Effects of Thermal Regimes, Starvation and Age on Heat Tolerance of the Parthenium Beetle Zygogramma bicolorata (Coleoptera: Chrysomelidae) following Dynamic and Static Protocols

Abstract

Temperature and resource availability are key elements known to limit the occurrence and survival of arthropods in the wild. In the current era of climate change, critical thermal limits and the factors affecting these may be of particular importance. We therefore investigated the critical thermal maxima (CTmax) of adult Zygogramma bicolorata beetles, a biological control agent for the invasive plant Parthenium hysterophorus, in relation to thermal acclimation, hardening, age, and food availability using static (constant) and dynamic (ramping) protocols. Increasing temperatures and exposure times reduced heat survival. In general, older age and lack of food reduced heat tolerance, suggesting an important impact of resource availability. Acclimation at constant temperatures did not affect CTmax, while fluctuating thermal conditions resulted in a substantial increase. Hardening at 33°C and 35°C improved heat survival in fed young and mid-aged but only partly in old beetles, while CTmax remained unaffected by hardening throughout. These findings stress the importance of methodology when assessing heat tolerance. Temperature data recorded in the field revealed that upper thermal limits are at least occasionally reached in nature. Our results therefore suggest that the occurrence of heat waves may influence the performance and survival of Z. bicolorata, potentially impacting on its field establishment and effectiveness as a biological control agent.

Thermal plasticity potentially mediates the interaction between host Chilo partellus Swinhoe (Lepidoptera: Crambidae) and endoparasitoid Cotesia flavipes Cameron (Hymenoptera: Braconidae) in rapidly changing environments

“…Hence such plasticity, or lack thereof, may mediate the host–parasitoid interactions in tropical agroecosystems in current and future climate change scenarios. Several studies investigating different insect taxa have also reported such RHH and demonstrated its potential to improve survival in rapidly changing thermal environments . Similarly, RHH also improved survival of C. partellus pupae and adults (Fig.…”

Plasticity and cross‐tolerance to heterogeneous environments: divergent stress responses co‐evolved in an African fruit fly

“…Kalra et al ., ), such correlations between traits of starvation and heat tolerance have been generally limited and showed no significant cross‐tolerance (see Bubliy et al ., ). A nonsignificant relationship between starvation and thermal tolerance has been observed in Ceratitis species (Nyamukondiwa & Terblanche, ), Drosophila melanogaster (Bubliy et al ., ), Tribolium castaneum (Scharf et al ., ) and Zygogramma bicolorata (Chidawanyika et al ., ). However, the current study suggests otherwise and points to possible mechanistic associations between starvation and heat tolerance (also see Kalra et al ., ).…”

Effect of starvation on expression of troponin complex genes and ER stress associated genes in skeletal muscles

“…longevity, fungal resistance and climbing activity [30]. Therefore, we also examined gene expression of decorin, one of proteoglycan type myokines produced and released by skeletal muscle cells ( Figure 3D).…”