First demonstration of the influence of photoperiod on the thermal requirements for development in insects and in particular the linden-bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

Abstract

Abstract. The influence of photoperiod on the thermal requirements for development was discovered for the first time in insects during experiments on the linden-bug, Pyrrhocoris apterus. The effect of photoperiod on the duration of linden-bug development at five constant temperatures (20, 22, 24, 26 and 28°C) was measured and the thermal requirements for development at three photoperiods (14, 17 and 20 h light per day) were calculated. Bugs from four geographic populations were used in these experiments: Pyatigorsk (44°02´N, 43°04´E), Borisovka (50°36´N, 36°01´E), Mikhailov (54°15´N, 39°0´E) and Ryazan (54°36´N, 39°42´E).From the values of individual development times at different temperatures the coefficient of linear regression of development rate (the inverse of the duration) on temperature and the thermal threshold for development were calculated. Both these parameters were found to decrease significantly with decrease in day-length for all four populations studied. It means that at shorter day-lengths nymphal development is less dependent on temperature compared to the development at longer day-lengths. These effects seem to be adaptive. The development times of nymphs at relatively high temperatures (above 24-25°C) are shorter under long-days than under short days which should be advantageous at the height of summer when the days are long and the weather is warm. In the contrast, at relatively low temperatures (below 24-25°C) the nymphs develop significantly faster under short-days than under long days, which is advantageous at the end of summer as it allows the nymphs to reach the adult stage, the only stage capable of overwintering. The influence of photoperiod on the thermal reaction norm appeared to be more or less gradual, i.e. the shorter the day-length the shallower the slope of the regression line of development rate on temperature and the lower the thermal threshold for development. An analysis of the literature shows that this effect of photoperiod on the thermal requirements for development is widespread among insects but has been overlooked by previous authors. The authors conclude that the variation in the development time observed in insects at different seasons, photoperiods or food regimes, or from different populations, etc., are generally due to some modification of the thermal reaction norms and more specifically to differences in the thermal requirements for development.

Photoperiod-temperature interaction-a new form of seasonal control of growth and development in insects and in particular a Carabid Beetle, Amara communis (Coleoptera: Carabidae)

“…Our studies on the linden bug Pyrrhocoris apterus at three photoperiods and five temperatures were the first to show that photoperiodic conditions do not simply accelerate or decelerate larval growth and development, as it was shown previously [15,16], but do change the thermal reaction norm [17]. The short-day photoperiod accelerates nymphal development, as compared to the longday one, at temperatures below 24°C, but at higher temperatures the pattern is reverse (Fig.…”

“…Thereby, we might expect some kind of short-day modification of thermal reaction norms in larvae late in season. [17]. From now on, x-axis is temperature, °C.…”

Photoperiodic control of development and reproduction in Harmonia axyridis (Coleoptera: Coccinellidae)

“…Diapause-inducing short day conditions sometimes (but by no means always) accelerates the development of the stages preceding diapause, thus increasing the percentage of the population that has time to prepare for overwintering (Zaslavski, 1988;Saunders, 2002;Lopatina et al, 2007). The data presented accords with this generalization, although in other coccinellid species the rate of development is independent of photoperiod (McMullen, 1967;Hodek & Hon k, 1996).…”

“…For example, in a recent detailed study of the influence of photoperiod on the pre-imaginal development of different populations of the linden bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae), the differences between the results obtained at short and long days varied, depending on temperature, from practically zero to more than 20% (Lopatina et al, 2007), while in similar experiments conducted with other representative of the same order, Orius strigicollis (Poppius) (Heteroptera: Anthocoridae), the maximum difference between the duration of pre-imaginal development under short and long days did not exceed 10% of the total (Musolin et al, 2004). Generally, the effect of photoperiod on the duration of insect development can vary from slight changes to a sharp increase, although in the last case not protracted development but diapause induction can occur (Tauber et al, 1986;Zaslavski, 1988;Saunders, 2002).…”

“…Significant differences between patterns and thresholds of two reactions would indicate their relative independence. However, such studies are rarely conducted (Zaslavski, 1988;Denlinger, 2002;Saunders, 2002;Musolin et al, 2004;Lopatina et al, 2007;Saunders, 2010). In particular, although photoperiodic responses are reported for many species of Coccinellidae (Hodek & Hon k, 1996, see Discussion for more references) in only a few are the influences of day length on the rate of the pre-imaginal development and the rate of reproductive maturation of adult females (or diapause induction) investigated over a range of photoperiods.…”