Search

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.03.019 Byline: Xing-Ping Liu, Hai-Min He, Xian-Ju Kuang, Fang-Sen Xue Abstract: It is generally thought that females preferentially mate with novel males rather than with males with which they have recently mated and polyandry can lead to greater reproductive success. We first examined female mate preference and then compared mating duration and female fitness between monogamy and polyandry in the cabbage beetle, Colaphellus bowringi Baly. In a simultaneous choice test, the majority of females remated with familiar males rather than novel males. Mating also lasted longer with familiar males. In a second experiment, monogamous females lived longer than polyandrous females. Although there was no significant difference in egg production between monogamous and polyandrous females, the former produced more viable eggs, with a higher hatching rate. These results suggest that monogamy is more advantageous for female fitness than polyandry in C. bowringi. Author Affiliation: Institute of Entomology and Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Jiangxi Agricultural University and Key Laboratory of Physiology, Ecology and Cultivation of Double Cropping Rice, Ministry of Agriculture, China Article History: Received 17 October 2009; Revised 23 November 2009; Accepted 22 March 2010 Article Note: (miscellaneous) MS. number: 09-00684R

Temperature is a key environmental factor for ectotherms and affects a large number of life history traits. In the present study, development time from hatching to pupation and adult eclosion, pupal and adult weights of the rice stem borer, Chilo suppressalis were examined at 22, 25, 28 and 31 °C under L18:D 6. Larval and pupal times were significantly decreased with increasing rearing temperature and growth rate was positively correlated with temperature. Larval and pupal developmental times were not significantly different between females and males. The relationship between body weight and rearing temperature in C. suppressalis did not follow the temperature–size rule (TSR), both males and females gained the highest body weight at 31 °C. Females were significantly larger than males at all temperatures, showing a female biased sex size dimorphism (SSD). Contrary to Rensch's rule, SSD and body weight in C. suppressalis tended to increase with rising temperature. Male pupae lost significantly more weight at metamorphosis compared to females. We discuss the adaptive significance of the reverse-TSR in the moth's life history. [ABSTRACT FROM AUTHOR]

Abstract: Thyrassia penangae enters winter diapause as a prepupa in a cocoon. Photoperiodism of diapause induction was systematically investigated in this moth. The photoperiodic response curves under 24-h light–dark cycles showed that this insect is a typical long-day species. The critical daylength was 13h 30min at 25°C, 13h at 30°C and 12h 20min at 28°C. Transferring experiments from a short day (LD 12:12) to a long day (LD 15:9) or vice versa indicated that photoperiodic sensitivity mainly occurs during the larval period. In experiments using non-24-h light–dark cycles, when the length of photophase exceeded the critical daylength (13.5h), was diapause inhibited effectively, even when the length of scotophase exceeded the critical nightlength (10.5h). Only when a long scotophase was combined with a short photophase, diapause was induced effectively. This result suggests that daylength measurement is more important than nightlength measurement in T. penangae. Night interruption experiments under 24-h light–dark cycles exhibited two points of apparent light sensitivity, but the photosensitive position was highly influenced by temperature and the length of scotophase. Nanda–Hamner experiments failed to reveal the involvement of a circadian system in this photoperiodic time measurement. All light–dark cycles from LD 12:12 to LD 12:72 resulted in a short day response, and all cycles from LD 14:4 to LD 14:72 resulted in a long day response, suggesting that photoperiodic time measurement in this moth is performed by a day-interval timer or an hourglass-like clock. [Copyright &y& Elsevier]

Temperature is a key environmental factor in ectotherms and influences many life history traits. In the present study, the nymphal development time, sex ratio and wing dimorphism of the small brown planthopper Laodelphax striatellus were examined under the conditions of constant temperatures, naturally varying temperatures (or different generations), and different temperatures combined with different photoperiod. The results showed that from 18 to 28 °C, the developmental time of nymphs was gradually shortened with the increase of temperature, whereas the high temperatures of 30 and 32 °C in the third to fifth instar nymphal stages and high summer temperature of 28.8 and 29.7 °C significantly delayed developmental time and resulted in higher mortality of nymphs. In all treatments, the developmental time was longer in females than males. The nymphs took significantly longer time to develop in the short daylength of 12 h than in longer daylengths of 13, 14, 15 and 16. Differences in developmental time were also found between wing morph, with long-winged individuals being significantly longer than the short-winged individuals at lower temperatures and significantly shorter than the short-winged individuals at higher temperatures. In all treatments, the sex ratio was stable, approaching 1:1, without being affected by temperature, generations and photoperiod. Photoperiod and temperature had significantly influence on the wing dimorphism. Long daylength combined with different temperatures resulted in significantly higher proportions of long-winged morph, whereas the low temperatures combined with the short daylengths in autumn and winter resulted in significantly high proportion of short-winged morph. This study broadens our understanding of the life-history traits of this planthopper and provides basic data for analyzing the effects of climate change on the planthopper reproduction. • Life-history traits of L. striatellus were tested at different rearing conditions. • Temperature, photoperiod, sexes, and wing morph affected nymphal development time. • High temperatures delayed nymphal time and resulted in high mortality. • Sex ratio was not affected by temperature, photoperiod and season. • Wing dimorphism ratio was affected by temperature and photoperiod. [ABSTRACT FROM AUTHOR]

Highlights: [•] The critical photoperiod for diapause induction was positively related to latitude. [•] Diapause duration was longer in northern populations at high temperatures. [•] Diapause duration was negatively correlated with latitude under natural conditions. [•] Diapause-inducing temperature on diapause duration had a significant effect. [•] Response of southern and northern populations to chilling was different. [ABSTRACT FROM AUTHOR]

Abstract: Adults of the cabbage beetle Colaphellus bowringi display a summer diapause in response to the exposure of their larvae to long photoperiods. In the present study, the inheritance of the photoperiodic response controlling summer diapause in C. bowringi by crossing a high diapause strain (D strain) with a laboratory selected nondiapause strain (N strain) was investigated under different photoperiods at 22, 25 and 28°C. The beetles in both reciprocal crosses and backcrosses showed a clear short-day response for the induction of diapause at all temperatures, similar to that of the D strain, suggesting that photoperiodic response of this beetle is heritable. The diapause incidences in the progeny from all the crosses under LD 15:9 or LD 12:12 at 25°C suggest that genetic and genetic–environmental interactions are involved in diapause induction. The incidence of diapauses in F1 progeny was significantly lower than that in the D×D strain but significantly higher than that in the N×N strain, indicating that the diapause capability is inherited in an incomplete dominant manner. The incidence of diapause was greater among the offspring of hybrid females when those females had a D strain mother or grandmother rather than a N strain mother or grandmother, indicating that maternal effects on diapause induction are stronger than paternal effects. The laboratory selected nondiapause strain also showed a short-day photoperiodic response at a low temperature of 22°C, indicating that the photoperiodic photoreceptor and photoperiodic clock still function in the nondiapause strain. [Copyright &y& Elsevier]