1,720,966 research outputs found
Recording and reproducing the diurnal oviposition rhythms of wild populations of the soft- and stone- fruit pest <i>Drosophila suzukii</i>
No full textDrosophila suzukii is a horticultural pest on a global scale which causes both yield and economic losses on a range of soft- and stone-fruit. Tackling this pest is problematic but exploiting behavioural rhythms could increase the impact of control. To do this, a better understanding of behavioural patterns is needed. Within this study we aimed to investigate rhythms in reproductive behaviour of wild D. suzukii under natural conditions in the field. Environmental parameters were also recorded to decipher how they influence these rhythms. Assays were then performed on laboratory cultures, housed under artificial conditions mimicking the temperature and light cycles, to see if these patterns were reproducible and rhythmic. We were able to promote field like oviposition patterns within the laboratory using realistic temperature and light cycles regardless of variations in other factors including substrate, humidity, and lighting type. Locomotion activity was also recorded under these mimicked conditions to identify how this behaviour interacts with oviposition rhythms. Both our field and laboratory assays show that oviposition behaviour is likely under the control of the circadian clock and primarily occurs during the day, but these patterns will be disrupted by unfavourable temperature conditions. This was also found within locomotion rhythms. With an increased understanding of how these behaviours are influenced by environmental conditions, we highlight the importance of using realistic temperature and light cycles when investigating behavioural patterns. From an increased understanding of D. suzukii behaviour we increase our ability to target the pest in the field
Control of daily locomotor activity patterns in Drosophila suzukii by the circadian clock, light, temperature and social interactions
No full textUnderstanding behavioural rhythms in a pest species can contribute to improving the efficacy of control methods targeting that pest. However, in some species the behavioural patterns recorded in artificial conditions contrast greatly with observed ‘wild-type’ behavioural rhythms. In this study we identify the determinants of daily activity rhythms of the soft and stone fruit pest Drosophila suzukii. The impact of gender, space, social housing, temperature, light, fly morph and the circadian clock on D. suzukii locomotor rhythms were investigated. Assays were performed under artificial laboratory conditions or more natural semi-field conditions to identify how these factors impacted daily locomotor behaviour. Daily locomotor activity patterns collected under semi-field conditions varied very little between the various sex and social condition combinations. However, in lab-based assays, individual and group-housed males often exhibited divergent activity patterns with more prominent hyperactivity at light/dark transitions. In contrast, hyperactivity responses were suppressed under lab protocols mimicking summer conditions for groups of females and mixed sex groups. Moreover, when environmental cues were removed, flies held in groups displayed stronger rhythmicity than individual flies. Thus, social interactions can reinforce circadian behaviour and resist hyperactivity responses in D. suzukii. Fly morph appeared to have little impact on behavioural pattern, with winter and summer morph flies displaying similar activity profiles under ‘April’ semi-field and laboratory mimic environmental conditions. In conclusion, separate and combined impacts of light, temperature, circadian clock function and social interactions were apparent in the daily activity profiles of D. suzukii. When groups of female or mixed sex flies were used, implementation of matching photoperiods and realistic daily temperature gradients in the lab was sufficient to recreate behavioural patterns observed in summer semi-field settings. The ability to leverage lab assays to predict D. suzukii field behaviour promises to be a valuable asset in improving control measures for this pest
Data from: Recording and reproducing the diurnal oviposition rhythms of wild populations of the soft- and stone- fruit pest Drosophila suzukii
No full textOviposition dataData collected from all oviposition assays. This file includes both field and laboratory collected data under various conditions. Excel was used to generate this file.OvipositionData.xlsxLocomotionDataActivity counts of locomotion. Originally recorded in MatLab and Clocklab and exported to an excel file.,Drosophila suzukii is a horticultural pest on a global scale which causes both yield and economic losses on a range of soft- and stone-fruit. Tackling this pest is problematic but exploiting behavioural rhythms could increase the impact of control. To do this, a better understanding of behavioural patterns is needed. Within this study we aimed to investigate rhythms in reproductive behaviour of wild D. suzukii under natural conditions in the field. Environmental parameters were also recorded to decipher how they influence these rhythms. Assays were then performed on laboratory cultures, housed under artificial conditions mimicking the temperature and light cycles, to see if these patterns were reproducible and rhythmic. We were able to promote field like oviposition patterns within the laboratory using realistic temperature and light cycles regardless of variations in other factors including substrate, humidity, and lighting type. Locomotion activity was also recorded under these mimicked conditions to identify how this behaviour interacts with oviposition rhythms. Both our field and laboratory assays show that oviposition behaviour is likely under the control of the circadian clock and primarily occurs during the day. However, consistent with prior reports we observed that these patterns become crepuscular when day-time temperature peaks exceeded 30°C. This was also found within locomotion rhythms. With an increased understanding of how these behaviours are influenced by environmental conditions, we highlight the importance of using realistic temperature and light cycles when investigating behavioural patterns. From an increased understanding of D. suzukii behaviour we increase our ability to target the pest in the field.</span
Implications of sub-lethal rates of insecticides and daily time of application on <i>Drosophila suzukii</i> lifecycle
No full textThe circadian clock is responsible for time keeping within an organism and influences not only behavioural patterns, but also physiological rhythms including toxin susceptibility. Drosophila suzukii Matsumura is a global horticultural pest, and identifying rhythms in insecticide susceptibility could contribute to improving integrated pest management practices. To determine whether time of application influences mortality, LC50 rates of cyantraniliprole, lambda-cyhalothrin, pyrethrum and spinosad were applied to groups of adult D. suzukii at two different times of day. Insecticides were directly applied using a benchtop sprayer. We found no influence of time on mortality or oviposition for any of the four insecticides applied. However, several discoveries were made regarding the impact of sub-lethal and lethal rates on D. suzukii mortality, oviposition and offspring survival over time. In most cases, all surviving females recovered from insecticide rates, and laid the same number of eggs as females treated with the water control. Seven days after application, females that were treated with the field rate of spinosad laid the same number of eggs as the control. The lowest rate of cyantraniliprole resulted in more eggs being laid, initially, with no negative impact on survival of eggs through to adult emergence. However, there were transgenerational impacts of egg to adult survival when parents were treated with sub-lethal rates of spinosad and lambda-cyhalothrin. Although no impact of daily phase of application was detected within this assay, the information surrounding how D. suzukii interacts with lethal and sub-lethal rates of insecticides is of great importance, especially for the resistance management of D. suzukii
Potential of the European earwig (Forficula auricularia) as a biocontrol agent of the soft and stone fruit pest Drosophila suzukii
No full textBACKGROUND: The unintentional introduction of Drosophila suzukii (Matsumura) from Asia has caused global economic losses in soft and stone fruit industries. Pesticide use can have unintended negative impacts on natural enemies, disrupting attempts to incorporate integrated pest management (IPM) programmes. Generalist predators could potentially act as biocontrol agents of D. suzukii. In this context, the predatory capabilities of the European earwig (Forficula auricularia) were investigated.RESULTS: In semi-field conditions, F. auricularia were effective at reducing thereproductive rate of D. suzukii in more densely populated enclosures. In controlled laboratory conditions, significant negative effects of earwigs were observed for both low (3 breeding pairs) and high (6 breeding pairs) D. suzukii densities. Both semi-field and laboratory experiments revealed that F. auricularia predation on adult D. suzukii could not account for the subsequent reductions in population density.CONCLUSIONS: Reductions in both larval and adult offspring in the presence ofearwigs indicate an impact on D. suzukii via predation prior to metamorphosis or disruption of oviposition. Although F. auricularia may predate D. suzukii populations, its capacity to act as a biocontrol agent may be limited. However, results suggest that F. auricularia may be a more effective biocontrol agent earlier in the growing season
Reducing <i>Drosophila suzukii</i> emergence through inter-species competition
No full textBACKGROUNDDrosophila suzukii has dispersed widely from its native Asian range since 2008. Its arrival in the UK is resulting in economic losses in soft‐ and stone‐fruit crops caused by larvae feeding on the flesh of ripening fruit. Although a large amount of research has been directed at controlling this pest, it is presently unknown how this invasive species interacts with native Drosophila species.RESULTSIn the work reported here, D. suzukii or Drosophila melanogaster adults were introduced to substrates pre‐inoculated with the eggs of the same or the other species in a laboratory choice assay. Drosophila melanogaster adult emergence was not affected by pre‐inoculation with D. suzukii. The rate of emergence of D. suzukii was significantly lower from medium pre‐inoculated by D. melanogaster than from blank medium. In a subsequent experiment, significantly more D. suzukii eggs were laid in blank medium than in D. melanogaster pre‐inoculated medium.CONCLUSIONThe presence of D. melanogaster in a substrate significantly reduced D. suzukii emergence and egg laying. This study raises research questions about how this reduction mechanism is driven and how it could be exploited as part of future integrated pest management practices
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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