Differences in the pre‐diapause and pre‐oviposition accumulation of critical nutrients in adult females of the beetle Colaphellus bowringi

Abstract

In many insect species, the differentiation of development between diapause and reproduction first becomes obvious during the diapause preparation (pre-diapause) and pre-oviposition phases. However, the differentiation of nutrient accumulation between these two phases remains unclear. We compared the weights of pre-diapause and reproductive adult female Colaphellus bowringi Baly (Coleoptera: Chrysomelidae), and measured their triacylglycerol (TAG), protein, and carbohydrate content from emergence until they had fed for 4 days post-eclosion. We also compared the ovarian development and accumulation of lipid droplets between pre-diapause and reproductive adult females in order to determine whether we could visually detect differences in nutrient allocation. The weights of both pre-diapause and reproductive females increased with duration of feeding. The fresh weight and water content of pre-diapause females was significantly lower than that of reproductive females after feeding for 3 days post-eclosion. Pre-diapause females channeled their reserves into TAG in the fat body, whereas reproductive females converted nutrients into proteins and carbohydrates for egg development. These results quantify differences in nutrient accumulation between pre-diapause and reproductive adult female C. bowringi, and provide clues for understanding the molecular mechanisms underlying differences in the allocation of nutrients between diapause and reproduction in insects.

Association between gut microbiota and diapause preparation in the cabbage beetle: a new perspective for studying insect diapause

“…Interestingly, a similar pattern has been reported in a study of mammalian obesity; compared to lean mice, obese mice underwent a 50% increase in the abundance of Firmicutes and a proportional reduction in that of Bacteroidetes 20. Therefore, the accumulation of lipids in diapause-destined C. bowringi 4 may be associated with an increase in human obesity-associated gut microbiota, such as Firmicutes . Some studies of rodents and humans have reached the opposite conclusion regarding the function of Proteobacteria in obesity212223, but most available evidence suggests that Proteobacteria can regulate host obesity24.…”

“…Some studies of rodents and humans have reached the opposite conclusion regarding the function of Proteobacteria in obesity212223, but most available evidence suggests that Proteobacteria can regulate host obesity24. Therefore, we think it possible that the higher abundance of Proteobacteria in diapause-destined C. bowringi may be related to fat storage during diapause preparation4.…”

“…Diapause-destined individuals generally store large fat reserves for diapause maintenance and post-diapause development134. However, it remains unclear how lipid is accumulated during diapause preparation, an important stage before diapause itself5.…”

“…Conversely, non-diapausing, reproductive insects store more proteins and carbohydrates in the ovary during the pre-oviposition period4. Interestingly, fat storage in diapausing insects seems to coincide with obese phenotypes9 suggesting that studies of animal obesity may help understand diapause.…”

“…Both types of female feed intensively during this period. Nutrients in reproductive females are mainly stored in the ovary in the form of proteins, while nutrients in diapause-destined females are primarily channeled to the fat body (the adipose and metabolic tissue of insects) in the form of triglycerides4. These two different patterns of nutrient distribution make an important contribution to subsequent reproduction or diapause317.…”