Spatial distributions of Cephus cinctus Norton (Hymenoptera: Cephidae) and its braconid parasitoids in Montana wheat fields

Weaver, David K.; Nansen, Christian; Runyon, Justin B.; Sing, Sharlene E.; Morrill, Wendell L.

doi:10.1016/j.biocontrol.2005.04.001

Cited by 46 publications

(48 citation statements)

References 22 publications

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“…At Conrad, 475, 963, and 276 larvae were collected in 2005, 2007, and 2008 In 2005, when only five plants were collected at each sampling plot, the coefficient of variation among samples averaged 65% in the interior plots and 19% at the edge. The higher coefficient of variation in the interior samples is because a few samples contained no larvae, which can happen primarily when lower population levels result in a distribution where most larvae are found on the field periphery Weaver et al 2005). For the remainder of the study, each sample consisted of ten plants and the coefficient of variation among samples within a date and site averaged 19.8% for the edge and 23.1% for the interior.…”

Section: Resultsmentioning

confidence: 99%

“…The parasitism was from two congeneric host-specific ectoparasitoids: Bracon cephi and B. lissogaster. Given that there are no characters available to distinguish between the two species of parasitoids as immatures (Runyon et al 2002;Weaver et al 2005), the level of parasitism reported was pooled for the two braconid species for all analyses. The designation of ''unknown factors'' refers to the observation of a dead larva, but the cause of death could not be readily determined.…”

Section: Methodsmentioning

confidence: 99%

“…Two congeneric parasitoids, the larval idiobionts, Bracon cephi (Gahan) and Bracon lissogaster Muesebeck (Hymenoptera: Braconidae), can suppress WSS populations in wheat in Montana, USA (Morrill 1998;Runyon et al 2002;Weaver et al 2005). These solitary ectoparasitoids attack WSS larvae feeding within various hosts, including feral grasses and cultivated wheat, by inserting their ovipositor through the stem wall to sting and paralyze the endophagous late-instars.…”

Section: Introductionmentioning

confidence: 99%

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Parasitism and the demography of wheat stem sawfly larvae, Cephus cinctus

et al. 2011

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Previous research has suggested that insect herbivores in protected environments have higher mortalities from biotic factors such as parasitism compared to herbivores in less protected situations, although overall mortalities in protected environments are often lower. However, this has not been examined using life table approaches. In this study, we used demographic methods to characterize the mortality dynamics of parasitism for pre-diapause wheat stem sawfly larvae, Cephus cintus Norton (Hymenoptera: Cephidae), a stem-mining wheat pest. Larvae were intensively sampled from commercial wheat fields at two locations in Montana, USA from 2005 through 2008. The feeding larvae present in the summer succumbed to only two mortality categories: parasitism and unknown factors. In Conrad, a location with relatively high densities of the parasitoids, mortality by parasitism was largely irreplaceable. In contrast, in Amsterdam, where parasitism did not occur to any appreciable degree, overall mortality remained relatively low.Keywords Multiple decrement life table Á Mortality risk Á Biological control Á Parasitoid Á Bracon cephi Á Bracon lissogaster

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Parasitism and the demography of wheat stem sawfly larvae, Cephus cinctus

et al. 2011

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“…As a univoltine species that has a short adult flight period and stage-specific oviposition requirements, it is particularly suited for targeted semiochemical intervention. The potential of implementing semiochemical based management that could be readily integrated with innate biological control from endemic, native braconid parasitoids Weaver et al , 2005 ) presents a unique opportunity to manage this chronic, severe pest.…”

Section: Discussionmentioning

confidence: 99%

Behavioural responses of wheat stem sawflies to wheat volatiles

Piesik

Weaver

Runyon

et al. 2008

Agri and Forest Entomology

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Abstract1 Adult wheat stem sawflies Cephus cinctus, pests of cultivated cereals that also infests wild grasses, migrate into wheat fields where they oviposit in elongating, succulent stems.2 Volatiles released by wheat plants at susceptible stages were analyzed to determine potential semiochemical compounds. Seven major compounds were identified and quantified.3 A Y‐tube bioassay was developed to evaluate upwind orientation of adult sawflies in response to an airstream that passed over elongated wheat plants. The bioassay was also conducted with synthetic volatile compounds. The compounds were tested using a range of concentrations spanning those identified in the airstream passing over wheat plants.4 A significant number of adult females were attracted to wheat plants when given a choice of either purified air or the air passing over plants.5 A significant number of female C. cinctus were attracted to (Z)‐3‐hexenyl acetate, β‐ocimene, and (Z)‐3‐hexen‐1‐ol, but were repelled by 6‐methyl‐5‐hepten‐2‐one. Females did not respond to (E)‐2‐hexenal, or (E)‐2‐hexenyl acetate. The behavioural responses were concentration dependent; the highest tested concentration of (Z)‐3‐hexenyl acetate was repellent to females of this species.6 Adult males did not discriminate between air passing over wheat plants and air from a purified airstream. Males did not respond to any tested synthetic compound at any concentration.7 The present study demonstrates for the first time that adult females of wheat stem sawfly display innate behaviours in response to synthetic volatiles. These results provide a basis for the potential development of resistant wheat varieties and for the development of semiochemically‐based pest management.

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“…The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat, Triticum aestivum L, in the northern Great Plains of the United States and the Canada (Weiss et al 1992;Weaver et al 2004;Weaver et al 2005). The annual losses caused by this insect exceeded $25 million in recent years in Montana (Weaver et al 2004;Nansen et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Influence of Fusarium and Wheat Stem Sawfly Infestation on Volatile Compounds Production by Wheat Plants

Piesik¹,

Wenda-Piesik²,

Weaver³

et al. 2009

Journal of Plant Protection Research

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Plants that were infested by the wheat stem sawfly emitted significantly increased amounts of the secondary metabolites linalool, linalool oxide, ß-farnesene, ß-caryophyllene, and 4-heptanone in comparison to uninfested plants. Wheat plants parasitized by Fusarium species also have emitted volatiles. The amount of volatiles released varied by infective species of Fusarium and volatile patterns varied over time for both sawfly infestation and pathogen infection. Plants that were stressed by both herbivory and pathogens emitted even greater amounts of certain volatiles. Surprisingly, larval sawfly mortality was much greater in plants infected by Fusarium species, and both mortality and the rate of volatile release varied by Fusarium. The role of these plant volatiles are further discussed in the context of defensive plant responses to Fusarium and sawfly infestation.

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Spatial distributions of Cephus cinctus Norton (Hymenoptera: Cephidae) and its braconid parasitoids in Montana wheat fields

Cited by 46 publications

References 22 publications

Parasitism and the demography of wheat stem sawfly larvae, Cephus cinctus

Parasitism and the demography of wheat stem sawfly larvae, Cephus cinctus

Behavioural responses of wheat stem sawflies to wheat volatiles

Influence of Fusarium and Wheat Stem Sawfly Infestation on Volatile Compounds Production by Wheat Plants

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