Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A bet-hedging strategy rather than just a classic fast life-history strategy exhibited by invasive fall armyworm.

Abstract

A common assumption is that invasive species always display a fast life-history strategy typically characterized by early reproduction and shortened lifespan. To examine the rapid life-history evolution of fall armyworm (FAW), Spodoptera frugiperda, an invasive species becoming a global threat to agriculture, life-history strategies of four different origins (native, African invasive, Asian invasive and lab-reared) were studied. The lab-reared populations exhibited a classic fast life-history strategy, they reproduced earlier and had a shortened reproductive lifespan compared to native populations. Similar to lab-reared populations, the African and Asian invasive populations reproduced earlier than native ones (μ: invasive AF, 8.00±0.27 d; invasive AS, 7.88±0.24 d; native, 8.78±0.23 d; lab-reared, 4.85±0.17 d). However, contrary to lab-reared populations, invasive populations spread their egg production over a longer period than native ones (σ: invasive AF, 2.40±0.22 d; invasive AS, 2.11±0.19 d; native, 2.06±0.19 d; lab-reared, 1.54±0.14 d). Invasive populations (invasive AF, 1330.36±56.63 eggs; invasive AS, 1013.6±40.95 eggs) therefore clearly had a higher total fecundity than native (784.24±33.53 eggs) and lab-reared (819.72±26.66 eggs) ones. Thus, earlier reproduction and elongated reproductive lifespan could promote invasion success, and this life history is best described as a bet-hedging strategy. Overall, a successful invasion may not simply rely on the fast life-history strategy. Instead, the life history could evolve quickly within invasive populations and may be accurately shaped by the complex invaded environment experienced by populations.