Differential expression of heat shock proteins and antioxidant enzymes in response to temperature, starvation, and parasitism in the Carob moth larvae, Ectomyelois ceratoniae (Lepidoptera: Pyralidae)

Abstract

Insects face diverse biotic and abiotic stresses that can affect their survival. Many of these stressors impact cellular metabolism, often resulting in increased accumulation of reactive oxygen species (ROS). Consequently, insects will respond to these stressors by increasing antioxidant activity and increased production of heat shock proteins (HSPs). In this study, the effect of heat, cold, starvation, and parasitism by Habroacon hebetor wasps was examined in the carob moth, Ectomyelois ceratoniae, to determine which responses were common to different stresses. For all stressors, malondialdehyde levels increased, indicative of oxidative stress in the insects. The activity of two antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), increased with each stress, suggesting that these enzymes were serving a protective role for the insects. Heat (46˚C for 100 min) and cold (-15˚C for 30 min) treatments caused significant mortalities to all developmental stages, but pretreatments of moderate heat (37˚C for 10 min) or cold (10˚C for 10 min) induced thermotolerance and reduced the mortality rates when insects were subsequently exposed to lethal temperatures. Quantitative RT-PCR confirmed that heat and cold tolerance were associated with up-regulation of two HSPs, HSP70 and HSP90. Interestingly, HSP70 transcripts increased to a greater extent with cold treatment, while HSP90 transcripts increased more in response to high temperatures. RNA interference (RNAi)-mediated knockdown of either HSP70 or HSP90 transcripts was achieved by injecting larvae with dsRNA targeting each gene's transcripts, and resulted in a loss of acquired thermotolerance in insects subjected to the heat or cold pretreatments. These observations provide convincing evidence that both HSP70 and HSP90 are important mediators of the acquired thermotolerance. Starvation and parasitism by wasps caused differential expression of the HSP genes. In response to starvation, HSP90 transcripts increased to a greater extent than HSP70, while in contrast, HSP70 transcripts increased to a greater extent than those of HSP90 during the first 48 h of wasp

Galleria mellonellalarvae fat body disruption (Lepidoptera: Pyralidae) caused by the venom ofHabrobracon brevicornis(Hymenoptera: Braconidae)

“…Hsp 90 gene expression was not significantly affected by the envenomation. Similar effects of both heat shock proteins were observed from the Carob moth larvae (Ectomyelois ceratoniae) on the first and second day after envenomation by H. hebetor (Farahani et al, 2020). Thus, we can speculate about manageable necrotic-like death (necroptosis) in the fat body cells of G. mellonella larvae under the influence of the venom components of H. brevicornis.…”

Intergenerational Effects of Early Life Starvation on Life-History, Consumption, and Transcriptome of a Holometabolous Insect

“…As typical stress response indicators, genes potentially encoding heat shock proteins and cytochrome P450s were differentially expressed, being partly up-and partly downregulated in A. rosae in response to starvation. Regulation of heat shock proteins in response to starvation has been reported elsewhere, including larvae of Lepidoptera and Hymenoptera (Farahani et al 2020;Wang et al 2012). These proteins act to stabilize and protect other proteins in the face of both abiotic and biotic stresses (Sørensen et al 2003;Farahani et al 2020).…”

“…Regulation of heat shock proteins in response to starvation has been reported elsewhere, including larvae of Lepidoptera and Hymenoptera (Farahani et al 2020;Wang et al 2012). These proteins act to stabilize and protect other proteins in the face of both abiotic and biotic stresses (Sørensen et al 2003;Farahani et al 2020). Cytochrome P450s are best known for their role in metabolism of xenobiotics by insects (Feyereisen 2012).…”

Two calcium‐binding chaperones from the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) involved in diapause

“…A few studies have revealed the requirement for molecular chaperones in diapause maintenance (MacRae, 2010) and starvation (Farahani et al, 2020). Elevated levels of chaperones inhibit stress-related, irreversible protein denaturation, and apoptosis (MacRae, 2010).…”

“…Elevated levels of chaperones inhibit stress‐related, irreversible protein denaturation, and apoptosis (MacRae, 2010). Hibernation‐ or starvation‐induced upregulation has been reported for genes encoding HSPs (Farahani et al, 2020; Hand et al, 2016; Li et al, 2007; Ren et al, 2016; Rinehart et al, 2007; G. Zhang et al, 2018); however, the response of other groups of chaperone genes to diapause or starvation is not known.…”