Transgenerational seasonal timer for suppression of sexual morph production in the pea aphid, Acyrthosiphon pisum

Abstract

Many aphid species switch reproductive modes seasonally, with the sexual generations appearing in autumn. Sexual generations are induced by short days. It has been reported that the appearance of sexual morphs is suppressed by a transgenerational factor (a seasonal timer) over several generations after hatching from overwintered eggs. The present study examined whether the seasonal timer measures the number of days from hatching or the number of generations from hatching using the pea aphid, Acyrthosiphon pisum Harris (Homoptera: Aphididae). Effects of temperature and photoperiod on the seasonal timer were also examined by successive rearing. The ability to produce sexual morphs was strongly suppressed in stem mothers (the foundress generation), and gradually recovered over successive generations produced during a few months. The duration for which the seasonal timer could function depended on the number of days from hatching and temperature, but not on photoperiod or the number of generations from hatching. We thus showed in a single study that the seasonal timer of the pea aphid has all the physiological characteristics shown in separate studies in different aphid species.

Insect photoperiodism: Seasonal development on a revolving planet

“…The photoperiodic response was then fully restored, the short-day treatment inducing oviparae that, in turn, produced diapause eggs. A similar transgenerational timer has been recorded in the pea aphid Acyrthosiphon pisum (Matsuda et al, 2017). It is possible that mechanisms preventing a maladaptive diapause under spring photoperiods are widespread, particularly at southern latitudes where winter ends whilst daylength is still short.…”

The Effects of Different Diets and Transgenerational Stress on Acyrthosiphon pisum Development

“…However, while A. pisum may be an important sap-feeding pest model, very little is known about its nymphal development compared to insect models that belong to other insect orders. Previous developmental studies in A. pisum have primarily focused on polyphenisms observed in the adult life stages; male vs. female, alate vs. apterous morphs, and sexual vs. asexual reproduction [4,5,6,7,8,9,10,11,12,13,14,15,16]. While understanding the development of these polyphenisms is extremely important in aphids, having a deeper understanding of nymphal development is also important because while these phenotypes are visible in adult life stages, patterning and fate specification occur during embryonic and nymphal life stages.…”

Ploidy dynamics in aphid host cells harboring bacterial symbionts

“…Viviparous insects were maintained on young, broad bean plants ( Vicia faba L.) in a 16 °C incubator, with a photoperiod of 16 h light:8 h dark (long-day conditions). Sexual morphs (oviparous females and males) were induced by short-day conditions (e.g., 8 h light:16 h dark) (Figure 2, S1, modified from [58, 60, 61] ). Viviparous females were randomly selected from the synchronized source populations and reared on young broad bean plants at 16 °C under long-day conditions.…”