Dormancy and the influence of photoperiod and temperature on sexual maturity in Nicrophorus nepalensis (Coleoptera: Silphidae)

Abstract

Carrion beetles (Nicrophorus spp.) use small vertebrate carcasses for food and reproduction. Their ecology and behaviors are highly affected by the availability of carcasses and the surrounding environmental conditions. Our results revealed that in subtropical Fushan, northern Taiwan, N. nepalensis was mainly active in spring (February to May), and could also be found in autumn (October and November); but there was no capture record in summer (June to September) and winter (December and January). A laboratory temperature tolerance study indicated that N. nepalensis adults become inactive at temperatures above 26°C, and had the highest mortality when the temperature was raised from 27°C to 28°C. Furthermore, N. nepalensis became sexually mature at 20°C, depending on the photoperiod: the longer the day, the lower the percentage of sexually mature 2‐week‐old females after emergence. In another experiment, N. nepalensis virgins were paired under three possible conditions at Fushan. At 15°C and 20°C, if carcasses were presented to the pairs within 3 days after emergence, all laid eggs in the second week after emergence. If carcasses were presented 1 week after emergence, most began to reproduce at 20°C with 12.5 h of daylight. However, at 15°C with 11 h of daylight, the carrion beetles hibernated first, and reproduced in the ninth week after emergence. At 25°C with 14 h of daylight, carrion beetles did not bury the mouse carcasses, the females did not lay eggs, and the adult lifespan was only one‐third of that at 20°C. This study revealed that both photoperiod and temperature influence the time needed to reach the sexual maturity of N. nepalensis; and also implied that the narrow temperature tolerance range and dormancy behavior of carrion beetles are highly regulated by those environmental factors.

Succession study on forensically important Coleoptera from India: a preliminary study and its forensic implications

“…Nercophila (Calosilpha) cyaniventris had been reported before similar studies conducted in India (Bharti & Singh 2003). Nicrophorus nepalensis is a carrion-feeding beetle and is known to be attracted to small carrions (Hwang & Shiao 2011), but there were only two specimens recorded during the active decay stage in this study. However, their appearance indicates its general presence in the study habitat and area.…”

Geographic variation in photoperiodic diapause induction and diapause intensity in Sericinus montelus (Lepidoptera: Papilionidae)

“…In insects, faster evolutionary response may occur in northern populations where selection is stronger and genetic variation is greater than in southern population, for example, the shift toward shorter critical photoperiods in response to climate warming on seasonality in Wyeomyia smithii (Bradshaw & Holzapfel, 2001). Diapause in insects of temperate regions is critically important for survival during the unfavorable season of the year and for synchronizing the active part of the life cycle with the favorable season, and local populations can use specific environmental stimuli to foresee seasonal changes in habitat (Tauber et al , 1986; Danks, 1987; Vinod & Sabu, 2010; Hwang & Shiao, 2011). Therefore, investigation on the geographic variation in traits related to diapause will enable better prediction of the impact of climate warming on insect species.…”

The Impact of Diet and Photoperiodism on the Life History ofThanatophilus sinuatus(Coleoptera: Silphidae)

“…Unfortunately, only minor investigations were performed on necrophagous beetles. For example, it was discovered that a longer day regime (increased light) delayed sexual maturity in the females of Nicrophorus nepalensis Hope, 1831 (Hwang and Shiao 2011), or the reproduction and ovarian development in Nicrophorus quadripunctatus Kraatz, 1877 (Nisimura et al 2002). Regarding other coleopteran taxa, the photoperiod also seemed to impact their development quite variably (e.g., Berkvens et al 2007, Lopatina et al 2011, Kutcherov et al 2018) Overall, such differences among the taxa illustrate the importance of correctly selecting the photoperiod regime for rearing each species.…”