Starvation influences allatotropin gene expression and juvenile hormone titer in the female adult oriental armyworm, Mythimna separata

Abstract

The first day of adult life is the sensitive stage for shifting migrants into the resident morphs of the oriental armyworm (OAW), Mythimna separata (Walker). The juvenile hormone (JH) titer, expression of the allatotropin (AT) gene, and their relationship were investigated in adult female migrants starved in the sensitive stage, to understand the underlying mechanism of changing migrants into resident OAWs. Haemolymph JH titers of the starved female adults were mostly elevated earlier than in controls, although not all differences were statistically significant. JH I titers in the starved moths were significantly higher than those in the controls on 1, 2, and 5 days after treatment (DAT), respectively. JH II titers in the starved moths were significantly higher than the controls through the period tested except on 5 DAT. JH II is the most likely regulator in changing migrants into resident morphs. The relative quantities of AT expression in the starved moths were higher through the period tested except on 5 DAT. AT expression and JH titers appear to be positively correlated, especially for those in earlier days of the adult life. We infer that AT is the important regulator of JH levels. A model for the shifting of migrants into resident morphs in the OAW is proposed.

Effects of Larval Density on Flight Potential of the BeetWebworm,Loxostege sticticalis(Lepidoptera: Pyralidae)

“…Larval crowding may induce migratory ßight behavior of adult L. sticticalis and prepare the adult for the demands of sustained ßight through its effects on the preoviposition period and triglyceride content. Both the length of preoviposition period and content of triglyceride of the moths were regulated by endocrine elements, like juvenile hormone (Luo et al 2001, Zhang et al 2008a. Further studies on the mechanisms by which larval density inßuences migratory ßight behavior of L. sticticalis will be necessary to explain these linkages.…”

Regulation of Migration inMythimna separata(Walker) in China: A Review Integrating Environmental, Physiological, Hormonal, Genetic, and Molecular Factors

“…Haemolymph JH titers of starved females for the most part were greater than in the controls. Relative AT expression was higher in starved moths through 4 d after treatment, and appeared to be positively correlated with JH titer during that period (Zhang et al 2008b). Based on these results, we proposed a model of the hormonal and physiological mechanisms underlying the shift of migrants into residents during the adult sensitive stage.…”

“…A recent novel Þnding showed that starving an adult, otherwise destined by larval rearing conditions to be a migrant, during the Þrst 24 h after eclosion activates JH synthesis by the corpora allata, which, in turn, accelerates female ovarian development (Zhang et al 2008b). This Þnding may expose the hormonal mechanism of adult secondary regulation of the decision to migrate in M. separata.…”

“…Zhang et al (2008b) used HPLC, semiquantitative RT-PCR and real time quantitative PCR techniques to examine the relationship between JH titer and expression of the AT gene in female M. separata migrants that were starved in the adult sensitive stage. The relationship between AT mRNA expression level and JH titers was strongly correlated, although measures differed slightly depending on the technique.…”

Effect of starvation on expression of troponin complex genes and ER stress associated genes in skeletal muscles

“…Thus, it is essential for insects to adapt to starvation by metabolism through various mechanisms, including gene regulation and enzyme (protein) modification. It is known that starvation influences expression levels of several genes such as allatotropin in the oriental armyworm, Mythimna separata, different mitochondrial genes in the mosquito, Aedes aegypti, and tissue-specific genes in the wood ant, Formica exsecta [15][16][17]. Starved insects are more susceptible to pathogens due to their compromised immune systems (e.g., Colorado potato beetle, Leptinotarsa decemlineata) [18].…”