Sequence and expression analysis of the spermatogenesis-specific gene cognates, wampa and Prosα6T, in Drosophila suzukii.

The sterile insect technique (SIT) is a highly effective biologically-based method for the population suppression of highly invasive insect pests of medical and agricultural importance. The efficacy of SIT could be significantly enhanced, however, by improved methods of male sterilization that avoid the fitness costs of irradiation. An alternative sterilization method is possible by gene-editing that targets genes essential for sperm maturation and motility, rendering them nonfunctional, similar to the CRISPR-Cas9 targeting of β2-tubulin in the genetic model system, Drosophila melanogaster.

Divergence in cell cycle progression is associated with shifted phenology in a multivoltine moth: the European corn borer, Ostrinia nubilalis.

Evolutionary change in diapause timing can be an adaptive response to changing seasonality, and even result in ecological speciation. However, the molecular and cellular mechanisms regulating shifts in diapause timing remain poorly understood. One of the hallmarks of diapause is a massive slowdown in the cell cycle of target organs such as the brain and primordial imaginal structures, and resumption of cell cycle proliferation is an indication of diapause termination and resumption of development.

A rapidly evolved shift in life-history timing during ecological speciation is driven by the transition between developmental phases.

For insect species in temperate environments, seasonal timing is often governed by the regulation of diapause, a complex developmental programme that allows insects to weather unfavourable conditions and synchronize their life cycles with available resources. Diapause development consists of a series of distinct phases including initiation, maintenance, termination and post-diapause development. The evolution of insect seasonal timing depends in part on how these phases of diapause development and post-diapause development interact to affect variation in phenology.

A comparison of the life-history traits between diapause and direct development individuals in the cotton bollworm, Helicoverpa armigera.

In order to understand the differences of life-history traits between diapause and direct development individuals in the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), the development time, body size, growth rate, and adult longevity were investigated between the two populations, which were induced under 12:12 L:D and 16:8 L:D photoperiods, respectively, at 20, 22, and 25°C. The results indicated that the larval development time, pupal weight, adult weight, and growth rate were significantly different between diapause and direct developing individuals. The diapause developing individuals had a significantly higher pupal and adult weight and a longer larval time compared with direct developing individuals.

Diapause induction and termination in Hyphantria cunea (Drury) (Lepidoptera: Arctiinae).

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.

Geographic variation in diapause induction and termination of the cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae).

Overwintering diapause in Helicoverpa armigera, a multivoltine species, is controlled by response to photoperiod and temperature. Photoperiodic responses from 5 different geographical populations showed that the variation in critical photoperiod for diapause induction was positively related to the latitudinal origin of the populations at 20, 22 and 25°C. Diapause response to photoperiod and temperature was quite different between northern and southern populations, being highly sensitive to photoperiod in northern populations and temperature dependence in southern populations.

Effect of photoperiod and temperature on the intensity of pupal diapause in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae).

The intensity of pupal diapause in the cotton bollworm, Helicoverpa armigera (Hübner) was investigated under both laboratory and natural conditions. By transferring diapausing pupae induced under LD 11:13, LD 12:12 and LD 13:11 at 20, 22 and 25 °C to 25 °C combined with LD 15:9 to terminate diapause the rearing day length of 11 h evoked greater intensity of diapause than did 12 and 13 h at 25 °C; whereas the rearing temperature of 25 °C evoked more intense diapause than did 20 and 22 °C under LD 11:13. By transferring diapausing pupae induced under LD 12:12 at 20 and 22 °C to six temperatures of 18, 20, 22, 25, 28 and 31 °C combined with LD 15:9 to terminate diapause, the duration of diapause was significantly shortened from 146 days at 18 °C to 24 days at 31 °C, showing that high temperatures significantly accelerate diapause development.

Inheritance of photoperiodic control of pupal diapause in the cotton bollworm, Helicoverpa armigera (Hübner).

Pupae of the cotton bollworm, Helicoverpa armigera display a diapause in response to the exposure of their larvae to short photoperiods and relatively low temperatures. Due to geographic variation in photoperiodic response, moths from a northern population, Langfang (39°32'N, 116°41'E), enter diapause in response to short daylengths (D strain) while moths from a southern population, Ledong (18°28'N, 108°53'E), exhibit no diapause under the same conditions (N strain). In the present study, crosses between the two strains are utilized to evaluate the inheritance of diapause under different photoperiods at temperatures 20, 22 and 25°C.