Diapause Induction and Termination in Hyphantria cunea (Drury) (Lepidoptera: Arctiinae)

Abstract

The fall webworm, Hyphantria cunea (Drury), enters facultative diapause as a pupa in response to short-day conditions during autumn. Photoperiodic response curves showed that the critical day length for diapause induction was 14 h 30 min, 14 h 25 min and 13 h 30 min at 22, 25 and 28°C, respectively. The photoperiodic responses under non-24 h light–dark cycles demonstrated that night length played an essential role in the determination of diapause. Experiments using a short day length interrupted by a 1-h light pulse exhibited two troughs of diapause inhibition and the effect of diapause inhibition was greater in the early scotophase than in the late scotophase. The diapause-inducing short day lengths of 8, 10 and 12 h evoked greater intensities of diapause than did 13 and 14 h. Diapause can be terminated without exposure to chilling, but chilling at 5°C for 90 and 120 d significantly accelerated diapause development, reduced mortality, and synchronized adult emergence. Additionally, the potential for H. cunea from the temperate region (Qingdao) to emerge and overwinter under field conditions in subtropical regions (Nanchang) of China was evaluated. Pupae that were transferred to Nanchang in early July showed a 60% survival rate and extremely dispersed pupal period (from 12 to 82 days), suggesting that some pupae may undergo summer diapause. Diapausing temperate region pupae that were moved out-of-doors in Nanchang during October showed approximately 20% overwintering survival; moreover, those pupae that overwintered successfully emerged the next spring during a period when their host plants would be available. The results indicate that this moth has the potential to expand its range into subtropical regions of China.

Rapid genetic structuring of populations of the invasive fall webworm in relation to spatial expansion and control campaigns

“…1), with FWW only being found at relatively low elevations (up to 589 m in Xinglong County [117.5°E, 40.42°N]). FWW might now be expected to expand further in a southerly direction until other ranges such as the Qinling Mountains and Dabie Mountains are reached (Li et al, 2009;Chen et al, 2014) and this could lead to future admixture of the two groups. The northward expansion of the eastern group might be limited by low temperature to the north of the original introduction site in the early stages, while the recent expansions may reflect climate change in recent years (Yu & Li, 2015;Hu et al, 2016) or an evolutionary increase in cold hardiness in the cold region (Xu et al, 2015).…”

Host–plant quality alters herbivore responses to temperature: a case study using the generalist Hyphantria cunea

“…Throughout the pre-experimental rearing stages, caterpillars were reared at a density of 20-30 individuals per dish in an environmental chamber set at 25°C and L16:D8 photoperiod. This photoperiodic condition was chosen to prevent caterpillars from entering diapause regardless of the experimental temperature they were exposed to (Gomi, 1997;Takeda, 2005;Chen et al, 2014).…”

“…Until recently, several studies have investigated biological aspects of H. cunea, including life-history and voltinism (Gomi & Takeda, 1996;Gomi, 2007;Gomi et al, 2007Gomi et al, , 2009), host-plant preferences and performance (Morris, 1967;Greenblatt et al, 1978;Williams & Myers, 1984), and diapause (Gomi, 1997;Li et al, 2001;Chen et al, 2014). To the best of our knowledge, this is the first work that investigates how the thermal responses of this generalist caterpillar are altered by the nutritional quality of host plant.…”

Photoperiodic control of diapause induction in the zygaenid moth <em>Thyrassia penangae</em> &ndash; involving day-length measurement

“…The central importance of night length was also seen in data for the flesh fly Sarcophaga argyrostoma (Robineau-Desvoidy) 5 in which the incidence of pupal diapause was very low in cycles containing a short night (eg, LD 12:8 and LD 16:8) with non-24-h light-dark cycles in which photophases of 10, 12, 14, and 16 h were combined with different lengths of scotophase of 4-24 h have been carried out on the zygaenid moth Pseudopidorus fasciata (Felder & Felder, 1862), the pine caterpillars Dendrolimus punctatus (Walker), the rice stem borer Chilo suppressalis (Walker), the Asian corn borer Ostrinia furnacalis, and the fall webworm Hyphantria cunea in our laboratory. [6][7][8][9][10] The photoperiodic response curves in these species all showed that the incidence of larval diapause was low or zero in cycles containing a short night (4 and 8 h), but high in cycles containing a long night (12,16,20, and 24 h), regardless of the length of the photophase, indicating that the length of the scotophase plays an essential role in the determination of diapause in these species.…”