Biosystematics of gall aphids (Aphididae, Homoptera) of western Himalaya, India
Garhwal and Kumaun ranges of Himalaya include 250 odd species of aphids infesting a number of agricultural and forest plants. Out of these only 52 species (20%) are found to be gall formers. Majority of these gall aphids (63%) are indigenous. Except 4 species which produce true galls on stems, all other species are known to produce leaf fold or leaf roll or leaf base galls.
In general, the gall forming aphid species are heteroecious i.e. alternate between their primary and secondary hosts in different periods of the year. However, a few have been found to be autoecious i.e. monophagous. These aphids are also highly polymorphic in nature. Unless morphs from both of their primary and secondary hosts are available their identities in some cases are difficult. It has been observed that the morphology of aphid galls, karyomorphology, host association, life cycle pattern and natural enemies (both predators and parasites) help in the identity of such aphids more precisely, particularly in the closely related species complexes.