The effect of the allelochemical quercetin on the survival of Lymantria dispar L.

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Neurohormones in insect stress: A review

The neurohormones are the master regulators of all life processes in insects and they create a strategy of stress protecting events. Neurohormones are synthesized mainly in insect brain neurosecretory neurons. Various stressors of different intensity cause specific changes which influence on neurosecretory neurons activity and synthesis of neurohormones (biogene amines, ecdysiotropins, ecdysiostatins, allatoregulatory neurohormones, adipokinetic neurohormones, etc.). Biogene amines in insects may function as neurohormones controlling carbohydrate and lipid metabolism as the primary response of the insects to the effect of stressors. Intermediary metabolism in insects is mainly regulated by adipokinetic hormones which supply organism by energy especially in extreme conditions. Stress induces changes in release of ecdysioregulatory and allatoregulatory neurohormones and modificates ecdysones and juvenile hormones synthesis in prothoracic gland and corpora allata. The involvement of hormones of an ecdysteroid or JH type in response to stress creates the danger of an untimely induction of morphogenetic process in target cells. Limiting the quantity of secreted hormones and shortening the period when target cells are sensitive to morphogenetic stimuli removes this danger.Neurohormoni regulišu sve životne procese insekata i kreiraju strategiju odgovora organizma na delovanje stresora. Neurohormoni se u najvećoj meri sintetišu u neurosekretnim neuronima protocerebralnog regiona mozga insekata. Stresori različitih osobina i intenziteta specifično menjaju aktivnost neurosekretnih neurona i sintezu neurohormona (biogenih amina, egdizotropina, egdizostatina, alatoregulatornih neurohormona, adipokinetičkih neurohormona itd.). Biogeni amini imaju ulogu u kontroli metabolizma ugljenih hidrata i lipida u početnim fazama stresnog odgovora insekata. Intermedijerni metabolizam je regulisan dobrim delom adipokinetičkim neurohormonima koji učestvuju u obezbeđivanju dovoljne količine energije koja je potrebna za prevazilaženje ekstremnih uslova. Stres izaziva promene u lučenju egdizoregulatornih i alatoregulatornih neurohormona i modifikuje intenzitet sinteze egdizona i juvenilnih hormona u protorakalnoj žlezdi i corpora allata. Promene u količini egdizona i juvenilnog hormona u stresu povećavaju rizik početka vremenski neadekvatnih morfogenetskih promena u tkivima insekata. Stresom izazvane promene u količini morfogenetskih neurohormona su ograničene a i periodi osetljivosti ćelija na morfogenetske stimuluse se menjaju u stresu ograničavajući donekle mogućnost neadekvatnih morfogenetskih promena.nul

Genetic variation and correlations of life-history traits in gypsy moths (Lymantria dispar L.) from two populations in Serbia

Periodic fluctuations in density impose different selection pressures on populations of outbreaking Lepidoptera due to changes in their nutritional environment. The maternal effects hypothesis of insect outbreak predicts the transmission of this nutritional "information" to subsequent generations and alterations in offspring life-history traits. To test for these time-delayed effects of the parental generation, we compared life-history traits and their variation and covariation among laboratory-reared gypsy moths hatched from egg masses collected from low- and medium-density populations. Decreased individual performance was recorded in offspring from the medium-density population, indicating reduced egg provisioning under crowding conditions. Genetic variance and covariance were also shown to be sensitive to density of the parental generation. In gypsy moths from the medium-density population, quantitative genetic analysis revealed significantly higher broad-sense heritabilities for development duration traits and demonstrated a trade-off between development duration and body size

Characterization of trypsin-like enzymes from the midgut of Morimus funereus (Coleoptera: Cerambycidae) larvae

The pH along the midgut of M. funereus larvae had different values, being acidic in the anterior section and basic in the middle and posterior sections. Elastase- and chymotrypsin-like activities were highest in the middle, low in the anterior, and negligible in the posterior section of the midgut. Trypsin-like activities were detected along the whole midgut, with more than 90% of activity in the anterior section. The level of elastase- and chymotrypsin-like activity was very low compared to trypsin-like activity. In the anterior section of the midgut, two isoforms of trypsin-like enzymes were found, both being basic and almost completely inhibited by benzamidine

The effects of cadmium on the life history traits of Lymantria dispar L.

Gypsy moth (Lymantria dispar L.) females and males were chronically exposed to three sublethal cadmium concentrations (10, 30 and 50 mg/g dry food mass) in order to assess the effects of cadmium on larval and pupal duration, pupal mass and longevity. On average, the presence of cadmium in food did not affect larval duration while shortened pupal duration and reduced pupal mass and longevity were recorded. The most significant effects were obtained at the highest cadmium concentration. Females and males did not differ in sensitivity of life history traits to cadmium exposure. It is concluded that (1) cadmium exerts a strong adverse impact on the growth and development of gypsy moths, and (2) the significance of the cadmium effects depends on the dose.Projekat ministarstva br. 14303

Changes in the physicochemical properties of geopolymer gels as a function of NaOH concentration

In the present paper, polymerization of alkali activated metakaolin (MK) and its structural changing, using 2M NaOH, 8M NaOH, and 16M NaOH solutions were followed by means of X-ray photoelectron spectroscopy (XPS), Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Raman spectroscopy and Scanning electron microscopy (SEM). XPS analysis revealed that changing of NaOH concentration did not affect the types of formed bonds in the material. At the same time, the amount of sodium and aluminum increased with the NaOH molarity. The latter steps could be especially interesting because it may indicate the possibility of 'dosing' the amount of Al incorporated by changing the NaOH concentration in the solution. DRIFT analysis revealed that the absorption band for AlIV located at 800 cm-1 is shifted towards the smaller values. Changing the concentration of NaOH, the chemical content did not change, but the structural changes are observed. Raman spectroscopy detected that the most dominant peaks at ∼400 cm-1 and 519 cm-1 originate from Si-O-Al and Si-O-Si bending modes. With increasing the NaOH concentration, peaks at 1019-1060 cm-1 become more prominent as a result of polymerization. Both analyzes (DRIFT and Raman) confirmed the presence of quartz. SEM analysis showed that different structures are created by changing the concentration of NaOH.У овом раду, праћена је полимеризација алкално активираног метакаолина (МК) и његове структурне промене, коришћењем 2М NaOH, 8М NaOH и 16М раствора NaOH. Промене су праћене рендгенском фотоелектронском спектроскопијом (XPS), дифузном рефлексијом инфрацрвене Фуријеове трансформације (DRIFT), Рамановом спектроскопијом и скенирајућом електронском микроскопијом (SEM). XPS анализа је показала да промена концентрације NaOH није утицала на типове формираних веза у материјалу. Истовремено, количина натријума и алуминијума се повећавала са моларношћу NaOH. Последњи кораци могу бити посебно интересантни јер могу указивати на могућност 'дозирања' количине Al инкорпорираног променом концентрације NaOH у раствору. DRIFT анализа је открила да је опсег апсорпције за AlIV који се налази на 800 cm-1 померен ка мањим вредностима. Променом концентрације NaOH, хемијски садржај се није мењао, али су уочене структурне промене. Раманова спектроскопија је открила да најдоминантнији пикови на 400 cm-1 и 519 cm-1 потичу из Si-О-Al и Si-О-Si начина савијања хемијских веза. Са повећањем концентрације NaOH, пикови на 1019-1060 cm-1 постају све израженији као резултат полимеризације. Обе анализе (DRIFT и Раман) потврдиле су присуство кварца. SEM анализа је показала да се променом концентрације NaOH стварају различите структуре

Influence of nutrient substrates on the expression of cellulases in Cerambyx cerdo L. (Coleoptera: Cerambycidae) larvae

The expression and distribution of digestive cellulases along the midgut of Cerambyx cerdo larvae were analyzed for the first time and are presented in this article. Four groups of larvae were examined: larvae developed in the wild; larvae taken from the wild and successively reared on an artificial diet based on polenta; and larvae hatched in the laboratory and reared on two different artificial diets. Seven endocellulase and seven β-D-glucosidase isoforms were detected in all midgut extracts of C. cerdo with a zymogram after native PAGE. We observed that C. cerdo larvae are capable of producing cellulase isoforms with different PAGE mobilities depending on the nutrient substrate. From our findings it can be assumed that, depending on the distribution of endocellulase and β-D-glucosidase, cellulose molecules are first fragmented in the anterior and middle midgut by endo-β-1,4-glucanase; subsequently, the obtained fragments are broken down by β-D-glucosidase mostly in middle midgut

Activity of gypsy moth dorsolateral neurosecretory neurons under increased rearing density

Lymantria dispar caterpillars were reared under two different rearing densities for the first three days of the 4th larval instar: 5 larvae that were kept in a Petri dish (V = 80 ml) belonged to the intense stress (D1 group); 5 larvae that were kept in a plastic cup (V = 300ml) belonged to the group exposed to less intense stress (D2 group). In the control group, single larvae were reared in a Petri dish. Morphometric changes in L1, L2 and L2’ dorsolateral neurosecretory neurons (nsn) were analyzed. After keeping 5 larvae in a Petri dish, the size of L2 neurosecretory neurons (nsn) significantly increased. Rearing 5 larvae in a plastic cup significantly increased the size of L1 nsn nuclei and the number of L2’nsn. A decrease in relative band densities in the region of molecular masses (11-15 kD) that correspond to prothoracicotropic hormones in the gypsy moth was observed in the electrophoretic profiles that were obtained after both treatments in comparison to the control group. [Acknowledgments. This study was supported by the Serbian Ministry of Education and Science (Grant No. 173027).

The effect of the allelochemical quercetin on the survival of Lymantria dispar L.

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Sensitivity of gypsy moth neurosecretory neurons to acute thermal stress

In gypsy moth caterpillars exposed to a temperature of 35°C (for 1, 12 and 24 h and caterpillars that were exposed to elevated temperature for 12 h and were allowed to recover for 12 h at 23°C), changes in the brain protein profiles and morphometric characteristics of A1’ medial and L2 lateral protocerebral neurosecretory neurons were analyzed. In all groups, protein bands with a molecular mass corresponding to that of members of heat-shock protein families were detected, indicating that acute exposure to this temperature likely induced the synthesis of HSP. Increased morphometric parameters of A1’ neurons and the large amount of neurosecretory material in the neuron body implicate that the temperature of 35°C is not in the temperature range that exerts stimulatory effects on growth and survival. Changes in the morphometric characteristics of L2 neurosecretory neurons from the lateral part of the protocerebrum, and retention of neurosecretory material in their cytoplasm indicate a low level of secretion