Effects of dropleg application technique during flowering of oilseed rape on insect pests

Hausmann, Johannes; Brandes, Meike; Heimbach, Udo

doi:10.1016/j.cropro.2019.104917

Cited by 6 publications

(8 citation statements)

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“…An inadequate application timing, and a high spraying frequency have increased the severity of resistance against pyrethroids (Højland et al 2015;Heimbach and Brandes 2016). A targeted use of insecticides for control of P. chrysocephala and other pests is necessary (Hausmann et al 2019;Brandes et al 2017) to avoid further resistance development and exposure of non-target organisms.…”

Section: Introductionmentioning

confidence: 99%

Effect of immigration time and beetle density on development of the cabbage stem flea beetle, (Psylliodes chrysocephala L.) and damage potential in winter oilseed rape

Conrad¹,

Brandes

Ulber

et al. 2021

J Plant Dis Prot

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In a semi-field net cage experiment set up in three growing seasons (2015–2018) at Julius-Kühn Institute Braunschweig, Germany, the influence of different release times of adult cabbage stem flea beetles, Psylliodes chrysocephala (early September, mid-September, early October) and different beetle densities (6.7, 13.3 and 20 beetles/m2) on reproduction and damage potential in winter oil seed rape was investigated. In parallel to the cage trials, the number of deposited eggs was assessed in small boxes exposed in the field. Beetles released in early September laid significantly more eggs compared to beetles released early October, with a maximum of 270 eggs per female. The early release of beetles resulted in significantly higher numbers of larvae in autumn, but this differed significantly between the years. Warm autumn or winter conditions led to continued egg laying and development, whereas cold conditions stopped the reproduction. Significant yield losses (25%) and significant plant losses during winter were only found in 2016/17 in treatments with an early release of high numbers of beetles (20 beetles /m2). The German damage threshold of 3–5 larvae per plant was reached when 13 beetles/m2 were released before 20th September and 20 beetles per m2 after 20th September. Data of this study can be used for a better damage prediction and a more targeted beetle control.

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Section: Introductionmentioning

confidence: 99%

Effect of immigration time and beetle density on development of the cabbage stem flea beetle, (Psylliodes chrysocephala L.) and damage potential in winter oilseed rape

Conrad¹,

Brandes

Ulber

et al. 2021

J Plant Dis Prot

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“…The trials were designed in a completely randomized block design with four replicates and five different treatments, including an untreated control. The distance between plots was 1 m (Table 1, for further information see also Hausmann et al 2019). Insecticides were applied once per year at full flowering, using both conventional spraying and dropleg spraying technique (Lechler 2020).…”

Section: Assessment Of the Vertical Distribution Of Insectsmentioning

confidence: 99%

“…Pollen beetle larvae were counted and stored in 70% ethanol at plot level. To determine parasitisation by T. heterocerus, the larvae were dissected and examined for parasitoid eggs (see Brandes et al 2018, andHausmann et al 2019). The number of larvae examined varied between years and sampling dates within a year (Supplementary Table S1).…”

Section: Assessment Of the Vertical Distribution Of Insectsmentioning

confidence: 99%

“…Field studies have also shown that the control of the pathogen S. sclerotiorum is not affected by the type of application technique (Dicke 2018;Weimar-Bosse et al 2017). However, the efficacy of insecticides applied with dropleg technique against the seed damaging insect pests is slightly reduced (Hausmann et al 2019).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to pollinators, parasitoids are another important insect guild in OSR, as they contribute considerably to the biological control of pests (Abram et al 2019;Kovács et al 2019;Ulber et al 2010b;Veromann et al 2010). Hence, the question arose whether applying systemic neonicotinoid insecticides to the lower vegetation layers using dropleg sprayers (Hausmann et al 2019) could target pests in the OSR canopy, while having no or reduced impact on their co-occurring parasitoids. Many parasitoids are abundant in the crop during the flowering period (Nissen 1997;Ulber et al 2010a) and insecticide application in this period can have detrimental effects on the parasitism rates of OSR pests such as cabbage seedpod weevil (Murchie et al 1997) or pollen beetle, Brassicogethes aeneus Fabricius (Coleoptera: Nitidulidae) (Jansen 2017;Neumann 2010).…”

Section: Introductionmentioning

confidence: 99%

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The effect of insecticide application by dropleg sprayers on pollen beetle parasitism in oilseed rape

et al. 2021

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Dropleg sprayers apply pesticides below the flower horizon of oilseed rape plants and thus reduce unwanted side effects on pollinating insects. Whether this technique benefits parasitoids of seed and pollen feeding insect pests has not been studied earlier. To answer this question, we first assessed the vertical distribution of pests and parasitoids using a portable aspirator. In addition, parasitism rates of pollen beetle, Brassicogethes aeneus Fabricius (Coleoptera: Nitidulidae), by the larval parasitoid Tersilochus heterocerus Thomson (Hymenoptera: Ichneumonidae) were compared in conventional and dropleg sprayed fields over four years (2016–2019), using the neonicotinoids thiacloprid and acetamiprid. Our results show that seed and pollen feeders were mainly found in the flowering canopy, while the predominant location of parasitoids was species-specific. Among pollen beetle parasitoids, Phradis interstitialis Thomson (Hymenoptera: Ichneumonidae) was more abundant below flowering canopy (63% of total catch), whereas T. heterocerus was mainly caught in the flowering canopy (84% of total catch). In the spraying experiments, average parasitism rates of pollen beetles by T. heterocerus ranged between 55 and 82% in the untreated controls. In the dropleg spray treatments, parasitism rates did not differ significantly from control levels, with the exception of thiacloprid application in 2019. In contrast, conventional spray applications resulted in a reduction of parasitism rates by up to 37% compared to the control for at least one of the insecticides in three out of four years. The impact of conventional application differed between years, which may be explained by the temporal coincidence between spray application and the immigration of parasitoids into the crop. We conclude that dropleg spraying exerts lower non-target effects on the main biological control agent of pollen beetle.

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Challenges for integrated pest management of Dasineura brassicae in oilseed rape

Hausmann

2021

Arthropod-Plant Interactions

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The use of insecticides in flowering oilseed rape (Brassica napus L.) against pest insects such as the brassica pod midge (Dasineura brassicae W.) often conflicts with the protection of pollinating and beneficial insects. Dasineura brassicae is a major pest insect in European oilseed rape production. However, a comprehensive and sustainable pest control strategy within the framework of integrated pest management (IPM) does not exist, and little research on the insect has been published during the past two decades. This paper reviews the existing knowledge about D. brassicae along its life cycle and is intended to form the basis for further research activities on pod-damaging pest insects in oilseed rape. Important knowledge gaps are identified, regarding the significance of natural enemies, diapause induction, and predictions on damage potential, based on initial pest insect population. The short lifespan of the adults is particularly challenging in praxis. The implementation of IPM for D. brassicae is discussed on the basis of the four IPM steps (set an economic threshold, establish pest monitoring, preventive measures, and direct control measures) and remaining hurdles, as well as potential solutions for a better IPM, are identified. For D. brassicae, there is no science-based economic threshold and no applicable monitoring methods for farmers, which hinders a field-specific damage forecast and the precise timing of insecticide applications. Research into improved monitoring (e.g. selective attractants, real-time monitoring using remote-sensing technologies) appears to be a promising step towards an integrated pest management of D. brassicae.

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Effects of dropleg application technique during flowering of oilseed rape on insect pests

Cited by 6 publications

References 10 publications

Effect of immigration time and beetle density on development of the cabbage stem flea beetle, (Psylliodes chrysocephala L.) and damage potential in winter oilseed rape

Effect of immigration time and beetle density on development of the cabbage stem flea beetle, (Psylliodes chrysocephala L.) and damage potential in winter oilseed rape

The effect of insecticide application by dropleg sprayers on pollen beetle parasitism in oilseed rape

Challenges for integrated pest management of Dasineura brassicae in oilseed rape

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