ИСТИНА

Balanophora is a genus of holoparasitic plants, which inhabit mainly in tropical regions of Asia. The genus divided to two subgenera (subgen. Balanophora and subgen. Balania) by merism of male flowers, while its female flowers are simplified to filiform structures. Species of the both subgenera inhabit the same territory (sympatric). In addition to morphological, ecological differences between the sympatric species are expectable, e.g. different system of pollination. Pollination biology of some species from subgen. Balanophora was investigated earlier. It was showed that B. abbreviata is pollinated by bees. Pyralid moths were recognized as pollinators of B. kuroiwai. Data on pollination of species from subgen. Balania are poor: ants and cockroaches were noted as visitors of B. tobiracola. The present research is dedicated to flowering biology of two species of Balanophora from different subgenera. Balanophora fungosa (subgen. Balanophora) and B. harlandii (subgen. Balania) were investigated in the same season and habitat in northern Vietnam. Inflorescences of the both species open acropetally. Within an inflorescence of B. harlandii, 8–16 flowers can be anthetic simultaneously; each flower remains anthetic for 1 day. Within an inflorescence of B. fungosa, 10–20 flowers can be anthetic simultaneously; each flower remains anthetic for 2–5 days. Inflorescences of both species were visited in daytime by flies (Calliphoridae, Drosophilidae, Syrphidae), wasps (Vespa sp.), ants (Formicidae, Mirmicidae), harvestmen (Phalangidae) and others. Drosophilid flies were the most frequent visitors of B. fungosa, while B. harlandii was visited predominantly by the wasps. Pollen grains of Balanophora were found at the bodies of the drosophilid flies and the wasps. On average, 102 pollen grains of Balanophora were found on the body of each wasp, while only 2 pollen grains were found on the body of each fly. Drosophilid flies visit male inflorescences of B. fungosa on average 433 times per day and visit female inflorescences 144 times per day. Wasps visit male inflorescences of B. harlandii on average 62 times per day and visit female inflorescences 18 times per day. It can be concluded, that drosophilid flies are the main pollinators of B. fungosa and wasps are the main pollinators of B. harlandii. However drosophilid flies can take minor part in pollination of B. harlandii as well as wasps can pollinate B. fungosa. The flies carry far less pollen than the wasps, but higher frequency of visits offsets this difference. As a result, sufficient effectiveness of pollination is ensured for the both species. Mechanism of plant-pollinator interaction is somewhat similar for B. fungosa and B. harlandii: sweet smell attracts insects and they feed on nectar as a reward. Probably, some differences in chemical composition of volatiles led to situation, when flies prefer one species but wasps prefer another one. Chemical change of volatiles and followed change of pollinators range can served as factors of divergence of this species during sympatric evolution.