Dispersal of the cabbage root fly

Finch, S.; Skinner, G.

doi:10.1111/j.1744-7348.1975.tb00490.x

Cited by 40 publications

(27 citation statements)

References 26 publications

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“…There are several approaches for translating such recapture distributions into a measure of dispersal rate (e.g., Dobzhansky and Wright 1943, Finch and Skinner 1975, Taylor 1980), but there is no consensus as to which method is superior (Kareiva 1981). 2-4.…”

Section: Methods and Experimental Designmentioning

confidence: 99%

Experimental and Mathematical Analyses of Herbivore Movement: Quantifying the Influence of Plant Spacing and Quality on Foraging Discrimination

Kareiva¹

1982

Ecological Monographs

254

168

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Using mark-recapture experiments, I studied the foraging movements of two cruciferfeeding flea beetles, Phyllotreta cruciferae and P. striolata. To determine the influence of distance between host patches, and their quality, on beetle movement, I released marked beetles in experimental arrays of collards (Brassica oleracea). I quantified and interpreted movement behavior by applying a passive diffusion model and a continuous-time Markov model to recapture distributions. These models provided both a standard protocol for interspecific comparisons and a formal tool for translating movements into steady-state foraging patterns.In homogeneous arrays (all collard patches of similar quality), P. cruciferae and P. striolata moved in accordance with a constant-coefficient diffusion model. The dispersal rates of both beetles increased as the distance between patches declined; thus, patches of collards acted as stepping-stones to accelerate beetle dispersal. Beetle movement was hampered by old-field vegetation; beetles moved along cultivated ground in lieu of entering dense stands of goldenrod. Under all experimental conditions, P. cruciferae was consistently more mobile than P. striolata.By differentially fertilizing and pruning collards, I created "lush" and "stunted" patches of collards, which were arranged alternately along linear arrays. To determine the influence of patch dispersion on foraging selectivity, I varied the distance between these patches of unequal quality. The degree of foraging discrimination exhibited by the beetles was greatest where patches were closest together, and declined as distance between patches increased. At comparable spacings, P. cruciferae consistently exhibited a higher degree of foraging discrimination than did P. striolata. I developed a Markov model of patch-to-patch dispersal in which each flea beetle's probability of movement depends on patch quality and distance to neighboring patches. Using 60-min observations of marked flea beetles to estimate model parameters, I found that the steady states of foraging discrimination predicted by the model matched the discrimination levels exhibited by undisturbed flea beetles in comparable control arrays of collard patches. Thus, simple movement rules were extrapolated into expected foraging behavior; the dependence of that foraging behavior on patch dispersion was shown to be mediated by varying levels of mobility. In particular, proximity between heterogeneous patches affords beetles greater opportunity for nonrandom foraging than when patches are widely scattered. Since movement is the mechanism by which beetles respond to heterogeneous environments, rates and patterns of movement determine each species' ability to concentrate its numbers on the best foodplants. P. cruciferae is more mobile than P. striolata and in turn can better adjust to variation in collard quality. The interplay between beetle movement and plant dispersion may have consequences well beyond the simple distribution of feeding activity among heterogeneous host patches.

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Section: Methods and Experimental Designmentioning

confidence: 99%

Experimental and Mathematical Analyses of Herbivore Movement: Quantifying the Influence of Plant Spacing and Quality on Foraging Discrimination

Kareiva¹

1982

Ecological Monographs

254

168

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“…However, yield losses in oilseed rape due to D. radicum have recently occurred in regions of France, possibly because of an increase in the area seeded to the crop (Brunel et al 1993). Moreover, even though most canola growers rotate crops from canola to other grains from year to year, the strong flight capability of root maggot adults (Finch and Skinner 1975) ensures that maggots emerging from eggs in one field can readily disperse to nearby fields as adults in the following year.…”

Section: Discussionmentioning

confidence: 99%

Root maggots (Delia spp., Diptera: Anthomyiidae) in prairie canola (Brassica napus L. and B. rapa L.): Spatial and temporal surveys of root damage and prediction of damage levels

Soroka¹,

Dosdall²,

Olfert³

et al. 2004

Can. J. Plant Sci.

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Soroka, J. J., Dosdall, L. M., Olfert, O. O. and Seidle, E. 2004. Root maggots (Delia spp., Diptera: Anthomyiidae) in prairie canola (Brassica napus L. and B. rapa L.): Spatial and temporal surveys of root damage and prediction of damage levels. Can. J. Plant Sci. 84: 1171-1182. The levels of infestation and damage to canola taproots caused by crucifer-feeding root maggots (Delia spp.)(Diptera: Anthomyiidae) were determined through surveys of commercial crops across the canola growing regions of western Canada. Canola root damage caused by Delia spp. maggots was measured at the end of the season by determining the percentage of plants infested (PPI) per field and estimating average damage levels (DL, on a scale of 0 to 5) to taproots. Over the course of the survey, 2890 canola fields were sampled. Infestation by root maggots occurred wherever canola is grown in western Canada. In the study, 96% of the fields surveyed in Manitoba and Saskatchewan and 99.8% of the fields in Alberta showed evidence of root maggot feeding, with PPI much higher than in provincial surveys of a decade previously. Geographical ecoregion significantly affected both PPI and DL. The greatest amount of damage over the largest area was found in western and northwestern Alberta, although localized areas with severely damaged roots occurred along the northern edge of the entire Parkland ecoregion. Over the entire survey area, Brassica rapa L. roots had greater PPI and DL than B. napus L. roots, although species differences were not significant in Saskatchewan or Manitoba. Data from the survey were correlated with weather variables to develop a model predicting the levels of damage inflicted by root maggots to canola roots. Of the weather variables investigated, temperature, especially the average temperature in the preceding July and August, had the greatest influence on PPI and DL. The warmer the temperatures of the preceding July and August, the lower the PPI and DL in the current year. Likewise, previous year's July and August precipitation influenced PPI and DL negatively. Other weather parameters had little consistent influence on PPI and DI. The predictive model for PPI and DL, developed from the 1995-1998 survey data, incorporated canola species, ecoregion, previous July-August and September-October temperatures and precipitation. The validity of the model was assessed using a set of survey data collected in Alberta from 1981 to 1983. Regression equations of predicted results on actual results were significant. However, r 2 values for the regressions were low, in part because of the few ecoregions surveyed and the lack of canola species data recorded in the earlier survey, and because of the large increase in infestation levels since the earlier data were collected. The study is a first step in forecasting the effects of root maggots across a wide geographic area featuring many different canola production practices. For personal use only.

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“…Wild females flew on average 1.5 m upwind in responding to host plant odour although the percentage of females responding, take off rate and other features of behaviour were indistinguishable from cultured flies. Finch & Skinner (1975) found that wild females dispersed at rates three times those of cultured females in the field.…”

Section: The B Ehavioural Mechanismsmentioning

confidence: 99%

MECHANISMS OF HOST PLANT FINDING IN ADULT CABBAGE ROOT FLY, DELIA BRASSICAE

Hawkes

Patton

Coaker

1978

Entomologia Exp Applicata

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The behavioural mechanisms by which Delia brassicae (Hoffm.) locates its host plants are reviewed. In a large wind tunnel, the principal mechanism appears to be upwind orientation and flight stimulated by host plant odour. Gravid females landed frequently while in an odour plume, the mean flight length being 0.5 m for cultured flies under a variety of conditions. On leaving the odour plume while overshooting the source or moving across the air flow, the majority of females turned downwind, circled and re-entered the plume.These conclusions are seen as an hypothesis of host plant finding and adequate means of testing its validity in field situations are required. The approach developed here was to identify features which were likely to be peculiar to this type of host plant finding. A computer model was built to simulate the events downwind of an odour source and this predicted that the "average" cultured female moves upwind at the relatively slow rate of 65m/day. In two mark and recapture experiments in the field, cultured females moved upwind at estimated mean rates of 80 and 95m/day when released downwind of a brassica plot.Analysis of the behavioural mechanisms underlying the location of host plants by insects has been carried out largely under laboratory conditions. The progression of research on the cabbage root fly, Delia brassicae (Hoffm.) appears to be typical, having passed through similar stages to that on other species. Some field experiments have been carried out (de Wilde, 1947;Traynier, 1965;Hawkes, 1974Hawkes, , 1975 but when detailed observations of behaviour or an analysis of the causation of behaviour are required, the difficulties of field experimentation have forced a retreat to laboratory situations (Traynier, 1967 a, b;Coaker & Smith, 1970; Nair & McEwen, 1976;Hawkes & Coaker 1976, 1979 Hawkes, Patton & Coaker, unpubl.). The present knowledge on host plant finding in D. brassicae has then been outlined by field experiments but elaborated in the laboratory. This paper reviews the existing knowledge and suggests that the conclusions of laboratory experiments should be seen as an hypothesis and not as an endpoint. Such hypotheses need to be tested in the field to determine whether they provide a valid basis for the understanding of the ecological process of host plant finding. This paper illustrates an approach to the problem of validation of hypotheses. *) Present address: --Fasanv/igen 4, 752 52 Uppsala, Sweden.

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Dispersal of the cabbage root fly

Cited by 40 publications

References 26 publications

Experimental and Mathematical Analyses of Herbivore Movement: Quantifying the Influence of Plant Spacing and Quality on Foraging Discrimination

Experimental and Mathematical Analyses of Herbivore Movement: Quantifying the Influence of Plant Spacing and Quality on Foraging Discrimination

Root maggots (Delia spp., Diptera: Anthomyiidae) in prairie canola (Brassica napus L. and B. rapa L.): Spatial and temporal surveys of root damage and prediction of damage levels

MECHANISMS OF HOST PLANT FINDING IN ADULT CABBAGE ROOT FLY, DELIA BRASSICAE

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