Can greenhouses eliminate the development of cold resistance of the leafminers?

Abstract

Latitudinal patterns for quantitative traits in insect are commonly used to investigate climatic adaptation. We compare the cold resistance of the leafminer (Liriomyza sativae) pupa among populations distributed from tropical to temperate regions, incorporating the thermal overwintering limit of the insect's range. The patterns of cold resistance for northern and southern populations differ. The southern populations significantly increased their cold resistance with latitude, showing a latitudinal pattern independent of seasons, acclimation regimes, and assay methods. In contrast, the northern populations showed no stable patterns; they were always intermediate in cold hardiness between the low-latitude and high-latitude populations within the overwintering limit. Integration of these data with those of the biologically similar congeneric leafminer, L. huidobrensis, suggests that a pattern shift in stress tolerance associated with the overwintering range limit is probably a general adaptive strategy adopted by freeze-intolerant species that have a high-latitude boundary of distribution, but can only overwinter and develop in protected greenhouses in harsh seasons. Considering the widespread availability of greenhouses for overwintering insects in northern China, we speculated that the large-scale existence of thermally-buffered microhabitats in greenhouses might eliminate the development of cold resistance of the leafminer populations. However, results suggest a strong selection for increased cold resistance for natural populations of Liriomyza species at higher latitudes that can overwinter in the field, but not for populations at latitudes above the thermal limit. Thus, habitat modification associated with greenhouses can limit gene flow and reduce cold tolerances even at latitudes above where the leafminers can overwinter in the field.

Evolution of Hsp70 Gene Expression: A Role for Changes in AT-Richness within Promoters

“…The coding sequences of the orthologous hsp s of these two species are very similar, e.g., the amino acid sequences encoded by their hsp70 s are 97% identical, but between the two species we found marked differences in how these genes' expression responds to a range of low and high temperature exposures [28]. Moreover, the temperature for onset and maximal induction of hsp expression of either species was consistent with the extreme thermal environments experienced by them [24], [28]. These results suggest that the pattern of hsp expression of the two Liriomyza species contributes to the species' diverged thermal stress tolerance [21], [28].…”

“…For example, L. sativae has a similar or lower level of gene expression than L. huidobrensis when the flies are subject to stressful temperature ranging from 35°C to 40°C. These two Liriomyza species inhabit climate zones posing different thermal challenges [21], [24] and it is likely that they have evolved different adaptations to heat stress, so that tuning Hsp gene expression is likely among these adaptations. Indeed, hsp 70 is a pleiotropic protein that, if expressed say too much, should disrupt cellular homeostasis possibly outweighing the benefits ensuing from better heat shock tolerance [5], [22], [25].…”

“…Hsps are molecular chaperones that help client proteins to recover proper folding when protein folding is perturbed by heat and other stress factors and help to initiate the degradation of misfolded proteins [22], [23]. Hsps have been shown to increase markedly the resistance to thermal and oxidative stress in D. melanogaster and other species [22], [23], [24]. Distinctive features of the transcriptional machinery involved in Hsps expression facilitate the rapid and massive expression of Hsps in response to thermal stress [1], [25].…”

Cloning and expression of genes encoding heat shock proteins in Liriomyza trifolii and comparison with two congener leafminer species

“…trifolii suggest that this pest could probably expose to cold climates in spring/post-winter and autumn/pre-winter, and its relatively lower cold tolerance may play an important role in the survival and development of the population. [1, 56–57]. …”

Volatiles released from bean plants in response to agromyzid flies

“…The vegetable leafminer mainly distributes in vegetable fields of southern China and in greenhouses in northern China, whereas the pea leafminer is widespread ranging from subtropical to temperate regions (Zhao and Kang 2000;Chen and Kang 2005). The pea leafminer has started to replace the vegetable leafminer as the predominant pest in all areas Kang 2004, 2005).…”