Mortality and infection of wireworm, Agriotes obscurus [Coleoptera: Elateridae], with inundative field applications of Metarhizium anisopliae

In an attempt to cause fatal infection of wireworm Agriotes obscurus [Coleoptera: Elateridae], Metarhizium anisopliae was applied in the field as factorial combinations of conidia formulated as granules at 3.68 g granules or 1.25 x 1010 cfu per 196 cm2 (6.38 x 107 conidia cm-2), as conidia mixed with soil at 1.26 x 1010 cfu per 2.986 cm3 soil (4.22 x 106 conidia cm-3 soil), and as conidia-coated wheat seed (100 wheat seeds or 4.16 x 109 cfu per 196 cm2 = 2.12 x 107 conidia cm-2). The treatments resulted in a significantly greater number of mycosed wireworms compared with the control over and during five sampling periods. Significant differences in total wireworm mortality and mycosed wireworms in the field occurred at any time ranging from 15 to 82 d following treatment. The treatments also caused a reduction in the number of wireworms found in the cores, implying that they had a repellent effect. Latent infection of wireworms became apparent after living wireworms from the field treatments died following incubation under laboratory conditions, in numbers significantly greater than the control. This study showed that M. anisopliae can be applied in the field and infect and kill wireworms, but only at concentrations exceeding 4 x 106 conidia cm-3 with the subject isolate, wireworm species, and field conditions used in this study.Dans une tentative d'infecter mortellement le ver fil de fer Agriotes obscurus [Coleoptera: Elateridae], le Metarhizium anisopliae a été appliqué au champ selon des combinaisons factorielles d'une formulation granulaire de conidies à 3,68 g de granules ou 1,25 x 1010 ufc par 196 cm2 (6,38 x 107 conidies cm-2), de conidies mélangées à du sol à 1,26 x 1010 ufc par 2,986 cm3 de sol (4,22 x 106 conidies cm-3 de sol) et de graines de blé enrobées de conidies (100 graines de blé ou 4,16 x 109 ufc par 196 cm2 = 2,12 x 107 conidies cm-2). Pendant cinq périodes d'échantillonnage, un nombre significativement plus grand de vers fil de fer mycosés a été observé pour les traitements comparativement au témoin. Des différences significatives en termes de mortalité totale des vers fil de fer et de vers fil de fer mycosés au champ sont apparues à toutes les périodes, variant de 15 à 82 j après le traitement. Les traitements ont aussi réduit le nombre de vers fil de fer trouvés dans le cylindre central, ce qui indique qu'ils ont eu un effet répulsif. L'infection latente des vers fil de fer s'est manifestée lorsque des spécimens vivants provenant des traitements au champ sont morts après incubation en laboratoire, en nombres significativement plus élevés que ceux provenant du témoin. Les résultats démontrent que le M. anisopliae peut être utilisé au champ et peut infecter et tuer les vers fil de fer, mais seulement à des concentrations excédant 4 x 106 conidies cm-3 en utilisant l'isolat, le ver fil de fer, ainsi que les conditions décrites dans la présente étude

Effect of Collection Month, Visible Light, and Air Movement on the Attraction of Male Agriotes obscurus L. (Coleoptera: Elateridae) Click Beetles to Female Sex Pheromone

Elaterid female sex pheromone, while currently used for monitoring the adult life stage (click beetle), has only recently been explored as a potential management tool. Consequently, there is little understanding of how abiotic and biotic conditions influence the response of click beetles to the pheromone. We examined whether the response of male Agriotes obscurus L. (Coleoptera: Elateridae) beetles to a cellulose-based formulation of female sex pheromone (‘pheromone granules’) is influenced by air movement, presence of visible light, and month of beetle collection. In addition, we investigated the distance from which beetles were attracted to the pheromone granules. Click beetle response was determined by measuring movement parameters in free-walking arena experiments. The response to pheromone was not affected by the presence or absence of visible light. We found that beetles collected earlier in the season had increased activity and interaction with pheromone under moving air conditions, compared to beetles collected later. When controlling for storage time, we confirmed that individuals collected in May were less active than beetles collected in March and April. In the field, beetles were recaptured from up to 14 m away from a pheromone granule source, with over 50% being recovered within 4.4 h from a distance of 7 m or less. Understanding how abiotic and biotic factors affect pest response to pheromone can lead to more effective and novel uses of pheromone-based management strategies

Survival of male click beetles, Agriotes obscurus L., (Coleoptera:Elateridae) during and after storage at different temperatures

Volume: 105Start Page: 113End Page: 11

Biogeography and genotypic diversity of Metarhizium brunneum and Metarhizium robertsii in northwestern North American soils

The biogeography and genotype diversity of Metarhizium species in northwestern North American soils was examined; twenty ecoregions were sampled, including 58 agricultural and 80 natural habitat subsites, and areas that were glaciated during the Pleistocene epoch. One hundred and twenty nine isolates of M. brunneum, 26 isolates of M. robertsii, four isolates of M. guizhouense, one isolate of M. flavoviride, and 55 isolates of Beauveria were recovered. Metarhizium and Beauveria species were isolated in diverse ecoregions within the study area, but a trend for increased isolation of Metarhizium species in western regions of the study area was observed. Consistent with this observation, the prevalence of M. brunneum and M. robertsii decreased at higher elevations, and the opposite was true for Beauveria. Both M. brunneum and M. robertsii were more commonly isolated from agricultural and natural habitat subsites, and considerable genotypic diversity was observed in both habitats and within the same subsite. Metarhizium robertsii but not M. brunneum was more commonly isolated from non-glaciated locations; however, less diversity and richness was observed for M. brunneum recovered from glaciated versus non-glaciated locations consistent with insular biogeography. The study has implications for microbial control strategies in the region.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author