Damage Thresholds for Cabbage Root Fly [<i>Delia radicum</i>(L.)] in Cauliflower Assessed from Pot Experiments

Bligaard, Jens

doi:10.1080/09064719950135713

Cited by 8 publications

(15 citation statements)

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“…Our results indicate that (at least when no plant mortality occurs) the impact of D. radicum on plants is linear, with no threshold: even the lowest pest densities limit plant growth and head mass. This is not exactly consistent with the findings of Bligaard (1999), which suggested threshold effects in the relationship between the biomass (a growth trait) of cauliflowers and D. radicum egg density. Our results therefore suggest that D. radicum can be harmful even when it does not kill the plants.…”

Section: Radicum Affects All Development and Growth Traits And Redcontrasting

confidence: 87%

“…Two hypotheses may explain this: 1) the maximum egg densities were not high enough to kill plants in our growing conditions or 2) the maximum egg densities should have killed the plants but the unexpected high developmental mortality of D. radicum led to an underestimation of the real harmfulness of this pest. In previous studies on cauliflower, El Titi (1979) and Bligaard (1999) reported significant plant mortality with much lower egg densities (respectively 60 and 25 eggs per plant), introduced when plants were at a similar developmental stage (~ 4 leaves). However, the link between pest density and damage is also likely to depend on plant growing conditions.…”

Section: The Absence Of Plant Mortality and D Radicum Mortalitymentioning

confidence: 92%

“…This threshold is still used by farmers and advisors in France to evaluate the intensity of pest infestation, but it is no longer relevant in terms of decision making because: i/ the chlorfenvinphos used by El Titi (1979) is now prohibited and ii/ the current protection strategy against the cabbage root fly is preventative and consists of drenching the roots of all leaf and flower Brassica vegetables with spinosad (Success™ 4) before planting. Also in cauliflower, Bligaard (1999) performed several experiments with varying times of infestation and found that plant biomass decreased when egg density rose from 0 to 25 eggs per plant, but final yield was not monitored. Only one study showed reduced production of surviving cauliflowers in response to D. radicum attack (El Titi 1977).…”

mentioning

confidence: 99%

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Assessing the relationship between pest density and plant damage: a case study with the belowground herbivore Delia radicum (Diptera: Anthomyiidae) on broccoli

et al. 2019

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For many crops, we have poor knowledge about the relationship between pest density and damage. However, investigating pest harmfulness is particularly relevant currently in the search for alternative crop protection strategies that are unlikely to totally suppress pest populations. Here, we assessed the harmfulness of Delia radicum (L.) on broccoli (Brassica oleracea var. italica Plenck). We worked inside insect-proof cages set up in the field with additional pitfall traps to remove ground dwelling predators. Plants were manually infested with 10 levels of pest density ranging from 0 to 100 individuals per plant, following a natural infestation pattern. Surprisingly, no plants died but almost 100% of the pests introduced died over the course of the experiment. However, all broccoli development and growth traits were negatively correlated with pest density and broccoli head mass at harvest decreased linearly with pest density. The observation over time of development and growth traits showed evidence of plant compensation, suggesting that the head mass of individual plants may have reached similar values if allowed to fully mature. The relationship between pest density and damage, together with forecast models of pest population dynamics could be used to develop decision support tools assessing the relevance of preventative treatments. Keywords Crop losses; plant traits; plant injury; damage; plant compensation. Introduction Throughout the history of agriculture, the development of pest management strategies has led to dramatic decreases in crop losses to pests (Oerke 2006). However, the predominant crop protection method, that is pesticide usage, has various negative consequences, notably on human health and the beneficial fauna of agro-ecosystems (Desneux et al. 2007; Geiger et al. 2010). Alternatives are therefore urgently needed, but in contrast to pesticides, most of these alternatives (push-pull, insect netting, intercropping…) are likely to have partial efficiency. For example, conservation biological control, based on the enhancement of natural enemy populations, is thought to be an interesting method for reducing crop losses (Eilenberg et al. 2001) but is incompatible with the complete suppression of pest populations because by

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Section: Radicum Affects All Development and Growth Traits And Redcontrasting

confidence: 87%

Section: The Absence Of Plant Mortality and D Radicum Mortalitymentioning

confidence: 92%

mentioning

confidence: 99%

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Assessing the relationship between pest density and plant damage: a case study with the belowground herbivore Delia radicum (Diptera: Anthomyiidae) on broccoli

et al. 2019

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“…[ 30 ] who reported 13 or more eggs per plant. Bligaard [ 31 ] noted that an artificial infestation with 100 eggs per plant resulted in a 5% reduction in plant growth. Bligaard [ 18 ] considered an average infestation of 21 eggs/infested plant, with 30% of plants infested, as an economic threshold (ET).…”

Section: Resultsmentioning

confidence: 99%

“…There are several possible causes for the absence of symptoms of wilting in 2011: egg and larval mortality, presence of natural enemies, or ability of the plants to tolerate a certain number of larvae. Bligaard [ 31 ] reported that the percentage of mortality of eggs and larvae is very high (between 47% and 61%). Eggs of D. radicum are resistant to low soil moisture and high temperature conditions, while larval survival tends to increase with an increase in soil temperature up to 33 °C and in the and moisture [ 32 ].…”

Section: Resultsmentioning

confidence: 99%

Seasonal Flight, Optimal Timing and Efficacy of Selected Insecticides for Cabbage Maggot (Delia radicum L., Diptera: Anthomyiidae) Control

Bažok

Ceranić-Sertić²,

Barčić³

et al. 2012

Insects

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In order to describe seasonal flight activity of the cabbage maggot Delia radicum (L.) adults in relation to Julian days (JD), degree-day accumulations (DDA) and precipitation, flight dynamics were followed weekly with the use of yellow sticky traps (YST). Climatic data were collected and DDA were calculated using the lower developmental threshold of 4.3 °C. The efficacy of four insecticides applied either as standard foliar treatment or through dipping the seedlings before transplanting was determined. Seasonal flight activity during the cultivation season of a mid-early variety of white cabbage was correlated with DDA and JD and was characterized by having two peaks. The first peak occurred between 119 ± 7.5 JD and 125.5 ± 8 JD when DDA was 471.35 ± 74.97 °C. The second occurred between 172.8 ± 6.1 JD and 179.3 ± 6.7 JD when DDA was 1,217.28 ± 96.12 °C. The DDA, cumulative capture of flies and JD are suitable for predicting the timing of insecticide application. Spraying with insecticides should be applied when the cumulative capture of flies reaches 100 flies/YST and when DDA reaches 400 °C. If only one parameter reaches the threshold, additional visual surveys should be employed to establish the level of infestation. Insecticides were able to ensure only partial control. In the future, alternative control tactics which employ seed treatments and nonpesticide measures should be investigated in Croatia.

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Trap cropping to control Delia radicum populations in cruciferous crops: first results and future applications

Rousse¹,

Fournet²,

Porteneuve³

et al. 2003

Entomologia Exp Applicata

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This study evaluates the efficacy of a new approach to the control of Delia radicum populations. We suggest associating the primary crop with a trap crop that is expected to be more attractive to D. radicum females and to attract and sustain their natural enemies such as Aleochara bilineata and A. bipustulata. Various cruciferous species were compared in terms of their preference for adult D. radicum females, and performance, as estimated by larval survival. Laboratory results were complemented by field experiments in which the selected trap crops were associated with broccoli plants. The following results were obtained. Of the six different cruciferous plant species tested, Delia radicum females showed a strong preference for Chinese cabbage, with turnip also being attractive. Following the laboratory results, turnip was chosen as a trap crop because it was easier to cultivate and presented good preference and performance. In the field experiments, Aleochara adults were present in higher numbers in plots associated with turnips than in pure broccoli plots. The presence of Aleochara adults in plots with turnips improved plant protection; as fewer broccoli plants were attacked, the attacked plants were less severely damaged, and more D. radicum pupae were parasitised than in pure broccoli plots. Delia radicum females did not lay fewer eggs on broccoli plants associated with turnips. Moreover, protection and parasitism were more effective in the rows closest to the central row of turnips, suggesting that Aleochara adults limit their activity to its immediate vicinity.

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Damage Thresholds for Cabbage Root Fly [Delia radicum(L.)] in Cauliflower Assessed from Pot Experiments

Cited by 8 publications

References 0 publications

Assessing the relationship between pest density and plant damage: a case study with the belowground herbivore Delia radicum (Diptera: Anthomyiidae) on broccoli

Assessing the relationship between pest density and plant damage: a case study with the belowground herbivore Delia radicum (Diptera: Anthomyiidae) on broccoli

Seasonal Flight, Optimal Timing and Efficacy of Selected Insecticides for Cabbage Maggot (Delia radicum L., Diptera: Anthomyiidae) Control

Trap cropping to control Delia radicum populations in cruciferous crops: first results and future applications

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