New Zealand Journal of
Agricultural Research abstracts
Host stage preference and
reproductive fitness of Aphidius
eadyi (Hymenoptera: Aphidiidae)
on Acyrthosiphon pisum
(Hemiptera: Aphididae)
X. Z. He
Q. Wang
Institute of Natural Resources
Massey University
Private Bag 11 222
Palmerston North, New Zealand
email: q.wang@massey.ac.nz
D. A. J. Teulon
New Zealand Institute for Crop
& Food Research Ltd
Private Bag 4704
Christchurch, New Zealand
Abstract Host
stage preference by Aphidius
eadyi
Starý, González &
Hall on pea aphid, Acyrthosiphon
pisum (Harris), and its effects
on the reproductive fitness of A.
eadyi, were studied in the
laboratory at 20 ± 1°C and RH 60–70% with a
photoperiod of 16 h light:8 h dark. Aphidius
eadyi females
accepted aphids of all stages
but preferred fourth instar nymphs and adults for oviposition. Females
developed increasingly faster with the increase of host stages, and
males developed faster than females in all host stages. The sex ratio
of resulting parasitoids was close to 1:1 from all host stages. The egg
load and body size of A. eadyi
progeny at emergence increased with increasing host stage at the time
of parasitisation. The host stage had non-linear relationships with the
number of eggs laid and aphids parasitised by A.
eadyi, and the body size of its
resulting progeny. Both host stage and body size of resulting
parasitoid progeny affected the egg load of newly emerged parasitoids
but the latter had more effect. The fourth instar aphids appeared to be
the most appropriate hosts for the mass-rearing programme because they
gave the best fitness return for the parasitoids. The field release of
parasitoids may be better timed when fourth instar aphids are the most
abundant because aphids parasitised at this stage produce few progeny.
Keywords Hymenoptera;
Aphidius eadyi; host stage;
preference; fitness; pea aphid; Acyrthosiphon
pisum
A04011; Received 11 February
2004; 15 November 2004; Online publication date 21 March 2005
New Zealand Journal of
Agricultural Research, 2005, Vol. 48:
157–163
0028–8233/05/4801–0157 © The Royal Society of New Zealand 2005
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