Influence of juvenile hormone and mating on oogenesis and oviposition in the codling moth,Cydia pomonella

Abstract

Oogenesis in the codling moth, Cydia pomonella, and the role of juvenile hormones (JHs) were addressed. Rudimentary ovarian structures were recognisable in day 3–4 pupae, when haemolymph JH was still undetectable by coupled gas chromatography‐mass spectrometry in the selected ion mode (GC‐MS/SIM). The presence of developing oocytes was observed by light microscopy on day 8, coincident with very low JH titres (0.74 ± 0.05 ng/ml JH II). Chorionation was only evident upon emergence, following an increase in JH in the pharate adult (0h old: 4.71 ± 0.34 ng/ml JH II). Analysis of haemolymph from virgin and mated females indicated that JH II was predominant, with approximately equal and lower quantities of JHs I and III (3.3‐ to 5.0‐fold less). When pupae or newly emerged adults were treated with JH homologues, no alteration in ovarian protein content was apparent, but the JH mimetic, fenoxycarb, depressed the number of oocytes filling ≥ 50% follicular volume. Chorion deposition was stimulated by JHs I, II, or III (10 μg), but not by fenoxycarb (0.05 μg, 10 μg). Mating provided correct stimuli for enhanced choriogenesis and egg laying, and, since haemolymph JH titres were concomitantly elevated (approximately 2‐fold), it was postulated that the rise in JH elicited both these events. Application of JHs to virgin females, however, could not mimic mating; only increases in choriogenesis were induced: JH‐treatment of virgins (or mated insects) significantly decreased oviposition rates over 24 and 48 h and markedly reduced the life‐time total number of eggs. Arch. Insect Biochem. Physiol. 41:186–200, 1999. © 1999 Wiley‐Liss, Inc.

Molecular characterization of DNA methyltransferase 1 and its role in temperature change of armyworm Mythimna separata Walker

“…Previous studies in pea aphid Acyrthosiphon pisum have identified that lots of DNA methylation genes showed connections with juvenile hormone (JH; Walsh et al, 2010), another study in honey bee also confirmed the relationship between DNA methylation and JH (Foret et al, 2012). The JH is well known to play roles in larvae stages (Lawrence et al, 2010;Li, Jia, & Li, 2019;Webb, Shu, Ramaswamy, & Dorn, 1999). Therefore, we presumed that depletion of DNA methylation process also affects the JH process.…”

Thermal response in adult codling moth

“…Physiological mechanisms underlying this behavioural alteration may include endocrinological changes. After mating, a marked increase in the juvenile hormone titre of female codling moths is noted (Webb et al, 1999). Changes in thermoregulatory behaviour within a single stage has also been detected for larvae.…”

Functional genomics of life history variation in a butterfly metapopulation

“…Female reproductive physiology. Sampling involved collection of hemolymph for biochemical analyses of protein and JH followed by counting chorionated eggs in dissected ovarian follicles as described in Webb et al (1999). Total soluble protein in hemolymph was first quantified and then separated using SDS-PAGE.…”