Symbiotic relationships between ants and aphids

The classical and contemporary literature devoted to symbiotic relationships between ants and aphids was analyzed. The most studied issues are: the totality of morphological and anatomical adaptations of partners to symbiosis, different degrees of aphids myrmecophilia, benefits and costs of insects during interaction. A lot of issues are still discussible. For instance, it is unknown whether the trophobiotical relationships between ants and aphids are mutualistic or intermediate between mutualism and exploitation. To clarify this vague point the study of symbionts behaviour is of great importance, however, it remains practically non-investigated either for aphids or ants. It is known only that nonmyrmecophilous aphids living within galls have rather complicated behaviour--their colonies are guarded with specialized castes of aphids-soldiers. As for the ants, till nowadays trophobionts (individuals looking after the aphids), which make up special functional group within ants family, have been described as passive foragers being occupied only with the honeydew collection and transportation. The recent investigations revealed that ants use behavioural schemes with different degree of complication interacting with aphids: from lonely foraging to professional specialization in working groups.