The leaf nitrogen content is generally accepted as an indicator of food quality and as a factor affecting host selection by phytophagous insects. The alate pea aphids (ACYRTHOSIPHON PISUM Harris, Aphididae) were given a choice among non-nodulated pea plants (PISUM sativum L.) supplied with one of four nitrate-N levels (0, 3, 15 and 30 mM). When whole plants were exposed to aphids for 7 days, the results indicated that the settling response of alatae, and subsequently the reproduction of alighted aphids, increased as the level of N supply or the concentration of total soluble nitrogen of the leaves increased, with the exception of the highest N supply (30 mM N). However, the density of settled alatae (in terms of number per unit leaf area) increased as the level of N supply decreased, being greatest on N-deficient plants (0 mM N treatment) and lowest density on N-sufficient (15 mM N) and N-excess (30 mM N) plants. In a free-choice experiment, equal-sized leaf discs taken from the different N treatments were exposed to alate adults for 24 h. The settling response of aphids was positively affected by leaf colour (yellowing), with the greatest number settled on yellow leaf discs (N-deficient plants) and fewest settled on green or dark-green discs (N-sufficient and N-excess plants). Relationships between level of N supply, total soluble nitrogen concentration, total chlorophyll concentration, plant growth parameters and aphid abundance (number of alatae per plant) or density (number of alatae per unit leaf area, or per leaf disc) were established. The implications of results for integrated aphid management were discussed.

Pathogenicity and virulence of entomogenous fungus, Verticillium lecanii, was studied on the pea aphid, ACYRTHOSIPHON PISUM. Vertalec, a commercial product of V. lecanii, was evaluated under controlled conditions. Second instar nymphs were inoculated with conidial suspensions at concentrations ranging from 104 to 108 conidia/ml, and sterile distilled water (containing wetting agent) as control, then caged on cutted alfalfa stems. Each concentration was replicated three times with 30 aphids treated per replicate. Temperature, relative humidity and photoperiod were maintained at 23±1°C, %97±3, and 16:8 (L:D), respectively. Aphids were monitored daily over 12 days for mortality and nymph production. All newborn nymphs and dead aphids were removed daily. Vertalec significantly increased aphid mortality (mean mortality because of mycosis increased form %45.55±6.93 at 104 conidia/ml to %95.55±4.45 at 108 conidia/ml). The LC50 value for pathogen was 5.14×104 conidia/ml. LT50 values for 105, 106, 107 and 108 conidia/ml were 10, 8, 6.5 and 5 days, respectively. At 104 conidia/ml LT50 value was not determined at experimental period. R0 values significantly decreased with increasing conidial concentration (mean R0 altered from 28.15±5.38 in control to 5.15±1.81 at 108 conidia/ml). Results indicated that vertalec can be an effective agent against pea aphids. Further studies are recommended for its evaluation under natural conditions.    

The pea aphid, ACYRTHOSIPHON PISUM (Harris) is one of the most important pests of pea throughout the world. Host stage preference under choice and no-choice tests and age-specific functional response of Praon volucre (Haliday) parasitizing A. PISUM were investigated. The experiments were carried out under laboratory conditions at 25± 1oC, 60 ± 5% RH and a photoperiod of 14: 10 h (L: D). Functional response of P. volucre was evaluated in adult lifetime at seven host densities (2, 4, 8, 16, 32, 64 and 128).Praon volucrestrongly preferred to oviposit into first and second instar nymphs in both choice and no-choice conditions. Parameter estimation of logistic regression revealed type III functional response for P. volucre in first and second days and type II from third to the end of parasitoid lifetime. The handling time (Th) and searching efficiency (a or b) were estimated using the Rogers equation. The shortest and longest handling times were at fourth day (Th=0.19 ± 0.04) and 8th day (Th=0.94 ± 0.15), respectively. The highest searching efficiency (a) was 0.048 ± 0.007 h-1 on third day and lowest searching efficiency was observed at the end of parasitoid lifetime (6th day-8th days). The maximum attack rate ranged from 126.31 nymphs/24 h on fourth day to 25.53 nymphs/24 h on 8th day. The results of this study revealed that the age of adult parasitoid can change the functional response from type III to type II, indicating that this factormay contribute to stabilization of parasitoid–prey dynamics.

The distribution pattern of pest population is one of the factors not only effects on sampling program and data analysis method, but also can be used to measure the density of pests and their natural enemies. Thus, the spatial distribution pattern of the pea aphid, ACYRTHOSIPHONPISUM Harris (Hem.: Aphididae) and its two major predators, HippodamiavariegataGoeze (Col.: Coccinellidae) and Coccinellaseptempunctata (Linnaeus, 1758) (Col.: Coccinellidae) was inv estigated by different dispersion indices through 2012 and 2013 growing season s. Dispersion pattern was determined by using Taylor's power law, Iwao's patchiness regression method and variance to mean ration test. Obtained results showed an aggregated distribution pattern of pea a phid and lady beetles. Based on R2 and p-value of regression analysis, Iwao's patchiness regression model provided a slightly more adequate description of variance/mean relationships than Taylor's power law. Among the species studied, the pea aphid adults and H. variegatashowed the highest and C. septempunctata showed the smallest coefficients of Taylor's power law respectively. These results provide a reliable basis to develop efficient sampling plans for estimating aphid and their natural enemies populations.

Sophora yellow stunt-associated virus (SYSaV) (Nanovirus, Nanoviridae) is a new nanovirus that recently identified in Iran with wide distribution. In the present study, the SYSaV infection of chickpea (Cicer arietinum L. ), lentil (Lens culinaris Medikus), liquorice (Glycyrrhiza glabra L. ), esfand (Peganum harmala L. ) and milk vetch (Astragalus sp. ) showing typical nanovirus symptoms including dwarfing and yellowing was tested by PCR and full-length sequencing of selected genome components. Results indicated that these samples are infected with SYSaV. In transmission experiments, the capability of cowpea aphid (Aphis craccivora ) and pea aphid (ACYRTHOSIPHON PISUM) to transmit SYSaV to healthy plants was evaluated under greenhouse conditions. While Aphis craccivora transmitted the virus from infected to healthy sophora plants, ACYRTHOSIPHON PISUM collected on naturally infected sophora plants transmitted the virus to sophora, chickpea and cowpea seedlings. Based on the results of this study, beside the main host (sophora), SYSaV is able to infect two other medicinal plants. In addition, the host range of the virus is not limited to the wild species and at least two legume crops are infected with SYSaV.

Prey preference of natural enemies is among the phenomena that should be considered in determining the efficacy of natural enemies. When the predators are faced with a choice between two or more preys, they often show their preference to one from among them. Temperature is one of the environmental factors that can affect insect foraging behavior. Two aphid species namely Aphis fabae and ACYRTHOSIPHON PISUM are of the ability to attack and damage bean plants. Prey preference of Iranian native species Hippodamia variegata as one of the efficient aphid predators, was examined on bean plants and on the two named species of aphids at different temperatures. The experiment was carried out at 15±1oC, 19±1oC, 23±1oC, 25±1oC, and 27±1oC, plus 70±10% of RH, and a photoperiodism state of 16:8 (L:D). Predator preference was analyzed through an application of Manly’s index of preference to the data with statistical analysis showing that at all temperatures for fourth instar larvae, male and female (except 15oC for the fourth instar larvae), A. fabae was preferred to ACYRTHOSIPHON PISUM. This experiment showed that H. variegata does not change its preference in response to temperature and it is assumed that at variable conditions of releasing the same trend be affected.

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.

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.

Cotton aphid, Aphis gossypii, and large cotton aphid, ACYRTHOSIPHON gossypii (Hom.: Aphididae) are the most important aphids of cotton fields in Iran. The large cotton aphid is more important in Khorasan, therefore this research was conducted in Kashmar region for determination of Economic Injury Level of this aphid during 1999-2000. The complete randomized block design with 3 replication was used and treatments included 0, 5, 10 and 15 aphid per leaf under cages measuring 2x2x1 m. For control of the aphids in check treatment, plants were sprayed with Confidor (250CC/h) S.ampling has been done from three upper leaves of 5 plants in each plot with 10 days interval. At the end of this study, datas concerning boll weight, %boll opening, yield and fiber length was analyzed with SAS and JMP. Economic injury level of this aphid was calculated using regression equations and Norton formula. Results indicated that EIL for large cotton aphid, ACYRTHOSIPHON gossypii in Kashmar was 6.3-6.9 aphid per 3 upper leaf of stem.

Fauna of aphids (Hemiptera: Aphididea) of Saman Region in Chaharmahal and Bakhtiari Province has been investigated during 2016-2017. The specimens were collected directly from plants by a fine brush or by beating the plants on a white tray and then preserved in Eppendorf tubes (2 ml) containing 75% alcohol. The collected specimens were mounted on slides and identified based on morphological characters. Totally 38 species in 22 genera of family, Aphididae, were identified as follows. New records for Chaharmahal and Bakhtiari Province are marked by an asterisk. ACYRTHOSIPHON loti (Theobald, 1913)*, ACYRTHOSIPHON PISUM (Harris, 1776), ACYRTHOSIPHON sp., Aphis (Toxoptera) aurantii (Boyer de Fonscolombe, 1841) *, Aphis craccivora (Koch, 1856), Aphis pomi (De Geer, 1773), Aphis gossypii (Glover, 1977), Brachycaudus (Brachycaudus) helichrysi (Kaltenbach, 1843), Brachycaudus (Prunaphis) cardui (Linnaeus, 1758), Brachycaudus (Thuleaphis) amygdalinus (Schouteden, 1905), Brachyunguis (Brachyunguis) harmalae (Das, 1918) *, Chaitophorus populeti (Panzer, 1804), Chaitophorus sp., Chromaphis juglandicola (Kaltenbach, 1843), Diuraphis (Diuraphis) noxia (Mordvilko, 1913), Dysaphis (Dysaphis) affinis (Mordvilko, 1928), Dysaphis (Pomaphis) plantaginea (Passerini, 1860), Forda hirsuta (Mordvilko, 1928), Hyalopterus amygdali (Blanchard, 1840), Hyalopterus pruni (Geoffroy, 1762), Macrosiphoniella (Macrosiphoniella) aktashica (Nevsky, 1928) *, Macrosiphoniella (Papillomyzus) sp., Macrosiphum euphorbiae (Thomas, 1878), Metopolophium (Metopolophium) dirhodum (Walker, 1849), Myzus (Nectarosiphon) persicae (Sulzer, 1776), Panaphis juglandis (Goeze, 1778), Panaphis sp., Pterochloroides persicae (Cholodkovsky, 1899), Rhopalosiphum nymphaeae (Linnaeus, 1761) *, Rhopalosiphum padi (Linnaeus, 1758), Rhopalosiphum sp., Sipha (Rungsia) elegans (Del Guercio, 1905), Sipha sp., Sitobion avenae (Fabricius, 1775), Smynthurodes betae (Westwood, 1849) *, Tinocallis (Sappocallis) saltans (Nevsky, 1929), Tinocallis sp., Therioaphis (Pterocallidium) trifolii (Monell, 1882).