Alberto Barrion, taxonomy consultant, International Rice Research Institute, Los Baños, Philippines, Ducheng Cai, Hainan University, Haikou, China, J. Catindig, S. Villareal, International Rice Research Institute, Los Baños, Philippines and Qianhua Yuan, Hainan University, China
Hymenoptera is the order of insects that comprises of wasps, bees, ants and parasitoids. From the human perspectives this group of insects is probably most beneficial, as they provide important ecosystem services, biological control and pollination. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the wings of the insects derived from the Ancient Greek word “hymen”, meaning membrane and “pteron”, meaning wing.
We used 6 insect sampling methods and collected 6, 531 individuals from 4 sampling sites, brought them back to laboratory, identified and counted them. There were 816 species from 260 genera in 36 families. The most dominant families were Scelionidae (1,465 individuals), Formicidae (1,333), Trichogrammatidae (947), Eulophidae(614), Braconidae (435), Encyrtidae(365), Mymaridae(332), Elasmidae (155) and Aphelinidae (136). The highest number of species was from Scelionidae (162 species), followed by Encyrtidae (110), Eulophidae (102), Braconidae (86), Mymaridae (47), Trichogrammatidae (34), Ceraphronidae and Chalcididae (25 each) and Pteromalidae (21). Of the total number of species identified, we found 123 species or 15% were new and previously unknown to science. The proportion of uncharted arthropods in Hainan Island is impressive. Earlier we also found new undescribed species of spiders. The large number of new species found in the expedition indicates that the arthropod biodiversity is high and many species are yet to be described.
The two functional groups of Hymenoptera in rice ecosystems were parasitoids represented by 25 families and constituting 77.4% (5,055 individuals) and predators in 5 families making up 22.2% (1,448 individuals). Only a small proportion was pollinators from 0.4% (28 individuals) from 5 families. This implies that the hymenoptera species contribute mainly to biological control services of rice ecosystems. Since rice is a self pollinated crop, the pollination service may not be as important for production, but are important indicators of ecosystem health. In Vietnam authorities launched a campaign to motivate farmers to conserve bees and their relatives.
Earlier we computed the species richness of the parasitoids and found that this index was related to the flowering flora of the neighboring habitats. Thus ecological engineering practices, like enriching the areas surrounding the rice crop with flowering plants as practiced in Vietnam and Thailand can restore resilience of rice fields to pest attacks.
The full report is available.