ISJ 9: 93-101, 2012 ISSN 1824-307X MINIREVIEW Expression of heat shock protein genes in insect stress responses L Zhao, WA Jones Biological Control of Pests Research Unit, National Biological Control Laboratory, Agricultural Research Service, United States Department of Agriculture, P.O. Box 67, Stoneville, MS 38776, USA Accepted May 14, 2012 Abstract The heat shock proteins (Hsps) that are abundantly expressed in insects are important modulators of insect survival. The expression of different Hsp genes are induced and modulated in insects in response to environmental inputs including abiotic stresses such as heat shock, ultraviolet radiation, chemical pesticides, as well as biotic stresses such as viruses, bacteria, fungi and other insects. This minireview will provide useful information related to the expression of Hsp genes in response to abiotic and biotic stressors as well as developmental regulation and modulation of Hsp genes involved with insect survival. Key Words: heat shock protein (Hsp); gene expression; abiotic stress; biotic stress Introduction Insects respond to elevated temperature and to a variety of chemical and physical stresses by a rapid increase in the synthesis of a set of conserved polypeptides collectively referred to as heat shock proteins (Hsps). Hsps, named according to their molecular weight, such as Hsp100, Hsp90, Hsp70, Hsp60, Hsp40, small Hsp (sHsp) and Hsp10, are a class of functionally related proteins involved in the folding and unfolding of other proteins. Ritossa first reported that heat and the metabolic uncoupler dinitrophenol induced a characteristic pattern of puffing in salivary gland chromosomes in the fruit fly, Drosophila busckii (Ritossa, 1962, 1963). This discovery eventually led to the identification of Hsps which were represented by these puffs. Increased synthesis of selected proteins in the cells of Drosophila following stresses such as heat shock was first reported in 1974 (Tissieres et al., 1974). An enormous literature has now accumulated that describes a wide variety of events in a cell’s response to a wide array of biotic and abiotic sources of stress in a variety of insects (Lindquist, 1981; Schlesinger, 1990; Wu, 1995; Garcia et al., 2002, Lakhotia, 2011). ___________________________________________________________________________ Corresponding Authors: Liming Zhao, Walker A Jones Biological Control of Pests Research Unit National Biological Control Laboratory Agricultural Research Service United States Department of Agriculture P.O. Box 67, Stoneville, MS 38776, USA E-mails: Liming.zhao@ars.usda.gov, walker.jones@ars.usda.gov Hsps are found in practically all living organisms, from bacteria to humans (Nevins, 1982; Wu et al., 1985; Walter et al., 1989; Marrs et al., 1993; Zhang et al., 1998; Kanagasabai et al., 2011). More than 7,000 related Hsps papers have been published in various journals. Table 1 lists Hsp genes expressed by insects in response to environmental stresses that have been published during past three decades. This minireview is focused on the expression of Hsp genes in response to abiotic and biotic stressors as well as developmental regulation. Abiotic stress responses Insects respond to elevated temperatures and to chemical and other stresses by an increase in the synthesis of Hsps. Hsps appear to serve a significant role in the insect’s responses to abiotic stressors such as elevated temperature (Garcia et al., 2003, Huang et al., 2007; Wang et al., 2008; Kostal and Tollarova-Borovanska, 2009; Zhao et al., 2009, 2010a), ultraviolet radiation (Rangel et al., 2008, Nguyen et al., 2009), drought and dehydration (Xu et al., 2010, Cornette and Kikawada 2011), anhydrobiosis (Lopez-Martinez et al., 2009, Gusev et al., 2010, Cornette and Kikawada, 2011), chemical (Planello et al., 2008, 2011), metal (Shu et al., 2010; Zhao et al., 2010b), nutrient (Benoit et al., 2011), injury or adaptation (Colinet et al., 2009; Kostal and Tollarova-Borovanska, 2009), hypoxia (Michaud et al., 2011) and double stranded RNA (Benoit et al., 2009, Kostal and Tollarova- Borovanska, 2009; Lu and Wan, 2011). 93 http://en.wikipedia.org/wiki/Protein http://en.wikipedia.org/wiki/Dinitrophenol mailto:Liming.zhao@ars.usda.gov mailto:walker.jones@ars.usda.gov http://en.wikipedia.org/wiki/Bacteria http://en.wikipedia.org/wiki/Human 94 Table 1 Examples of heat shock protein gene expression in insects Species Heat shock proteins References Aedes aegypti Hsp26, Hsp83, Hsp70, Hsc70 Zhao et al., 2009 Aedes aegypti Hsp26, Hsp83, Hsp70 Zhao et al., 2010a Aedes aegypti, arthropods Hsp70 Benoit et al., 2011 Aedes aegypti, Anopheles gambiae, Culex pipiens Hsp70, Hsp90 Benoit et al., 2009 Apis mellifera Hsp70 Elekonich, 2009 Belgica antarctica sHsp*, Hsp70, Hsp90 Lopez-Martinez et al., 2008; Lopez-Martinez et al., 2009 Belgica antarctica sHsp, hsp70, Hsp90 Rinehart et al., 2006 Bemisia tabaci Hsps** Mahadav et al., 2009 Bemisia tabaci Hsp23, Hsp70, Hsp90 Lu and Wan, 2011 Bombyx mori Hsp40, Hsp70, Hsp90, Hsc70*** Hong et al., 2010 Bombyx mori Hsp20.4, Hsp40, Hsp70, Hsp90 Ponnuvel et al.,2010 Bombyx mori Hsps, Hsp83, Hsp70, Hsp 90, Hsp 84, Hsp62, Hsp60, Hsp52, Hsp33 Sosalegowda et al., 2010 Calanus finmarchicus Hsp21, Hsp22, p26, Hsp90, Hsp70 Aruda et al., 2011 Chironomus ramosus Hsp70 Datkhile et al., 2010 Chironomus riparius Hsp40, Hsp90 Park and Kwak, 2008 Chironomus riparius Hsp70 Planello et al., 2008 Chironomus riparius Hsp70, Hsc70 Planello et al., 2011 Chortoicetes terminifera Hsp40, Hsc70, Hsp90, Hsp20.5, Hsp20.6, Hsp20.7 Chapuis et al., 2011 Culex quinquefasciatus Hsp70 Zhao et al.,2010b Drosophila melanogaster Hsps Lindquist, 1981 Drosophila sHsps, Hsp22 Berger et al.,1985 Drosophila melanogaster Hsp23, Hsp27 Dubrovsky et al., 1994 Drosophila Hsp70 Zhang and Odenwald, 1995 Drosophila melanogaster Hsp70, Hsp26 Lohe et al., 1995 Drosophila melanogaster Hsp23 Dubrovsky et al., 1996 Drosophila melanogaster Hsp22, Hsp23, Hsp26, Hsp27, Hsp40, Hsp60, Hsp67Ba, Hsp68, Hsp70Aa, Hsc70-1, Hsp83 Colinet et al., 2009 Drosophila Hsp90 Pflanz and Hoch, 2000 Drosophila melanogaster Hsps Takahashi et al., 2011 Galleria mellonella Hsp90 Wojda and Jakubowicz, 2007 Lepinotus reticulates, Liposcelis entomophila Hsp70, Hsp23, Hsp27 Guedes et al., 2008 Liriomyza huidobrensis Hsp90, Hsp70, Hsp60, Hsp40, Hsp 20 Huang et al., 2007 Manduca sexta Hsp70/Hsc70 Rybczynski and Gilbert, 1995 Penaeus monodon Hsp21, Hsp70, Hsp90 Rungrassamee et al., 2010 Plodia interpunctella sHsp, Hsc70, Hsp90 Shim et al., 2008 Polypedilum vanderplanki Hsps Cornette et al., 2010 Polypedilum vanderplanki Hsp90, Hsp70, Hsc70, Hsp60, Hsp20, Hsp23 Gusev et al., 2011 Pteromalus puparum Hsc70 Wang et al., 2008 Pyrrhocoris apterus Hsp70, Hsc70 Kostal and Tollarova-Borovanska, 2009 Sarcophaga crassipalpis Hsp90, Hsp70, Hsp60, Hsp40, sHsps Michaud et al., 2011 Sarcophaga crassipalpis Hsps, Hsp23, Hsp70, Hsp90 Rinehart et al.,2007 Sarcophaga crassipalpis Hsp23, Hsp70, Hsp90 Hayward et al., 2005 Spodoptera frugiperda Hsp70, Hsp70 Lyupina et al., 2010 Spodoptera litura Hsp70, Hsp90 Shu et al., 2010 Stratiomys singularior Hsp70, Hsp68 Garbuz et al., 2011 Steinernema carpocapsae Hsps Hao et al., 2009 Tribolium castaneum Hsp83 Xu et al., 2010 * Small heat shock proteins. ** Heat shock protein family. ***Heat shock protein chaperones and modulation of Hsp genes involved with insect survival. 95 Temperature Hsps can protect cells and organisms from thermal damage. In the red flour beetle, Tribolium castaneum, the expression of the Hsp83 gene could be induced with heat stress at 40 ºC for 1 h in teneral and mature beetles (Xu et al., 2010). High temperature can alter gene expression including Hsps and other genes in a vector mosquito population using suppression subtractive hybridization (Zhao et al., 2009). AeaHsp26 and AeaHsp83 are important markers of stress and may function as critical proteins to protect and enhance survival of Aedes aegypti larvae and pupae (Zhao et al., 2010a). Different sequential thermal shocks can trigger different mechanisms of cellular protection against stress in the cone-nose bug, Panstrongylus megistus, allowing the insect to adapt to different ecosystems (Garcia et al., 2002). Pretreating insects with a mild heat stressor can induce expression of Hsp genes and result in protection from subsequent stresses. This phenomenon has been termed "rapid heat hardening" and is apparently caused by the resolubilization of proteins that were denatured during the stressing episode (Huang et al., 2007; Manwell and Heikkila, 2007; de Crecy et al., 2009; Elekonich 2009; Mahadav et al., 2009; Rangel et al., 2010). Mild heat hardening improves thermotolerance of the pea leafminer, Liriomyza huidobrensis, which significantly increased the expression of mRNA levels of Hsp70 and Hsp20 but at the cost of impairment of fecundity (Huang et al., 2007). The induced expression of mRNA may play an important role in balancing the functional tradeoff of thermal protection and reproductive impairment (Huang et al., 2007). Hsps also play important roles of the recovery phase for repairing chilling injuries (Colinet et al., 2009). It has been demonstrated that expressed levels of Hsp genes of males and females are different in the silverleaf whitefly, Bemisia tabaci (Lu and Wan, 2011). The survival rate of females fed dsRNA significantly decreased following exposure to 44 ºC for 1 h, but male survival rate was not significantly affected (Lu and Wan, 2011). Their study also revealed that the optimum mRNA expression of Hsp genes in females promoted a higher survival rate under heat shock conditions; Hsp23 and Hsp70 played a key role in heat tolerance in females but not in males, and Hsp90 showed no significant role in heat tolerance in either females or males (Lu and Wan, 2011). Antarctic flightless midge, Belgica antarctica, has adapted in the Antarctica’s terrestrial environment, whose larvae survived the lengthy austral winter to complete their two years life cycle (Rinehart et al., 2006). In survival strategies, larvae B. antarctica constitutively up- regulates its heat shock proteins and maintain a high inherent tolerance to temperature stress (Rinehart et al., 2006). The midge larvae have adopted the unusual strategy of expressing Hsps continuously, possibly to facilitate proper protein folding in a cold habitat to enhance thermotolerance (Rinehart et al., 2006). Ultraviolet radiation Solar radiation can be important sources of abiotic stress for herbivorous insects living in close association with plants. Greater homeostatic capabilities as revealed at the proteomic level could explain the higher tolerance of the alate morph of the aphid, Macrosiphum euphorbiae, to environmental stress and its more stable performance and fitness (Nguyen et al., 2009). A tropical species of radiation-tolerant midge, Chironomus ramosus, has been shown to express elevated levels of Hsp70 mRNA and proteins in salivary gland cells of larvae immediately after gamma radiation exposure (Datkhile et al., 2011). The expressed Hsp70 might be one of the gamma radiation-induced stress proteins required during the early stages of radiation stress management in aquatic midge larvae (Datkhile et al., 2011). Ultraviolet radiation can affect cross protection. Elevated tolerance to UV radiation and heat-shock may be induced in conidia produced by fungi exposed to sublethal stresses other than heat or UV radiation during mycelial growth (Rangel et al., 2008). Drought dehydration and anhydrobiosis Some insects are able to survive the loss of almost all their body water content, entering a latent state known as anhydrobiosis. Hsp genes were identified as important up-regulated genes for anhydrobiosis in the sleeping chironomid, Polypedilum vanderplanki (Cornette et al., 2011). Expression of the Hsps mRNA in response to dehydration in the A. aegypti, Anopheles gambiae and Culex pipiens is different, and knock-down expressions of the transcripts using RNAi have revealed potential functions of the Hsps in maintenance of water balance in these mosquito species (Benoit et al., 2009). Interestingly, it has been demonstrated that in the flesh fly, Sarcophaga crassipalpis, expression levels for most of the Hsp genes were significantly up-regulated during hypoxia, suggesting an important role for Hsp genes in responding to low oxygen environments (Michaud et al., 2011). The molecular responses of dehydration, rehydration and overhydration were investigated in larvae of the Antarctic midge, B. antarctica (Lopez- Martinez et al., 2009). Using suppression subtractive hybridization, heat shock proteins (sHsp, Hsp70, Hsp90) were found the most responsive to changes in the hydration state in all genes examined (Lopez-Martinez et al., 2009). The authors speculated that the midge larvae are thus responding quickly to water loss and gain by expressing genes that encode Hsps and other proteins contributing to maintenance of proper protein function, protection and overall cell homeostasis during times of osmotic flux, a challenge that is particularly acute in the Antarctic environment (Lopez-Martinez et al., 2009). Chemicals and metals Expression of Hsp70 and other Hsp genes was significantly induced after exposure of oriental leafworm moths, Spodoptera litura, to zinc. The 96 results also showed that the induced response of S. litura Hsp90 to zinc was more sensitive than that of Hsp70, whereas the inhibited response of Hsp70 was much stronger than that of Hsp90 (Shu et al., 2010). Magnesium is crucial for baculovirus transmission in Culex nigripalpus and Culex quinquefasciatus larvae. Target transcripts up/downregulated by magnesium included Hsp70. Magnesium can alter gene transcription in a vector mosquito population, and understanding this process can provide insight into the mechanistic role of magnesium in baculovirus transmission (Zhao et al., 2010b). Chromosomal responses to heat and heavy metal shocks were studied in the trichogen polytene chromosomes of the Australian sheep blowfly, Lucilia cuprina (Joshi and Tiwari, 2000). Arsenate and mercury, two of the most common toxic environmental chemical pollutants, also induced almost the same set of puffs, suggesting that a common set of gene loci encoding heat shock proteins is responsive to diverse environmental stresses (Joshi and Tiwari, 2000). The function of Hsps and other genes has been recently studied using dsRNA interference (RNAi) knock down techniques (Benoit et al., 2009; Kostal and Tollarova-Borovanska, 2009; Papaconstantinou et al., 2010). In addition, heat treatment can be used as a control tactic against stored-product insects such as the psocid, Liposcelis entomophila, a major concern in stored grain (Guedes et al., 2008). Biotic stress responses Biotic stress mainly refers to the stress that occurs as a result of damage to plants and animals by other living organisms such as bacteria, viruses, fungi, parasites, beneficial and harmful insects, weeds, and cultivated or native plants. Recently, many reports have shown that Hsp genes are induced by virus, bacteria, fungi, and insects to confer protection against stressors (Selkirk et al., 1987; Wojda and Jakubowicz, 2007; Mahadav et al., 2009; Hong et al., 2010; Lyupina et al., 2010; Rungrassamee et al., 2010; Ying and Feng, 2011). High population densities are involved in resistance to other ecologically relevant types of stresses (Chapuis et al., 2011). Parasites Stressor-induced tissue damage is involved in various diseases. Parasites are undoubtedly a biotic factor that produces stress. Parasitoid virulence and host resistance are complex interactions depending on metabolic rate and cellular activity. Among other factors, natural control of variably susceptible host populations by aphid parasitoids is more likely at moderate to high temperatures (Bensadia et al., 2006). Serratia symbiotica is a facultative symbiont of pea aphids (Acyrthosiphon pisum) that provides tolerance to heat stress. Although S. symbiotica has a major influence on its host's metabolism and resistance to heat, it induces little change in gene expression in its host (Burke and Moran, 2011). Envenomization by the ectoparasitoid, Bracon hebetor, on the expression of sHsp,Hsc70 and Hsp90 in the lepidopteran host, the Indian meal moth, Plodia interpunctella, suggested that upregulation of Hsp genes may produce potent factors that have important roles in the mechanism of host-parasitoid relationships (Shim et al., 2008). Steinernema carpocapsae is an insect-parasitic nematode widely used in pest control programs. Hsp genes have been detected in the cDNA library of the parasitic phase of S. carpocapsae, and has provided useful information for the study of the parasitic mechanisms exhibited by this parasitoid (Hao et al., 2009). Cross-protection Cross-protection occurred in the honeycomb moth, Galleria mellonella, when larvae were exposed to mild heat-shock at 38 ºC, showing an enhanced humoral immune response after microbial infection in comparison to infected animals grown at 28 ºC, and was correlated with the changes in Hsp90 protein and increased level of 55kDa protein, suggesting Hsp90 may play a significant role in converging pathways involved in insect immune response and heat-shock (Wojda and Jakubowicz, 2007). The whitefly B. tabaci causes tremendous losses to agriculture by direct feeding on plants and by vectoring several families of plant viruses (Mahadav et al., 2009). Using DNA markers and biological characteristics, the B. tabaci species complex was shown to have over 10 genetic biotypes, including the most dominant and damaging B and Q biotypes, which differ considerably in fecundity, host range, insecticide resistance, virus vectoring ability and in the symbiotic bacteria they harbor (Mahadav et al., 2009). Exposing B biotype whiteflies to heat stress changed its gene expression, suggesting that these clear-cut differences between biotype response are due to differences in adaptation of one biotype over another and are partly responsible for observed changes in the local and global distribution of both biotypes (Mahadav et al., 2009). Pathogens Baculovirus expression systems are broadly used for recombinant protein production in lepidopteran cells or larvae. In transgenic silkworms using its heat-shock proteins, the expression levels of the transgenes were found to be under the control of a hsp-promoter driven by a specific activator (Hong et al., 2010). It has been shown that the His-tagged baculovirus expression system featuring the chaperone effect Hsp70 and HOP70 of transgenic silkworms increased the yield of soluble and functional foreign gene products (Hong et al., 2010). Another study showed that baculoviruses serve as a stress factor that can activate both death-inducing and cytoprotective pathways in infected cells (Lyupina et al., 2010). The infection potentiated the response to heat shock by boosting the Hsp/Hsc70s content in infected cells several-fold http://en.wikipedia.org/wiki/Stress_(biological) http://en.wikipedia.org/wiki/Native_plant 97 in comparison with uninfected cells (Lyupina et al., 2010). Addition of a known inhibitor of inducible Hsps decreased the rate of viral DNA synthesis in infected cells and markedly suppressed the release of budded viruses, indicating the importance of the heat shock response for baculovirus replication (Lyupina et al., 2010). There is speculation that an immune response rather than tolerance to these proteins allows, not only for an immediately protection from infection by a variety of pathogens, but also for immune surveillance, an activity of the immune system that eliminates abnormal and damaged cells (Schlesinger, 1990). A sudden increase in temperature results in heat shock stress of cultured shrimp such as the giant tiger prawn, Penaeus monodon. Under heat shock conditions, only Hsp90 was induced in all tissues of P. monodon when compared to its untreated level (Rungrassamee et al., 2010). The expression levels of Hsp70 and Hsp90 in P. monodon were significantly increased after a 3-h exposure to the marine bacterium, Vibrio harveyi (Johnson and Shunk) Baumann, where the Hsp21 transcript was induced later after a 24-h exposure, suggesting putative roles and involvement of Hsp genes as a part of an immune response against V. harveyi (Rungrassamee et al., 2010). Developmental regulation and mutants Development Hsp genes are developmentally regulated in the different insects. Diapause, the dormancy common to overwintering insects, evokes a unique pattern of gene expression. Most Hsp genes are up-regulated, which appears to be common to diapause in species representing diverse insect orders including Diptera, Lepidoptera, Coleoptera and Hymenoptera as well as in diapause that occur in different developmental stages including embryos, larvae, pupae and adult stages (Rinehart et al., 2007). One study of the multivoltine silkworm B. mori provides an overview of the differential expression levels of metabolic enzyme and Hsp genes in non-diapause and diapause-induced eggs within 48 h after oviposition, confirming the major role of in early embryogenesis (Ponnuvel et al., 2010). It has been demonstrated that up-regulation of Hsp genes during diapause is a major factor contributing to cold-hardiness of overwintering insects (Rinehart et al., 2007). Research on the flesh fly, Sarcophaga crassipalpis, has shown Hsp23 and Hsp70 are strongly up-regulated during pupal diapause (Rinehart and Denlinger, 2000). Expression patterns of Hsp genes and other genes associated with pupal diapause were reported in S. crassipalpis (Hayward et al., 2005). Expression of Hsp90 gene was downregulated two days after pupariation, while Hsp23 and Hsp70 transcripts were up-regulated just after the start of diapause, 5 days after pupariation (Hayward et al., 2005). Although both cold and heat shock evoked elevated expression, the response of Hsp90 to heat shock and cold shock remained intact during diapause, which indicates differential regulation of Hsp genes during diapause and in response to thermal injury inflicted on diapausing pupae (Rinehart and Denlinger, 2000). However, expression of most of the Hsp genes examined did not vary in response to diapause, perhaps because the diapause of Calanus finmarchicus, a key component of marine food webs, is not associated with extreme environmental conditions (Aruda et al., 2011). During the early stages of Drosophila development, the heat-shock response cannot be induced (Fang et al., 2001). It is thought that the adverse effects on cell cycle and cell growth brought about by Hsp70 induction must outweigh the beneficial aspects of Hsp70 induction in the early embryo (Fang et al., 2001). Early Drosophila embryos are refractory to heat shock as a result of dHSF nuclear exclusion (Fang et al., 2001). However, the late embryo can respond to heat shock (Fang et al., 2001). Steroid hormone In cultured Drosophila cells, Northern blot analysis showed that sHsp genes can be induced by high temperature shock and by exposure to physiological doses of the insect molting hormone ecdysterone (Berger et al., 1985). The ecdysone causes dramatic changes in the genetic programs leading to the pupation of D. melanogaster, and regulates developmental changes in transcription and chromatin structure of four small hsp genes (Dubrovsky et al., 1996). It has been shown that the ecdysone response element is necessary but not sufficient for full developmental expression of Hsp23 in the late third instar and that there is another regulatory element (Dubrovsky et al., 1996). In the tobacco hornworm Manduca sexta, ecdysteroids coordinate molting and metamorphosis of insects. Ecdysteroids are produced by the prothoracic glands under the acute control of the brain neuropeptide prothoracicotropic hormone, which upregulated Hsc70 synthesis both translational and transcriptional levels (Rybczynski and Gilbert, 1995). Mutants Mutations can be an important means for insects to adapt to various environmental stresses and to survive in new environments. Mutants from Drosophila had little effect on two measures commonly used to assess heat tolerance, heat- knockdown time and heat hardening ability, suggesting that more subtle heat-related fitness components need to be examined for the effects of these mutations (Johnson et al., 2011). The quantitative trait locus found in the Drosophila melanogaster genome encompassed Hsps and 19 heat-responsive genes, suggesting that they were strong candidates for triggering heat resistance, emphasizing the advantages of genome-wide deficiency screening using isogenic deficiency libraries (Takahashi et al., 2011). During oogenesis in mutant females of the fruit fly, Drosophila virilis, following heat stress, there is an increase in early vitellogenic oocyte degradation and some http://en.wikipedia.org/wiki/Charles_Johnson http://en.wikipedia.org/w/index.php?title=Constantin_Auguste_Napol%C3%A9on_Baumann&action=edit&redlink=1 98 degradation of late-forming egg chambers (Gruntenko et al., 2003). Gruntenko and his colleague showed that 20-hydroxyecdysone levels change following heat stress in mutant females of D. virilis (Gruntenko et al., 2003). Other mutants of the Mnn1 gene of D. melanogaster are hypersensitive to several stressors and display increased genome instability when subjected to conditions such as heat shock, generally regarded as non-genotoxic (Papaconstantinou et al., 2010). Menin, a widespread regulator of heat shock gene expression and a critical factor in the maintenance of genome integrity, also links the stress response to the control of genome stability in D. melanogaster (Papaconstantinou et al., 2010). Conclusions Hsp genes are induced and modulated in insects in response to environmental factors including abiotic and biotic stresses. Hsp genes are also developmentally regulated, which is important for insects to survive and adapt to their environments. The very widespread occurrence of Hsp activity in insects will have a significant bearing on insect adaptability as our climate changes. It may be likely that via Hsp activity, many pest and beneficial species will be able to adapt to global warming more than previously thought. Changes in environmental conditions can rapidly shift allele frequencies in populations of species linked to evolutionary responses to pollution, global warming and other changes (Hoffmann and Willi, 2008). New technologies such as microarray, suppression subtractive hybridization and quantitative real-time PCR advances promise to accelerate the development of genetic methods including the genomic function for monitoring insects’ adaptation to environmental change in several ways. Hsps may play an important role in biodiversity. Many exotic invasive species displace native fauna, while others have little or no effect. The mechanisms for the differences often elude explanation. It is likely that Hsps could be playing a role in competition for space and resources. If Hsps prove to have a more widespread effect on resistance to parasites and diseases, future methods might be developed that allows increased susceptibility of pests and increased resistance to host defense by natural enemies, which would provide a great boost to biological control success while reducing pesticide use. Food security would be enhanced by similar technology development. 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