Figure 2.

Effect of the RNAi-mediated knockdown of the ecdysone receptor complex (SchgrEcR/SchgrRXR) on the reproductive physiology of female S. gregaria. Locusts were injected as described in materials and methods. One part of the locusts (N = 15–20) was dissected on day 12 of the adult stage to assess ovary and oocyte growth (A,B,D,E,G), the other part of the locusts (N = 12) were kept alive to check copulation behaviour, fecundity and fertility (C and F). (A,B) Ovary of a representative (A) control locust (basal oocyte length = 3.1 mm) and (B) dsEcR/RXR-treated locusts (most basal oocytes resorbed, 2^nd cycle oocytes just started vitellogenesis and were about 2 mm in length). (C) Starting from day 10 of the adult stage the females were assayed for displaying mating behaviour, by allowing them to mate with mature virgin males. The cumulative percentage of females that mated is presented (N = 12). No significant differences can be observed (Log-rank (Mantel-Cox) test). (D) Ovarioles from control (left, basal oocyte length = 7 mm) and dsEcR/RXR-treated locusts (right, basal oocyte length = 7 mm). (E) Histological sections of the basal oocytes from a control locust (left, length = 3 mm – width = 0.5 mm) and a dsEcR/RXR-treated locust (right, length = 4.5 mm – width = 0.7 mm). (F) The number of eggs per egg pod was counted, as well as the number of hatchlings per egg pod. The data represent mean ± S.E.M. (bars), as well as the individual number of eggs (Ο) or hatchlings (X) per egg pod (N control = 12; only 1 out of 12 dsEcR/RXR-treated locusts laid eggs). (G) Magnification of the follicular cell layer of the basal oocytes shown in E (same order). Scale bars: A, B & D = 1 mm; E = 200 µm; G = 50 µm.