On the biology of Holopothrips chaconi sp.n. (Thysanoptera: Phlaeothripinae) from leaf-vein galls on Piper species (Piperaceae) in Costa Rica

Abstract

Most species of the Neotropical genus Holopothrips are associated with plant galls but very little is known about their biology. Here, we provide observations on the biology of a new species of Holopothrips associated with leaf-vein galls on four species of Piper at a cloud forest site (Zurquí de Moravia) in Costa Rica. This species colonized the galls soon after the gall-inducing cecidomyiid or one of its parasitoids emerged, and several generations of thrips appeared to occupy the empty galls. A total of 175 empty galls from 34 leaves were collected, brought to the laboratory for dissection under the microscope, and the contents quantified.Holopothrips occupied approximately 75 % of the galled leaves and among the latter they occupied about 40 % of the galls. Every combination of adults, nymphs and eggs was found, which implies that adult thrips move in and out of galls, and possibly do not defend their galls from invasion by other members of their species. However, when disturbed, both nymphs and adults raise the tip of their abdomen and emit a distinctive odor, suggesting a defensive reaction against potential predators. Preliminary evidence suggests that they feed on gall tissue lining the inner cavity and spend very little time outside the galls. The thrips is described as a new species, and is one of only four known species of Holopothrips to have the unusual condition of two pairs of epimeral setae on the pronotum. This new species was compared to these other three Holothrips species, and the remarkable variation of the female spermatheca and the male sternal pore plate is illustrated. Further research is needed to confirm that several generations of thrips occupy empty galls, to determine whether adult thrips do indeed move between galls, and to explore in greater detail their possible chemical defense. Rev. Biol. Trop. 63 (4): 1035-1042. Epub 2015 December 01.

Holopothrips molzi sp.n. (Thysanoptera, Phlaeothripidae): natural history and interactions in Myrtaceae galls

“…Holopothrips molzi exhibited a higher tendency to stay in the gall and defend itself by raising the abdomen and secreting an anal droplet. The same behaviour is observed in other galling thrips, including Gynaikothrips species, and other Holopothrips species (Zamora et al 2015). In tubuliferans, these anal secretions usually have repellent substances and are frequently used to keep predators away (Blum 1991;Suzuki et al 2004).…”

“…It has two pairs of epimeral setae (Fig. 7), a character state that is shared with some other species of the genus, such as the South American H. conducans (Priesner) and H. tillandsiae Mound & Marullo, also H. chaconi Zamora et al from Costa Rica (Zamora et al 2015). This characteristic, however, might not be a good indicator of phylogenetic relationship, and is known to vary within H. mariae Mound & Marullo, with some individuals bearing only one pair of epimeral setae, and others two pairs.…”

Insect galls from the Botanical Garden of the Museu Nacional (Rio de Janeiro, RJ, Brazil)

“…Several publications have reported gall invasion by thrips. Some species invade galls soon after the gall-inducer emerged as Holopothrips chaconi Zamora, Hanson and Mound, 2015 in Costa Rica (Zamora et al, 2015), a successor in galls of Cecidomyiidae on Piper (Piperaceae), but other species invade galls still occupied by the inducer as Myrciathrips variabilis Mendonça, 2016 (Cavalleri et al, 2016). Both species feed on gall tissues.…”