The ‘floppy-wing’ morph of the subterranean termite Reticulitermes labralis has a secondary reproductive function

Abstract

Three types of replacement reproductives exist within termite colonies: nymphoids developed from nymphs, ergatoids from workers, and adultoids from alates. To date, the only two types of replacement reproductives described in Reticulitermes are nymphoids and ergatoids. We found that in addition to alates, the sixth stage nymphs (N6 nymphs) of R. labralis could also undergo eclosion and become one of two secondary reproductive types: (1) nymphoids or (2) floppy wing form reproductives (FFR). The FFRs would become replacement reproductives within their natal colony after wing shedding. These reproductives have a light pigmentation, with slight sclerotization of their floppy wings, and are capable of producing offspring within their natal colony. FFRs differed in morphology to the alates after eclosion. We found that oogenesis had completed yolk accumulation and reached the vitellogenesis stage in alates. By contrast, the vitellogenic oocytes were absent at the end of ovarioles in FFRs, nymphoids, and N6 nymphs, showing that oogenesis did not reach the vitellogenesis stage. In other words, the ovarian status of FFRs would more likely resemble nymphoids rather than primary reproductives. Microsatellite analyses of four loci indicated that FFR individuals, workers, and alates were all produced by sexual reproduction. Thus, FFRs can be classified as another type of secondary reproductives in addition to the nymphoid and ergatoid morphs in R. labralis. The R. labralis FFR is similar to the adultoids in higher termites except for its larval characteristics, which adds to the evidence that R. labralis is a transitional species between the lower and higher termite.