Three species of wireworms (Coleoptera: Elateridae) known to cause severe damage to potatoes in Europe and Asia have been introduced to Canada and are now well established as pests in the westernmost ...province of British Columbia (BC) (
Agriotes obscurus
and
A. lineatus
) and the eastern provinces of Nova Scotia and Prince Edward Island (
A. obscurus
,
A. lineatus
and
A. sputator
). Conventional insecticide-based efforts to control these invasive pests have had serious environmental impacts, or are failing to prevent severe economic damage from occurring to potatoes in some key potato production areas. Research toward developing an IPM programme for these exotic species has been completed or is underway in Canada, including the following: biological and ecological studies, development of monitoring and risk assessment programmes, and development of insecticidal and alternative control strategies. This research is summarized and implications for wireworm management in Europe are discussed. In addition to wireworms, one of the primary economic insect pests of potatoes in BC is the tuber flea beetle,
Epitrix tuberis
(Coleoptera: Chrysomelidae). The larvae of this beetle feed on developing or mature daughter tubers, producing surface channels or tracks and holes directly into the tuber. In the past, growers would apply 7–10 foliar sprays of broad-spectrum insecticides per growing season, which was not always successful in controlling this pest. In the EU, a newly identified flea beetle,
Epitrix papa
sp. n., as well as the North American species,
E. cucumeris
, have been identified as attacking potatoes initially in Portugal (2004) and later also in Spain. The potential spread of these emergent pests to various EU and non-EU countries is of concern, and if established would require the development of management strategies. The former development of a highly effective IPM programme developed in BC for
E. tuberis
is discussed, as is its potential for
E. papa
and
E. cucumeris
management in Europe.
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.
Performance and distribution of phytophagous insects are driven by direct and indirect competitive interactions. Plant-feeding arthropods have been shown to interact indirectly through the plants' ...response to herbivory. In the case of systemically induced plant responses, this interaction extends to herbivores inhabiting different parts of a plant, for example, above- and belowground herbivores. Plant-induced responses elicited by root herbivores have been shown to affect feeding and development of aboveground herbivores. However, little is known about how root feeding affects host choice behavior of aboveground herbivores, including both adult oviposition behavior and larval host acceptance. Here, we report that root feeding by the wireworm, Agriotes lineatus, influences oviposition decisions and larval leaving rate of an aboveground herbivore, Spodoptera littoralis. In choice experiments, female S. littoralis deposited more and larger egg batches on undamaged plants when compared with wireworm-infested plants. In a larval feeding experiment, a higher percentage S. littoralis larvae moved away from the wireworm-infested plant onto a neighboring undamaged plant as compared with larvae feeding on previously undamaged plants. Larvae did not show an increased tendency to leave when feeding on plants previously exposed to conspecific larvae. Our results show that indirect interactions between belowground and aboveground herbivores extend to behavioral avoidance, both in terms of oviposition and larval feeding decisions. This allows the foliar herbivore to avoid systemic plant responses elicited by root herbivory, which likely represent reduced food quality and increased apparency toward natural enemies.
The present work describes the immune response of wireworm larvae, Agriotes lineatus (L.) (Coleoptera: Elateridae) when challenged with two species of entomopathogenic nematodes, Steinernema feltiae ...(Filipjev) (Strongyloidea: Steinernematidae) and Heterorhabditis bacteriophora (Poinar) (Rhabiditoidea: Heterorhabditidae). Two main immunological processes including cellular and humoral reactions have been addressed. Total haemocyte counts after infection with H. bacteriophora increased quickly in initial times, but decreased over time post-injection (at 12 and 16 h). Instead, haemocyte numbers after infection with S. feltiae was unchanged in the early stage, but significantly decreased until 16 h post-injection. Plasmatocytes and granulocytes showed more significant changes compared to other haemocytes. The encapsulation response to parasites was significantly different against two nematode species. Particularly, S. feltiae was almost unrecognized by host haemocytes (5.85 % of encapsulated parasites). Assays with H. bacteriophora showed 23.5 % of encapsulated nematodes. From 8 to 12 h after H. bacteriophora infection, an increase in phenoloxidase activity was detected, while in the larvae injected with S. feltiae the enzymatic activity decreased gradually reaching the lowest level 16 h post-injection. This is the first report on the modulation of immune response of wireworm larvae after infection with entomopathogenic nematodes.
The wireworm Agriotes lineatus (L.) (Coleoptera: Elateridae) is a serious agricultural pest of various vegetables and fruits throughout the world. To find an effective and safe biological control ...agent against this pest, we investigated the bacterial flora of A. lineatus. Nineteen different bacterial strains were isolated and identified as Paenibacillus sp. (Ag1), Cellulomonas sp. (Ag2), Bacillus subtilis (Ag3), Staphylococcus sp. (Ag4), Enterococcus mundtii (Ag5), Staphylococcus sp. (Ag6), Sphingobacterium sp. (Ag7), Staphylococcus pasteuri (Ag8), Arthrobacter gandensis (Ag9), Bacillus sp. (Ag10), Chryseobacterium sp. (Ag11), Streptomyces sp. (Ag12), Oerskovia turbata (Ag13), Bacillus thuringiensis (Ag14), Pseudomonas fluorescens (Ag15), Oerskovia jenensis (Ag16), Arthrobacter gandavensis (Ag17), B. thuringiensis (Ag18), and Pseudomonas plecoglossicida (Ag19) based on conventional and molecular tests. A. gandavensis and P. plecoglossicida were isolated for the first time from any insect. The insecticidal effects of these 19 bacterial isolates and the additional 11 isolates belonging to Bacillus genus isolated from different hosts were tested on third instar larvae of A. lineatus. Ag17 (A. gandavensis), Ag18 (B. thuringiensis), and Ag19 (P. plecoglossicida) from the bacterial flora of A. lineatus, and two Bacillus isolates (Bacillus circulans Ar1 from Anoplus roboris and B. thuringiensis subsp. kurstaki BnBt from Balanicus nucum) showed 100% mortality 10 days after treatment. Our results indicate that the bacterial isolates tested in this study may be considered as a possible microbial control agent against A. lineatus.
► Nineteen bacterial strains from Agriotes lineatus were isolated and identified. ► Virulence of A. lineatus and different Bacillus isolates was tested on A. lineatus. ► Arthrobacter gandavensis, Bacillus thuringiensis and Pseudomonas plecoglossicida caused 100% mortality. ► Among Bacillus isolates, Bacillus circulans and B. thuringiensis caused 100% mortality. ► Some strains showed potential for biological control.
We determined that spinosad interacts synergistically with the biocontrol agent Metarhizium anisopliae (Metch) Sorokin to increase the mortality of two wild-collected wireworm species, Agriotes ...lineatus (L.), and Agriotes obscurus (L.). Bioassays were performed using a M. anisopliae isolate originally acquired from a local wireworm cadaver. M. anisopliae was applied as a soil drench at 3.3 102 and 104 conidia per gram sand, respectively. Soil drenches also were prepared using a commercial formulation of the actinomycete toxins spinosyn-A and spinosyn-D (common name spinosad) at sublethal doses of 1.5, 3, and 6 ppm active ingredient per gram sand. Combined treatments of spinosad and M. anisopliae were synergistic in causing mortality for all spinosad concentrations. Wireworm feeding activity was reduced after exposure to both spinosad and M. anisopliae and was found to be concentration dependent. The high mortality and reduced rate of wireworm feeding suggest that spinosad and M. anisopliae treatment combinations should be tested in the field.
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.
Wireworms, the subterranean larval stage of click beetles (Coleoptera: Elateridae), are an important pests of potatoes throughout the world. Laboratory assays were done to identify virulent strains ...of entomopathogenic nematodes (EPN) and fungi against wireworm,
Agriotes lineatus (L.) (Coleoptera: Elateridae). A fungus,
Metarhizium anisopliae (Metsch), Sorokin strains V1002 and LRC181A, caused 90 and 100% mortality of
A. lineatus, 3 weeks post-inoculation. Other
M. anisopliae strains caused mortality ranging between 10 and 70%, whereas strains of
Beauveria bassiana (Balsamo) Vuillemin and
Paecilomyces fumosoroseus (Wize) were non-pathogenic to
A. lineatus. The EPN,
Heterorhabditis bacteriophora Poinar strain UWS1, caused significantly greater mortality (67%) to
A. lineatus than other EPN species (0–50%), 3 weeks post-inoculation. The organophosphate insecticide Mocap 10G gave 100% control. The present results suggest that
M. anisopliae strain V1002 has considerable potential for the control of the wireworm tested.
Competition and herbivory are two major factors that can influence plant growth and plant defence. Although these two factors are often studied separately, they do not operate independently. We ...examined how aboveground herbivory by beet armyworm larvae (Spodoptera exigua) and belowground herbivory by wireworms (Agriotes lineatus) influenced competition between the plant species Jacobaea vulgaris and Leucanthemum vulgare exposed to three competition levels (no, intra-, and interspecific competition). In addition, we studied the effects of herbivory and competition on pyrrolizidine alkaloid (PA) concentrations in leaves of J. vulgaris. For J. vulgaris, aboveground herbivory significantly reduced shoot biomass while belowground herbivory increased root biomass. Biomass of L. vulgare was not affected by herbivory. Competition caused a reduction in biomass for both plant species, but herbivory did not affect the outcome of the competition. However, competition significantly influenced the amount of leaf damage experienced by the plants. A L. vulgare plant had significantly less damage from aboveground herbivores when grown together with J. vulgaris than when grown alone or in intraspecific competition, while a J. vulgaris plant experienced lowest damage in conditions of intraspecific competition. The total PA concentration in J. vulgaris leaves was highest for plants exposed to interspecific competition. Root herbivory caused an increase in the relative concentration of N-oxides, the less toxic form of PAs, in leaves of plants that were grown without competition, but a decrease in plants exposed to competition. Our study shows that competition and herbivory but also the type of competition and whether herbivory occurs above- or belowground, all influence plant performance. However, overall, there was no evidence that herbivory affects plant–plant competition.
Konkurrenz und Herbivorie sind zwei wichtige Faktoren, die das Pflanzenwachstum und die pflanzliche Verteidigung beeinflussen. Auch wenn die beiden Faktoren oft getrennt untersucht werden, wirken sie nicht unabhängig voneinander. Wir untersuchten, wie oberirdische Herbivorie durch Zuckerrübenraupen (Spodoptera exigua) und unterirdische Herbivorie durch Schnellkäferlarven (Agriotes lineatus) die Konkurrenz zwischen Jacobaea vulgaris und Leucanthemum vulgare beeinflussten, die drei Konkurrenzszenarien ausgesetzt waren: keine Konkurrenz, intra- und interspezifische Konkurrenz). Zusätzlich untersuchten wir die Effekte von Herbivorie und Konkurrenz auf die Konzentrationen von Pyrrolizidinalkaloiden (PA) in den Blättern von J. vulgaris. Bei J. vulgaris reduzierte oberirdische Herbivorie signifikant die oberirdische Biomasse, während unterirdische Herbivorie die Wurzelbiomasse erhöhte. Die Biomasse von L. vulgare wurde durch Herbivorie nicht beeinflusst. Konkurrenz führte bei beiden Pflanzenarten zu einer Reduktion der Biomasse, aber die Herbivorie beeinflusste nicht das Ergebnis der Konkurrenz. Indessen beeinflusste die Konkurrenz signifikant das Ausmaß der Blattschäden an den Pflanzen. Eine Leucanthemum vulgare-Pflanze erlitt signifikant geringere Schäden durch oberirdische Herbivoren, wenn sie zusammen mit J. vulgaris wuchs, als wenn sie allein oder zusammmen mit Artgenossen wuchs, während eine J. vulgaris-Pflanze den geringsten Schaden bei intraspezifischer Konkurrenz erlitt. Die gesamte PA-Konzentration in den Blättern von J. vulgaris war am höchsten bei Pflanzen in interspezifischer Konkurrenz. Wurzelfrass verursachte eine Zunahme der relativen Konzentration von N-Oxiden, der weniger toxischen Form der PA, in Blättern von Pflanzen, die ohne Konkurrenz wuchsen, aber eine Abnahme bei Pflanzen unter Konkurrenzbedingungen. Unsere Untersuchung zeigte, dass Konkurrenz und Herbivorie, aber auch der Typ der Konkurrenz und ob die Herbivorie ober- oder unterirdisch erfolgte, die Wuchsleistung der Pflanzen beeinflusste. Indessen gab es keinen Hinweis auf einen Effekt der Herbivorie auf die Konkurrenz zwischen Pflanzen.
1
The range of attraction of YATLOR pheromone traps was studied to gain information on the number of traps needed for mass trapping of males of two Agriotes species.
2
Male click beetles of the ...species Agriotes lineatus (L.) and Agriotes obscurus (L.) (25–30 individuals per release point) were marked and released at a distance of 2, 5, 10, 15, 20 and 60 m from a pheromone trap both along and opposite to the known prevailing wind direction. Traps were regularly inspected over approximately 1 month. The percentage of recaptured beetles was calculated and analyzed using analysis of variance. Maximum sampling ranges and effective sampling areas were calculated.
3
Averaged over all five trials and distances, approximately 40% of the released beetles (A. lineatus and A. obscurus) were recaptured. The percentage recapture of male adults was significantly affected by release distance, whereas no differences were found for species and release direction.
4
Males were recaptured from all release points and the percentage recapture decreased (in part significantly) with increasing distance from 76% (2 m) to 35% (15 m) and 9% (60 m), respectively. Most of the beetles were recaptured within the first 3 days after release, independent of the distance, except 60 m. The effective sampling area for A. lineatus was 1089 m2 after 12 days and increased to 1735 m2 after 30 days. Corresponding values for A. obscurus were considerably higher: 1518 m2 for 12 days and 2633 m2 for 30 days.
5
We conclude that the range of attraction of the pheromone traps for A. lineatus and A. obscurus is comparatively low, providing high percentage recapture only for release distances up to 10 m. Accordingly, any approach targeted on preventing mating by male mass trapping would require a dense network of pheromone traps.
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