Digestive enzyme activity and macromolecule content in the hemolymph of differentially adapted Lymantria dispar L. populations after short-term increases in ambient temperature.

Global, unpredictable temperature increases have strong effects on all organisms, especially insects. Elucidating the effects of short-term temperature increases on midgut digestive enzymes (α-glucosidase, lipase, trypsin, and leucine aminopeptidase - LAP) and metabolic macromolecules in the hemolymph (proteins, lipids, and trehalose) of phytophagous pest larvae of Lymantria dispar is important for general considerations of insect adaptation to a warming climate and potential pest control options. We also wanted to determine whether the different adaptations of L. dispar populations to environmental pollution might affect their ability to cope with heat stress using larvae from the undisturbed, Kosmaj forest and disturbed, Lipovica forest. Heat treatments at 28 °C increased α-glucosidase activity in both larval populations, inhibited LAP activity in larvae from the polluted forest, and had no significant effect on trypsin and lipase activities, regardless of larval origin. The concentration of proteins, lipids, and trehalose in the hemolymph of larvae from the disturbed forest increased, whereas the population from the undisturbed forest showed only an increase in proteins and lipids after the heat treatments. Larval mass was also increased in larvae from the undisturbed forest. Our results suggest a higher sensitivity of digestive enzymes and metabolism to short-term heat stress in L. dispar populations adapted to pollution in their forest habitat, although climate warming is not beneficial even for populations from unpolluted forests. The digestive and metabolic processes of L. dispar larvae are substantially affected by sublethal short-term increases in ambient temperature.

Effects of dietary fluoranthene on tissue-specific responses of carboxylesterases, acetylcholinesterase and heat shock protein 70 in two forest lepidopteran species.

In this study, responses of carboxylesterases, acetylcholinesterase, and stress protein Hsp70 were examined in the midgut and midgut tissue, and brain of fifth instar larvae of Lymantria dispar L. and Euproctis chrysorrhoea L. following chronic exposure to dietary fluoranthene. Specific carboxylesterase activity increased significantly in the midgut tissue of E. chrysorrhoea larvae treated with a lower fluoranthene concentration. The specific patterns of isoforms expression, recorded in larvae of both species, enable efficient carboxylesterase activity as a significant part of defense mechanisms. Increased Hsp70 concentration in the brain of L. dispar larvae points to a response to the proteotoxic effects of a lower fluoranthene concentration. Decreased Hsp70 in the brain of E. chrysorrhoea larvae in both treated groups can suggest induction of other mechanisms of defense. The results indicate the importance of the examined parameters in larvae of both species exposed to the pollutant, as well as their potential as biomarkers.

Pygidial glands of the blue ground beetle Carabus intricatus: chemical composition of the secretion and its antimicrobial activity.

Pygidial gland secretions are used as repellent defensive allomones in ground beetles. We provide the first precise data on the chemical composition and antimicrobial potency of the secretion of the blue ground beetle, as well as on the morphology of its pygidial glands. The latter structures were not previously studied chemoecologically and morphologically, and we hypothesized that their secretion may have some antimicrobial action, as is the case with certain Carabus species. Gas chromatography-mass spectrometry (GC-MS) was used to identify methacrylic and angelic acids as dominant chemicals in the secretion from individuals of three populations of the blue ground beetle in Serbia. We tested its secretion against selected strains of medically important microorganisms. The secretion exibits antimicrobial action against certain bacterial species and all tested micromycetes. The most significant antifungal effect of the secretion was against Penicillium ochrochloron, which is more sensitive to the secretion than to commercial antifungal drugs ketoconazole and bifonazole. Bifonazole achieved minimum inhibitory concentrations against Trichoderma viride at more than three times higher value than did the secretion, indicating a significant antifungal effect of the secretion against this micromycete as well. Additionally, we tested commercially available standards of two dominant chemicals in the secretion to investigate their interaction and antimicrobial role in the secretion. Finally, we describe all glandular morpho-functional units of the blue ground beetle. Our results suggest that the secretion of the blue ground beetle may serve not only defensive but also antimicrobial functions, which likely aid the survival of this beetle in the microbial-rich forest litter habitat.

Biological effects of chronic exposure of Blaptica dubia (Blattodea: Blaberidae) nymphs to static and extremely low frequency magnetic fields.

In this paper, we analyzed the effects of chronic exposure (5 months) to static magnetic field (110 mT; SMF) and extremely low frequency magnetic field (ELF MF; 10 mT, 50 Hz) on Blaptica dubia nymphs. We have examined acetylcholinesterase (AChE) activity and heat shock protein 70 (HSP70) level, two sensitive biomarkers of stress in terrestrial insects. Relative growth rate (RGR), as a life history trait, was estimated. AChE activity was determined spectrophotometrically and HSP70 levels were quantified using indirect non-competitive ELISA and Western blotting. Calculated RGR was significantly changed upon exposure to both types of ambiental MFs. The effects of chronic exposure of B. dubia nymphs to SMF and ELF MF (50 Hz) were observed as decreased activity of AChE. The increased level of HSP70 was present only after exposure to SMF. The strength of ELF MF was most likely below the energy level needed to induce the expression of this stress protein. Different patterns of the expression of two HSP70 isoforms, where isoform 2 was sensitive only to SMF, are most likely a possibly switch - off in the expression of constitutive and/or inducible HSP70 isoforms.

Tissue-specific responses of Lymantria dispar L. (Lepidoptera: Erebidae) larvae from unpolluted and polluted forests to thermal stress.

In this paper the effects of increased environmental temperature on the relative growth rate (RGR) and developmental time in 5th instar L. dispar larvae originating from unpolluted and polluted forests were analyzed. As indicators of the level of generated reactive oxygen species in thermal stress, we estimated midgut and hemolymph activity of the antioxidative enzymes, superoxide dismutase (SOD) and catalase (CAT), as well as the detoxifying enzymes glutathione S-transferase (GST), carboxylesterase (CaE) and acetylcholinesterase (AChE) from the midgut and brain tissue. We also examined the influence of induced thermotolerance as a species' ability to overcome the negative effects of this stressor. In larvae originating from the unpolluted forest, the midgut is the primary location of increased SOD and CAT activity and induced thermotolerance did not modified their activity in either tissue. In larvae from the polluted forest, in both tissues SOD activity was more sensitive to an increased temperature and induced thermotolerance than CAT. Carboxylesterase responded diversely to thermal stress depending on the analyzed tissue regardless the origin of larvae, while the activity of GST and AChE in tissue depended on the origin of larvae. Induced thermotolerance modified the activity of detoxifying enzymes in larvae originating from the polluted forest. Combining the selected parameters into an integrated biomarker response (IBR) the GST, CaE and AChE battery emerged as a potential biomarker for thermal stress in L. dispar larvae.

The pygidial gland secretion of the forest caterpillar hunter, Calosoma (Calosoma) sycophanta: the antimicrobial properties against human pathogens.

Recently, various insect secretions have been tested as possible antimicrobial agents. In beetles, these secretions are essentially products of various exocrine glands, of which particular emphasis is on pygidial glands that are common for the suborder Adephaga. The antimicrobial potential of the pygidial gland secretion isolated from the adults of Calosoma sycophanta against human pathogens has been tested and compared with the potential of other carabid species, particularly within the tribe Carabini. The antimicrobial assay includes a microdilution method which was applied in order to determine the minimal inhibitory, minimal fungicidal and minimal bactericidal concentrations. It has been tested the effect of the secretion against eight strains of fungal and eight strains of bacterial species. The secretion sample of the tested carabid species has shown statistically significant antifungal effect against all strains of treated micromycetes, the highest in comparison with previously tested carabids (Carabus spp., Laemostenus punctatus and Abax parallelepipedus). Aspergillus versicolor proved to be the most sensitive micromycete, while the remaining seven fungal strains have shown the same level of sensibility. In comparison with commercial mycotics ketoconazole and bifonazole, applied as positive controls, the tested secretion showed much higher antifungal activity for all fungal strains. Antibacterial effect has been manifested only against one bacterial strain (Escherichia coli), contrary to other previously studied carabid species. These observations might have a significant impact on the ecological domain and possible purpose in biomedical studies and applications in the future. Additionally, morpho-histology of the pygidial glands of C. sycophanta is investigated and discussed.

Antimicrobial activity of the pygidial gland secretion of three ground beetle species (Insecta: Coleoptera: Carabidae).

The antimicrobial properties of the pygidial gland secretions released by the adults of the three ground beetle species, Carabus ullrichii, C. coriaceus, and Abax parallelepipedus, have been tested. Microdilution method was applied for detection of minimal inhibitory concentrations (MICs), minimal bactericidal concentrations (MBCs), and minimal fungicidal concentrations (MFCs). Additionally, morpho-histology of the pygidial glands is investigated. We have tested 16 laboratory and clinical strains of human pathogens--eight bacterial both gram-positive and gram-negative species and eight fungal species. The pygidial secretion samples of C. ullrichii have showed the strongest antimicrobial effect against all strains of treated bacteria and fungi. Staphylococcus aureus, Lysteria monocytogenes, and Salmonella typhimurium proved to be the most sensitive bacterial strains. Penicillium funiculosum proved to be the most sensitive micromycete, while P. ochrochloron and P. verrucosum var. cyclopium the most resistant micromycetes. The pygidial secretion of C. coriaceus has showed antibacterial potential solely against Pseudomonas aeruginosa and antifungal activity against Aspergillus fumigatus, A. versicolor, A. ochraceus, and P. ochrochloron. Antibacterial properties of pygidial gland secretion of A. parallelepipedus were achieved against P. aeruginosa, while antifungal activity was detected against five of the eight tested micromycetes (A. fumigatus, A. versicolor, A. ochraceus, Trichoderma viride, and P. verrucosum var. cyclopium). Commercial antibiotics Streptomycin and Ampicillin and mycotics Ketoconazole and Bifonazole, applied as the positive controls, showed higher antibacterial/antifungal properties for all bacterial and fungal strains. The results of this observation might have a significant impact on the environmental aspects and possible medical purpose in the future.

Response of α-glucosidase in gypsy moth larvae to acute and chronic dietary cadmium.

We investigated the effects of acute and chronic treatments with cadmium at 10 µg Cd/g dry food and 30 µg Cd/g dry food on α-glucosidase activity of the 4th instar larvae of Lymantria dispar (Lepidoptera: Lymantriidae) as well as subsequent recovery. Enzyme inhibition was recorded during acute exposure to 30 µg Cd/g dry food and during chronic treatment at the lower metal concentration. After three days recovery from 10 µg Cd/g dry food, the α-glucosidase activity returned to the control level. One-way ANOVA showed that cadmium significantly influenced the activity of α-glucosidase during all treatments. The index of phenotypic plasticity was higher during chronic treatment at 10 µg Cd/g dry food than at 30 µg Cd/g as well as during the recovery. We detected four glucosidase isoforms by NATIVE PAGE. The activities and expressions of the isoforms depended on both larval genotype and cadmium treatment.

Responses of PTTH-producing neurosecretory neurons in Lymantria dispar caterpillars exposed to cadmium.

Lymantria dispar, as most invasive insect species, is very adaptable and reacts quickly to changing environment. Neuroendocrine system first reacts to stress in insects, and specific neurohormonal reorganization may be used in early heavy metal risk assessment. Prothoracicotropic neurohormones (PTTH) control ecdysteroid synthesis (morphogenetic and stress hormones) in insects. In this article, we report the presence of PTTH immunoreactive molecules in L2' dorsolateral neurosecretory neurons (nsn) in caterpillar brains and changes after exposure to pollutant stress of different intensity. For 3 days, after molting into the 4th instar, caterpillars of Lymantria dispar were fed with a high wheat germ diet without (control) or with added cadmium (experimental groups: 10, 30, 100, 250 µg Cd/g dry food weight). Changes in PTTH producing L2' nsn and differences in the intensity of protein bands in the region of PTTH molecular mass (Mr 11-15 kDa) were analyzed. The number of L2' neurons tended to decrease except in the group given the highest cadmium concentration (250 µg). The neurons were enlarged after acute treatment especially in the group given the highest cadmium concentration. The size of L2' nsn nuclei was decreased only in the group fed with 30 µg Cd. Protein band intensity in the Mr region of PTTH remained unchanged in all groups except for the group given the diet with the highest Cd concentration.

Sourcing chitin from exoskeleton of Tenebrio molitor fed with polystyrene or plastic kitchen wrap.

In this work we have characterized and compared chitin sourced from exoskeleton of Tenebrio molitor larvae fed with polystyrene or plastic kitchen wrap combined with bran in the ratio 1: 1 with chitin sourced from larvae exoskeleton fed only with bran. Analysis of the frass by ATR-FTIR showed very similar spectra and confirmed degradation of the plastic feed components, while ATR-FTIR analysis of the exoskeleton verified the absence of any plastic residue. Deproteinization followed by demineralization produced 6.78-5.29 % chitin, showing that plastic (polystyrene or plastic kitchen wrap) in the larvae diet resulted in heavier insect exoskeleton, but yielded slightly less chitin, with the lowest value obtained for plastic kitchen wrap in the insect diet. The deacetylation degree of 98.17-98.61 % was determined from measured ATR-FTIR spectra. XRD analysis confirmed the presence of α-chitin with a crystallinity index of 66.5-62 % and crystallite size 4-5 nm. Thermogravimetric analysis showed similar degradation curves for all chitin samples, with two degradation steps. These results show that chitin sourced from exoskeleton of T. molitor larvae fed with plastic (polystyrene or plastic kitchen wrap) and contributing to significant biodegradation of major polluting materials can be a feasible and alternative source of chitin, further promoting a bio-circular economy.

Antioxidative enzymes, alkaline phosphatases and Hsp70 expression in larvae of Lymantria dispar (Lepidoptera: Erebidae) from unpolluted and polluted forests after chronic cadmium treatment.

Long-term exposure of populations to pollution may result in enhanced ability to cope with environmental stress. To compare the responses of two Lymantria dispar populations living in unpolluted and polluted forests (UP and PP, respectively), we chronically exposed larvae to cadmium at concentrations of 50 and 100 µg Cd/g dry food (Cd1 and Cd2, respectively). We examined cadmium accumulation in the midgut and hemolymph, activities of superoxide dismutase (SOD), catalase (CAT), and alkaline phosphatases (ALP) in the midgut, as well as Hsp70 protein expression in the midgut, hemolymph, and brain and evaluated these parameters as biomarkers of cadmium contamination. Larvae from PP, fed a control diet, showed higher activity of SOD and increased Hsp70 expression compared with larvae from UP. Excessive amounts of Cd were accumulated in the midgut of all Cd-fed larvae, whereas Cd content in the hemolymph was elevated only in larvae from PP after Cd2 treatment. In larvae from UP, Cd2 treatment decreased the activity of CAT and induced the expression of Hsp70 in the midgut and hemolymph. In larvae from PP, exposure to both Cd concentrations strongly attenuated SOD and CAT activities, while Hsp70 expression was not induced in any organ/tissue. Cd did not affect ALP activity in either population. Midgut Cd content proved to be a suitable indicator of Cd contamination for both polluted and unpolluted habitats.

Effect of magnetic fields on antioxidative defense and fitness-related traits of Baculum extradentatum (insecta, phasmatodea).

This study aimed to determine the effect of magnetic fields on the antioxidative defense and fitness-related traits of Baculum extradentatum. Following exposure to magnetic fields, antioxidative defense (superoxide dismutase (SOD), catalase (CAT) activities, and total glutathione (GSH) content) and fitness-related traits (egg mortality, development dynamics, and mass of nymphs) were monitored in nymphs. The experimental groups were: control (kept out of influence of the magnets), a group exposed to a constant magnetic field (CMF) of 50 mT, and a group exposed to an alternating magnetic field (AMF) of 50 Hz, 6 mT. We found increased SOD and CAT activities in animals exposed to constant and AMFs, whereas GSH activity was not influenced by experimental magnetic fields. No differences were found in egg mortality between control and experimental groups. Significant differences in the time of development between the control and the CMF group were observed, as well as between the CMF and the AMF group. No differences were found in the mass of the nymphs between the three experimental groups. In conclusion, CMF and AMF have the possibility to modulate the antioxidative defense and some of the fitness-related traits in B. extradentatum.

Changes in activity of non-specific esterases in cadmium treated Lymantria dispar larvae.

Many biochemical, physiological and histological criteria have been used as indicators of exposures and effects of the contaminants. These changes can indicate the response of an organism to a specific environmental stressor. In the present paper, the effect of the acute and chronic exposure to cadmium as well as recovery from two cadmium concentrations (10 and 30 µgCd/g dry food) on gypsy moth (Lymantria dispar) midgut esterases was investigated. The influence of cadmium on trait plasticity was also examined. Esterases showed great sensitivity to low metal concentrations during acute and chronic treatments. Their activities during short-term exposure and after recovery significantly depended on cadmium concentrations. The esterases had greater index of plasticity during chronic treatments with 10 and 30 µgCd/dry food. Five esterase isoforms between 64 and 250 kDa were detected. Isoforms of esterases exposed to any of the two cadmium effects differed among several egg-masses. Isozymes were distinguished in one egg-mass during different cadmium treatments. We conclude that these enzymes could be considered potential and sensitive non-selective biomarkers for the presence of cadmium in food.

The effects of temperature stress and population origin on the thermal sensitivity of Lymantria dispar L. (Lepidoptera: Erebidae) larvae.

Increased environmental temperature is one of the most frequent stresses effecting metabolic rate in herbivorous insect species. Our goal was to compare the influence of increased environmental temperature and induced thermotolerance on the activity of midgut phosphatases and brain tissue hsp70 concentration in 5th instar Lymantria dispar larvae originating from an unpolluted and polluted forest. Induced thermotolerance (larval pre-treatment at high, sub-lethal temperature) increases the species ability to overcome the negative effects of thermal stress, therefore we monitored the effect of this regime in larvae originating from both forests. Thermal regimes in this experiment predominantly influenced the alkaline phosphatases activity and it was affected by temperature, population origin, and their combined effect. Total acid phosphatases activity was changed only by the joint effect of temperature and population origin. Brain hsp70 concentration was under a significant individual and joint effect of temperature and population. In both populations, brain tissue hsp70 concentration and alkaline phosphatases activity should be taken under consideration as a battery with biomarker potential for thermal stress in L. dispar larvae as a bioindicator species.

Implications of long-term exposure of a Lymantria dispar L. population to pollution for the response of larval midgut proteases and acid phosphatases to chronic cadmium treatment.

Cadmium (Cd) presence in terrestrial ecosystems is a serious threat that requires continuous development of biomonitoring tools. Ideally, a suitable biomarker of exposure should respond to the toxicant consistently in different populations regardless of previous exposure to pollution. Here we considered the activities and isoform patterns of certain proteases and acid phosphatases (ACP) in the midgut of Lymantria dispar larvae as well as the integrated biomarker response (IBR) for application in Cd biomonitoring. We compared the responses of caterpillars originating from unpolluted and polluted localities after they had been chronically subjected to dietary Cd (50 and 100 µg Cd/g dry food). The population inhabiting the unpolluted forest was far more sensitive to Cd exposure as the activities of total proteases, trypsin (TRY) and leucine aminopeptidase (LAP) were mostly reduced while the activities of total and non-lysosomal ACP were increased. Non-lysosomal ACP activity was elevated in larvae from the contaminated site in response to the higher Cd concentration. Exposure to the metal resulted in numerous alterations in the pattern of enzyme isoforms, but the responses of the two populations were similar except that larvae from the polluted locality were more tolerant to the lower Cd concentration. Non-lysosomal ACP activity and the appearance of ACP isoforms 4 and 5 together with the IBR index are the most promising indicators of Cd presence, potentially applicable even in populations with a history of exposure to pollution. TRY and total ACP activities could be used to monitor populations at uncontaminated localities.

Sensitivity of midgut physiological parameters of Lymantria dispar L. larvae to benzo[a]pyrene in populations with different multigeneration contact to environmental pollutants.

Accumulation of organic pollutants in the environment calls for sensing physiological parameters adequate to indicate the presence of contaminants and their effects on ecosystems. Evidence points to the importance of insect adaptations in their habitats for the assessment of sensitive biomarkers so we examined the influence of origin and multigenerational adaptations of the Lymantria dispar larvae to chronic benzo[a]pyrene (B[a]P) treatment under laboratory conditions. The main aim was to compare reactions of larvae from unpolluted and polluted forests using alkaline phosphatase (ALP), acid phosphatase (ACP), and carboxylesterase (CE) specific activities in the midgut, including electrophoretic isoform patterns; midgut expression levels of Hsp70, larval development time (DT), and midgut mass (MM), after chronic exposure to 5 and 50 ng of B[a]P/g dry food weight. The biomarker potential of these parameters regarding larval pre-exposure history to pollution was estimated by principal component analysis (PCA). B[a]P treatment resulted in inhibition of ALP activity, a rise of CE activity, and reduction of MM in larvae from the unpolluted forest, while the population from the polluted forest showed significant elevation of Hsp70 expression in the midgut, prolonged DT, and reduction of MM. PCA confirmed variations in responses of the selected parameters regarding population origin. The obtained results provide insight into insect population variability concerning physiological responses to pollutants. It is indicative that all investigated physiological parameters of L. dispar larvae showed origin-dependent responses to long-term presence of B[a]P, which may be of great importance in ecotoxicological research.

Effects of fluoranthene on digestive enzymes activity and relative growth rate of larvae of lepidopteran species, Lymantria dispar L. and Euproctis chrysorrhoea L.

Fluoranthene is one of the most abundant polycyclic aromatic hydrocarbon pollutants in the environment and it may accumulate in plant leaves which are the main food source for phytophagous insect species. The aim of this study was to establish the effects of dietary fluoranthene on specific activities of digestive enzymes and expression of their isoforms in the midgut, and the relative growth rates of Lymantria dispar and Euproctis chrysorrhoea larvae. Exposure to fluoranthene led to significantly decreased trypsin activity in the midgut of larvae of both species. Leucine aminopeptidase activity decreased significantly in the midgut of L. dispar larvae exposed to the lower concentration of fluoranthene, but that enzyme activity showed the opposite trend in E. chrysorrhoea larvae. There was no pollutant induced changes in lipase activity in L. dispar, while elevated enzyme activity was recorded in the midgut of E. chrysorrhoea larvae exposed to the lower concentration of fluoranthene. Different patterns of expression of enzyme isoforms were noticed. Relative growth rates of both species significantly decreased in fluoranthene treated larvae. These responses indicate to the significance of relationships between physiological changes and fitness-related traits in L. dispar and E. chrysorrhoea larvae affected by pollutant, and contribute to understanding the mechanisms of their adjustment to stressful conditions.

Effects of cadmium on protocerebral neurosecretory neurons and fitness components in Lymantria dispar L.

Changes in fitness components including larval stage duration, relative growth rate (RGR), and mass of the gypsy moth, Lymantria dispar L. (Lepidoptera: Lymantriidae), were investigated in caterpillars fed a synthetic diet with or without a cadmium supplement (10, 30, 100, 250 microg Cd/g dry food weight). Morphometric changes of large protocerebral dorsomedial A2 neurosecretor neurons, their nuclei and the electrophoresis profiles of brain proteins were analyzed in the 4 instar gypsy moths fed the examined diets. The duration of the fourth larval instars were prolonged and RGR and body mass reduced if the caterpillars were fed diets containing high concentrations of cadmium (100 and 250 microg). The size of large A2 dorsomedial neurosecretory neurons and their nuclei were significantly higher in larvae fed the diets supplemented with 10, 100 and 250 microg Cd. A large amount of neurosecretory material appeared in dorsomedial neurosecretory neurons in larvae fed diets with 100 and 250 microg Cd. Differences in larval brain protein profiles in the region of molecular mass ranges (Mr) of 98 kDa, 46 kDa and 3.4-6.1 kDa were identified in the experimental groups.

The impact of chronic exposure to a magnetic field on energy metabolism and locomotion of Blaptica dubia.

Purpose: This study deals with a comparative analysis of the effects of chronic exposure to a static magnetic field (SMF) and an extremely low frequency magnetic field (ELF MF) in Blaptica dubia nymphs. The outcome of such treatment on insect and fat body mass, glycogen and total lipid content in the fat body and locomotion, as an energy demanding process, were examined.Materials and methods: One-month-old nymphs of B. dubia were exposed to an SMF (110 mT) or ELF MF (50 Hz, 10 mT) for 5 months. Their locomotion was monitored in the 'open-field' test for 10 min and expressed as travel distance, time in movement and average speed while in motion. After that, fat body mass and content of its main components (glycogen and total lipids) were determined. Nymph body mass was also estimated after 1 and 5 months of MF treatment.Results: Chronic exposure to the SMF and ELF MF decreased nymph body mass and glycogen content in the fat body but increased all examined parameters of locomotion. In addition, chronic SMF treatment elevated total lipid content in the fat body, while chronic ELF MF treatment reduced fat body mass and total lipid content.Conclusions: These findings indicate that B. dubia nymphs are sensitive to the applied MFs and possess different strategies for fuel usage in response to the SMF and ELF MF in order to satisfy increased energy demands and to overcome stressful conditions.

Plastic responses of larval mass and alkaline phosphatase to cadmium in the gypsy moth larvae.

Biochemical analyses can point to toxicant presence before its effects can be detected at higher organizational levels. We investigated responses of larval mass and alkaline phosphatase (ALP) to different cadmium treatments in 4th instar gypsy moth larvae from 20 full-sib families. Changes in trait values and trait plasticities as well as their variation were monitored after acute and chronic exposure or recovery from two cadmium concentrations (Cd(1)=10microg and Cd(2)=30microg Cd/g dry food). Larval mass only decreased, without returning to the control level at recovery stage following chronic cadmium challenge. Acute stress did not change trait value but increased genetic variance of larval mass. Significant ALP activity changes, sensitivity of isozyme patterns (Mr of 60, 64, and 85kDa) and increased variation in ALP plasticity during acute exposure to cadmium point to its possible aplication as an exposure biomarker.