FNZ 10 - Tubulifera (Insecta: Thysanoptera) - Life History and Host Relationships
Mound, LA; Walker, AK 1986. Tubulifera (Insecta: Thysanoptera). Fauna of New Zealand 10, 144 pages.
(
ISSN 0111-5383 (print),
;
ISBN 0-477-06784-0 (print),
).
Published 22 Sep 1986
ZooBank: http://zoobank.org/References/0C947CDE-29D0-411A-8AB1-E16C06255989
Life History and Host Relationships
The eggs of Phlaeothripidae are deposited on the available substrate, whether this is the leaf or flower of a host plant in phytophagous species, or a dead leaf or the bark of a tree in fungus-feeding species. The pattern in which eggs are deposited varies between species, depending to some extent on whether social behaviour has been developed to any degree. Thus, fungus-feeding species which live in groups and exhibit male polymorphism can be expected to deposit their eggs in communal batches (Crespi 1986a, b). These eggs will usually be laid horizontally, but Ananthakrishnan et al. (1984) note that the eggs of some species stand vertically. The egg surface often shows an hexagonal pattern, and at hatching the egg ruptures along the lines of this pattern, there being no operculum (cf. at least some species of Terebrantia; Kirk 1985). Some Idolothripinae, particularly large species such as Idolothrips spectrum, are probably ovoviviparous. Conclusive observations have not been made on New Zealand species, but one female of Carientothrips badius collected in January 1979 from Rocklands (CO) had a well developed larva in its abdomen.
The only detailed study of the life history of any Phlaeothripidae in New Zealand has been on Haplothrips niger (Doull 1949, Yates 1952). However, probably all species have two active, feeding larval instars succeeded by three almost inactive, and probably non-feeding, pupal instars. These stages can be distinguished from each other by the form of the antennae and (when present) wing buds (Fig- ures 5 and 6). Each first-instar larva is probably enclosed in its embryonic cuticle as it begins to emerge from the egg, but this is soon ruptured and shed (Kirk 1985). Many first-instar larvae of Phlaeothripidae - and more particularly second-instar larvae - are brightly coloured, usually with red transverse bands or spots on a white background, and sometimes with the cuticle around the setal bases dark. These colour patterns may be species-specific, but no attempt has been made here to study these larvae as they have been collected too infrequently. Their detailed structure seems to be even more uniform than that of adults. The propupa and the first and second pupae are less distinctively coloured, although the second pupae increasingly show the colours of the pharate adult through their cuticle. Adults and immature stages usually occur together in overlapping generations, except where the habitat is short-lived, as in the few flower-living species.
Behavioural studies on thrips are rare, but social behaviour has been demonstrated in one unusual species from Panama (Kiester & Strates 1983). Moreover, Crespi (1986a, b), working with Hoplothrips karnyi and Elaphrothrips tuberculatus in Michigan, and with Hoplothrips pedicularius in Britain, has observed combat between males in order to secure access to a mate, and egg-guarding by both sexes. Similar behaviour could probably be observed among those fungus-feeding species on dead wood in New Zealand which show sexual dimorphism and size polymorphism in males.
Of the 68 species from New Zealand, 25 are known to feed by ingesting fungal spores, and a further 26 are assumed to feed on fungal hyphae or the external digestion products of fungal decay. Most of them live in concealed habitats, such as under bark or in leaf litter, and are rarely seen unless searched for. Two species are known to be predators of mites: the introduced Haplothrips kurdjumovi, which is known only from orchards; and the native Apterygothrips collyerae, which is found in a wide range of open habitats. Three other species (Yarnkothrips kolourus, Podothrips orarius, and P. turangi ) may also be predatory, all on scale insects, but this requires confirmation. The three Lissothrips species feed on mosses or possibly lichens. This leaves nine species which probably feed on higher plants: four Apterygothrips species found in association with grasses and sedges, and assumed to be phytophagous; Liothrips vaneecki, a minor pest of lily bulbs; two Teuchothrips species, one specific to Callistemon and one to Cassinia; Haplothrips niger, a pest of clover flowers; and H. salicorniae, which has been collected only from Salicornia on salt marshes.