Environmental Entomology (2014) 43, 1542-1551

Mohammad Reza Nematollahi, Yaghoub Fathipour, Ali Asghar Talebi, Javad Karimzadeh and Myron Philip Zalucki (2014)
Parasitoid- and hyperparasitoid-mediated seasonal dynamics of the cabbage aphid (Hemiptera: Aphididae)
Environmental Entomology 43 (6), 1542-1551
Abstract: The population dynamics of the cabbage aphid, Brevicoryne brassicae (L.), its parasitoid, Diaeretiella rapae McIntosh, and hyperparasitoids, Pachyneuron spp., were quantified under field conditions during 2011–2013, by examining synchronization, parasitoid: aphid ratio, possible effect of density on the finite rate of increase, and spatial coincidence. The rates of parasitism and hyperparasitism were based on rearing field-collected mummies and live parasitized aphids, and density of the aphid were estimated using heat extraction and subsampling techniques. Only one parasitoid, D. rapae (80% on average), and two hyperparasitoid species from the genus of Pachyneuron (6.5% on average), namely Pachyneuron aphidis (Bouché) and Pachyneuron groenlandicum (Holmgren), were reared from the aphid mummies. Significant Pearson's time lagged correlations for percentage parasitism versus aphid density and for percentage hyperparasitism versus mummy density indicated that 2–3 wk is needed for D. rapae and Pachyneuron spp. to show impact on their respective host's population. In early spring, the parasitoid: aphid ratio was low (0.11 on average) while aphid density was increasing. Based on Taylor's power law, D. rapae and Pachyneuron spp., as well as B. brassicae, had an aggregated distribution among canola plants. Moreover, a high degree of spatial overlap was found between D. rapae and B. brassicae and between Pachyneuron spp. and D. rapae. In general, the parasitoid had good spatial coincidence with its aphid host but because of a lack of parasitoid-host synchronization and low parasitoid: aphid ratio, impact on the host population was low.
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Link to article at publishers website
Database assignments for author(s): Yaghoub Fathipour, Ali Asghar Talebi, Myron P. Zalucki, Javad Karimzadeh

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
population dynamics/epizootiology
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Brevicoryne brassicae
Diaeretiella rapae (parasitoid)	Brevicoryne brassicae