Thermal plasticity in the invasive south American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Vimbai L Tarusikirwa; Reyard Mutamiswa; Sinead English; Frank Chidawanyika; Casper Nyamukondiwa

doi:10.1016/j.jtherbio.2020.102598

Thermal plasticity in the invasive south American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

J Therm Biol. 2020 May:90:102598. doi: 10.1016/j.jtherbio.2020.102598. Epub 2020 Apr 18.

Authors

Vimbai L Tarusikirwa¹, Reyard Mutamiswa², Sinead English³, Frank Chidawanyika², Casper Nyamukondiwa⁴

Affiliations

¹ Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana.
² Department of Zoology and Entomology, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa.
³ School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
⁴ Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana. Electronic address: nyamukondiwac@biust.ac.bw.

PMID: 32479393
DOI: 10.1016/j.jtherbio.2020.102598

Abstract

South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating invasive global insect pest of tomato, Solanum lycopersicum (Solanaceae). In nature, pests face multiple overlapping environmental stressors, which may significantly influence survival. To cope with rapidly changing environments, insects often employ a suite of mechanisms at both acute and chronic time-scales, thereby improving fitness at sub-optimal thermal environments. For T. absoluta, physiological responses to transient thermal variability remain under explored. Moreso, environmental effects and physiological responses may differ across insect life stages and this can have implications for population dynamics. Against this background, we investigated short and long term plastic responses to temperature of T. absoluta larvae (4th instar) and adults (24-48 h old) from field populations. We measured traits of temperature tolerance vis critical thermal limits [critical thermal minima (CT_min) and maxima (CT_max)], heat knockdown time (HKDT), chill coma recovery time (CCRT) and supercooling points (SCP). Our results showed that at the larval stage, Rapid Cold Hardening (RCH) significantly improved CT_min and HKDT but impaired SCP and CCRT. Heat hardening in larvae impaired CT_min, CCRT, SCP, CT_max but not HKDT. In adults, both heat and cold hardening generally impaired CT_min and CT_max, but had no effects on HKDT, SCP and CCRT. Low temperature acclimation significantly improved CT_min and HKDT while marginally compromising CCRT and CT_max, whereas high temperature acclimation had no significant effects on any traits except for HKDT in larvae. Similarly, low and high temperature acclimation had no effects on CT_min, SCPs and CT_max, while high temperature acclimation significantly compromised adult CCRT. Our results show that larvae are more thermally plastic than adults and can shift their thermal tolerance in short and long timescales. The larval plasticity reported here could be advantageous in new envirnments, suggesting an asymmetrical ecological role of larva relative to adults in facilitating T. absoluta invasion.

Keywords: Acclimation; Environmental stress; Hardening; Invasive species; Pinworm; Thermal tolerance.

MeSH terms

Animals
Body Temperature Regulation / physiology*
Larva / physiology*
Moths / physiology*
Solanum lycopersicum / parasitology
Temperature