Biocontrol Science and Technology (2013) 23, 79-91

R.S. Oliveira, M.V. Sampaio, S.E. Ferreira, L.C.M. Ribeiro and J. Tannús-Neto (2013)
Low parasitism by Diaeretiella rapae (Hym.: Braconidae) of Lipaphis pseudobrassicae (Hemip.: Aphididae): pre- or post-ovipositional host resistance?
Biocontrol Science and Technology 23 (1), 79-91
Abstract: While the aphid Lipaphis pseudobrassicae (Davis) (Hemip.: Aphididae: Macrosiphini) is considered one of the preferred hosts of Diaeretiella rapae (McIntosh) (Hym.: Braconidae: Aphidiinae) in several parts of the world, field surveys in Uberlandia (Brazil) found parasitism of this aphid to not exceed 10%. This study sought to determine the cause of this low parasitism, as well as the effects of parasitism on the intrinsic growth rate of the aphid population. We evaluated parasitism, percentage emergence, developmental time, longevity, number of attacks and number of parasitoid larvae in L. pseudobrassicae and compared these to the same characteristics in Brevicoryne brassicae (L.) and Myzus persicae (Sulzer). The lowest percentage of parasitism was found in L. pseudobrassicae, followed by M. persicae and B. brassicae. The ratio between the number of parasitoid larvae and the number of ovipositions in L. pseudobrassicae ranged from 0.02 to 0.03, while, in B. brassicae, it was between 0.41 and 0.44 and, in M. persicae, between 0.62 and 0.80, indicating high mortality rates of early stages of D. rapae in L. pseudobrassicae. Parasitism by D. rapae reduced the r_m of L. pseudobrassicae. The r_m for parasitised aphids was only 63% of that for unparasitised aphids. However, no hosts died before reaching adulthood, and 83% of parasitised aphids were still able to reproduce. As a result, the r_m of the aphid was positive, resulting in population growth of L. pseudobrassicae, even among individuals parasitised during the second instar. Our results indicate the existence of L. pseudobrassicae genotypes that are completely resistant to D. rapae.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Marcus Vinicius Sampaio

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Myzus persicae		Brazil (south)
	Brevicoryne brassicae		Brazil (south)
	Lipaphis pseudobrassicae		Brazil (south)
Diaeretiella rapae (parasitoid)	Myzus persicae		Brazil (south)
Diaeretiella rapae (parasitoid)	Brevicoryne brassicae		Brazil (south)
Diaeretiella rapae (parasitoid)	Lipaphis pseudobrassicae		Brazil (south)