Impact of hot events at different developmental stages of a moth: the closer to adult stage, the less reproductive output

Abstract

Hot days in summer (involving a few hours at particularly high temperatures) are expected to become more common under climate change. How such events at different life stages affect survival and reproduction remains unclear in most organisms. Here, we investigated how an exposure to 40 °C at different life stages in the global insect pest, Plutella xylostella, affects immediate survival, subsequent survival and reproductive output. First-instar larvae showed the lowest survival under heat stress, whereas 3rd-instar larvae were relatively heat resistant. Heat exposure at the 1st-instar or egg stage did not influence subsequent maturation success, while exposure at the 3rd-instar larval stage did have an effect. We found that heat stress at developmental stages closer to adult stage caused greater detrimental effects on reproduction than heat stress experienced at earlier life stages. The effects of hot events on insect populations can therefore depend critically on the timing of the event relative to an organism’s life-cycle.

Stage-specific heat effects: timing and duration of heat waves alter demographic rates of a global insect pest

“…These hypotheses have been supported in laboratory experiments. For example, exposing early life-stages of P. xylostella (Xing et al 2014;Zhang et al 2015), eggs of Manduca sexta and Wyeomyia smithii (Zani et al 2005) and early instar nymphs/larvae of Metopolophium dirhodum (Ma et al 2004b) and Harmonia axyridis (Knapp and Nedvěd 2013) to acute [i.e. high amplitude but short duration (few hours)] heat stress did not affect female fecundity or adult phenotype.…”

“…Demographic effects of hot periods are likely to be stage specific due to thermal tolerance (Bowler and Terblanche 2008;Zhang et al 2015), and the physiological response to temperature (Folguera et al 2010;Forster and Hirst 2012) typically change during the ontogeny of organisms. For example, adult amphibians and reptiles are able to tolerate higher temperatures for a longer time than those at earlier life-stages (e.g.…”

“…For example, adult amphibians and reptiles are able to tolerate higher temperatures for a longer time than those at earlier life-stages (e.g. eggs or larvae) (Sherman 1980;Xu and Ji 2006;Telemeco 2014), while in invertebrates, juvenile stages often have a higher tolerance (Krebs and Loeschcke 1995;Klok and Chown 2001;Ma et al 2004a;Lyons et al 2012;Zhang et al 2015). It is also possible that the effects of temperatures experienced during early life-stages could also be carried over to alter adult traits.…”

Constraints to Vegetable Production Resulting from Pest and Diseases Induced by Climate Change and Globalization: A Review

“…Egg production and the adult stage of this insect were decreased at higher temperatures. However, the larval stage was found to be highly tolerant to high temperatures (Zhang et al, 2015). This means that there could be implications when managing this insect pest under high temperatures in the near future.…”

“…This can result in more severe damage to crops if farmers are failing to control insect pests. Different stages in the life cycle of an insect can respond differently to high temperatures (Zhang et al, 2015). Some insects can be highly favoured by high temperatures, influencing their population positively, whereas some insects can result to high mortality rates under high temperatures.…”