Transcriptomic analysis provides insights into the immune responses and nutrition in Ostrinia furnacalis larvae parasitized by Macrocentrus cingulum

Abstract

Macrocentrus cingulum is a principal endoparasite of Ostrinia furnacalis larvae. M. cingulum larvae repress host immune responses for survival and ingest host nutrients for development until emerging. However, most investigations focused on the mechanisms of how wasps repress the host immunity, the triggered immune responses and nutrient status altered by wasps in host are neglected. In this study, we found that parasitized O. furnacalis larvae activated fast recognition responses and produced some effectors such as lysozyme and antimicrobial peptides, along with more consumption of trehalose, glucose, and even lipid to defend against the invading M. cingulum. However, the expression of peroxidase 6 and superoxide dismutase 2 (SOD 2) was upregulated, and the messenger RNA (mRNA) levels of cellular immunity-related genes such as thioester-containing protein 2 (TEP 2) and hemocytin were also reduced, suggesting that some immune responses were selectively shut down by wasp parasitization. Taken together, all the results indicated that parasitized O. furnacalis larvae selectively activate the immune recognition response, and upregulate effector genes, but suppress ROS reaction and cellular

The selective regulation of immune responses by matrix metalloproteinase MMP14 in Ostrinia furnacalis

“…To assess the involvement of Of MMP14 in bacteria‐infected O. furnacalis larvae, dsMMP14‐treated larvae were injected with 1 × 10 4 cells of P. aeruginosa or M. luteus for survival assay according to our previous study (Chen et al. , 2022). dsGFP combined with bacteria injections were used as a control.…”

“…furnacalis larvae were reared on an artificial diet under a 16 h light : 8 h dark photoperiod at 25 °C, 80% relative humidity in a 200 mL canning jar. Pupae were collected in a 40 cm × 40 cm × 40 cm cage, adults were fed with 20% honey for mating and egg production as previously described (Chen et al, 2021;Chen et al, 2022). Day 1, 4th-instar larvae were fed with a fresh diet containing 50 μg/mL tetracycline to eliminate indigenous bacteria.…”

“…, 2022a; Chen et al. , 2022b). MMP14 is required for tissue development and remodeling (Taylor et al.…”

Nitric Oxide-Induced Calcineurin A Mediates Antimicrobial Peptide Production Through the IMD Pathway

“…All the S2 cells were plated in 12-well plates at 1×10 6 cells/well for different treatments (1 mL medium per well). Asian corn borers, O. furnacalis larvae were reared using an artificial diet at 25 ± 1°C, RH > 80%, and with a photoperiod of 16 h light and 8 h darkness ( 13 , 50 ).…”

“…Different immune challenges induce local and/or systemic responses ( 7 , 8 ), suggesting that immune signaling pathways are extensively interlocked ( 9 ). Limited nutrients and short life spans for most insects require them to properly allocate energy between immune responses and other physiological processes such as development and reproduction ( 10 – 13 ). To maximize the reward of energy investment in immune responses, the interlocked immune signaling pathways must be regulated elaborately to avoid excessive immune responses.…”