Gall-Inducing Aphids of Populus spp. in Razavi Khorasan Province, with Introducing Two New Species for Iranian Fauna

Poplar trees in Iran are hosts to a number of aphid species, some of which cause excrescences on leaves and other growing parts. These abnormal growths are classified as either galls or pseudogalls but innumerable gradations between the apparently normal and abnormal plant structures have made differentiation difficult. Galls are vegetable excrescences resulting from insect activities and usually sheltering the immature stages of the producers. The aphid genus Pemphigus Hartig, 1839 (Hemiptera: Sternorrhyncha) contains over 70 species widely distributed in the Holarctic, of which, 46 are known to form galls on leaves or twigs of Populus L. Aphids of the genus Pemphigus are usually holocyclic and heteroecious between a primary host, and several herbaceous secondary hosts. The majority of the family representatives are dioecious or heteroecious. Such species migrate from primary hosts (tree species) where they form galls characteristic in their size and shape to roots of secondary hosts (herbs or tree species). Only few species are monoecious, i.e. with life cycle occurring on one host species. Reviewing taxonomic related literature showed that the knowledge of Iranian galling aphids is still limited. So far 7 species e.g. P. borealis Tullgren, 1909, P. bursarius Linnaeus, 1758, P. immunis Buckton, 1896, P. populi Courchet, 1879, P. protospirae Lichtenstein, 1884, P. spyrothecae Passerini, 1856 and P. vesicarius Passerini, 1861 have been reported from Iran.
This study was conducted during the growing season of 2017. The study area, Razavi Khorasan province (35.1020° N, 59.1042° E) is located in the North eastern Iran, where no study has previously been carried out. The galls were collected from the leaves, petioles and branches of poplars, according to their location, and taken from them. Also some galls with aphids were put into vials filled with 75% alcohol for morphological studies. Sampling, preparation and identification of specimens were done according to the Blackman and Eastop (2000)). Specimens was approved by Dr. Roman Hałaj in Entomological Laboratory of the Upper Silesian Nature Society of Poland. Systematic knowledge, host plants, and synonyms of determined species were taken from Blackman and Eastop (2000) and Rezvani (2001).
Nine gall-inducing aphid species belonging to genus Pemphigus, Tribe Pemphigini and subfamily Eriosomatinae were found on four host plants. The occurrence of Pemphigus passeki (Börner), 1952 (Hem.: Aphididae) and Pemphigus populinigrae (Schrank), 1801 (Hem.: Aphididae) on Populus nigra in Iran are reported for the first time. The other recorded gall aphids are: 1-Pemphigus borealis which its galls are more or less oval in shape with a rather smooth surface galls, often merged into groups of 4-6 at the base (even up to 10). 2-Pemphigus bursarius with galls of more or less spherical, pear-shaped or pouch-like, green, yellow-green, sometimes red-brown in color. 3- Pemphigus immunis which its galls are walnut shape (c.a 4 cm in diameter), with think walls and uneven, wrinkled and often cracked surface, usually occurring individually, less often in small groups but always separated from one another. 4- Pemphigus passeki with galls at the base of the lamina, this gall was collected only from Neyshabour city. 5- Pemphigus populi with gall of more or less spherical or oval, more or less irregularly blobbed, almost always narrower at the base than at the top, pear-shaped or even slenderer, placed on the upper side of the lamina on the main nerve usually close to its base, size of a hazelnut, most often green in color. 6- Pemphigus populinigrae Schrank, 1801 with elongated galls and running along the main nerve, rather smooth, in their majority bright reddish and rather without yellowish tint, only partly open from the bottom side of the lamina. 7- Pemphigus protospirae with flattened and strongly spirally twisted galls, the twists are smaller and more numerous (more than 5) than those formed by P.spyrothecae. Galls very often on all the petiole and the base of lamina, shiny, green or green with red spot. 8- Pemphigus spirothecae with galls in the form of flattened and spirally twisted petiole, with the number of twists not exceeding 5 (usually 3-5). Galls are green, yellow-green to red-brown. 9- Pemphigus vesicarius with galls of combe-like, crown like or club-shaped, always with very distinct processes.
This preliminary research on gall-inducing aphids and their host plants in NE Iran added two new records of species to Iranian aphid fauna and 5 new records to Razavi Khorasan province. Previously about 485 aphid species were known for Iran. By the present study, the Iranian aphid fauna has at least 487 species. However, the number of insects especially aphids recorded from Iran is far from complete. Most probably due to the fact that the Iranian fauna has been poorly investigated and many areas have been sampled only sporadically