Influence of mulberry cultivars Morus spp. on the production and quality of silkworm Bombyx mori L. (Lepidoptera: Bombycidae) cocoons

The success of sericiculture greatly depends on the availability of mulberry cultivars with agronomic characteristics that maximize the production and quality of silkworm, Bombyx mori L., cocoons. The effect of the cultivars Miura (standard) and Korin, and the hybrids SM 14, SM 63, SK 1, SK 4 and FM 86 was evaluated on silkworm development, and on cocoon production and quality, at the Instituto Agron?mico do Paraná, IAPAR, in Londrina, PR, Brazil (23 +/- 3 degrees C; 61 +/- 8% RH). The experiment was arranged in a randomized block design with four replicates. Larvae feeding either on 'SK 4' or on 'Korin' showed a higher weight compared to that of larvae feeding on 'Miura'. Cocoon weight (both sexes) and pupae weight (male) obtained with larvae fed on SK 4 were higher compared with that of insects that fed on Miura; there was no difference among the remaining treatments. Silk net weight was independent of the cultivar used. Cocoon shell weight was similar amongst insects raised on 'Miura' and on the other mulberry materials. The percentage of cocoon spinning was higher than 90% in all treatments, with the spinning concentrating in the first two days. The proportion of first grade cocoons varied from 80% (SK4) to 90%. The results obtained with the studied cultivars were either similar or superior to that of the standard cultivar Miura with emphasis to 'SK 4', thus showing the potential use of these cultivars in sericulture in the state of Paraná.     

Effect of temperature and humidity on development, survival and oviposition in laboratory populations of Eriworm, Philosamia ricini (Boisduval) (Lepidoptera Saturniidae)

Experiments were conducted on laboratory populations of Eriworm, Philosamia ricini Boisduval to study the effect of temperature and humidity on development, growth, survival and oviposition. Experiments were performed at four different temperatures (22 +/- 2 degrees C, 26 +/- 2 degrees C, 28 +/- 2 degrees C and 34 +/- 1 degrees C) each with three different humidities (50%, 70% and 90% relative humidity). Shortest developmental period (42 days) was observed in 28 +/- 2 degrees C and 70% RH. Longest developmental period was (63.6 days) observed in 22 +/- 2 degrees C at 50% RH. Highest larval weight (9.1 g) was found in 28 +/- 2 degrees C at 70% RH. Best pupal weight was observed in 26 +/- 2 degrees C at 70% RH. Weight of silk material was found to be maximum in 26 +/- 2 degrees C at 70% RH. Survival was best in 28 +/- 2 degrees C and 26 +/- 2 degrees C at 70% RH. Oviposition was found to be highest in 28 +/- 2 degrees C at 70% RH.     

Effect of storage time and temperature and the variation among replicate tests (on different days) on the performance of spore disks and strips.

Laboratory-prepared spore disks were stored for 96 weeks at 22 degrees C with 50% relative humidity (RH) and at 4 degrees C with less than 1% RH. At the same time commercial spore strips were stored for 64 weeks at 22 degrees C with 50% RH. The spore count per unit and the heat resistance were measured at the beginning of the experiment and after 16, 32, 48, 64, 80, and 96 weeks of storage. The laboratory-prepared spore disks stored at 4 degrees C with less than 1% RH showed less change in numbers of spores per disks and decrease in the survival time than did the disks stored at 22 degrees C with 50% RH. Both the laboratory-prepared spore disks and the commercial spore strips stored at 22 degrees C with 50% RH decreased in survival times with increased storage time. The relative change in the survival times with storage was less for the commercial spore strips than for the laboratory-prepared spore disks.     

Infectivity of Echinococcus granulosus protoscolices under different conditions of temperature and humidity

The aim of this study was to examine the effect of different temperatures and humidities on the infectivity of Echinococcus granulosus protoscolices. Eighteen dogs (6 groups, n = 3 each) were fed with offal mince harbouring approximately 20,000 protoscolices of E. granulosus of different viabilities. Dogs were infected with E. granulosus protoscolices of: (1) 5% viability at -10 degrees C and 50% relative humidity (RH); (2) 30% viability at 0 degrees C and 60% RH; (3) 20% viability at +10 degrees C and 65% RH; (4) 15% viability at +30 degrees C and 75% RH; (5) 11% viability at +40 degrees C and 80% RH; (6) 68% viability (control group). Dogs in each group were necropsied at 29-49 days post-infection. Mean intensities of E. granulosus recovered from dogs were 256.7 +/- 60.3 in the second group; 32.7 +/- 7.1 in the third group; 40.3 +/- 15.5 in the fourth group and 1533 +/- 513 in the control group. However, no parasites were recovered from the first and fifth groups. Results obtained in the present study show that larval stages could be infective for 1 to 4 weeks during spring, autumn or winter months when maximal temperatures are approximately 0-10 degrees C. In conclusion, cold-storage depots in slaughterhouses and abattoirs where sheep carcasses might be discarded should be kept at -20 degrees C for 2-3 days, dogs should be properly controlled and adequate control programmes must be established in areas where the disease is endemic.     

Notes on the life-history of the rabbit flea Caenopsylla laptevi ibera Beaucournu & Marquez, 1987 (Siphonaptera: Ceratophyllidae) in eastern Spain

The rabbit flea Caenopsylla laptevi ibera occurs in arid environments of central and eastern Spain. Although the fleas breed during the coolest, most humid part of the year, the larvae survive and grow in sand at only 50-60% relative humidity. At 22 degrees C and 80% relative humidity eggs hatch in six days and the cocoon stage is reached 10-11 days after hatching. Female fleas emerge from pupation at about 17 days after cocoon spinning; males emerge a little later at a mean of 20 days. Adult fleas are mainly found on the host Oryctolagus cuniculus. Measurements of burrow microclimate confirmed that in south-eastern Spain burrow humidity was adequate for the development of C. I. ibera larvae over most of the year. However, breeding may be restricted for at least part of the year, as the larvae of C. I. ibera apparently cannot complete development at 25 degrees C or above. In the laboratory, fleas can enter a prolonged quiescent period while in the cocoon. This is possibly a facultative, pre-pupal diapause and the likely mechanism that accounts for the disappearance of adult fleas from the field by spring and their reappearance each autumn.     

Effect of relative humidity and air temperature on survival of hepatitis A virus on environmental surfaces.

Stainless steel disks (diameter, 1 cm) were contaminated with fecally suspended hepatitis A virus (HAV; strain HM-175) and held at low (25% +/- 5%), medium (55% +/- 5%), high (80% +/- 5%), or ultrahigh (95% +/- 5%) relative humidity (RH) at an air temperature of 5,20, or 35 degrees C. HAV survival was inversely proportional to the level of RH and temperature, and the half-lives of the virus ranged from greater than 7 days at the low RH and 5 degrees C to about 2 h at the ultrahigh RH and 35 degrees C. In parallel tests with fecally suspended Sabin poliovirus (PV) type 1 at the low and ultrahigh RH, all PV activity was lost within 4 h at the low RH whereas at the ultrahigh RH it remained detectable up to 12 h. HAV could therefore survive much better than PV on nonporous environmental surfaces. Moreover, the ability of HAV to survive better at low levels of RH is in direct contrast to the behavior of other enteroviruses. These findings should help in understanding the genesis of HAV outbreaks more clearly and in designing better measures for their control and prevention.     

Effect of relative humidity and air temperature on survival of hepatitis A virus on environmental surfaces.

Stainless steel disks (diameter, 1 cm) were contaminated with fecally suspended hepatitis A virus (HAV; strain HM-175) and held at low (25% +/- 5%), medium (55% +/- 5%), high (80% +/- 5%), or ultrahigh (95% +/- 5%) relative humidity (RH) at an air temperature of 5,20, or 35 degrees C. HAV survival was inversely proportional to the level of RH and temperature, and the half-lives of the virus ranged from greater than 7 days at the low RH and 5 degrees C to about 2 h at the ultrahigh RH and 35 degrees C. In parallel tests with fecally suspended Sabin poliovirus (PV) type 1 at the low and ultrahigh RH, all PV activity was lost within 4 h at the low RH whereas at the ultrahigh RH it remained detectable up to 12 h. HAV could therefore survive much better than PV on nonporous environmental surfaces. Moreover, the ability of HAV to survive better at low levels of RH is in direct contrast to the behavior of other enteroviruses. These findings should help in understanding the genesis of HAV outbreaks more clearly and in designing better measures for their control and prevention.     

Development of a Melting Tablet Containing Promethazine HCl Against Motion Sickness

The purpose of this study was to design a 'Traveller Friendly Drug Delivery System' for PM-HCl. Conventional promethazine (PM-HCl) tablets are bitter, need to be taken 1 h before symptoms and water is also needed. Taste-masked granules were produced with Eudragit E100 by extrusion, and analyzed with FTIR, DSC, and XRD. Tablets formulated from granules by direct compression using Ac-Di-Sol, Polyplasdone-XL, Primojel and ion-exchanger Tulsion339 and evaluated for mass uniformity, friability, tensile strength, drug content uniformity, water absorption ratio, in-vitro and in-vivo disintegration time and in-vitro dissolution studies. The observed drug-polymer interactions and reduced crystallinity may be reasons for increased dissolution rates. The formulated tablets were disintegrated within 15 s. Tablets (25 mg PM-HCl) with Ac-Di-Sol (4%) showed complete release within 1 min, while marketed conventional tablets (Phenergan; Rhone-Poulec) release 25% during the same period. A preliminary stability studies for the prepared tablets carried at 30 +/- 2 degrees C/60 +/- 5% RH, and 40 +/- 2 degrees C/75 +/- 5%RH for 3 months showed no significant changes in the tablets quality at 30 +/- 2 degrees C/60 +/- 5% RH. However, at 40 +/- 2 degrees C/75 +/- 5%RH marked increase in in-vitro disintegration time, tensile strength and decrease in friability and water absorption ratio was found. The present studies indicate the abilities of Eudragit E 100 for taste masking and improving the dissolution profile of PM-HCl after complexation. In addition, by employing cost effective direct compression method, fast-dissolving tablets of 400 mg total weight with an acceptable quality could be prepared.     

Development of Aphidius colemani Viereck (Hym.: Braconidae, Aphidiinae) and alterations caused by the parasitism in the host Aphis gossypii Glover (Hem.: Aphididae) in different temperatures

Aphidius colemani Viereck is among the main natural enemies used for biological control of Aphis gossypii Glover. The objective of the present study was to evaluate the development of A. colemani and the alterations caused by the parasitism in the host A. gossypii in different temperatures and to estimate the thermal requirements of the parasitoid. The experiments were carried out in controlled environmental chambers at 16, 19, 22, 25, 28 and 31 +/- 1 degrees C, 70 +/- 10% RH, and 12h photophase. Second-instar nymphs of A. gossypii were parasitized once and kept individually in glass tubes (2.5 cm x 8.5 cm), containing leaf disc of cucumber (2 cm) and 1% water/agar solution. The development time of A. colemani, from oviposition to mummies (11.9, 9.8, 7.7, 6.4 and 6.4 days) and from oviposition to adult (19.4, 16.2, 12.6, 10.5 and 10.7 days) decreased with the increase of the temperature from 16 degrees C to 25 degrees C. The rates of mummies and the emergence of the parasitoid, and its longevity also decreased with the increase of the temperature. Mummies were not produced at 31 degrees C. The lower temperature threshold of A. colemani was 5.94 degrees C and its thermal constant was 200 degrees-day. The alterations caused by the parasitoid in the A. gossypii host were minimized at 31 degrees C, where 98% of the host did not show symptoms of parasitism and produced nymphs. The temperature of 22 degrees C was optimal for the development time of A. colemani.     

Changes in NMR relaxation times in soybean and wheat seeds equilibrated at different temperatures and relative humidity

The relationship between equilibration injury and equilibration dependence of the transverse relaxation time (T2) measurements was examined using NMR in two different seed species (sensitive-soybean and tolerant-wheat) differing in their sensitivity to seed equilibration conditions. The T2 values of both seed species declined with high temperature (45 degrees C) and low RH (5.5-1%) and, also with high temperature (45 degrees C) and high RH (74.5-100%) conditions. A comparison of injury based on electrolyte leakage, seed germination percentage and T2 indicated that membrane permeability increased both at high temperature (45 degrees C) and low RH (5.5-1%) and high temperature (45 degrees C) and high RH (74.5-100%) seed equilibration conditions. There was an increase in T2 until 11.5% and 5.5% RH in soybean and wheat species respectively, followed by a decline. Loss of seed viability during equilibration at very low RH (5.5-1%) at 45 degrees C, and similarly at high RH (74.5-100%) at 45 degrees C indicates that the changes in T2 are probably due to the loss of membrane injury.     

Ecdysteroid as a mediator in the regulation of silk protein synthesis and its influence on silkworm (Bom., Lepidoptera) genome

Abstract:  Ecdysteroid is one of the two most important insect hormones, which controls growth and developmental activities of insect. In silkworm, Bombyx mori L., basically ecdysteroid induces molting and metamorphosis in larvae and exogenous administration hastens the silk synthetic activity and cocoon spinning process but it strictly depends on the time of administration. In the present study, we administered phytogenous ecdysteroid to the 48-h-old 5th instar silkworm, B. mori at a single dose of 2  μ g per larva to study its effects on the larval growth, cocoon and silk variables. The possible role of ecdysteroid in altering the developmental sequence of silkworm and thereby its effect on cocoon and silk production at molecular level have been tried to get elucidated. The genomic DNA was isolated from the posterior silk gland on day 5 and 7 of the 5th instar from the ecdysteroid treated and the control larvae and was randomly amplified with arbitrary primers. The result presented notable variation in the amplified product suggesting the participation of ecdysteroid in regulating the silk gene. The feeding period of treated larvae was unaffected while the cocoon characters exhibited considerable improvement. The filament traits also were improved notably in the treated larvae. The participation of ecdysteroid in the silk biosynthetic process with its physiological and molecular implications was discussed.     

Water loss and metabolic water in starving Argas reflexus nymphs (Acari: Argasidae)

Basic components of the water balance were determined in A. reflexus unfed second instar nymphs kept at 30 degrees C and different relative humidities in darkness. At 2.5% and 32.5% RH, A. reflexus survived for 170+/-60 and 246+/-71 days, respectively. At 56%, 75.5% and 96.5% RH, the experiment was terminated after 168 days without any mortality. The initial water content of hydrated A. reflexus kept at 85% RH was 70.3+/-1.8% while the water content was close to 50% in ticks dehydrated at /=56% suggesting that A. reflexus increased its oxidative metabolism under dehydrating conditions and thus delayed lethal dehydration. Interestingly, the dry mass of dead ticks was almost identical irrespective of whether the ticks had previously been kept at 2.5% and 32.5% RH, i.e. irrespective of their different survival periods. This raises the question whether the ticks had died by dehydration or by exhaustion of energy reserves.     

PTTH--a potential growth activator in silkworm,Bombyx mori L. for enhancing silk production

In silkworm, prothoracicotropic hormone (PTTH), directly or indirectly controls silk production and spinning activity along with juvenile hormone (JH). An effort was made to exploit the potential of PTTH by indirectly activating silk gland for increasing silk productivity using short chain synthetic analogues of PTTH. The analogy in action was also established using PTTH extracted from the silkmoth. Different doses of 42 synthetic PTTH analogues, viz., 2.5, 5, 10 and 20ppm and 3.3 mg/ml of PTTH extracted from silkmoth heads were administered orally to V instar silkworm larvae (Race:KAxNB4D2 and PMxNB4D2) at 0-144 hr at an interval of 24 hr. The analysed data showed an improvement of about 14 - 23% in KA x NB4D2 and about 10-14% in PMxNB4D2 in respect of cocoon shell weight on administration of some of the synthetic PTTH analogues. The PTTH extracted from the adult brain also showed similar effect. The structural analogy of synthetic PTTHs (which improved the shell weight) with original PTTH and its probable mode of action in silkworm are discussed.     

Pulsed nuclear magnetic resonance study of 39K in frog striated muscle.

Samples of 1 M KCl solution and 10 samples of intact frog striated muscle were studied at 4-7 degrees C and/or at 21-22 degrees C. Field inhomogeneity was minimized by using small sample volumes and by using a superconducting magnet designed specifically to provide highly homogeneous fields. In the present experiments, magnetic field inhomogeneity was measured to contribute less than 15% to the free induction decay observed for intracellular 39K. The signal-to-noise ratio of the measurements was enhanced by means of extensive time-averaging. The rates of nuclear relaxation for 39K in aqueous solution were 22 +/- 3 (mean +/- 95% confidence limits) s-1 at 4-7 degrees C and 15 +/- 2 s-1 at 21-22 degrees C. For intracellular 39K, (1/T2) was measured to be 327 +/- 22 s-1 and 229 +/- 10 s-1 at the lower and higher temperatures, respectively. The corresponding values for (1/T1) in the same muscle samples were 198 +/- 31 s-1 and 79 +/- 15 s-1 at 4-7 degrees C and at 21-22 degrees C, respectively. These results for 39K are similar to those previously obtained for intracellular 23Na. Since less than 1% of the intracellular 23Na has been estimated to be immobilized, fractional immobilization of intracellular 39K is also likely to be insubstantial.     

Thermal comfort zones in the Vietnamese

Thermally comfortable zones in Vietnamese were investigated during winter in Hanoi. The subjects were 21 males (age: 19.7 +/- 0.4 yrs; height: 165 +/- 1.5 cm; body mass: 55.1 +/- 1.1 kg) and 19 females (age: 19.7 +/- 0.4 yrs; height; 155.6 +/- 1.7 cm; body mass: 45.6 +/- 1.3 kg). Each participant entered singly the climatic chamber controlled at 22 degrees C and 40% RH. After 20 min rest, the participant was requested to indicate on a 7-point scale (Table 1) how he or she felt to the room temperature given. Then, the room temperature increased by 1 degrees C over 10 min every 20 min. Just before the rise of the room temperature, the participant judged his or her thermal sensation. More than 90% of the participants felt 24-29 degrees C of the room temperature as "slightly cool", "neutral" and "slightly warm" (Table 2). We defined these sensations as "thermally comfort". These thermally comfortable zones were quite higher than those (20-24 degrees C) recommended by ISO-7730 (1994). We discussed these discrepancies in terms of higher establishment of thermoregulatory set-point in the Vietnamese.     

Physiological and metabolic responses to work in heat with graded hypohydration in tropical subjects

Studies were conducted on 25 healthy male volunteers aged 20-25 years drawn randomly from the tropical regions of India. The subjects initially underwent an 8 day heat acclimatization schedule with 2 hours moderate work in a climatic chamber at 45 degrees C DB and 30% RH. These heat acclimatized subjects were then hypohydrated to varying levels of body weight deficits, i.e. 1.3 +/- 0.03, 2.3 +/- 0.04 and 3.3 +/- 0.04%, by a combination of water restriction and moderate exercise inside the hot chamber. After 2 hours rest in a thermoneutral room (25 +/- 1 degree C) the hypohydrated subjects were tested on a bicycle ergometer at a fixed submaximal work rate (40 W, 40 min) in a hot dry condition (45 degrees C DB, 30% RH, 34 degrees C WBGT). Significant increases in exercise heart rate and oral temperature were observed in hypohydrated subjects as compared to euhydration. Sweat rate increased with 1% and 2% hypohydration as compared to euhydration, but a significant decrease was observed with 3% hypohydration. Na+ & K+ concentrations in arm sweat increased with increase in the level of hypohydration. Oxygen consumption increased significantly only when hypohydration was about 2% or more. It appears that the increased physiological strain observed in tropical subjects working in heat with graded hypohydration is not solely due to reduced sweat rates.     

广西桑蚕茧丝质量与性能指标的测定分析

本研究对广西桑蚕茧的茧丝质量与性能指标进行了测定分析.结果表明,广西桑蚕茧外形略小,茧层丝胶含量、茧层易溶丝胶含量、丝胶溶解性以及茧丝纤度等主要指标均与江浙夏秋用桑蚕茧有明显差异.桑蚕茧的茧层丝胶含量、易溶丝胶含量随庄口、季节不同而有显著差异;春季桂南地区的蚕茧茧层丝胶含量高于桂西北地区,秋季刚好相反.茧层易溶丝胶含量在11.6%～14.4%之间,约占丝胶总含量的41%～45%,茧层易溶丝胶含量和解舒率呈显著的正相关关系,即茧层易溶丝胶含量越多,蚕茧解舒越好.庄口和季节是影响桑蚕茧层易溶丝胶含量高低与蚕茧解舒优劣的重要因素.广西桑蚕茧层丝胶对煮茧温度更敏感,茧丝纤度粗细变化开差大.因此,我们认为目前困扰广西桑蚕茧加工技术突破的原因之一是缫丝工艺技术,采用传统缫丝工艺技术难以正常发挥广西桑蚕茧的茧丝优势与特性.     

Effects of relative humidity on cocoon formation and survival in the braconid wasp Cotesia glomerata

Abstract The effects of relative humidity (RH) on cocoon formation and survival in the braconid parasitoid wasp Cotesia glomerata (L.) (Hymenoptera: Braconidae) are investigated under various humidity conditions (50, 75, 90, 95 and 100% RH) at 20 °C and under an LD 16 : 8 h photoperiod. The mortality rate at the time of egression from hosts under 100% RH is significantly higher than for other RHs. Cocoon clusters formed at 100% RH spread significantly more than those formed at 50, 75, or 90% RH. Developmental periods differ significantly among RHs under which wasps developed. The mean period from the egression from hosts to adult emergence is 8.7 days when developed at 50–95% RHs, and 8.0 days at 100% RH. The emergence rates of C. glomerata that are maintained under the same humidity conditions after egression from hosts are not significantly different among RHs. However, emergence rates from cocoons that are transferred from 100% RH to 50 and 75% RH are < 70%, although the rates are > 90% in most cases. Some wasps do not emerge from cocoons: more than 60% die after adult eclosion at all RHs; the relative frequency of adult deaths is approximately 90% at 50% RH. Relative humidity influences the cluster and cocoon status strongly: both good clusters and cocoons are formed at low RHs. Emergence rates from cocoons of different ranks are significantly different: the rates of low‐rank cocoons are low at low RHs. The survival of C. glomerata is affected strongly by RH through cocoon formation.     

Controlling membrane cholesterol content. A role for polyunsaturated (docosahexaenoate) phospholipids

The molecular organization of cholesterol in 1,2-didocosahexaenoylphosphatidylcholine (22:6-22:6PC) and 1-stearoyl-2-docosahexaenoylphosphatidylcholine (18:0-22:6PC) bilayers was investigated. Using low- and wide-angle X-ray diffraction (XRD), we determined that the solubility of the sterol at 20 degrees C was 11 +/- 3 mol % in 22:6-22:6PC vs 55 +/- 3 mol % in 18:0-22:6PC bilayers. Solubility in the dipolyunsaturated membrane rose to 17 +/- 3 mol % at 40 degrees C, while in the saturated-polyunsaturated membrane there was no change within experimental uncertainty. We compared the molecular orientation of [3alpha-(2)H(1)]cholesterol incorporated into 22:6-22:6PC bilayers to its solubility limit and into 18:0-22:6PC bilayers to a comparable concentration (10 mol %) in solid-state (2)H NMR experiments. The sterol possessed a tilt angle alpha(0) = 24 degrees +/- 1 degrees in 22:6-22:6PC that was independent of temperature over a range from 20 to 40 degrees C. In contrast, the value was alpha(0) = 21 degrees +/- 1 degrees in 18:0-22:6 bilayers at 20 degrees C and increased to alpha(0) = 24 degrees +/- 1 degrees at 40 degrees C. We attribute the low solubility of cholesterol in 22:6-22:6PC membranes to steric incompatibility between the rigid steroid moiety and the highly disordered docosahexaenoic acid (DHA) chain, which has the potential to promote lateral heterogeneity within DHA-rich membranes. Considering 22:6-22:6PC to be the most unsaturated phospholipid found in vivo, this model membrane study provides a point of reference for elucidating the role of sterol-lipid interactions in controlling local compositional organization. Our results form the basis for a model that is consistent with cholesterol's ability to modulate the activity of certain neural transmembrane proteins.     

Development rates of two Xenopsylla flea species in relation to air temperature and humidity

The rate of development of immature fleas, Xenopsylla conformis Wagner and Xenopsylla ramesis Rothschild (Siphonaptera: Xenopsyllidae) was studied in the laboratory at 25 degrees C and 28 degrees C with 40, 55, 75 and 92% relative humidity (RH). These fleas are separately associated with the host jird Meriones crassus Sundevall in different microhabitats of the Ramon erosion cirque, Negev Highlands, Israel. This study of basic climatic factors in relation to flea bionomics provides the basis for ecological investigations to interpret reasons for paratopic local distributions of these two species of congeneric fleas on the same host. Both air temperature and RH were positively correlated with duration of egg and larval stages in both species. Change of humidity between egg and larval environments did not affect duration of larval development at any temperature. At each temperature and RH, the eggs and larvae of X. ramesis did not differ between males and females in the duration of their development, whereas female eggs and larvae of X. conformis usually developed significantly faster than those of males. For both species, male pupae developed slower than female pupae at the same air temperature and RH. Air temperature, but not RH, affected the duration of pupal development. At each humidity, duration of the pupal stage was significantly longer at 25 degrees C than at 28 degrees C: 15.3+/-1.7 vs. 11.7+/-1.2 days in X. conformis; 14.1+/-2.0 vs. 11.5+/-1.7 days in X. ramesis, with a significantly shorter pupal period of the latter species at 25 degrees C. These limited interspecific bionomic contrasts in relation to basic climatic factors appear insufficient to explain the differential habitat distributions of X. conformis and X. ramesis.