Diapause in Pentatomoidea 513
11.3.2 Temperature
Although temperature usually acts as a mere modifier of the photoperiodic effect, in some insects it is
known to be the main cue of diapause induction. The leading role of temperature in diapause induction
has been most clearly demonstrated in tropical insects (Denlinger 1986).
Among the pentatomoids in which temperature has been studied from this standpoint, winter adult
diapause has been found to be controlled primarily by temperature only in the pentatomid Andrallus
spinidens. This predaceous, polyphagous species is distributed in the tropical and subtropical
regions. In southern Japan (Takanabe; 32°N), it occurs on herbaceous plants in rice and other fields
where it actively feeds on larvae of the noctuid moths Spodoptera litura F. and Aedia leucomelas
(L.) (Shintani et al. 2010) and usually produces three or four generations a year. To control such a
multivoltine seasonal cycle and form winter adult diapause in autumn, insects usually use day length
as a cue (see Section 11.3.1 and Chapter 12), but this species utilizes a different cue. The long-term
mean temperature in this region is 26.8°C at the beginning of September and 22.3°C at the end of
September. Adults enter winter diapause primarily in response to this decrease of temperature, not
the change of day length. Nymphs hatching at the end of October usually are not able to complete
development to adults before winter and, apparently, cannot form diapause. Only adults can enter
diapause and survive until spring. Therefore, it is important for the population to enter diapause
before October.
In laboratory experiments, when nymphs and then adults of Andrallus spinidens were reared and then
maintained under constant conditions, diapause could be induced in all photoperiodic regimes tested
(with duration of the photophase of 12 to 16 h) but only at temperatures below 25°C. At higher tempera-
tures, all individuals actively developed (i.e., were nondiapausing) irrespective of day length (Figure
11.5). Sensitivity to temperature is present at the nymphal and adult stages in this species. Diapause is
terminated during winter under the influence of low temperatures, and the adult bugs resume their activ-
ity in spring (Shintani et al. 2010). Thus, the multivoltine seasonal cycle of A. spinidens is controlled
primarily by the temperature, whereas photoperiod seems to perform only an additive function (Saulich
and Musolin 2012).
Other examples of the control of winter diapause induction by temperature as in Andrallus spinidens
are rare. For insects in the Temperate Zone, temperature’s effect as a modifier of the PhPR during dia-
pause induction seems to be more important and widespread. Even though many environmental factors
likely influence the PhPR, in most species the modifying effect of temperature is the strongest.
1230.0°C27.5°C25.0°C22.5°C20.0°C13 14 15 16FIGURE 11.5 Effect of photoperiod and temperature on induction of winter adult diapause in the pentatomid Andrallus
spinidens from Takanabe, Japan (32°N). Nymphs were reared to adults and then maintained under constant experimental
conditions: temperature is indicated on the left; photoperiod on the top of the figure (as photophases, in hours). Light sec-
tors: reproductive (i.e., nondiapause) females; black sectors: diapause females. (From Y. Shintani, Y. Masuzawa, Y. Hirose,
R. Miyahara, F. Watanabe, and J. Tajima, Entomological Science 13: 273–279, 2010, with permission.)