Abstract: 【Aim】 Small heat shock proteins (sHSPs) play important roles in resisting external environmental pressure in insects. This study aims to explore the functions of a small heat shock protein gene, sHSP19.8, in the growth and development of the cotton bollworm, Helicoverpa armigera, and its role in response to high temperature stress and insecticidal protein, so as to provide a foundation for further exploring its action mechanisms and controlling the cotton bollworm. 【Methods】 The full-length cDNA sequence of sHSP19.8 gene was cloned from H. armigera by RCR and RACE, and analyzed by bioinformatics software. The expression levels of sHSP19.8 gene in the 5th instar larvae of the Cry1Ac-susceptible cotton bollworm exposed to 40℃ for 1 h and 2 h and fed with the artificial diet containing 30 μg/mL Cry1Ac for 1 h and 2 h, respectively, were detected by qRT-PCR. Meanwhile, the expression patterns of sHSP19.8 gene in different developmental stages (1st-5th instar larva, pupa and adult) and tissues (foregut, midgut, hindgut, Malpighian tubules and cuticle) of the 5th instar larvae of the Cry1Ac-susceptible and resistant cotton bollworm were also assayed by qRT-PCR. 【Results】 The fulllength cDNA sequence of sHSP19.8 from H. armigera was obtained and named HaHSP19.8 (GenBank accession no.: XP_021195228.1). It is 608 bp in length with an open reading frame (ORF) of 528 bp, encoding 175 amino acids. The encoded protein has the typical α-crystallin domain (ACD). After induction by high temperature of 40℃ and 30 μg/mL Cry1Ac, HaHSP19.8 showed over-expression in the 5th instar larvae of the Cry1Ac-susceptible cotton bollworm. HaHSP19.8 was ubiquitously expressed in all the examined developmental stages and tissues of the 5th instar larvae of the Cry1Ac-susceptible cotton bollworm, with relatively higher expression levels in adults and the 5th instar larvae, and the cuticle, Malpighian tubules and midgut of the 5th instar larvae. However, HaHSP19.8 showed lower expression levels in all the examined developmental stages and tissues of the 5th instar larvae of the Cry1Ac-resistant cotton bollworm than in those of the Cry1Ac-susceptible cotton bollworm. 【Conclusion】 The results suggest that HaHSP19.8 may participate in the growth and development of the cotton bollworm to resist the environment stress, and may be involved in the resistance to Cry1Ac.

Key words: Helicoverpa armigera, small heat shock protein, sHSP19.8, Cry1Ac, expression analysis