Lethal temperatures of citrus blackflyAleurocanthus woglumi [Hom.: Aleyrodidae] and its parasite,Amitus hesperidum [Hym.: Platygasteridae]

Seasonally acclimatized citrus blackfly (CBF),Aleurocanthus woglumi Ashby, and its parasite,Amitus hesperidum Silv. were exposed to extreme temperatures for 3-hour periods and survivorship measured. In summer experiments, the LD₅₀ for CBF adults and 1st instar nymphs occurred between 40° and 45°C. The LD₅₀ forA. hesperidum adults occurred between 35° and 40°C and increased with decreased humidity, although some adults could continue to emerge from parasitized CBF up to 45°C. In winter experiments, the LD₅₀ for CBF eggs and adults occurred between ?5° and ?10°C and for other CBF stages between ?10° and ?15°C. The LD₅₀ for adultA. hesperidum, and survival and emergence of the parasites from CBF both occurred between ?10° and ?15°C. Comparing data from the 2 seasons shows that adults are the most temperature sensitive stage of CBF and the parasite is more temperature sensitive than CBF, especially at higher temperatures. Correlating lethal temperature data with field meteorological conditions shows that short-term temperature exposures cannot be expected to stop the potential spread of CBF orA. hesperidum through Florida.     

Susceptibility of the cigarette beetle Lasioderma serricorne (Coleoptera: Anobiidae) to hypoxia

The susceptibility of the cigarette beetle Lasioderma serricorne (F.) to hypoxia was examined at three different oxygen concentrations (0.5?C0.8, 1.0?C1.3, and 2.0?C2.3?%) and four different temperature/humidity (RH) conditions: 30?°C/75?% RH, 25?°C/75?% RH, 20?°C/43?% RH, and 15?°C/43?% RH. The influence of humidity on mortality was also examined at three humidity levels (21, 43, and 75?% RH) at 1.0?C1.3?% oxygen (O₂) and 25?°C. Our results revealed that adult beetles were the most tolerant at 2.0?C2.3?% O₂ and that the larvae were the most tolerant at O₂ levels <1.0?C1.3?%. Mortality increased with increasing temperatures and decreasing O₂ concentrations. At 30?°C, 75?% RH, and 0.5?C0.8?% O₂, the 99?% lethality (LT₉₉) of larvae was 6.9?days; however, it increased to 20?days when the temperature was decreased to 25?°C or when O₂ levels were increased to 1.0?C1.3?%. Humidity also influenced mortality of both larval and adult beetles. LT₉₉ values for larvae at 25?°C and 1.0?C1.3?% O₂ were 24.0, 44.6, and 50.2?days at 21, 43, and 75?% RH, respectively. Results of this study indicate that a controlled atmosphere (CA) with reduced oxygen levels (<0.5?C0.8?% O₂) represents an effective measure for disinfesting stored tobacco as an alternative to conventional phosphine fumigation at temperatures >30?°C.     

Radiosensitivity and Biological Effects of Gamma and X-Rays on Germination and Seedling Vigour of Three Coffea arabica Varieties

Effects of gamma and X-ray treatments were studied on three varieties of Coffea arabica (Kent, Mundo Novo and Geisha) to determine their radiosensitivity and relative biological effects. The coffee varieties seeds were subjected to 0, 50, 100, 150, 200 and 400 Gy of gamma and X-rays from Cobalt 60 (⁶⁰Co) source irradiation. The irradiated seeds were pre-germinated in Petri dishes placed in a germination chamber, whilst some were sown in the greenhouse for germination studies. Data were collected on germination date and rate, root and hypocotyl length to determine the relative biological effectiveness of treatments and the optimum dose. The results showed varieties responding differently to the irradiations and doses. There was a decrease in germination with increasing doses of the irradiation. The X-ray-treated seeds had less germination percentage and seedling vigour measured at 28 days after treatment compared to the gamma-irradiated seeds. The irradiation effects on germination suggest that lower doses of X-rays give the same Relative Biological Effects as higher gamma doses for both growth chamber and greenhouse germination for Geisha at LD₅₀, where the effects were similar for the two irradiations. Whereas 50–100 Gy stimulated germination and seedling vigour, 150 Gy adversely affected germination and no germination occurred at 200–400 Gy. The study concluded that all the coffee varieties evaluated are sensitive to gamma and X-ray irradiation in terms of germination, seedling vigour and biological effects with an optimum dose of 50–100 Gy. Therefore, both gamma and X-rays could be utilized in a future mutational breeding programme for coffee seedlings.

     

Physiological and molecular studies on the effect of gamma radiation in fenugreek (Trigonella foenum-graecum L.) plants

This experiment assessed the biochemical changes in fenugreek plants exposed to gamma radiation. Two pot experiments were carried out during two growing seasons of 2015 and 2016. Seeds were subjected to five doses of gamma irradiation (25, 50, 100, 200 and 400?Gy) and were immediately planted into soil pots in a greenhouse. The experimental analysis was performed in M₁ and M₂ generations. Significant differences between irradiated and control plants were detected for most studied characters in M₁ and M₂ generations. It was demonstrated that low doses of gamma irradiation led to gradually increases in growth, yield characters, leaf soluble protein concomitantly with increases in the contents of phenolic and flavonoids compounds particularly at 100?Gy. These changes were accompanied by a substantial increase in ascorbic acid, α-tocopherol and retinol contents. Proline content was increased under all doses of gamma rays in M₁ generation and the highest amount of proline was obtained at 200?Gy with visible decrease in M₂ generation under the same dose. Meanwhile, the highest dose of gamma radiation (400?Gy) decreased all the studied parameters in both mutagenic generations as compared with control plants. In addition, gamma irradiation doses induced changes in DNA profile on using five primers and caused the appearance and disappearance of DNA polymorphic bands with variation in their intensity. These findings confirm the effectiveness of relatively low doses of gamma rays on improving the physiological and biochemical criteria of fenugreek plants.     

The lethal effects of gamma irradiation on larvae of the Huhu beetle, Prionoplus reticularis: a potential quarantine treatment for New Zealand export pine trees

Gamma irradiation was investigated as a possible method for disinfestation of huhu beetle larvae, Prionoplus reticularis White, in Pinus radiataD. Don. Larvae of four representative size classes were irradiated at six doses, and the lethal dose (LD₉₉) calculated from mortality data 3 days and 10 days post treatment. All larval size classes showed a similar sensitivity to gamma irradiation and required 3677 Gray (Gy) and 2476 Gy for a LD₉₉ 3 and 10 days post-treatment, respectively. The penetration of gamma irradiation into pine wood was found to be lowest in freshly cut logs, and decreased linearly at a rate of 0.698 Gy mm^–1 of wood. The penetration was greatest in wood that had been stored for 2 years, and decreased 0.512 Gy mm^–1 of wood. These results are likely to be correlated with wood moisture content. Gamma irradiation appears to be a potential alternative method to fumigation for quarantine treatment of P. reticularis.     

Effect of different eriophyid and tetranychid mango mite species on development,longevity, fecundity and predation of Typhlodromus mangiferus Zaher and El-Brolossy (Acari: Phytoseiidae)

Effects on development, longevity, fecundity and predation of the predatory phytoseiid mite Typhlodromus mangiferus Zaher and El-Brolossy were studied in the laboratory at different temperatures and relative humidities using four prey mite species: the motile stages of the eriophyid mango bud mite Aceria mangiferae Sayed, the eriophyid leaf coating and webbing mite Cisaberoptus kenyae Keifer, the eriophyid mango rust mite Metaculus mangiferae (Attiah) and nymphs of the tetranychid mango red mite Oligonychus mangiferus (Rahman and Sabra). The increase of different temperatures and decrease of relative humidities from 25°C and 60% to 30°C and 55% and 35°C and 50% shortened development and increased reproduction and prey consumption. The developmental durations were almost similar when the predator was fed on eriophyids compared to that on tetranychid. The maximum reproduction (2.70, 2.08, 1.97 and 1.66 eggs/ ♀ /day) was recorded at the highest temperature and the lowest relative humidity, while the minimum reproduction (1.7, 1.54, 1.53, and 1.06 eggs/ ♀ /day) was noted at the lowest temperature and highest relative humidity with all mango prey species. Life table parameters indicated that feeding of T. mangiferus on A. mangiferae led to the highest reproduction rate (rm = 0.204 and 0.139 females/female/day), while feeding on O. mangiferus gave the lowest reproduction rate (rm = 0.137 and 0.116) at 35°C and 50% relative humidity and 25°C and 60% relative humidity, respectively. T. mangiferus seems to be a voracious predator of both mango eriophyid and tetranychid mites. The adult female daily consumed about 127 A. mangiferae, 97 C. kenyae, 86 M. mangiferae, and 18 O. mangiferus at 35°C and 50% relative humidity, while it devoured only 99.81, 86, 81, and 15 individuals, respectively at 25°C and 60% relative humidity. The present study revealed that each injurious mite is thought to be profitable prey species to T. mangiferus as a facultative predator.     

Effects of sublethal doses of chlorfluazuron on insemination and number of inseminated sperm in the common cutworm, Spodoptera litura (F.) (Lepidoptera: Noctuidae)

Sublethal doses (LD₁₀: 1.00 ng larva^?1; or LD₃₀: 3.75 ng larva^?1) of chlorfluazuron were applied topically to the cuticles of newly moulted fifth instars of the common cutworm, Spodoptera litura (F.) (Lepidoptera, Noctuidae). During mating, the treated males transferred spermatophores of a significantly lower weight into females. The weight of spermatophores transferred by LD₃₀‐treated males was significantly lower than the weight of spermatophores transferred by LD₁₀‐treated males, which was in turn significantly lower than the weight of spermatophores transferred by untreated males. The transfer of spermatophores was delayed by 5–15 min in LD₁₀‐ and LD₃₀‐treated males. However, mating duration was not affected by chlorfluazuron treatment. The transfer of spermatozoa was also delayed by 5–10 min in LD₁₀‐ and LD₃₀‐treated females. Polygynous male adults mated an average of ten times during their lifespan of 11–13 days when paired every day with a new virgin female of the same age. The number of matings per polygynous male was not affected by chlorfluazuron treatment, but the first mating was delayed by 1 day. The number of inseminated sperm found in the spermatophore averaged 10.3 (± 2.1) × 10⁵ over the lifespan of a male, in which the number of eupyrene sperm was 5.4 (± 1.1) × 10⁵. The number of inseminated eupyrene sperm decreased by 66% and 88%, respectively, in LD₁₀‐ and LD₃₀‐treated males. No significant reduction in the number of inseminated eupyrene sperm was observed when females were treated with LD₁₀ or LD₃₀ doses, nor was there a significant reduction when both sexes were treated with the LD₁₀ or LD₃₀ doses relative to treatment of males with the same doses. The ratio of inseminated eupyrene to apyrene sperm was not affected by chlorfluazuron treatment.     

Comparative longevity of Australian orchid (Orchidaceae) seeds under experimental and low temperature storage conditions

Seeds from ten terrestrial orchid species, nine from the south‐west Australian biodiversity hotspot (Caladenia arenicola, Caladenia flava, Caladenia huegelii, Diuris laxiflora, Microtis media ssp. media, Pterostylis recurva, Pterostylis sanguinea, Thelymitra crinita and Thelymitra macrophylla) and one from south‐east Australia (Diuris fragrantissima), were placed into experimental storage to assess their relative longevity and likely optimal conditions for long‐term conservation seed banking. Seeds from all species were desiccation tolerant, germinating after drying at 23% relative humidity (C. arenicola, C. huegelii, P. sanguinea and T. macrophylla) or 5% relative humidity (C. flava, D. laxiflora, M. media ssp. media, P. recurva and T. crinita) at 23 °C. From automatedly determined moisture adsorption and desorption isotherms at 23 °C, these equate to tolerance of drying to 0.03–0.06 g water g^?1 dry weight or 0.013–0.028 g water g^?1 dry weight, respectively. Results of storage experiments at a range of moisture contents and temperatures suggest conventional seed bank storage at ?18 °C after equilibration at c. 23% relative humidity (at 23 °C) may be suitable for most of the species, although there was higher germination of P. recurva seeds stored at ?80 °C and of M. media ssp. media seeds equilibrated at 75% relative humidity. However, there was considerable variation in germination of seeds sampled after different storage periods, making it difficult to identify optimal storage conditions definitively. Results of comparative longevity storage experiments at 60% relative humidity and 40 °C suggest seeds from these orchid species are short‐lived compared with non‐orchid species, and with Australian species in particular. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 26–41.     

Effect of gamma irradiation of an acid tea soil from East Pakistan on nitrogen mineralization and nitrification during subsequent incubation

Summary Ammonium- and nitrate-N levels were determined after 13 weeks of incubation (30°C, 80% maximum water-holding capacity) of a ‘tea soil’ (pH 4.2) which had been subjected to varying doses of gamma irradiation (0.05 to 2.00 Mrad) just before incubation. The extent of accumulation of mineral-N (NH₄-N+NO₃-N) during incubation was little affected by any dose of gamma irradiation. Nitrate accumulation during incubation was not affected by 0.05 Mrad but decreased with increasing dose and was completely inhibited by doses of 0.5 Mrad or higher. The results are discussed in relation to the possible occurrence of heterotrophic nitrification in the acid tea soil.     

Entomopathogenic fungus as a biological control agent against Rhyzopertha dominica F. (Coleoptera: Bostrychidae) on stored wheat

To evaluate the pathogenicity of Metarhizium anisopliae (Metschinkoff) Sorokin (Deuteromycotina: Hyphomycetes) a bioassay was designed under laboratory conditions against Rhyzopertha dominica F. (Coleoptera: Bostrychidae) on stored wheat. The fungus was applied at the dose rates of 8 × 10³, 8 × 10⁵, 8 × 10⁷ and 8 × 10⁹ conidia/kg of wheat and the bioassay was conducted at 25°C with 60% relative humidity. The data regarding the mortality was recorded after 7 and 14 days exposure intervals. All the treatments gave the significant mortality of R. dominica and M. anisopliae of 8 × 10⁹ conidia/kg was found to be the most effective after a 14-day exposure interval. There was greater production of progeny when the low rate of M. anisopliae was applied to wheat. Overall, our study showed that M. anisopliae is vigorous when applied at a high dose rate which revealed an effective control of R. dominica and also played a pivotal role in the integrated pest management program (IPM) of stored wheat insect pests.     

Insect Freezing Protection in <Emphasis Type="Italic">Pterostichus brevicornis</Emphasis> (Carabidae)

THERE are conflicting opinions concerning the mechanisms of freezing protection and survival in adult insects^{1, 2} generally resulting from a lack of consideration of pre-experimental conditions (that is, temperature exposure) or inappropriate analytical procedures. The ground beetle, Pterostichus brevicornis, has a circumpolar distribution with populations in some glacial refugia. Here it aggregates and overwinters in decayed stumps in the Fairbanks locale while ambient temperatures lower than ?40° C have been recorded. Lower lethal temperatures (LD₅₀) for winter acclimatized forms are near ?87° C³ and limited survival has been recorded after brief exposures to ?196° C (liquid N₂).     

Effect of Temperature on Development and Reproduction of <Emphasis Type="Italic">Epilachna dodecastigma</Emphasis> (Wied.) (Coleoptera: Coccinellidae)

The effect of five constant temperatures of 21, 24, 27, 30 and 33 °C on adult life span, reproduction, oviposition behavior and larval developmental time of a bitter gourd inhabited coleopteran insect Epilachna dodecastigma (Wied.) (Coccinellidae) was determined in laboratory conditions under 70 ± 5 % relative humidity and a photoperiod of 12 L : 12 D. Larval developmental time of E. dodecastigma decreased as temperature increased from 21 to 33 °C. Life table data revealed that overall mortality was lowest at 27 °C and highest at 21 °C. Females lived longer than males at all temperatures; but longevity decreased with increase in temperature. Pre-oviposition period decreased significantly with increase in temperature up to 27 °C and thereafter increased at a slower rate; whereas oviposition period decreased significantly with increase in temperature. Fecundity and egg viability increased significantly with an increase in temperature up to 27 °C and thereafter decreased at a slower rate. The intrinsic rate of increase (r _m ) was 0.1703, 0.1984, 0.2235, 0.2227 and 0.2181 day^?1 at 21, 24, 27, 30 and 33 °C, respectively. The net reproductive rate and finite rate of increase was highest at 27 °C (R _o  = 112.05; λ = 1.4233) and lowest at 21 °C (R _o  = 51.23; λ = 1.2581).     

Aptness of Beauveria bassiana and enhanced diatomaceous earth (DEBBM) for control of Rhyzopertha dominica F.

A diatomaceous earth formulation enhanced with bitterbarkomycin (DEBBM) combined with Beauveria bassiana (Balsamo) Vuillemin was evaluated against lesser grain borer Rhyzopertha dominica F. (Coleoptera: Bostrychidae) under laboratory conditions. DEBBM was applied at the rates of 15 and 30 ppm alone as well as in combination with 6.69 × 10⁶, 6.69 × 10⁸ and 6.69 × 10¹⁰ conidia/kg of wheat. Mortality of treated adults was recorded after 5, 10 and 15 days of exposure. Bioassays were carried out at 20, 25 and 30°C with 55 and 75% relative humidity. The emergence of progeny was also assessed 60 days post exposure. The combined use of DEBBM and B. bassiana considerably increased adult mortality especially at increasing temperatures and longer exposure intervals compared with DEBBM and B. bassiana alone. Progeny production was less in wheat treated with high dose rates of DEBBM +B. bassiana. The per cent mycosis in the cadavers was maximum where B. bassiana was applied at low dose rates. The results of the present study indicated that a combination of DEBBM and B. bassiana may provide effective control of R. dominica.     

Effects of gamma radiation on different developmental stages of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae)

Ionizing radiation is increasingly used as an alternative to post‐harvest crop fumigation by methyl bromide. We studied the effects of gamma irradiation on Helicoverpa assulta (Lepidoptera: Noctuidae) at different stages of development to determine the minimal dose for the prevention of normal emergence of adults. We selected five doses of gamma rays (100, 200, 300, 400 and 500 Gy) based on preliminary experiments and irradiated eggs, larvae, pupae and adults. A dose of 100 Gy to eggs allowed 21.83% of larvae to pupate, but these all died during the pupal stage. A dose of 100 Gy to last‐instar larvae caused larval or pupal death, or the emergence of abnormal adults; no normal adults developed. Irradiation of pupae with doses of 300 Gy and above resulted either in their death or emergence of abnormal adults; however, after 100 or 200 Gy, normal adults emerged and F₁ eggs were produced, but no eggs hatched. Following irradiation of adults, eggs were produced at all doses, although the numbers were significantly decreased compared to untreated controls (P < 0.05; 69.45–125.50 vs. 475.05 eggs per female); however, none of the eggs hatched. As prevention of normal emergence is a key outcome for measuring the effectiveness of radiation, then the 100 Gy dose was effective for irradiation of eggs and larvae, and 300 Gy for pupae.     

Factors Affecting Dalapon Absorption and Translocation in Johnsongrass

The factors affecting the absorption and translocation of ¹⁴C-dalapon (2.2-dichloropropionic acid) in johnsongrass were studied. Johnsongrass [Sorghum halepense (L.) Pers.] was first pot-grown in a greenhouse and then treated and placed in controlled-environment chambers. Absorption of ¹⁴C-dalapon into johnsongrass leaves and subsequent translocation occurred continuously within the plant during a 48-h period after treatment. Gas chromatographic analysis of johnsongrass extracts showed that the dalapon molecule was translocated intact. Absorption and translocation of ¹⁴C-dalapon increased as the droplet volume of the diluent was increased from 0.2 to 5.0 μl per treated spot. At 21 and 32°C, translocation of ¹⁴C-dalapon from a 2-cm treated leaf section into the plant was greater at 100% than at 35% relative humidity. At 38°C, translocation was greater at 35% than at 100% relative humidity. The addition of 0.5% surfactant to the dalapon solution increased translocation under all environmental conditions studied. The addition of 0.1 M KH₂PO₄ to dalapon-surfactant solutions increased ⁴-dalapon translocation under high temperature (38°C), especially at 35% relative humidity.     

Cold,freezing, and desiccation tolerance of the limpet Acmaea digitalis (Eschscholtz)

Cold, freezing, and desiccation tolerance were examined in the limpet, Acmaea digitalis (Eschscholtz). Fifty percent of the experimental population survived freezing at temperatures between ?10 ° and ?12 °C for at least 24 hr. In this temperature range, 60–80 % of the body water was frozen. The LD₅₀ for water loss by desiccation was 76.5% ± 1.3_δ. At 70–80% body water loss, solutes were concentrated between 350 and 500%. Some limpets failed to survive immersion in 450% seawater for 6 hr (100% scawater = salinity of 31‰), suggesting that much of the damage from freezing and desiccation was from an increased solute concentration. No glycerol could be detected in extracts of the foot and the visceral mass of A. digitalis during winter, confirming similar results in studies carried out on other intertidal molluscs.     

Effect of thermal annealing on the structural and optical properties of tris‐(8‐hydroxyquinoline)aluminum(III) (Alq3) films

Tris‐(8‐hydroxyquionoline)aluminum (Alq₃) was synthesized and coated on to a glass substrate using the dip coating method. The structural and optical properties of the Alq₃ film after thermal annealing from 50°C to 300°C in 50° steps was studied. The films have been prepared with 2 to 16 layers (42–324 nm). The thickness and thermal annealing of Alq₃ films were optimized for maximum luminescence yield. The Fourier transform infrared spectrum confirms the formation of quinoline with absorption in the region 700 ? 500/cm. Partial sublimation and decomposition of quinoline ion was observed with the Alq₃ films annealed at 300°C. The X‐ray diffraction pattern of the Alq₃ film annealed at 50°C to 150°C reveals the amorphous nature of the films. The Alq₃ film annealed above 150°C were crystalline nature. Film annealed at 150°C exhibits a photoluminescence intensity maximum at 512 nm when excited at 390 nm. The Alq₃ thin film deposited with 10 layers (220 nm) at 150°C exhibited maximum luminescence yield. Copyright © 2014 John Wiley & Sons, Ltd.     

Factors affecting sporulation and germination of Pandora nouryi (Entomophthorales: Entomophthoraecae), a pathogen of Myzus persicae (Homoptera: Aphididae)

Pandora nouryi discharged large numbers of primary conidia between 8 and 25°C from cadavers on the surface of water-agar. At 8°C conidial discharge lasted for 120 h, but most conidia were produced within 48 h when temperature was >15°C. Saturated humidity alone was not enough to allow for sporulation to occur freely and where RH?<?95%, no conidia were discharged. Light did not affect the pattern of conidial production nor the total number of conidia. Germination percentages of conidia on the surface of water-agar were 40 and 66% at 8 and 30°C, respectively, and were significantly lower than that at 15–25°C where germination was >95%. Conidia on leaves germinated well when RH?>?74%, while no germination occurred when RH?<?100% on cover slips. All eight insecticides tested entirely inhibited conidial germination at recommended doses (R), in particular, both the organophosphorus pesticides Lorsben (chlorpyrifos) and the organochlorine pesticides Thiodan (endosulfan) completely inhibited conidial germination even at 0.2R dose.     

Toxicity and Sublethal Effects of Phthalides Analogs to Rhyzopertha dominica

Phthalides and their precursors have demonstrated a large variety of biological activities. Eighteen phthalides were synthesized and tested on the stored grain pest Rhyzopertha dominica. In the screening bioassay, compounds rac‐(2R,2aS,4R,4aS,6aR,6bS,7R)‐7‐bromohexahydro‐2,4‐methano‐1,6‐dioxacyclopenta[cd]pentalen‐5(2H)‐one ( 15 ) and rac‐(3R,3aR,4R,7S,7aS)‐3‐(propan‐2‐yloxy)hexahydro‐4,7‐methano‐2‐benzofuran‐1(3H)‐one ( 17 ) showed mortality similar to the commercial insecticide, Bifenthrin® (≥90 %). The time (LT₅₀) and dose (LD₅₀) necessary to kill 50 % of the R. dominica population were determined for the most efficacious phthalides 15 and 17 . Compound 15 presented the lowest LD₅₀ (1.97 μg g^?1), being four times more toxic than Bifenthrin® (LD₅₀=9.11 μg g^?1). Both compounds presented an LT₅₀ value equal to 24 h. When applied at a sublethal dose, both phthalides (especially compound 15 ), reduced the emergence of the first progeny of R. dominica. These findings highlight the potential of phthalides 15 and 17 as precursors for the development of insecticides for R. dominica control.     

The effects of temperature and moisture on survival capacity,cuticular permeability,hemolymph osmoregulation and metabolism in the scorpion,Centruroides hentzi (banks) (scorpiones,buthidae)

• 1.1. The temperature and water relations of Centruroides hentzi females were investigated. At 12 and 72% relative humidity (RH), the lower and upper Lt₅₀ were -4.5 and 43.7°C, and -4.7 and 45.1°C, respectively. When exposed to high temperature stress, survivorship was significantly greater under mesic conditions.
• 2.2. Cuticular water loss was higher under xeric conditions (12% RH), ranging from 0.061 mg/cm²/hr at 30°C to 0.211 at 41°C.
• 3.3. Exposure to dry air (0–5% RH) resulted in a significant increase in hemolymph osmolality: from 441 to 688 mOsm over a 5 day period.
• 4.4. Mean oxygen consumption rates increased from 161.7 mm³/g/hr at 34°C to 541.6 at 44°C. ATPase activity was significantly higher in animals acclimated and tested at 35°C.