Effects of photoperiod on body size and hormone titres relating to diapause regulation in Cotesia vestalis (Hymenoptera: Braconidae)

• Published in: Canadian entomologist 2013-08, Vol.145 (4), p.369-386
• Main Authors: Hao, Zhong-Ping, Zhao, Yan-Qun, Yuan, Zhong-Qin, Shi, Zu-Hua
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Body size; Eggs; Entomology; Fundamental and applied biological sciences. Psychology; Growth hormones; Hormones; Insects; Photobiology; Physiology; Physiology, Biochemistry, Development, & Genetics; Protozoa. Invertebrata; Studies
• ISSN: 0008-347X; 1918-3240
• DOI: 10.4039/tce.2013.6

Photoperiods influence diapause beyond the maternal generation in Cotesia vestalis (Haliday) (Hymenoptera: Braconidae). The sizes, 20-hydroxyecdysone (20E), and juvenile hormone III (JH III) contents in the G1 diapausing prepupae, G0 nondiapausing prepupae, adults, and G1 eggs from C. vestalis cultures reared under three photoperiods (8:16 hours light:dark, 12:12 hours light:dark, and 16:8 hours light:dark) were measured to investigate the hormones’ roles on maternal information transmission and diapause regulation. Results showed that the body size of G1 diapausing prepupae was significantly larger than that of G0 nondiapausing prepupae. The sizes of G0 prepupae, female abdomens, and G1 eggs under eight-hour light were significantly larger than those under 16-hour light. The 20E content in diapausing prepupae was significantly lower than that in nondiapausing prepupae, whereas JH III content did not show significantly difference under the same photoperiod. The 20E content in maternal prepupae, mated females and G1 eggs decreased as the light period was reduced. Juvenile hormone III contents in G0-mated females and G1 eggs (after oviposition) under three photoperiods showed no significant differences. These findings suggest that 20E may play a critical role in diapause regulation of C. vestalis, and be used as a maternal environmental message to be transmitted to the next generation. La photopériode influence la diapause au-delà de la génération maternelle chez Cotesia vestalis (Haliday) (Hymenoptera: Braconidae). Nous avons mesuré les tailles et les contenus en 20-hydroxyecdysone (20E) et en hormone juvénile III (JH III) chez des prénymphes G1 en diapause, des prénymphes G0 non en diapause, des adultes et des œufs G1 dans des cultures de C. vestalis élevées sous trois conditions de photopériode (8:16 heures, 12:12 heures et 16:8 heures de lumière:obscurité) afin de déterminer le rôle des hormones sur la transmission de l'information maternelle et la régulation de la diapause. Nos résultats indiquent que la taille corporelle des prénymphes G1 en diapause est significativement plus grande que celle des prénymphes G0 non en diapause. Les tailles des prénymphes G0, des abdomens des femelles et des œufs G1 gardés sous 8 heures de lumière sont significativement plus grandes que celles observées sous des conditions de 16 heures de lumière. Le contenu en 20E des prénymphes en diapause est significativement plus bas que celui des prénymphes non en diapause, alors