Effects of the chitin synthesis inhibitor complex nikkomycin on oogenesis in the mite Tetranychus urticae

Abstract

Some effects of the chitin synthesis inhibitor complex nikkomycin on oogenesis in the two‐spotted spider mite Tetranychus urticae were demonstrated by means of electron microscopy. Four main effects were evident, depending on the oogenetic stages. Nuclear defects, observed in oogonia and primary oocytes, included a widened nuclear envelope, the intermembranous spaces of which were filled with electron‐dense material, and the occurrence of small electron‐dense agglomerations and altered nucleoli inside the nuclei. Cytoplasmic defects occurred mainly in nurse cells and involved electron‐dense granular areas accompanied by mitochondria, and large cisternae and vesicles of rough endoplasmic reticulum. Yolk synthesis in oocytes could be inhibited, as shown by the lack of yolk droplets or the presence of abnormal yolk droplets. Both phases of egg shell synthesis were disturbed, resulting in an inhibition of egg deposition. Mechanisms based upon the oogenetic effects of the metabolite complex nikkomycin are discussed.

Egg-Shells in mites: Cytological aspects of vitelline envelope and chorion formation inPergamasus barbarusberlese (Gamasida, Pergamasidae)

“…As far as the latter process is concerned, the Acari have only occasionally been investigated. Several studies have dealt with ticks (Diehl, 1970;Hecker and Aeschlimann, 1970;Brinton and Oliver, 1971;Diehl, et al, 1982) and spider mites (Tetranychidae) (Dittrich and Streibert, 1969;Mothes and Seitz, 1981;Mothes-Wagner, 1984; Mothes-Wagner and Seitz, 1984), but egg-shell formation in most of these publications has been only briefly mentioned. Similarly, the information on the fine structure of egg shell in mites has been presented only in a few cases: gamasid mites (Witalinski, 1977), ticks (Diehl, et al, 1981), and acarid mites (Mazzini and Baiocchi, 1983;Callaini and Mazzini, 1984).…”

RNA Interference-Based Silencing of the Chitin Synthase 1 Gene for Reproductive and Developmental Disruptions in Panonychus citri

“…The results of the present study are in line with previous studies, which revealed that eggshell amalgamation occurs in two phases, and ds- PcCHS1 strongly down-regulates chitin synthesis. All of these effects led to the disturbance of egg deposition [ 34 ]. A significantly reduced egg laying rate in response to the inhibition of PcCHS1 has been previously reported in different pest species [ 35 , 36 , 37 ].…”