Pest Of Oilseed Rape Research Articles

Differences in colour preference among pollen beetle species (Coleoptera: Nitidulidae)

AbstractPollen beetles (Coleoptera: Nitidulidae) are major pests of oilseed rape and other crucifers. Efficient and timely management of these pests can greatly be improved by effective monitoring of their spatial and temporal distribution. In field trials in Hungary, we have discovered striking differences in colour responsiveness among pollen beetle species: Brassicogethes aeneus F. 1775 (earlier Meligethes aeneus) and B. viridescens F. 1775 responded most strongly to fluorescent yellow traps, whereas B. coracinus Sturm 1845, Fabogethes nigrescens Sturm 1845 and Meligethes atratus Olivier 1790 were most attracted to blue or white traps. Differences in the spring flight period were also recorded, with B. aeneus and B. viridescens flying ca. 1 month earlier than the other three species. Further tests established that funnel traps having both fluorescent yellow and blue colour cues are the most efficient in attracting a wide range of pollen beetle species. On the other hand, fluorescent yellow traps can be used to detect and monitor B. aeneus specifically.

Flower fields and pesticide use interactively shape pollen beetle infestation and parasitism in oilseed rape fields

Abstract Pollen beetles (Brassicogethes spp.) are the main pests of oilseed rape (OSR, Brassica napus) in Europe and responsible for massive yield losses. Upcoming pesticide resistances highlight the need for other means of crop protection, such as natural pest control. Sown flower fields aim to counteract the decrease of insect biodiversity in agricultural landscapes by providing resources to ecosystem service providers. However, the optimal age and size of flower fields to increase natural pest control is still unclear. We conducted experiments on 31 OSR fields located along a gradient of landscape‐scale semi‐natural habitat (SNH). OSR fields were located adjacent to flower fields which differed in age, continuity and size, or adjacent to crop fields or calcareous grasslands. Pesticide‐free areas were established to examine interactive effects of pesticide use and flower field characteristics. The abundance of pollen beetle adults and larvae, parasitism and superparasitism rates in OSR were recorded at increasing distances to the adjacent sites. Flower fields and calcareous grasslands increased pollen beetle parasitism when compared to OSR fields neighbouring crop fields. The threshold for effective natural pest control of 35% could be reached in the pesticide‐free areas of OSR fields adjacent to calcareous grasslands and flower fields maintained continuously for at least 6 years. In pesticide‐sprayed areas, pollen beetle parasitism and superparasitism declined with increasing distance to the adjacent field. Furthermore, flower fields larger than 1.5 ha were able to improve pollen beetle parasitism more than smaller fields. Synthesis and applications. To promote natural pest control in oilseed rape (OSR), large flower fields should be maintained for several years, to create stable habitats for natural enemies. The continuous maintenance of flower fields should be preferred, as ploughing and resowing after 5–6 years decreased the positive effects of the flower fields on natural pest control in adjacent OSR fields. However, pesticide use can abrogate positive effects of flower fields on pollen beetle parasitism. This study highlights that sown flower fields have the potential to increase natural pest control in OSR, but this potential is depending on its age, continuity and size and can be hindered by pesticide use.

Attractiveness of oilseed rape cultivars to Brassicogethes aeneus and Ceutorhynchus obstrictus as a potential control strategy

The abundances of two pests, pollen beetle (Brassicogethes aeneus (Fabricius, 1775)) and cabbage seed weevil (Ceutorhynchus obstrictus (Marsham, 1802)), were measured before flowering and in the full bloom of oilseed rape cultivars with different phenologies (two yellow-flowering: DK Exssence (the earliest), DK Sensei (the latest) and one white-flowering in time between yellow-flowering cultivars), and the differences in their abundance in the selected cultivars were determined in plot experiments during 2015–2018. No significant differences in pollen beetle and cabbage seed weevil occurrence were observed between the cultivars in the pre-flowering period, but during flowering, the two yellow-flowering cultivars were more attractive than the white-flowering cultivar for both pests. In the white-flowering cultivar, 57% and 69% reductions in the pollen beetle and cabbage seed weevil populations, respectively, were found relative to the two with yellow flowers. Thus, the use of white-flowering cultivar (less attractive, later flowering) as the main crop and the yellow-flowering cultivar (more attractive, earlier flowering) at field edges, with the width of the one-track line, could serve as a strategy to manage oilseed rape pests during flowering. This control strategy which combines more and less attractive oilseed rape cultivars may contribute to a reduction in the use of pesticides and their negative impact on the environment.

Report from the Agri-Food Charities Partnerships (AFCP) Forum on Management of Oilseed Rape Diseases and Pests

In his welcome and introduction, Graham Jellis, the AFCP Chairman, firstly explained that the Forum was a hybrid event, with around 25 participants in person at the University of Hertfordshire and up to 100 joining online from the UK and abroad. He expressed his gratitude to the University of Hertfordshire for hosting the Forum. Graham explained that the purpose of AFCP is to allow the various agricultural sector charities in the UK to communicate and work together, wherever possible, to benefit UK agriculture and beyond. Further details on the AFCP and its member charities can be found on: https://www.afcp.org.uk. AFCP member charities have funded much of the research on oilseed rape pests and diseases being presented at this Forum.

Anther-Feeding-Induced RNAi in Brassicogethes aeneus Larvae

The biosafety aspect of applying double-stranded RNA (dsRNA) in crop pest management is rooted in dsRNA's mode of action, which displays nucleotide sequence-specificity to a particular region of a messenger RNA (mRNA), against which the insecticidal dsRNA is designed. This prominent and promising class of insecticides therefore has the potential to target a single pest species while conferring negligible effect on non-target organisms. Recent studies examining the effect of target-specific dsRNA in adults of the pollen beetle Brassicogethes aeneus, a major pest of oilseed rape (Brassica napus) crops in Europe, suggest the potential for developing a gene-silencing approach within integrated B. aeneus management. The present study examines the efficacy of target-specific dsRNA on target-mRNA silencing, and subsequent gene-silencing-induced mortality, in B. aeneus larvae, as this life stage represents a critical target for achieving optimal integrated B. aeneus control. Treatment applications occurred via feeding on dsRNA-treated anthers for 3 d. We observed variable gene-silencing efficacy, all target treatments having a significant or marginally significant effect after 3 d of dsRNA feeding, with greater variability at 6 d. These results further validated significant gene-silencing-induced mortality observed for one of the target treatments. Moreover, gene-silencing-induced mortality occurred at a quicker rate in B. aeneus larvae compared to what has been previously observed in B. aeneus adults. Finally, we consider refinements that must be made to B. aeneus larval bioassay setups to promote and strengthen future larval studies regarding this important crop pest species.

Widespread resistance of pollen beetles to pyrethroids in Czechia with no evidence for kdr mutation

The pollen beetle Brassicogethes aeneus (Fabricius, 1775) (Coleoptera: Nitidulidae) is one of the most important pests in oilseed rape (Brassica napus L. var. oleifera Moench) in Czechia. Wide-spread resistance development to pyrethroids in pollen beetle populations was documented in many European countries, including Czechia. The susceptibilities of 10 local pollen beetle populations originating from 10 localities in Czechia to lambda-cyhalothrin, tau-fluvalinate, thiacloprid, indoxacarb and chlorpyrifos were evaluated in 2017–2020 using glass vial bioassays. A high level of resistance to lambda-cyhalothrin was recorded in all the evaluated populations of the pollen beetle. The proportion of the populations resistant to tau-fluvalinate varied between years from 30% to 60%, and in 2018 and 2020, all the tested populations were classified as resistant. Despite the high level of resistance to pyrethroids, a kdr mutation known to cause resistance in the pollen beetle was not detected in any of the 244 tested individuals. In 2017–2020, the first local populations of the pollen beetle with decreased susceptibility to thiacloprid occurred. The LD90 of thiacloprid exceeded the field application dose in 100% and 90% of populations in 2018 and 2020, respectively. All the tested populations were susceptible to indoxacarb and chlorpyrifos. Cross-resistance between lambda-cyhalothrin and thiacloprid and between tau-fluvalinate and thiacloprid was found using data from 2017 to 2020. No cross-resistance between lambda-cyhalothrin and tau-fluvalinate was detected.

Sampling pollen beetle (Brassicogethes aeneus) pressure in oilseed rape: which method is best?

BACKGROUNDThe pollen beetle (Brassicogethes aeneus) is the most abundant pest of oilseed rape in spring and is potentially one of the most damaging. Adults feed on the pollen within closed flower buds and the damage leads to bud abscission, resulting in podless stalks and yield reduction. Several methods are currently used to monitor the pressure of this insect, such as counting the numbers of adults on the plants, quantifying the number of buds damaged by the insect before flowering or counting the number of podless stalks before harvest. We conducted experiments to evaluate the robustness of these sampling methods and compared their results. We also describe how pollen beetles damage the plants to understand the limitations of methods based on damage estimation.RESULTSMethods based on adult abundance lack robustness. We observed that most of the damage to buds is caused by pollen beetles feeding on small buds (< 3 mm), and that this damage can be quantified later in the season, indicating that methods based on the count of podless stalks are robust. Different methods gave consistent results and quantification of the pressure on the primary raceme can be a good proxy for pressure on the whole plant.CONCLUSIONSStandardised methods for assessment of pollen beetle pressure will enable comparison of pest management strategies between different studies and facilitate the development of alternative control strategies for this pest.© 2021 Rothamsted Research. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High genetic diversity and strong genetic structure of Strongyllodes variegatus populations in oilseed rape production areas of China

BackgroundStrongyllodes variegatus (Fairmaire) is a major insect pest of oilseed rape in China. Despite its economic importance, the contribution of its population genetics in the development of any suitable protection control strategy for the management of oilseed rape crops is poorly studied. It is a much urgent need to prevent its spread to the rest of the world.ResultsUsing the sequences of mitochondrial DNA cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) as genetic markers, we analyzed the population genetic diversity and structure of 437 individuals collected from 15 S. variegatus populations located in different oilseed rape production areas in China. In addition, we estimated the demographic history using neutrality test and mismatch distribution analysis. The high level of genetic diversity was detected among the COI and Cytb sequences of S. variegatus. The population structure analyses strongly suggested three distinct genetic and geographical regions in China with limited gene flow. The Mantel test showed that the genetic distance was greatly influenced by the geographical distance. The demographic analyses showed that S. variegatus had experienced population fluctuation during the Pleistocene Epoch, which was likely to be related to the climatic changes.ConclusionOverall, these results demonstrate that the strong genetic structure of S. variegatus populations in China, which is attributed by the isolation through the geographical distance among populations, their weak flight capacity and subsequent adaptation to the regional ecological conditions.

Proteogenomic insight into the basis of the insecticide tolerance/resistance of the pollen beetle Brassicogethes (Meligethes) aeneus

The pollen beetle is a major pest of oilseed rape. Although various resistance mechanisms have been identified, such as kdr (mutation in the sodium channel) and metabolic resistance (CYP overexpression), other “hidden” factors also exist. Some studies have stressed the importance of epistasis as a genetic background. The combination of kdr and metabolic resistance appears to be unfavorable under field conditions in the absence of pesticide selection. The regulation of detoxification enzymes can play an important role, but we highlight different detoxification markers compared to those emphasized in other studies. We also stress the importance of studying the role of markers identified as pathogenesis-related protein 5-like (PR5; upregulated by insecticides) and highlight the role of RNA (DEAD-box) helicases (downregulated by insecticides). Thus, we suggest the importance of epigenetic drivers of resistance/tolerance to pesticides. The key results are similar to those of our previous study, in which deltamethrin treatment of the pollen beetle was also investigated by a proteogenomic approach. Indeed, the mechanism leading to resistance of the pollen beetle may be an innate mechanism that the pollen beetle can also employ in natural habitats, but under field conditions (pesticide exposure), this mechanism is used to survive in response to insecticides. SignificancePesticide resistance is a serious problem that hampers the successful production of crops. Understanding the mechanisms of insecticide resistance is highly important for successful pest control, especially when considering integrated pest management. Here, using a proteogenomic approach, we identified novel markers for understanding pollen beetle resistance to pesticides. In addition, future studies will reveal the role of these markers in the multiresistance of pollen beetle populations. We highlight that the proteins identified as PR5, which are known to occur in beetles and are similar to those in plants, may be responsible for tolerance to multiple stresses. In addition, our results indicate that the RNA helicases that exhibited changes in expression may be the epigenetic drivers of multiresistance. The nature of these changes remains an open question, and their relevance in different situations (responses to different stresses) in natural habitats in the absence of pesticides can be proposed.

Targeting a coatomer protein complex-I gene via RNA interference results in effective lethality in the pollen beetle Brassicogethes aeneus

The pollen beetle Brassicogethes aeneus is a serious pest of oilseed rape (Brassica napus) in Europe. Management of this pest has grown difficult due to B. aeneus’s development of resistance to pyrethroid insecticides, as well as the pressure to establish control strategies that minimise the impact on nontarget organisms. RNA interference represents a nucleotide sequence-based, and thus potentially species-specific, approach to agricultural pest control. The present study examined the efficacy of targeting the coatomer gene coatomer subunit alpha (αCOP), via both microinjection and dietary exposure to exogenous complementary dsRNA, on αCOP-silencing and subsequent mortality in B. aeneus. Beetles injected with dsRNA targeting αCOP (at 0.14 µg/mg) showed 88% and 100% mortality at 6 and 10 days post-injection, respectively; where by the same time after dietary exposure, 43%–89% mortality was observed in the 3 µg dsRNA/µL treatment, though the effect was concentration-dependent. Thus, the effect was significant for both delivery routes. In working towards RNA-based management of B. aeneus, future studies should include αCOP as a target of interest.

Gut microbiota degrades toxic isothiocyanates in a flea beetle pest.

Microbial symbionts of herbivorous insects have been suggested to aid in the detoxification of plant defense compounds; however, quantitative studies on microbial contribution to plant toxin degradation remain scarce. Here, we demonstrate microbiome-mediated degradation of plant-derived toxic isothiocyanates in the cabbage stem flea beetle Psylliodes chrysocephala, a major pest of oilseed rape. Suppression of microbiota in antibiotic-fed beetles resulted in up to 11.3-fold higher levels of unmetabolized isothiocyanates compared to control beetles but did not affect other known detoxification pathways in P.chrysocephala. We characterized the microbiome of laboratory-reared and field-collected insects using 16S rRNA amplicon sequencing and isolated bacteria belonging to the three core genera Pantoea, Acinetobacter and Pseudomonas. Only Pantoea isolates rapidly degraded isothiocyanates in vitro, and restored isothiocyanate degradation in vivo when reintroduced in antibiotic-fed beetles. Pantoea was consistently present across beetle life stages and in field and lab populations. In addition, Pantoea was detected in undamaged tissues of the host plant Brassica rapa, indicating that P.chrysocephala could possibly acquire an isothiocyanate detoxifying bacterium through their diet. Our results demonstrate that both insect endogenous mechanisms and the microbiota can contribute to the detoxification of plant defense compounds and together they can better account for the fate of ingested plant metabolites.

Mitochondrial genome and phylogenetic analysis of Psylliodes punctifrons Baly (Coleoptera: Chrysomelidae: Galerucinae)

We sequenced and annotated mitochondrial genome (mitogenome) of oilseed rape pest Psylliodes punctifrons Baly for the first time. The mitogenome is 15,611 bp, and the nucleotide composition of 37 genes is highly A + T biased (A: 34.2, C: 11.6, G: 12.1, and T:42.1). All PCGs start with ATN and stop with TAR, except COX3 and ND4 that stop with incomplete codon T—. The phylogenetic tree confirms that P. punctifrons is clustered with other Psylliodes species. This study enriches the mitogenomes of agricultural pests.

Kairomone-assisted trap cropping for protecting spring oilseed rape (Brassica napus) from pollen beetles (Coleoptera: Nitidulidae).

Pollen beetles are key pests in oilseed rape (OSR) production. These beetles use visual and olfactory cues to locate their host plants at specific phenological stages, hence trap cropping may represent an alternative pest control strategy. In this study, a trap crop strategy for spring OSR was developed. To elaborate such a trap cropping system, a pest control measure that eradicates the attracted beetles in the trap crop before they migrate further into the main crop was included in the final trap cropping strategy. Testing yellow-flowering turnip rape and one yellow- and two cream-coloured flowering OSR cultivars as potential crops in different trap cropping strategies, we found that pollen beetles clearly preferred turnip rape over the cream-coloured and yellow OSR cultivars, and preferred the yellow OSR cultivar over the two cream-coloured cultivars. This behaviour was related to the plant growth stage and associated volatile and colour signals of the tested cultivars. Using turnip rape as a trap crop and testing kairomone- or insecticide-assisted trap cropping as the pest control strategy was as effective as compared with whole fields treated with a standard pesticide. Combining a turnip rape cultivar as trap crop with kairomone traps placed in the trap crop as a killing agent may enable renunciation of pesticides in spring OSR production. © 2020 Society of Chemical Industry.

The potential of the solitary parasitoid Microctonus brassicae for the biological control of the adult cabbage stem flea beetle, Psylliodes chrysocephala.

The cabbage stem flea beetle (CSFB), Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), is a major pest of oilseed rape, Brassica napus L. (Brassicaceae), within the UK and continental Europe. Following the withdrawal of many broad‐spectrum pesticides, most importantly neonicotinoids, and with increased incidence of pyrethroid resistance, few chemical control options remain, resulting in the need for alternative pest management strategies. We identified the parasitoid wasp Microctonus brassicae (Haeselbarth) (Hymenoptera: Braconidae) within CSFB collected from three independent sites in Norfolk, UK. Parasitism of adult CSFB was confirmed, and wasp oviposition behaviour was described. Moreover, we show that within captive colonies parasitism rates are sufficient to generate significant biological control of CSFB populations. A sequence of the M. brassicae mitochondrial cytochrome oxidase 1 (MT‐CO1) gene was generated for rapid future identification. Moroccan specimens of Microctonus aethiopoides (Loan), possessing 90% sequence similarity, were the closest identified sequenced species. This study represents the first description published in English of this parasitoid of the adult cabbage stem flea beetle.

Evaluating the effect of seven plant essential oils on pollen beetle (Brassicogethes aeneus) survival and mobility

Plant essential oils (EOs) represent an area of interest for managing agricultural pests. We examined the insecticidal efficacy of seven plant EOs on the survival and mobility of the pollen beetle Brassicogethes aeneus, a primary pest of oilseed rape (Brassica napus) in Europe. Topical dosing tests showed the EO of the inner bark of Cinnamomum verum (cinnamon) to be the most effective EO examined in our study. Subsequent bioassays, exposing B. aeneus to oilseed rape plant surfaces sprayed with various concentrations of C. verum EO, additionally suggested a concentration threshold at which this EO may significantly control B. aeneus populations. We suggest that further studies on B. aeneus examine the effect of certain pure compounds associated with the most promising EOs (individually as well as in binary combinations) in order to reveal optimal chemical composition and ratios to exploit within a B. aeneus management framework.

System of phytosanitary monitoring of winter oilseed rape pests in the south of Ukraine

System of phytosanitary monitoring of winter oilseed rape pests in the south of Ukraine

Identification and evolution of glucosinolate sulfatases in a specialist flea beetle

Glucosinolates, a characteristic group of specialized metabolites found in Brassicales plants, are converted to toxic isothiocyanates upon herbivory. Several insect herbivores, including the cabbage stem flea beetle (Psylliodes chrysocephala), prevent glucosinolate activation by forming desulfo-glucosinolates. Here we investigated the molecular basis of glucosinolate desulfation in P. chrysocephala, an important pest of oilseed rape. Enzyme activity assays with crude beetle protein extracts revealed that glucosinolate sulfatase (GSS) activity is associated with the gut membrane and has narrow substrate specificity towards the benzenic glucosinolate sinalbin. In agreement with GSS activity localization in vivo, we identified six genes encoding arylsulfatase-like enzymes with a predicted C-terminal transmembrane domain, of which five showed GSS activity upon heterologous expression in insect cells. PcGSS1 and PcGSS2 used sinalbin and indol-3-ylmethyl glucosinolate as substrates, respectively, whereas PcGSS3, PcGSS4, and PcGSS5 showed weak activity in enzyme assays. RNAi-mediated knock-down of PcGSS1 and PcGSS2 expression in adult beetles confirmed their function in vivo. In a phylogenetic analysis of coleopteran and lepidopteran arylsulfatases, the P. chrysocephala GSSs formed a cluster within a coleopteran-specific sulfatase clade distant from the previously identified GSSs of the diamondback moth, Plutella xylostella, suggesting an independent evolution of GSS activity in ermine moths and flea beetles.

The potential use of drones to help natural pest control - an example using carabids

Small automated flying vehicles (drones, by common name) are undergoing very fast development, and the range of their potential use is also fast expanding. One possible application in agriculture is to disperse biological control agents in areas that are otherwise inaccessible, or the distribution of natural enemies is uneconomic for various reasons. We develop the use of multirotor type drones (DJI S-900) as a possible vehicle to field-disperse carabid beetle adults as an inoculative biological control release against oilseed rape pests. We selected Pterostichus cupreus as a representative of common, larger species, and Anchomenus dorsalis as a similar representative of smaller species. To test the robustness of these species to being dispersed by drones, we subjected the two carabid species to simulated "drop tests", using a specially modified 1 L-sized dispenser that can be fitted to the drone. We mixed 15-20 adults with two media, buckwheat bran and vermiculite and allowed the machine "dispersing" them under laboratory conditions. Subsequently, we checked the "distributed" beetles for mortality, bodily damage, and feeding capacity. Our first tests show that A.dorsalis is suitable for drone-based distribution while the larger species likely requires further modification of the dispensing system, due to the larger size and motility of this species. The dropping caused no mortality or physical damage to A.dorsalis but some of the P.cupreus lost tarsal segments. Feeding was not impaired in either species, though. In summary, drone technology opens promising possibilities for the widening of biological control possibilities in various situations in agriculture.

Intraspecific seasonal variation of dormancy and mortality of Phelipanche ramosa seeds

SummaryPhelipanche ramosa (Branched broomrape) is an obligate root parasitic plant that is a major pest of oilseed rape in France. Knowledge on seed viability and dormancy under field conditions is crucial to understand how to control P. ramosa, but is as yet unknown. Our study aimed to quantify these processes with a 2‐year seed burial experiment. Two genetically distinct populations of P. ramosa were studied, collected on winter oilseed rape (population O) and hemp (population H). Seed mortality was very low in both populations (4–7% per year). Although obligate parasitic seeds are assumed to germinate only after exposure to germination stimulants from host root exudates, a high proportion of population H seeds germinated spontaneously (up to 90%). Seeds of both populations displayed seasonal dormancy, with timing and magnitude depending on the population. Dormancy was low at the time each native host crop is usually sown. Populations differed in germination dynamics, with seeds of population H germinating faster. The difference in behaviour that we observed between populations is consistent with reported adaptations of pathovars to their preferred hosts. The results indicate that the parasitic plant management requires targeting at the populations concerned. For example, delayed sowing is more promising against population O than against population H.

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

Spraying of insecticides and fungicides during the flowering stage of oilseed rape (Brassica napus L.) could be necessary to control insect pests (such as Ceutorhynchus obstrictus (Marsham) and Dasineura brassicae (Winnertz)) and pathogens (Sclerotinia sclerotiorum (Lib.) de Bary). In contrast to the conventional application technique, dropleg nozzles are kept below the flowering canopy to restrict the exposure of pollinators to active ingredients of insecticides. The Julius Kühn-Institut (JKI) tested the efficacy of different insecticides using the dropleg technique compared to the conventional technique, on insect pests in field trials conducted from 2015 to 2017 in the area of Braunschweig. The crop was treated at full flowering (BBCH 65) for three consecutive years. The tested insecticides were Biscaya (72 g a. i. ha−1 thiacloprid), Mavrik (48 g a. i. ha−1 tau-fluvalinate), and Mospilan SG (40 g a. i. ha−1 acetamiprid). The adults and larvae of oilseed rape pests that drop to the ground were collected using water trays. The emergence of new generation beetles (Brassicogethes aeneus (Fabricius), C. obstrictus) was recorded from BBCH 78 onwards, using photoeclectors. At least twice during each season, oilseed rape plants were assessed for D. brassicae injury. The new dropleg application technique showed similar efficacy on pest insects compared to the conventional spraying technique. Nevertheless, the abundance of pests was not always sufficient to get clear results. Results especially on D. brassicae indicate that the dropleg technique had a comparable efficacy under moderate pest pressure conditions observed in our study. Further research under conditions with a higher abundance of C. obstrictus, as well as research on the effects of dropleg technique on parasitoids of oilseed rape pests, is needed. The population of B. aeneus population was reduced slightly less using dropleg instead of conventional application technique. In all the years, the yields did not differ significantly with regard to the conventional and dropleg application techniques.