Table1_Transcription dynamics of heat shock proteins in response to thermal acclimation in Ostrinia furnacalis.DOCX

Acclimation to abiotic stress plays a critical role in insect adaption and evolution, particularly during extreme climate events. Heat shock proteins (HSPs) are evolutionarily conserved molecular chaperones caused by abiotic and biotic stressors. Understanding the relationship between thermal acclimation and the expression of specific HSPs is essential for addressing the functions of HSP families. This study investigated this issue using the Asian corn borer Ostrinia furnacalis, one of the most important corn pests in China. The transcription of HSP genes was induced in larvae exposed to 33°C. Thereafter, the larvae were exposed to 43°C, for 2 h, and then allowed to recover at 27 C for 0, 0.5, 1, 2, 4, 6, and 8 h. At the recovery times 0.5–4 h, most population tolerates less around 1–3 h than without recovery (at 0 h) suffering continuous heat stress (43 C). There is no difference in the heat tolerance at 6 h recovery, with similar transcriptional levels of HSPs as the control. However, a significant thermal tolerance was observed after 8 h of the recovery time, with a higher level of HSP70. In addition, the transcription of HSP60 and HSC70 (heat shock cognate protein 70) genes did not show a significant effect. HSP70 or HSP90 significantly upregulated within 1–2 h sustained heat stress (43 C) but declined at 6 h. Our findings revealed extreme thermal stress induced quick onset of HSP70 or HSP90 transcription. It could be interpreted as an adaptation to the drastic and rapid temperature variation. The thermal tolerance of larvae is significantly enhanced after 6 h of recovery and possibly regulated by HSP70.</p

Mortality of microcapsules and protoxins after different treatment on the Asian corn borer.

*<p>Heat: 50°C treated for 5 days.</p>a<p>The means within a column were not significantly different (P≥0.05) by <i>t</i>-test (LSD).</p>b<p>The means within a column were significantly different (P<0.05) by <i>t</i>-test (LSD).</p

CLSM photos of the FITC-Cry1Ac loaded microcapsules.

<p>CLSM photos of the FITC-Cry1Ac loaded microcapsules.</p

Bioassay results of the microencapsulated proteins’ effect on the Asian corn borer.

<p>Bioassay results of the microencapsulated proteins’ effect on the Asian corn borer.</p

SDS-PAGE of the encapsulation process.

<p>Lane 1, protein molecular weight marker. Lane 2, protoxin of Cry1Ac before being mixed with the microcapsules. Lanes 3–4, suspension and deposition together with capsules while loaded at pH 3. Lanes 5–6, suspension and deposition together with the capsule while loaded in water.</p

Effect of desiccation on protoxins and microcapsules.

<p>Lane 1, protein molecular weight marker. Lane 2, Cry1Ac protoxins. Lane 3, after desiccation at room temperature, the protoxins were redissolved in an equal amount of 50 mM Na₂CO₃ buffer. Lane 4, microcapsules with Cry1Ac protoxins. Lane 5, releasing suspension of the microcapsules after desiccation at room temperature and redissolution in 50 mM Na₂CO₃ buffer.</p

Stability of free and encapsulated Cry1Ac after heat treatment.

<p>A: Lane 1, Cry1Ac protoxins stored at 4°C. Lane 2, microcapsules with Cry1Ac stored at 37°C for 5 days. Lane 3, microcapsules with Cry1Ac stored at 4°C. Lane 4, Cry1Ac protoxins stored at 37°C for 5 days. B: Lane 1, Cry1Ac protoxins stored at 4°C. Lane 2, Cry1Ac protoxins stored at 50°C for 5 days. Lane 3, microcapsules with Cry1Ac stored at 4°C. Lane 4, microcapsules with Cry1Ac stored at 50°C after 5 days.</p

Release experiment detected by SDS-PAGE.

<p>Lane 1 and Lane 5, protein molecular weight marker. Lane 2, suspension of capsules loaded at pH 3. Lane 3, suspension of capsules in 50 mM, Na₂CO₃, pH 10.2. The protoxins were loaded at pH 7. Lane 4 and Lanes 6–8, releasing suspension of capsules loaded at pH 3. Among them, Lane 4, Lane 6 and Lane 7, releasing suspension in 50 mM Na₂CO₃, pH 10.2 for 2 hours, 30 hours, and 40 hours, respectively. Lanes 8–9, releasing suspension in water for 30 hours and 40 hours, respectively.</p

Synergistic effects between Cry1Ac and Cry1Ie toxins on ACB.

<p>Synergistic effects between Cry1Ac and Cry1Ie toxins on ACB.</p

Mortality of ACB larvae of four strains fed on plant tissues of Bt corn and non-Bt corn hybrids.

<p>Mortality of ACB larvae of four strains fed on plant tissues of Bt corn and non-Bt corn hybrids.</p