Seasonal abundance of the oleander aphid, Aphis nerii Boyer de
Fonscolombe and its associated parasitoids on duranta plants were studie in
Zagazig and Mansoura during the three seasons 2004/05, 2005/06 and
2006/07. Obtained data revealed that:
A. nerii infestation of duranta started by late September and early
October, respectively. It continued to late March in the three season. The
aphid numbers ranged between 10.88-48.04, 9.40-38.16 and 8.44-39.52
individuals/leaf, respectively in Zagazig during the three seasons. While, in
Mansoura the infestation started earlier in the first half of September. It
continued to early March. The aphid numbers ranged between 16.08-52.16,
15.72-37.56 and 14.00-41.00 individuals/leaf, respectively during the three
seasons.
In Zagazig, the aphid abundance showed three peaks in the three
seasons of study. The mean numbers of aphids/leaf was 25.64, 25.04 and
22.75, respectively during the three seasons, meanwhile in Mansoura the
aphid abundance showed three peaks in first season, four peaks in second
season and two peaks in third seasons. The mean numbers of aphids/leaf
were 26.63, 24.91 and 24.83, respectively during the three seasons.
Five hymenopterous parasitoids, Diaeretiella rapae (M`Intosh),
Aphidius sp. (Aphidiidae), (primary parasitoids) Pachyneuron sp.
(Pteromalidae), Alloxysta sp. (Cynipidae) and Aphidencyrtus sp.
(Encyrtidae) (Hyper parasitoids) were recorded..
D. rapae was the most dominant one, where it occupied 86.68 and
79.57 %, while, Aphidius sp. was 13.32 and 20.43 % in Zagazig and
Mansoura, respectively during the three seasons of study.
Pachyneuron sp. occupied 52.13, 61.62 %, while Aphidencyrtus sp.
was 26.95, 21.4% and Alloxysta sp. was 20.92 and 16.97 % in Zagazig and
Mansoura, respectively during the three season of study.
Total means of parasitism rates of primary parasitoids; D. rapae and
Aphidius spp. were 9.77, 8.69, 12.66 % and 3.39, 7.32, 7.34 % in Zagazig
and Mansoura during the three seasons, respectively.