479-483 ◽  
Author(s):  
J. C. Guppy ◽  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Sampling Plan ◽  
White Grubs ◽  
Sample Unit ◽  
Sampling Variation

AbstractA study of sampling variation in the white grubs Phyllophaga fusca Froelick and P. anxia LeConte in a permanent meadow showed that inter-plot differences occurred in 70% of the samples. Block differences were rarely significant. For all stages, the most appropriate sample unit was a 1 ft cube of soil and sod. The number of samples required was inversely proportional to population density; this relationship was graphed for three levels of sampling precision.

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
Keyword(s):  
Spatial Pattern ◽  
Poisson Distribution ◽  
Negative Binomial ◽  
Immature Stages ◽  
Expected Number ◽  
Chi Square ◽  
Binomial Series ◽  
Binomial Parameter ◽  
Hylemya Brassicae ◽  
Cabbage Maggot

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.

Notes on the Stages and the Biology of Baryodma ontarionis Casey (Coleoptera: Staphylinidae), a Parasite of the Cabbage Maggot, Hylemya brassicae Bouché (Diptera: Anthomyiidae)

1953 ◽  
Vol 85 (1) ◽  
pp. 1-8 ◽  
Author(s):  
E. H. Colhoun
Keyword(s):  
Natural Enemies ◽  
Immature Stages ◽  
Aleochara Bilineata ◽  
European Species ◽  
Hylemya Brassicae ◽  
Cabbage Maggot

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.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole Microtus Montanus

2005 ◽  
Vol 29 ◽  
pp. 49-51
Author(s):  
Alita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Climatic Factors ◽  
Small Rodents ◽  
Microtus Montanus ◽  
Small Measure ◽  
Long Term Studies

A variety of hypotheses has been proposed to explain multiannual fluctuations in population density ("cycles") of small rodents (for reviews see Finerty 1980, Taitt and Krebs 1985). Doubtless, such cycles - known since antiquity (Elton 1942) - result from an interaction of a multitude of factors. However, the inability of extant hypotheses, alone or in combination, to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

DIAPAUSE IN THE CABBAGE MAGGOT, HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE)

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

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.

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