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Insects 2012, 3(4), 989-1000; doi:10.3390/insects3040989
Article

Transmission of a Gammabaculovirus within Cohorts of Balsam Fir Sawfly (Neodiprion abietis) Larvae

1
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 and 1,2,*
Received: 17 September 2012; in revised form: 27 September 2012 / Accepted: 1 October 2012 / Published: 19 October 2012
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Abstract: Nucleopolyhedroviruses (NPV: Gammabaculovirus: Baculoviridae) of diprionid sawflies (Diprionidae: Hymenoptera) are highly host specific and only infect the midgut epithelium. While still alive, infected sawfly larvae excrete NPV-laden diarrhea that contaminates food sources. The diarrhea can then be consumed by conspecific larvae, resulting in rapid horizontal transmission of the virus. To better understand the efficacy of Gammabaculovirus-based biological control products, the horizontal spread of such a virus (NeabNPV) within cohorts of balsam fir sawfly (Neodiprion abietis) larvae was studied by introducing NeabNPV-treated larvae into single-cohort groups at densities similar to those observed during the increasing (field study) and peak (laboratory study) phases of an outbreak. In field studies (~200 N. abietis larvae/m2 of balsam fir (Abies balsamea) foliage), NeabNPV-induced mortality increased positively in a density-dependent manner, from 23% (in control groups) to 51% with the addition of one first-instar NeabNPV-treated larva, to 84% with 10 first–instar-treated larvae. Mortality was 60% and 63% when one or 10 NeabNPV-treated third-instar larva(e), respectively, were introduced into groups. Slightly higher levels of NeabNPV-induced mortality occurring when NeabNPV-treated larvae were introduced into first- rather than third-instar cohorts suggests that early instars are more susceptible to the virus. In the laboratory (~1330 N. abietis larvae/ m2 of foliage), NeabNPV-caused mortality increased from 20% in control groups to over 80% with the introduction of one, five or 10 NeabNPV-treated larvae into treatment groups of first-instar larvae.
Keywords: Gammabaculovirus; Neodiprion abietis; nucleopolyhedrovirus; balsam fir sawfly; Abies balsamea; disease transmission; pest management Gammabaculovirus; Neodiprion abietis; nucleopolyhedrovirus; balsam fir sawfly; Abies balsamea; disease transmission; pest management
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Graves, R.; Quiring, D.T.; Lucarotti, C.J. Transmission of a Gammabaculovirus within Cohorts of Balsam Fir Sawfly (Neodiprion abietis) Larvae. Insects 2012, 3, 989-1000.

AMA Style

Graves R, Quiring DT, Lucarotti CJ. Transmission of a Gammabaculovirus within Cohorts of Balsam Fir Sawfly (Neodiprion abietis) Larvae. Insects. 2012; 3(4):989-1000.

Chicago/Turabian Style

Graves, Roger; Quiring, Dan T.; Lucarotti, Christopher J. 2012. "Transmission of a Gammabaculovirus within Cohorts of Balsam Fir Sawfly (Neodiprion abietis) Larvae." Insects 3, no. 4: 989-1000.


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