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Host plant‐related variation in thermal tolerance of E ldana saccharina
Author(s) -
Kleynhans Elsje,
Conlong Des E.,
Terblanche John S.
Publication year - 2014
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1111/eea.12144
Subject(s) - biology , abiotic component , pest analysis , host (biology) , botany , saccharina , horticulture , population , zoology , ecology , algae , demography , sociology , laminaria
Understanding tolerance of thermal extremes by pest insects is essential for developing integrated management strategies, as tolerance traits can provide insights into constraints on activity and survival. A major question in thermal biology is whether thermal limits vary systematically with microclimate variation, or whether other biotic or abiotic factors can influence these limits in a predictable manner. Here, we report the results of experiments determining thermal limits to activity and survival at extreme temperatures in the stalk borer E ldana saccharina W alker ( L epidoptera: P yralidae), collected from either S accharum spp. hybrids (sugarcane) ( P oaceae) or C yperus papyrus L . ( C yperaceae) and then reared under standard conditions in the laboratory for 1–2 generations. Chill‐coma temperature ( CT min ), critical thermal maximum ( CT max ), lower lethal temperatures ( LLT ), and freezing temperature between E . saccharina collected from the two host plants were compared. CT min and CT max of E . saccharina moths collected from sugarcane were significantly lower than those from C . papyrus ( CT min = 2.8 ± 0.4 vs. 3.9 ± 0.4 °C; CT max = 44.6 ± 0.1 vs. 44.9 ± 0.2 °C). By contrast, LLT of moths and freezing temperatures of pupae did not vary with host plant [ LLT for 50% ( LT 50 ) of the moth population, when collected from sugarcane: −3.2 ± 0.5 °C, from C . papyrus : −3.9 ± 0.8 °C]. Freezing temperatures of pupae collected from C . papyrus were −18.0 ± 1.0 °C and of those from sugarcane −17.5 ± 1.8 °C. The E . saccharina which experienced the lowest minimum temperature (in C . papyrus ) did not have the lowest CT min , although the highest estimate of CT max was found in E . saccharina collected from C . papyrus and this was also the microsite which reported the highest maximum temperatures. These results therefore suggest that host plant may strongly mediate lower critical thermal limits, but not necessarily LLT or freezing temperatures. These results have significant implications for ongoing pest management and thermal biology of these and other insects.