THRIPS IN WETLAND HABITATS

Most thrips live in terrestrial habitats and have terrestrial pupation sites. Adaptation to an aquatic habitat by thrips is uncommon, and th rips have never been considered as a distinctive ecological entity cha racteristic of wetland biotopes. From the scant picture of the scenari o of wetland thrips and their host plant association gathered from own observations as well as from scattered literature, three ecological s tages representing a continuum of adaptation of thrips to the wetland habitat are recognized. (1) All Life stages are passed on non-submerge d leaves (phyllosphere) or flowers (anthosphere) of the aquatic plant, and there is tolerance to occasional submersion. (2) An aquatic pupat ion site is required, the adults and larvae living on non-submerged pa rts of aquatic plants. These two ecological types together constitute the hydrophilous or semiaquatic species. (3) A submerged phyllosphere is required for the adults to live and multiply. All life stages live on fully soaked or submerged parts of the host plant. These are the aq uatic thrips. The prevailing concept that all Tubulifera pupate on the host substrate near adults or larvae needs to be revised. There are m any species that do not do so. However, precise information on this as pect requires more data. Seventeen species of thrips are identifiable as hydrophilous insects. Besides, there are two species of aquatic thr ips. All of them belong to the family Thripidae of the Order Terebrant ia. Amynothrips andersoni (Order Tubulifera), associated with alligato rweed in waterways in S. America and USA, is not hydrophilous, since i t is not dependent on aquatic environment and prefers plants in terres trial situations. A requirement for, or dependence on, an aquatic habi tat is eminently shown by the monophagous Hawaiian species Organothrip s bianchii Living on wetland tare, but not on tare growing on dryland.