BioControl (1999) 44, 403-419

James R. Fuxa and Arthur R. Richter (1999)
Classical biological control in an ephemeral crop habitat with Anticarsia gemmatalis nucleopolyhedrovirus
BioControl 44 (4), 403-419
Abstract: Anticarsia gemmatalis nucleopolyhedrovirus(AgNPV) was released as a single spray in soybean at two sites in Louisiana, near Crowley and BatonRouge, after which viral prevalence and populationdensity were monitored for 3--4 years. Each site hada plot with no treatment (control) and twovirus-treated plots, one planted with soybean yearlyfor 3--4 years, and the other planted with soybeanfor 3--4 years except for rotation to a differentcrop in year 2. In year 1, the single spray ofAgNPV resulted in viral prevalence rates rangingfrom 25--100% A. gemmatalis mortality overthe entire growing season. By the end of thisseason, viral accumulation in soil averaged 4.1 ×10⁴ occlusion bodies (OB)/g at Crowley and 7.4× 10³ OB/g at Baton Rouge, which had a sandiersoil than Crowley. At Crowley, prevalence of AgNPVreached 49% insect mortality in the unrotated plotin year 2, and 31% in the rotated plot and 38% inthe unrotated plot in year 3, in spite of moderateto low population densities of A. gemmatalis. At Baton Rouge, AgNPV prevalence decreased to peakprevalence rates of 25% insect mortality in year 2,4% in year 3, and 11% in year 4, even though A. gemmatalis population densities were moderate inyears 2 and 3. Viral concentration in soildecreased to 2.7 × 10² OB/g (rotated plot) and1.4 × 10⁴ OB/g (unrotated plot) by the end ofyear 3 at Crowley and to 10 OB/g (rotated plot) and31 OB/g (unrotated plot) by the end of year 4 atBaton Rouge. In forward stepwise multipleregressions, the concentration of OB in soil wassignificantly (p = 0.0001) and positively correlatedwith AgNPV prevalence, but correlations of the latter parameter with host population densityand rainfall were not significant (p > 0.05). Prevalence rates of the fungal entomopathogen Nomuraea rileyi were significantly (p < 0.01) andnegatively correlated with AgNPV prevalence atCrowley but not in the combined data set. Prevalence of N. rileyi was negativelycorrelated (p = 0.0001) with precipitation andpositively correlated (p = 0.0001) with A.gemmatalis population density. The researchdemonstrated that AgNPV can be introduced andestablished for long-term suppression of A.gemmatalis in an ephemeral crop habitat, butcertain site-related conditions, perhaps relating tosoil, are necessary for its continued success.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
classical biocontrol/new introduction

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Anticarsia gemmatalis	Soybean (Glycine max)	U.S.A. (mid S)
Alphabaculovirus angemmatalis (entomopathogen)	Anticarsia gemmatalis	Soybean (Glycine max)	U.S.A. (mid S)