Influence of rearing temperature on triacylglycerol storage in the pea aphid, Acyrthosiphon pisum

Abstract

Total fatty acids in the pea aphid reared at low temperatures increased significantly compared to that at high rearing temperatures. This change is reflected in a large increase of myristic acid, which occurs exclusively in triacylglycerols. When aphids were moved from 25°C to a lower rearing temperature at 10°C, saturated fatty acids accumulated over time, reaching a maximum at 16th day. When aphids were moved to 4°C, a temperature below the developmental threshold, those aphids did not accumulate saturated fatty acids. Similar results were observed when aphids were exposed to sequential decrease in rearing temperature. However, both total fatty acids and myristic acid in the aphids from the treatments of sequential decreasing rearing temperature were significantly higher compared to those in the aphids from the treatments of sudden decreasing rearing temperature. This result, therefore, supports the hypothesis that cold-adapted aphids can survive under threshold temperature for a longer period of time than noncold-adapted aphids. Acetyl-CoA carboxylase activity in the aphids at 25°C was twofold higher than that in the aphids at 10°C, whereas fatty acid synthase activities in the aphids reared at 25 and 10°C are similar. Aphids reared at 10°C showed a threefold reduction in reproduction rates. This reduced production of new nymphs reduces energy demand and would allow for accumulation of energy in the form of triacylglycerols. Therefore, the increased level of saturated fatty acids in aphids reared at low temperature is probably related to lower utilization of fatty acids rather than increased rates of biosynthesis.

Striking clone-specific nymph deformity in pea aphid exposed to heat stress

“…There was a distinct rise in metabolomic fingerprints of lipids and fatty acids following exposure to thermal stress, which was consistent across clones. Lower reproductive rates under thermal stress may protect the accumulation and utilisation of saturated fatty acids and that can aid in alleviating the energetically costly effects of stress [77]. This is well documented under lower temperatures, e.g ., diapause [78], but consistent with the findings provided by Klepsatel et al (2019) [79] on D. melanogaster , the described lipid metabolic response may be universal under low or high temperatures.…”

Exposure to heat stress leads to striking clone-specific nymph deformity in pea aphid

“…There was a distinct rise in metabolomic fingerprints of lipids and fatty acids following exposure to thermal stress, which was consistent across clones. Lower reproductive rates under thermal stress may protect the accumulation and utilisation of saturated fatty acids and that can aid in alleviating the energetically costly effects of stress [ 81 ]. This is well documented under lower temperatures, e .…”

Serratia symbiotica Enhances Fatty Acid Metabolism of Pea Aphid to Promote Host Development

“…By contrast, suppression of lipogenesis in the pea aphid had little effect on the titer of Serratia , suggesting that lipids may not be necessary for the proliferation of Serratia , possibly because of its fatty acid synthetic ability in [ 32 , 40 ]. Since the fat body is the central repository of nutrients and energy, the enhanced lipid storage in lipid droplets can also better meet the aphid’s energy demands for growth, in addition to enhanced tolerance to the heat or cold stresses [ 41 ].…”