Family: THRIPIDAE

 

About 1750 species in 260 or more genera are currently recognised in the family Thripidae. These insects have been found in all parts of the world from Greenland to the Sub-Antarctic Islands. The adults have simple or forked emergent sense cones on antennal segments III & IV, and the number of antennal segments varies from 6 to 9 (usually 7 or 8). The forewings are slender with two longitudinal veins in addition to the costal vein, the marginal cilia arise from sockets that are shaped like a figure 8, and the wing surface is covered with microtrichia. However, in many species the adults of one or both sexes are wingless. Females have a saw-like ovipositor comprising 4 valves. The life cycle comprises the egg, two larval instars that feed actively, two pupal instars that do not feed, and then the adults.

The generic classification of the Thripidae is now reasonably stable, but attempts to recognise suprageneric groups are less successful. Two major subfamilies, the Panchaetothripinae and Thripinae, are usually recognised, and ThripsID2001 provides a key to these groups. In recent years two further, but much smaller, subfamilies, the Dendrothripinae and Sericothripinae, have been recognised (Bhatti, 1989; Mound, 1997, 1999), although in ThripsID2001 the taxa involved are considered within the Thripinae. Various attempts by earlier authors to recognise a series of tribes and subtribes are also mentioned under the heading Thripinae.


Sub-family THRIPINAE

About 1400 species in rather more than 200 genera are currently recognised in the Thripinae, with a further 86 species and 10 genera in the Dendrothripinae and 130 species and 4 genera in the Sericothripinae. The subfamily Dendrothripinae is well characterised, by the presence in all of the species of a 'lyre-shaped' metathoracic endofurca (Mound, 1999). The subfamily Sericothripinae is less well characterised, although most of the species have a distinctively sclerotised patch on the pronotum, and tergite IX bears a transverse row of 3 (instead of 2) pairs of major setae (Bhatti, 1973). Earlier authors have included genera such as Scirtothrips along with Sericothrips and its relatives, on the grounds that all the species have closely spaced rows of microtrichia laterally on the tergites. However, this character state is not considered a good indicator of relationships, because similar microtrichial fields are developed to varying extents in other Thripinae, including Thrips tabaci.

Traditionally, various tribes and sub-tribes have been recognised within the Thripinae, although the morphological basis for these has weak support. For example, the 'Chirothripini' has been used for a series of genera in which all of the species live only on grasses. However, the structural similarities between the species of Limothrips and the species of Chirothrips may owe more to the similarities of their habitats than to their evolutionary relationships. Similarly the subtribe Aptinothripina or Anaphothripina has been used for a range of species in which the pronotum does not bear any long setae. Currently there is little evidence to support the recognition of any groups between subfamily and genus amongst the Thripinae.

The members of the Thripinae show a wide diversity of biologies. Many species breed on leaves, and many of the most advanced species breed in flowers. Members of a few genera are predatory on other small arthropods. Many Thripinae feed only on grasses, and some feed only on ferns, but very few Thripinae are known to feed on fungi. Some of the most highly derived species are remarkably flexible in their biology, feeding on leaves, in flowers and also acting as predators on mites. Species with this range of biologies include some of the most important pests and vectors of tospoviruses on crops.

         

Anisopilothrips venustulus

(Panchaetothripinae)

Caliothrips striatopterus

(Panchaetothripinae)

Chaetoanaphothrips signipennis

(Thripinae)

Thrips australis

(Thripinae)