Alfalfa (Medicago Sativa) is one of the most important forage plants in Iran. Several pests like aphids cause damage to these plants. One of the important aphids is the spotted alfalfa aphid (THERIOAPHIS TRIFOLII). In order to study the genetic variation of this pest, samples were taken from alfalfa fields of different provinces of Iran (Kerman, Fars, Kohkiloieyeh, Lorestan, Hamadan, Kermanshah, Kurdistan, West Azerbaijan, Markazi and Esfahan provinces) during 2007-2009. Seven RAPD primers were used in PCR test. At the range of 200-400 bp., 68 bands out of 88 had polymorphism. The primers A11 and CO4 had the highest polymorphisms that were 77.78 and 73.68 percent respectively. The related dendrogram showed 3 clusters and the second cluster had two sub clusters. In this research genetic differences were seen between collected samples from various regions, but no relationship was observed between these differences and altitudes, longitude, and position of the sampling locations.

Spotted alfalfa aphid (THERIOAPHIS TRIFOLII) is an important pest of alfalfa. For study of proteome response to that aphid feeds, leaf sampling was made of alfalfa (Hamadani genotype) under treatment and control conditions. Leaf tissue proteome analysis identified 208 protein spots detectable in staining by Coomassie blue. Of these, according to t-test, 16 spots were significantly different at 1% (P≤ 0. 01). The protein spots with significant expression changes, were searched by isoelectric point and molecular weight in databases and identified responsive possible proteins to pest stress conditions. Classification of identified proteins based on functional groups, showed that the highest of proteins change have been expressed in relation to stress, including protein disulfide isomerase, aldehyde dehydrogenase, heat shock proteins, polyphenol oxidase and proxiredoxins. The results revealed the activity of alfalfa at the level of protein expression to develop resistance to pest aphid spotted.

Population dynamics of three main alfalfa aphids, namely: pea aphid, Acyrthosiphon pisum (Harris), spotted alfalfa aphid, THERIOAPHIS TRIFOLII forma maculata (Buckton), black alfalfa aphid, Aphis craccivora Koch, and their most abundant predators and parasitoids in three sites and in two subsequent years in Isfahan, Iran, were investigated. The results revealed that frequency and temporal occurrence of alfalfa aphids and their natural enemies in different regions were varied, but aphid natural enemy populations were more or less coincident with aphid populations. Populations of aphids were mainly affected by alfalfa harvesting, ambient temperature, and coccinellid predators. Hemipterous predators in contrast with coccinellids, had little effect on aphid populations. Parasitoids seem to be effective on low populations of alfalfa aphids. Air humidity and rainfall had no effect on populations of alfalfa aphids.

In the current study some information is presented about the distribution and associations between alfalfa aphids and their parasitoids in different regions in 11 provinces of Iran, as well as identification key to the parasitoids. The main aphids were THERIOAPHIS TRIFOLII maculata (Buckton) and Acyrthosiphon pisum (Harris) followed by Aphis craccivora Koch and Acyrthosiphon kondoi Shinji. The distribution pattern of these aphids showed a discrepancy in different regions. THERIOAPHIS TRIFOLII maculata was almost distributed in all studied areas, but A. craccivora mostly distributed in lower regions including the deserts of the east and central parts of Iran. Acyrthosiphon pisum and A. kondoi were mainly occurred inhigher altitude regions.Trioxys complanatus Quilis and Praon exsoletum (Nees) were found to be specific parasitoids of T.TRIFOLII maculata, and collected, with a few exceptions, in all studied regions. The species of Acyrthosiphon were mainly attacked by Aphidius ervi Haliday followed by A. smithi Sharma & Subba Rao and A. eadyi Stary, Gonzalez & Hall. Lysiphlebus fabarum (Marshall) was the common parasitoid of A. craccivora, but Ephedrus persicae Froggatt locally found to show host specificity on this aphid. Praon volucre (Haliday) was occasionally found to attack A. pisum and A. craccivora, but the other parasitoids including Aphidius colemani Viereck, Lysiphlebus confusus Tremblay & Eady and Diaeretiella rapae (McIntosh) were only reared from A. craccivora. Considering the occurrence of alfalfa aphids together with their parasitoids in almost all studied areas, it seems that more attention should be paid to the parasitoids of alfalfa aphids, especially the specific ones, along with other control methods in an integrated pest management programme.

During a two-year (2004-2005) survey of alfalfa aphids and their natural enemies in Isfahan, a total of four aphid species and 58 species of their natural enemies comprised of 45 predatory species, 11 parasitoid species and two species of parasitic mites were collected and identified. Moreover, five hyperparasitoid species were collected. On each sampling date, six 20-sweep samples were taken using a 38cm-diameter sweep-net and also six 20-stem were sampled. The results showed that the mean percent of Hippodamia variegata Goeze, Nabis spp., Deraeocoris spp., Orius spp., Geocoris spp. and aphid parasitoids in strip-harvested field were 38%, 95%, 119%, 57%, 100% and 122%, respectively; higher than those in conventionally-harvested field. In contrast, the mean percent of Acyrthosiphon pisum (Harris) and THERIOAPHIS TRIFOLII (Monell) forma maculata (Buckton) were 24% and 28%, respectively; lower in strip-harvested field than in conventionally-harvested field.

Using water yellow traps, population fluctuation of winged aphids, vector of potatoes viral diseases, has studied in four districts of Hamedan province including Hamedan, Kaboodar ahang, Ghahavand and Assadabad during 1998-2000 period. In this connection, four species belonging to family Aphididae and one species of family Drepanosiphidae were collected. Among vector species THERIOAPHIS TRIFOLII forma maculata (Buckton) with 65-91% of total collected population tored other species in all above mentioned district. The other important species, collected in lower number, were Acyrthosiphon pisum (Harris), Myzus persicae (Sulzer), Macrosiphom euphorbiae (Thomas) and Aphis frangullae gossypii (Glover). Kaboodarahang with lowest population of aphid vectors and shortest period of aphid presence in potato fields considered as the most suitable region and Hamedan district owing to high vector population and longest presence of aphids in fields showed to be the most unsuitable site for basic seed potato production the other two districts are evaluated as intermediary to two above-mentioned regions.