Paper Wasp, a pollinator or a food robber of orchid?

 

Parapolybia varia Fabricius

Parapolybia varia (Paper wasps) was observed on Coelogyne stricta and Coelogyne longipes. The Coelogyne species produced sweet exudate which attracted the pollinators. The active visitation of wasp on the orchid was observed during the sunny day. In C. stricta (D. Don) Schltr., other  two wasp Polistes sp., Vespula sp. and a bumble bee were also observed  visiting in search of the sweet exudate at the base of the labellum and column. P. varia was observed scanning the flower, rachis and peduncle for more than 5 minutes or until distracted by biotic or abiotic interference such as wind and or human being. 

The wasp landed on the inflorescence and then move on the labellum, inserting its head in the floral whorl consuming the exudate. When the wasp retreated from the flower, the head or the thorax came in contact with the column removing the pollinia and attaching it on the head or thorax by viscidium. The anther cap weakly covering the pollinia so, it got removed by gentle movement by the wind or the wasp. It was interesting to note that after the attachment of pollinia the wasp usually tend to immediately remove the pollinia using its hind legs. The irritation or the load of the pollinia might have forced the wasp to remove the pollinia rather than transporting it to stigma of other flowers, which is incidental in all cases. The process of pollinia being removed from the column was observed for most of the flower but no pollinia was found on the stigma. Therefore, P. varia can be classified as a Probable pollinator.

According to Cheng et al. (2009) greenish yellow is the dominant colour in Coelogyne species which is related with wasp pollinated orchids and nectar secretion was not reported in the Coelogyne species. In contrast Kumar, Deepika and Raju (2018) stated the wasp are the generalist pollinator that usually explore flowers which provide exposed nectar and have short perianth since they are known to have short tongue. The flowers visited by wasp usually have dull colour such as reddish brown, dirty purple, or dirty brown. Wasp species were found to visit Coelogyne longipes and C. stricta, which have easy accessible nectar. Color of the C. longipes flower was reddish brown that might have stimulated the wasp to forage for food.

Paper wasp head in contact with anther of C. longipes and pollina attached to the leg as it was immediately removing it from its head. It was an interesting observation made from the study and more studies can be done on it to understanding whether the paper wasps might be the confirmed pollinator or food robber of orchids. The food robber insect do not assist in pollination.