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Abstract
SUMMARY
Aphids are considered among the most serious insect pests of different plants world wide including Egypt . Many species are common as major pests attacking ornamental plants . The economic importance of aphids is attributed to their high reproductive potential and their ability to transmit plant pathogenic viruses ( vectors ).
Nowadays, the ornamental plants are expected to play an important role in increasing the national income. So many new areas are cultivated , which suffer from the attack of several pests among them aphids.
1- ECOLOGICAL STUDIES :
Survey of aphid species was conducted as an essential work to determine the different aphid species infesting 19 kinds of ornamental plants in the public Alexandria gardens (Antoniadis Montazah and EL-Maamoura) and Saba Basha’s garden of the faculty of Agriculture to study some ecological aspects . This survey was carried out through the period from March 2002 to August 2004 under natural field conditions. it is worth mentioning that the population dynamics of aphids depend on the geographical region.
1.1. Survey of aphid species infesting ornamental plants :
The taxonomic survey revealed that a total of fourteen aphid species representing eight genera belonging to tow subfamilies (Aphidinae with thirteen species and Lachninae, respectively belonging to super family, Aphidoidea were collected and identified on different ornamental plans. However, as shown in the systematic position the genus Aphis occurred by five species and each of genus Hyalopaterus and Macrosiphum represented by tow species for each one.
1. Aphis citricola : The green citrus aphid , is among the polyphagous aphid species with high distribution with high populations during spring and summer seasons. It was on four ornamental kinds with large numbers .
2. A. craccivora : The cowpea aphid or black legume aphid or groundnut aphid, is a polyphagous species and ranked the most distribution with high populations on paper flower plants (Bougainvillea spp.) in spring . It was found in moderate and low number on four kinds of ornamental plants .
3. A. gossypii: The cotton aphid or melon aphid , is also polyphagous species . was found in small colonies on three ornamental plant species , i.e. in bark tree (Cassia nodosa) and occurred in high numbers during spring and summer seasons on Myoporum pictum .
4. A. nerii: The oleander aphid , occurred with high colonies as a monophagous species on Nerium oleander all year round throughout the present investigation .
5. A punicae: The duranta aphid or pomegranate aphid , is also polyphagous species. It was found in different criteria of population densities on three ornamental plant species , i.e. in small population on Coleus blumei and Acalypha wilkesiana during spring , while this aphid species infested Duranta Spp. All year round .
6. Hyalopterus pruni : The plum aphid , occurred in high populations on bamboo