Differing non‐linear, lagged effects of temperature and precipitation on an insect herbivore and its host plant

Abstract

1. Multivariate climate change is expected to impact insect densities and plant growth in complex, and potentially different, ways. Tea (Camellia sinensis) is a unique crop system where the increase in quality from chemical defences induced by Empoasca onukii (Homoptera: Cicadellidae) feeding can outweigh reductions in yield and make attack by this leafhopper desirable to tea farmers. Differential impacts of weather attributes on tea and herbivores could impact feasibility of this unique farming strategy in a rapidly changing climate.2. We monitored leafhopper densities and tea shoot growth at a tea farm in Fujian Province, China for 2 months (June and July). We used distributed lag non-linear models to capture potentially delayed and non-linear effects of weather attributes on tea growth and leafhopper densities.3. Weather attributes had contrasting effects on leafhopper density and tea shoot growth. Leafhopper densities were highest with low daily mean and maximum temperatures, while warm temperatures favoured tea growth. Effects of temperature on leafhoppers were delayed, while effects on tea growth were immediate. Precipitation reduced tea growth, and had a delayed positive effect on leafhopper density.4. The delayed effects of weather attributes on leafhoppers indicate that earlier, less conspicuous life stages (i.e. eggs and early instar nymphs) may be susceptible to desiccation. Although increasing annual mean temperature is commonly predicted to benefit multivoltine insect pests, our results show that cool, wet conditions benefit E. onukii during summer months when they are most abundant. These results have implications for tea green leafhopper management strategies.

Predicting the seasonal flight activity of Myzus persicae, the main aphid vector of Virus Yellows in sugar beet

“…Indeed, our data was available only until 2014, but temperature and precipitation patterns are rapidly changing and will continue doing so in the next decades, leading to novel weather conditions that are not represented in our data. Insect populations exhibit complex and non‐linear responses to climate changes, making them prone to shifts in their functioning that are very difficult to predict 77,78 . This additional layer of uncertainty should be kept in mind when predicting in new situations.…”

“…Insect populations exhibit complex and non-linear responses to climate changes, making them prone to shifts in their functioning that are very difficult to predict. 77,78 This additional layer of uncertainty should be kept in mind when predicting in new situations.…”

Delayed effects of climate on vital rates lead to demographic divergence in Amazonian forest fragments

“…When they finally do, the resulting leaf drop (Janssen et al, 2021) and treefalls allow for light penetration to the forest understory (Canham et al, 1990; Leitold et al, 2018), triggering a boom in the growth and flowering of understory plants (Bruna & Oli, 2005). Similar delayed changes in the local environment could also influence the foraging behavior of a plant's pollinators (Bruna et al, 2004; Stouffer & Bierregaard, 1996), seed dispersers (Uriarte et al, 2011), or herbivores (Scott et al, 2021). While more work is needed to explain why the (delayed) effects of SPEI on H. acuminata survival and growth are greater in fragments than forest interiors, one hypothesis, motivated by recent intriguing results from other systems (Sapsford et al, 2017), is that the greater litterfall on edges (Vasconcelos & Luizão, 2004) may be altering the abundance of pathogens or mycorrhizae.…”

Delayed effects of climate on vital rates lead to demographic divergence in Amazonian forest fragments

“…When they finally do, the resulting leaf drop (Janssen et al, 2021) and treefalls allow for light penetration to the forest understory (Canham et al, 1990; Leitold et al, 2018), triggering a boom in the growth and flowering of understory plants (Bruna & Oli, 2005). Similar delayed changes in the local environment could also influence the foraging behavior of a plant’s pollinators (Bruna et al, 2004; Stouffer & Bierregaard, 1996), seed dispersers (Uriarte et al, 2011), or herbivores (Scott et al, 2021). While more work is needed to explain why the (delayed) effects of SPEI on H. acuminata survival and growth are greater in fragments than forest interiors, one hypothesis, motivated by recent intriguing results from other systems (Sapsford et al, 2017), is that the greater litterfall on edges (Vasconcelos & Luizão, 2004) may be altering the abundance of pathogens or mycorrhizae.…”

“…When they finally do, the resulting leaf drop (Janssen et al, 2021) and treefalls allow for light penetration to the forest understory (Canham et al, 1990;Leitold et al, 2018), triggering a boom in the growth and flowering of understory plants (Bruna & Oli, 2005). Similar delayed changes in the local environment could also influence the foraging behavior of a plant's pollinators (Bruna et al, 2004;Stouffer & Bierregaard, 1996), seed dispersers (Uriarte et al, 2011), or herbivores (Scott et al, 2021).…”