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Populations of various economic species of wireworms are increasing in the key cereal crop production areas of Canada and the United States. To address this problem, seed treatments are under development that both provide crop protection and significantly reduce populations equivalent in effectiveness to the formerly used but now deregistered organochlorine lindane. Herein, we evaluated isocycloseram (PLINAZOLIN technology), the first isoxazoline (GABA-gated Chloride Channel Allosteric Modulator) agricultural insecticide, as a seed treatment for the protection of cereal crops from the sugarbeet wireworm, Limonius californicus (Mannerheim). In wheat and barley field trials conducted over 4 years under extreme wireworm pressure, isocycloseram applied as a seed treatment at 5.0–7.5 g AI/100 kg seed was as effective as or more effective than the current industry standard thiamethoxam at 20.0 g AI/100 kg seed in protecting crop stand and yield. Isocycloseram also reduced neonate wireworms (produced from eggs during the growing season) and resident wireworms (in the field at the time of planting) to levels expected from the formerly used seed treatment lindane. [ABSTRACT FROM AUTHOR]

Larvae of two species of click beetle, Agriotes obscurus and Agriotes lineatus , are important pests of vegetable and field crops in both Europe and North America. Both species have been long and extensively studied, but to date little is known regarding the maturation and egg development of female beetles relative to their swarming periods. This knowledge is important for developing wireworm management tactics that target female beetles, as these would ideally eliminate the beetles before they oviposit. This paper is an attempt to address this knowledge gap. We dissected 2,450 female A. obscurus and 477 female A. lineatus collected in southwestern British Columbia in 2015–2020, and describe how their abdominal lipid content and number of mature eggs change during their swarming period. Based on the presence of mature and immature eggs, active ovarioles, and lipid content, we propose 6 consecutive beetle maturity stages. Beetles collected early in the season have high lipid content and no eggs. Over time, immature, then mature eggs appear and the lipid content decreases dramatically. Ovarioles are generally active throughout the swarming period, even when lipids are no longer present, suggesting that for these species egg laying may continue until the end of the season, and that fecundity depends both on a beetle's original lipid content at emergence, and subsequent diet. [ABSTRACT FROM AUTHOR]

We present findings of a general survey of pest wireworms in Alberta, Saskatchewan, and Manitoba conducted from 2004 to 2019; the first such survey of the Canadian Prairie provinces since that published by Glen et al. (1943). Samples were collected from 571 farmland locations where crop damage from wireworms was observed or suspected, and a total of 5,704 specimens (3,548 larvae, 2,156 beetles) were identified. Most specimens (96.9%) were identified as Hypnoidus bicolor (3,278), Selatosomus aeripennis destructor (1,280), Limonius californicus (842), and Aeolus mellillus (125). This suggests that H. bicolor has replaced S. a. destructor as the predominant species and that the relative importance of L. californicus as a pest species has increased since earlier reports. Despite the relatively small number of specimens collected per location (approx. 10), H. bicolor and S. a. destructor , and S. a. destructor and L. californicus were frequently collected at or near the same location (within 1 km). We provide species records and incidence of co-occurrence at different spatial scales, discuss potential reasons for and implications of shifts in species composition, implications of species co-occurrence for managing wireworm pests in crop production, and outline pertinent research needs. A path analysis approach used to correlate incidence of the main species with various soil characteristics indicated that organic matter, cation exchange capacity, and water retention capacity all had a significant species-specific influence on wireworm presence. [ABSTRACT FROM AUTHOR]

Following the deregistration of lindane, several neonicotinoid insecticides have been registered as seed treatments for controlling wireworms in cereal crops. Unlike lindane, which did both, neonicotinoids provide crop protection but do not reduce wireworm populations. Hence populations of various economic species are growing in key wheat production areas of the United States and Canada, and there is a need for novel seed treatments that match the efficacy of lindane. Herein we evaluated broflanilide, a novel GABA-gated Cl- channel allosteric modulator that differs from the cyclodienes (e.g. lindane) in that it binds to a unique site in the GABA receptor. As such, broflanilide confers a new mode of insecticidal action (Group 30 MOA), and is the first meta-diamide insecticide developed. When evaluated in field trials over 7 yr at various rates, broflanilide at 5.0 g [AI]/100 kg wheat seed was as effective at protecting wheat stand from wireworm (Agriotes obscurus) injury as the current industry standard thiamethoxam at 20–30 g [AI]/100 kg seed. In addition, broflanilide at 5.0 g reduced neonate wireworms (produced from eggs laid in established wheat during the growing season) and resident wireworms (in the field at time of planting) by 73.1 and 81.1%, respectively, which is comparable to that reported for the previous industry standard lindane (75.3 and 57.6%, respectively). These studies show that broflanilide at 5.0 g [AI] will provide consistent wheat stand protection (equal to thiamethoxam at 20–30 g [AI]), and A. obscurus wireworm population reduction (equal to lindane at 59 g [AI]), and will do so at far lower dosages per hectare. [ABSTRACT FROM AUTHOR]

Abstract: A study was conducted to determine the attractive range of traps baited with Agriotes obscurus pheromone to male beetles in both still air and wind conditions. This information is crucial for evaluating the potential of mass trapping when aiming to reduce beetle populations. Groups of 10 beetles were released at 14 points spaced 1 m apart along a linear track, at one end of which was a pheromone and wind source. Beetle response to the pheromone and/or wind was recorded 150 s after release and characterized as orienting either towards or away from the pheromone and/or wind source. Data analysis indicated the attraction range of the sex pheromone is <5 m in still air, which is considerably lower than estimates from previous studies and emphasizes the challenge of mass trapping this species in the field. The attraction range increased when there was air flow. Unexpectedly, not all male beetles respond to the pheromone, and beetles are inclined to move downwind even in the presence of pheromone. The latter finding suggests that wind direction may influence beetle dispersal and mate finding in the field. The implications of these results for determining the efficacy of mass trapping as a management approach are discussed. [ABSTRACT FROM AUTHOR]

Mark-release-recapture was used to investigate the dispersal of click beetles in spring wheat or fallow fields using edge or centre field releases. Three types of pitfalls were used: gutter traps near field margins, as well as conventional pitfall traps or cross-traps consisting of four gutter trap arms leading to a central pitfall. Capture of naturally occuring beetles was concurrently recorded., In total, 6952 marked Agriotes obscurus (males and females) and Agriotes lineatus (males) were released and 14.74% were recaptured at some time during the present study. Recovery rates ranged from 3.54% to 28.5%., Agriotes obscurus dominated wild populations, with 4011 males and 1672 females trapped compared with 17 males and three females for A. lineatus. Males dominated early in the period, although the sex ratio tended towards equality as the season progressed., Generally, captures of A. obscurus males released in equal numbers at field edges followed a uniform distribution. There were differences for wild beetles caught in the same traps., Spatial trapping patterns of wild and marked beetles across the fields were similar. Within 19 h of release at the field edges A. obscurus males were captured >30 m away., The crop type had a significant interspecific effect on trap counts for males and an intraspecific effect on A. obscurus females, reinforcing the need for caution when using trapping systems to monitor adult stages of these pests., The results of the present study demonstrate that uncropped field margins comprise sources of click beetles. We also conclude that click beetles disperse much further than reported previously. [ABSTRACT FROM AUTHOR]