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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]

A study was conducted to determine whether arrays of pheromone traps could be used to reduce populations of male Agriotes obscurus ( AO) and Agriotes lineatus ( AL) adults in a confined nonfarmed habitat (grassy dyke)., Traps placed 3 m apart in 15 × 2 arrays captured significantly more AL than AO, although the trap catch varied with location for both species and was inversely related to the number of nearby competing traps., Models of beetle movement indicated that a considerable proportion of males ( AL: 18.4-71.8%; AO: 35.0-58.3%) collected in the arrays had moved in from elsewhere and that AL beetles are more active than AO beetles. AL beetles frequently entered AO traps unless both trap types were present in the array, whereas AO rarely entered AL traps., Concurrent catches in pitfall traps placed inside and outside pheromone trapping zones indicated the trap arrays significantly reduced male (but not female) AO and AL beetles inside their respective arrays, that AO traps reduced AL beetles in AO arrays, and that both AL and AO traps could potentially reduce the number of mating pairs in these arrays., The implications of these results in determining the efficacy of this approach as a click beetle management approach are discussed. [ABSTRACT FROM AUTHOR]

The present study was conducted using mark-released populations of male Agriotes obscurus ( AO) and Agriotes lineatus ( AL) adults to simulate the spatial and temporal capture rates of wild beetle populations in dense arrays of pheromone traps in a confined, nonfarmed habitat., Two parallel rows of traps, spaced 3 m apart along corridors of grassy dyke, recaptured 85.6% of AO and 77.8% of AL with arrays of their respective pheromone traps, mostly within the first week of release. In arrays of mixed AO and AL traps, recapture rates were 77.8% and 83.3%, respectively., In arrays with only AO traps, 31.2% of AL males released within the arrays mistakenly entered the AO traps, which declined to only 2.2% when released in arrays with both AO and AL traps. In arrays with only AL traps, only 0.7% of released AO were mistakenly taken in the AL traps, and only 0.3% mistakenly entered AL traps in mixed AO and AL trap arrays., Between 34.4-38.9% of AO and 21.1-25.6% of AL released in areas immediately adjacent to the trapping arrays were caught, mostly in the outermost traps., The implications of these results for determining the efficacy of mass trapping as a click beetle management approach are discussed. [ABSTRACT FROM AUTHOR]

Insecticide options for controlling Delia radicum (L.) (Diptera: Anthomyiidae) in brassica crops are now limited, and alternatives are needed. Vertical mesh barriers impede females reaching, and ovipositing in, small-scale crops. We tested this pest management technique in a commercial crop to determine whether such barriers would also reduce dispersal of females at larger scales, and whether there was any detectable pattern to the spatial distributions of female D. radicum, eggs, and damage in a rutabaga crop [ Brassica napabrassicae (L.) Mill (Brassicaceae)]. A mesh fence of 1.3 m high with an externally facing 30-cm overhang was erected around the perimeter of a 2.7-ha field. Yellow sticky traps were positioned at 12 points outside and at 104 locations along transects inside the barrier to capture adult flies. Eggs were sampled from soil around 10 plants at 62 locations and damage was assessed at harvest using a subset of 38 of these locations. There was a substantial reduction (up to 96%) in the number of female flies caught per trap inside the fence compared with outside and a change in the male:female sex ratio from 0.36 outside to 0.92 inside. Female numbers inside and outside were related and sampling date, trap location, and trap face explained significant proportions of the variance in both data sets. There was no relationship between the size of the population and the distance flies penetrated into the field or the proportion of flies recovered in the outer 10 m. Female, egg, and damage counts were largely restricted to the perimeter of the field. Although eggs and damage were related, trap counts did not reflect their spatial distributions. Damage was related to oviposition in the later weeks leading up to harvest. We conclude that yellow sticky traps are an ineffective monitoring tool compared with egg sampling, exclusion barriers can reduce numbers of females reaching a crop, and the system has the potential to deliver reductions in damage and pest control costs at a commercial scale. [ABSTRACT FROM AUTHOR]

The effects of carbon dioxide and the induction of morbidity on aversion learning in larvae of the Pacific Coast wireworm Limonius canus LeConte (Coleoptera: Elateridae) are discussed. Wireworms preconditioned by exposing them one or four times to odour of Tefluthrin 20SC and Dividend XLRTA [Syngenta Crop Protection (Canada), Inc., Canada] during the induction of temporary morbidity subsequently contact tefluthrin-treated wheat seeds in soil bioassays for as long as naïve (i.e. not preconditioned) larvae but are repelled four to five-fold more frequently by Dividend-treated seeds in soil bioassays than naïve wireworms, suggesting that wireworms are capable of associating a novel odour (i.e. Dividend) with morbidity but require a minimum of 10–15 min subsequent contact time with treated seeds before being repelled. Wireworms preconditioned by exposure to peppermint odour during the induction of morbidity are not subsequently repelled by peppermint odour in soil bioassays, suggesting that wireworms are either not capable of aversion learning or that the presence of a CO2 source and/or a suitable host plant may override a negative cue (i.e. peppermint odour). In studies conducted in the absence of soil, a host plant and CO2 production, wireworms are repelled slightly by droplets of 1.0% but not 0.1% peppermint oil. Previous exposure to peppermint odour or contact with peppermint oil-treated filter paper during one induction of morbidity does not increase the repellency of wireworms to 1.0% peppermint oil significantly. Repellency to 1.0% peppermint oil is almost eliminated when morbidity is induced five times in the absence of peppermint odour but is restored when peppermint odour is present during preconditioning. These findings suggest that wireworm sensitivity to repellent compounds decreases when repeatedly made moribund, although the results are not sufficient to conclude that wireworms are capable of associative learning. [ABSTRACT FROM AUTHOR]

1 The production of new insect pheromones for pest monitoring proceeds at a greater rate than their evaluation, with the consequential possibility of premature introduction. Fundamental to their successful deployment is the determination of a consistent relationship between adult male pheromone trap catches and pest damage. In the present study, adult pheromone traps and larval bait traps were used to examine spatial relationships between two species of Agriotes beetle and wireworms at the field scale. 2 The spatial distributions of adult male Agriotes lineatus and Agriotes obscurus in two fields were determined and compared with the distribution of their larvae. Data were assembled as spatially referenced trap counts, and analysed for evidence of aggregation and clustering using Spatial Analysis by Distance IndicEs (SADIE) methodology. Spatial stabilities of adult populations between sampling dates were tested using association tests. Spatial and quantitative linkages between adult and larval trap catches were also tested. Moreover, a new way of adapting SADIE methodologies is presented for situations where two datasets within an area do not share the same sampling points. 3 There was no significant difference in variance : mean relationships for the two species but there were differences in their spatial distributions, and this is a definitive example of the general argument stating that it is important to consider spatial as well as count data in ecological studies. The spatial distribution of A. lineatus varied between sampling occasions at both sites whereas A. obscurus had consistently significant SADIE indices over time at one site, and adult catches could also be linked to larval distributions and counts. It is proposed that observed differences between the two species can be explained by interference between traps and dissimilar movement rates. There was some evidence of an edge effect at the field boundaries. 4 The distance between pheromone traps is related to the time that elapses before adjacent traps interfere with trap captures and this limits the detection of statistically significant spatial patterns. It is shown that the current practice of adding trap counts for different Agriotes species and treating them as numerically equivalent is insufficiently robust to be recommended at this stage. 5 The implications for the use of sex pheromone traps in wireworm pest management are considered. It is concluded that pheromone traps, as currently used, will not reliably indicate where wireworms occur in a field, and that the complexity of interpreting adult male trap counts limits quantitative predictions of population size. [ABSTRACT FROM AUTHOR]

1. Understanding the spatiotemporal ecology of invertebrates in agricultural ecosystems is important for developing management strategies to enhance biodiversity and reduce pesticide use. There is increasing recognition that studies need to be undertaken at scales larger than the field but the ability to do this is often resource limited. Pheromone traps, developed for pest management, can provide a relatively cheap means of collecting data across wide geographical scales. In this study we used such traps to examine the spatial stability of two species of agrioted beetles in non-farmed habitats over a period of 3 years. 2. The spatial distributions of adult male Agriotes lineatus and Agriotes obscurus were sampled from April until July at a number of sites across 950 ha on Westham Island, British Columbia, Canada. Data were assembled as spatially referenced cumulative trap counts by species and year, and analysed for evidence of aggregation and clustering using spatial analysis by distance indices (SADIE) methodology. Both intraspecific and interspecific association analyses were then carried out. A further set of analyses considered the spatial associations between different sampling dates in 2004. 3. Agriotes lineatus was clustered into patches and gaps at the landscape scale in all 3 years, and A. obscurus showed similar spatial structure in 2002 and 2003. For both species, spatiotemporal stability at the landscape scale was evident. There was also a positive association between the two species in 2 out of the 3 years, suggesting that they were responding in a similar manner to the landscape environment. 4. Synthesis and applications. This study showed that there was substantial temporal stability in the spatial structures of A. lineatus and A. obscurus in non-farmed habitats, and that the two species respond in a broadly similar way to a heterogeneous agricultural landscape. This suggests that models to predict distributions within a landscape could be developed to guide decisions about where to grow vulnerable crops. Identification of the environmental factors that differentiate between clusters and gaps in their spatial distributions may also make it possible to manipulate populations and reduce their impact as pests without recourse to insecticides. Moreover, our results extend the spatial scales over which SADIE statistics have been used, and demonstrate the usefulness of pheromone trapping as a sampling method in addressing ecological questions at a landscape scale. [ABSTRACT FROM AUTHOR]

The persistence and retention of active ingredients in granules of Thimet 15G (phorate 15% by weight), Dyfonate 10G (fonofos 10% by weight), Counter 15G (terbufos 15% by weight), and Furadan 10G (carbofuran 10% by weight) were determined in silt loam and organic muck agricultural soils typical of the lower Fraser River valley (BC, Canada). In June 1995, treatment bags made of polyester cloth (7.5 x 7.5 cm) containing granules of a single insecticide, either alone or with soil, were placed during spring planting in the bottom of the furrow and retrieved periodically until April 1996. The parent component of each insecticide declined monotonically except for carbofuran (logistic decline). In the silt loam (organic muck) soil, the average June-to-October first-order rate constants and half-lives were 0.009 (0.010)/d and 80 (71) d for fonofos, 0.012 (0.009)/d and 58 (82) d for phorate, and 0.032 (0.015)/d and 21 (47) d for terbufos; the half-life of carbofuran was 129 (97) d. By December, the average amounts of fonofos and phorate in silt loam (organic muck) were 26% (range: 17-40%; 14% [range: 3.4-21%]) and 21% (range: 15-30%; 10% [range: 5.0-24%]) of the initial amounts of active ingredients measured at time zero, respectively. By April, the percentages dropped to 16% (range: 7.8-24%; 2.3% [range: 0-7.7%]) and 7.3% (range: 1.9-25%; 0.6% [range: 0-1.9%]). During this period, about 95% of the active ingredients were granule bound, the rest remaining in the bag. Only low levels of terbufos and carbofuran persisted in both soils from December to April of the following year. Results indicate an enhanced probability for poisoning of waterfowl and raptors because of the high levels of active ingredients retained on granules of all four insecticides in both soils in the fall. The risk of acute poisoning by phorate and fonofos continued though the winter. [ABSTRACT FROM AUTHOR]