Abstract
Small heat shock proteins (sHsps) function in the response of insects to abiotic stress; however, their role in response to biotic stress has been under-investigated. Mythimna separata, the oriental armyworm, is polyphenetic and exhibits gregarious and solitary phases in response to high and low population density, respectively. In this study, three genes were identified encoding sHsps, namely MsHsp19.7, MsHsp19.8 and MsHsp21.4, and expression levels in solitary and gregarious M. separata were compared. The deduced protein sequences of the three MsHsps had molecular weights of 19.7, 19.8 and 21.4 kDa, respectively, and contained a conserved α-crystalline domain. Real-time PCR analyses revealed that the three sHsps were transcribed in all developmental stages and were dramatically up-regulated at the 6th larval stage in gregarious individuals. Expression of the three MsHsps was variable in different tissues of 6th instar larvae, but exhibited consistent up- and down-regulation in the hindgut and Malpighian tubules of gregarious individuals, respectively. In addition, MsHsp19.7 and MsHsp19.8 were significantly induced when solitary forms were subjected to crowding for 36 h, but all three MsHsps were down-regulated when gregarious forms were isolated. Our findings suggest that population density functions as a stress factor and impacts MsHsps expression in M. separata.
Highlights
High population density is a complex stress that impacts the morphology, behavior, life history and physiology of insects [1,2,3] and their population dynamics in the field [4]
Three small Hsps (sHsps) genes were obtained from M. separata,and named MsHsp19.7, MsHsp19.8, and MsHsp21.4 based one their respective predicted molecular weight (GenBank accession number: MN503276, MN503277, and MN503278, respectively)
Multiple sequence alignments revealed that the three MsHsps contained a conserved α-crystallin domain, which was composed of approximately 100 amino acids and six βstrands (Fig 1)
Summary
High population density (crowding) is a complex stress that impacts the morphology, behavior, life history and physiology of insects [1,2,3] and their population dynamics in the field [4]. To overcome the unfavorable effects of crowding, insects skillfully adopt one or more strategies. Insects may alter their phenotype or behavior to adapt to crowding or they may reallocate resources normally used for basic functions (e.g. development, reproduction, nutrient assimilation, and immunity) to cope with changes in population density [5,6,7]. Phase polyphenism is a phenotypic adaption to crowding that has been observed in Orthopterans, Lepidopterans, Hemipterans and Coleopterans [6, 8,9,10].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
