Fine structure of the scolopophorous organs in the pedicel of three species of Thysanoptera (Insecta)

Abstract

The fine structures and arrangements of the scolopidia in the pedicel of 3 species of thrips, Thrips validus (Thripidae), Aeolothrips intermedius (Aeolothripidae), and Haplothrips aculeatus (Phlaeothripidae) (Thysanoptera) are surprisingly uniform, although these species belong to families with considerable morphological differences in other parts of the body. As a rule, there are 32 scolopidia in each pedicel. Five groups (scoloparia) of 5 scolopidia and one group of 6 scolopidia belong to the Johnston's organ. In contrast to the typical structure known from other insects, 10 scolopidia of Johnston's organ in Thysanoptera have only 2 (not 3) sensory cells. Four of these show 2 sensory cilia of the “thin” type, 6 have one cilium of the “thick” and one of the “thin” type. Although amphinematic scolopidia are characteristic of the Johnston's organ, 2 of the scoloparia in the pedicel of Thysanoptera contain one mononematic scolopidium. Because of their structure and position, it is unlikely that these scolopidia belong to the type of scolopophorous organ found in the pedicel of most Neoptera, viz., the central organ, which is characterized by mononematic scolopidia. Therefore, the central organ of Thysanoptera is probably represented only by the remaining isolated mononematic scolopidium.