The effect of cold temperature exposure and long‐day photoperiod on the termination of the reproductive diapause of newly emerged female Pissodes strobi (Coleoptera: Curculionidae)

Abstract

1 There is confusion in the literature concerning a possible reproductive diapause in the adult white pine weevil Pissodes strobi. 2 We evaluated the effects of temperature, photoperiod, feeding substrate and mating status on the sexual maturation and oviposition of female white pine weevils. 3 Less than 30% of female P. strobi became sexually mature and laid eggs without experiencing dormancy under a temperature regime of 2 C for 4 weeks. 4 Among the females that experienced a cold temperature treatment after emergence, 80% laid eggs after dormancy when exposed to a long-day (LD 16 : 8 h) photoperiod and 17.6% laid eggs when exposed to a short-day (LD 8 : 16 h) photoperiod. 5 Significantly more eggs were laid by all the females (with and without a cold treatment) when subjected to a long-day photoperiod compared with a shortday photoperiod. 6 A period of cold temperature followed by exposure to a long-day photoperiod with warmer temperatures is required to break reproductive diapause and to obtain a good oviposition response in female P. strobi. 7 This study reveals the existence of much intraspecific variation in the response of the white pine weevil to temperature and photoperiod with respect to the induction and termination of reproductive diapause.

Optimal Low Temperature and Chilling Period for Both Summer and Winter Diapause Development in Pieris melete: Based on a Similar Mechanism

“…For a large number of insects in temperate regions, a period of low temperature accelerates the development of diapause, and the length of the chilling period required for the termination of diapause varies among individuals within a population and among populations within the same species [3], [5]. In some insects, diapause development cannot be completed under constant diapause-inducing conditions and lower temperature is required for the completion of diapause, therefore, few or no individual complete diapause under constant diapause-inducing conditions [18]–[21]. In many insects, a chilling treatment shows significant influence on diapause termination, but is not a prerequisite for the completion of diapause, and a longer period of chilling generally facilitates the synchronization of diapause completion [22]–[29].…”

Aggregation and mating success of Capnodis tenebrionis (Coleoptera: Buprestidae)

“…The probability of observing an aggregation of beetles increased with the density of the beetle population, the temperature and the day‐length. Such a seasonal response is characteristic of insects and reflects the relative importance of these factors on the physiology of such exothermic species (Zhou, ; Trudel et al ., ; Kwon et al ., ). The absence of aggregations in the field site at the end of the summer season (when temperatures were cooler) despite the increase in local population density (due to the emergence of the next generation) provides further confirmation of the key role that environmental factors play in the formation of aggregations.…”

Ultra-estrutura dos ovaríolos de Tropidacris collaris (Stoll) (Orthoptera: Romaleidae) submetido a três fotoperíodos

“…Assim, segundo Figueira et al (2000) e Fonseca et al (2001) a temperatura, a umidade relativa do ar e o fotoperíodo podem afetar o potencial reprodutivo e o desenvolvimento dos insetos, atuando positiva ou negativamente sobre o número de indivíduos de uma população. Várias pesquisas mostram ainda que o fotoperíodo induz ou interrompe a diapausa, torna o dia mais curto ou mais longo, afeta o desenvolvimento, a reprodução, o tamanho do ovário e a biologia de inúmeros grupos taxonômicos de insetos (Trudel et al 2002, Velarde et al 2002, Macedo et al 2003. De acordo com Lenteren (1989) também a ovogênese nos insetos é controlada por fatores externos como o fotoperíodo, o que se dá através do sistema neuroendócrino, onde as condições de dias curtos levam à inativação dos corpora allata, resultando em baixos teores do hormônio juvenil e preparação para diapausa.…”