Allatotropic and nervous control of corpora allata in the adult male loreyi leafworm, Mythimna loreyi (Lepidoptera: Noctuidae)

Abstract

Summary Allatotropic activity is found in methanolic extracts of the brain–suboesophageal ganglion (SOG)–corpora cardiaca (CC) complex from virgin males of Mythimna loreyi Duponchel (Lepidoptera, Noctuidae). Corpora allata (CA) from 6‐day‐old virgin males exhibit low rates of release of Juvenile Hormone (JH) acid (JHA) in vitro. Release of JHA can be activated by the addition of an extract of brain–SOG–CC complex in a dose‐dependent manner, and this allatotropic activation can be sustained consistently in the continuous presence of such extracts. Based on its trypsin sensitivity and heat stability, the allatotropic factor is most likely a peptide. The allatotropic activity is dependent on the concentration of calcium ions in the medium, with the highest activation achieved beyond 2 m m. The results of nerve transection experiments suggest that both nervi corporis allati I (NCA I) and NCA II are involved in mediating the allatotropic control of CA in vitro. Isolated CA alone show significantly higher rates of release of JHA than the intact brain–SOG–CC–CA complex during the first 3 h of incubation, but the release of JHA reaches almost the same range in both groups by the end of the fourth hour of incubation.

Neuropeptides regulating development and reproduction in insects

“…The mode of action of Manse‐AT to stimulate JH synthesis in the CA of M. sexta is thought to proceed via inositol phosphate and intracellular Ca 2+ as second messengers (Reagan et al ., 1992). The involvement of Ca 2+ in the allatotropic action of an extract from brain‐CC‐suboesophageal ganglion of the leafworm, Mythimna loreyi, is also indicated in studies by Kou & Chen (2000).…”

“…Although several allatotropic factors have been identified on the basis of bioassays that demonstrate a stimulation of the CA (for a review, see Gäde et al ., 1997; Gilbert et al ., 2000b; recent articles are provided by Kou & Chen, 2000; Tu et al ., 2002; Elekonich & Horodyski, 2003), the primary structure of only two is known, namely Manse‐AT from M. sexta and Aedae‐AT from the mosquito Aedes aegypti (Table 1). Manse‐AT was first isolated from the head of pharate adults of M. sexta (Kataoka et al ., 1989).…”

Allatotropic activity in the suboesophageal ganglia and corpora cardiaca of the adult male loreyi leafworm,Mythimna loreyi

“…The JHA release rate was determined using the in vitro radiochemical assay Tobe and Pratt, 1974;Wennauer and Hoffmann, 1988). In our previous study, CA from 6-dayold male adults (A/6) showed low biosynthetic activity and this low activity CA can be highly stimulated by extracts Kou and Tu, 1998;Kou and Chen, unpublished data). A/6 CA were dissected under lepidoptera saline (Jones and Yin, 1989).…”

A neural mechanism of nuclear receptor expression and regionalization

“…The hypothesis that the expression of EcR‐B1 may be induced by juvenile hormone (JH) 43 not only has not been validated in experiments, but admission of that hypothesis would be a tautological statement since the JH synthesis by corpora allata is also cerebrally regulated by brain neuropeptides, allatotropins and allatostatins 44,45 and by neurogenic signals via nervi corporis allati I and nervi corporis allati II, coming from the suboesophageal ganglion 45 …”