Photoperiod 16L Research Articles

Heat stress abatement during the dry period influences metabolic gene expression and improves immune status in the transition period of dairy cows

Heat stress (HT) and photoperiod affect milk production and immune status of dairy cows. The objective was to evaluate the effects of HT abatement prepartum under controlled photoperiod on hepatic metabolic gene expression and cellular immune function of periparturient Holstein cows (n=21). Cows were dried off 46 d before expected calving date and assigned to treatments by mature equivalent milk production. The treatments were 1) HT and 2) cooling (CL), both imposed during a photoperiod of 14L:10D. Rectal temperature was measured twice daily, whereas respiration rate was measured 3 times/wk at 1500h during the entire dry period. After calving, cows were housed in a freestall barn with cooling, and milk yield was recorded daily up to 140 d in milk. Liver samples were taken at dry off, −20, 2, and 20 d relative to calving by biopsy. Under a similar schedule, neutrophil function was determined in blood of cows on HT (n=12) and CL (n=9). Blood samples were taken on −46, −32, −18, 0, 14, 28, and 42 d relative to calving for measurement of metabolites and were collected twice daily from −7 to 2 d relative to calving for prolactin (PRL) analysis. The HT cows had greater concentrations of PRL at 0 d relative to calving (150 vs. 93; SEM=11 ng/mL) and had higher afternoon rectal temperatures (39.4 vs. 39.0; SEM=0.04°C) and elevated respiration rates (78 vs. 56; SEM=2 breaths/min) during the prepartum period compared with CL cows. Relative to HT cows, CL cows had greater hepatic expression of PRL-R, SOCS-3, and CAV-1 mRNA. Neutrophil oxidative burst was greater in CL cows relative to HT cows at 2 d (61 vs. 42; SEM=6%) and at 20 d (62 vs. 49; SEM=5%) relative to calving, and phagocytosis was greater in CL cows at 20 d (47 vs. 33; SEM=4%) relative to calving compared with HT cows. Humoral response, as measured by IgG secretion against ovalbumin challenge, was greater for CL cows at −32 d (0.44 vs. 0.33; SEM=0.05 OD) and −21 d (0.60 vs. 0.50±0.04 OD) relative to calving compared with HT cows. These results suggest that HT abatement during the dry period improved innate and acquired immune status as measured by neutrophil function and immunoglobulin secretion against ovalbumin challenge, and altered hepatic gene expression related to PRL signaling in the periparturient period or subsequent lactation.

Larval diapause of Monochamus urussovi and photoperiodic effects on larval development in tree bolts

AbstractTo determine the larval diapause and the effect of photoperiod on development in Monochamus urussovi (Coleoptera: Cerambycidae), larvae were reared on Abies sachalinensis and Picea jezoensis logs and bolts. Larvae stopped developing in the final instar at 25°C and 16L : 8D (16 h light and 8 h dark) whereas an exposure to 5°C in the dark (134 days) following acclimation at 12°C under natural daylength led to adult emergence. When larvae were reared under 8L : 16D or 16L : 8D at 25°C with an intervening period of chilling at 5°C in the dark (112 days), a photoperiod of 8L : 16D induced a shorter time required for adult emergence after being returned to 25°C, and smaller adult body size than 16L : 8D.

Diet influence on egg production of the copepod Acartia tonsa (Dana, 1896)

Egg production in the copepod Acartia tonsa was evaluated using different densities of the microalgae Thalassiosira weissflogii, Chaetoceros muelleri and Isochrysis galbana. Male and female were kept under controlled conditions (salinity 30, 20 degrees C, photoperiod 12L:12D), acclimated to the experimental conditions and left over a period of 24 h to allow copulation. Algal densities tested were equivalent in biovolume and corresponded to 0, 2.5, 5, 10, 20, 40 and 60.10(3) cells.mL-1 of T weissflogii. Ten acclimated female were separated, transferred to glass bottles and exposed for further 24 h to the corresponding experimental medium. After this period, the eggs were fixed and counted. Copepod egg production reached a threshold value when T weissflogii, C. muelleri and I. galbana were supplied at 10.10(3), 140.10(3) and 640.10(3) cells.mL-1, respectively. Mean egg production corresponded to 28.0 +/- 0.5, 20.1 +/- 1.0 and 22.0 +/- 3.5 eggs.female-1 .day-1, respectively. Copepods fed T weissflogii showed the highest mean egg production while those fed I. galbana reached a maximum egg production when the algae were supplied at a density two- to fourfold higher, considering the biovolume of T weissflogii and C. muelleri. These differences are explained considering the different sizes of the microalgae used to feed the copepods.

Effects of temperature and irradiance on early development of Chondrus ocellatus Holm (Gigartinaceae, Rhodophyta)

Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedling nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures (10-28 degrees C) and irradiances ( 10, 60 mu mol photons m(-2)s(-1)) with a photoperiod of 12L:12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10-25 degrees C, and have the highest relative growth rate at 20 degrees C. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 mu mol photons m(-2)s(-1) was more suitable than 10 mu mol photons m(-2)s(-1). The optimum temperature and irradiance for the development of seedlings was 20 degrees C and 60 mu mol photons m(-2)s(-1), respectively.

Efeito da maturação e temperatura na germinação de sementes de Phoenix canariensis hort. ex Chabaud - Arecaceae

Phoenix canariensis hort. ex Chabaud, originária das Ilhas Canárias, é uma palmeira que apresenta grande valor ornamental. A propagação das palmeiras, de modo geral, é considerada lenta, desuniforme e influenciada por vários fatores, como estádio de maturação e temperatura. Devido à sua importância e à falta de informações na literatura sobre a propagação da espécie, este trabalho teve como objetivo estudar o efeito do estádio de maturação e da temperatura na germinação de sementes de P. canariensis. Realizou-se um experimento cujo delineamento experimental foi inteiramente casualizado em esquema fatorial 2 x 5 (2 para maturação e 5 para temperatura), com quatro repetições de 25 sementes. Frutos de colorações alaranjada (intermediário) e marrom (maduro) foram despolpados e os diásporos, colocados em caixas plásticas (tipo gerbox) contendo vermiculita como substrato, nas temperaturas de 25, 30, 35, 20-30 e 25-35 ºC, com fotoperíodo de 16 h de luz e 8 h de escuro, utilizando-se câmaras incubadoras tipo BOD com controle de temperatura e fotoperíodo. Pelos resultados, conclui-se que a condição que permitiu maior porcentagem de germinação das sementes de P. canariensis foi a partir de frutos maduros (de coloração marrom), na temperatura alternada de 20-30 ºC, atingindo 98% de germinação.

Sperm Reception and Egg Production of Mating-Interrupted, Single-Mated, and Multiple-Mated Females of Neoseiulus californicus (McGregor) at Different Temperatures (Acari: Phytoseiidae)

Sperm transfer during the mating process and subsequent egg production were observed in a predaceous mite species, Neoseiulus californicus, at 18, 25, 30, and 35°C with a photoperiod of 16L:8D. Mating was disrupted at predetermined time points, and female egg production was counted daily. In addition, other females were allowed to mate repeatedly with new males throughout the oviposition period, and egg production was observed. To quantify the volume of sperm transferred from males to females, mated females were sacrificed and mounted immediately after copulation, and the diameter of the spermatophore within the female spermatheca was measured. The results indicated that both sperm volume and egg production increased with mating duration at all temperatures. However, the engorgement of female spermatheca by a spermatophore and subsequent female egg production began at an earlier stage of copulation (after a shorter mating duration) under higher temperatures. Multiple-mated females often had more than one spermatophore in their spermatheca, which was never observed in single-mated females, and the former laid more eggs than the latter at all temperatures. However, total egg production by multiple-mated females did not differ at 25, 30, and 35°C. The reproductive characteristics of N. californicus and their significance to the mite's life history are discussed from the perspective of biological control of one of their primary prey species, spider mites.

Heat-stress abatement during the dry period: Does cooling improve transition into lactation?

Environmental factors, especially temperature and light exposure, influence the health and productivity of dairy cows during lactation, possibly via similar physiological mechanisms. For example, heat stress is a critical component of decreased milk yield during summer. However, less is known about the effect of heat stress during the dry period. The objective of this study was to evaluate the effects of heat stress prepartum under a controlled photoperiod on lactation performance and hepatic metabolic gene expression of periparturient multiparous Holstein cows (n=16). Cows were dried off approximately 46 d before expected calving date and assigned to treatment randomly after blocking by mature equivalent milk production and parity. Treatments consisted of either heat stress (HT) or cooling (CL) with fans and sprinklers, both under a photoperiod of 14L:10D. Rectal temperature was measured twice daily during the dry period. After calving, cows were housed in a freestall barn with cooling devices, and milk yield was recorded daily up to 210 d in milk. Blood samples were taken from dry off until +42 d relative to calving for metabolites and from −2 until +2 d relative to calving for hormone analysis. Daily dry matter intake was measured from −35 to +42 d relative to calving. Liver biopsies were collected at dry off, −20, +2, and +20 d relative to calving for cows on HT (n=5) and CL (n=4) to measure mRNA expression of suppressors of cytokine signaling-2 (SOCS-2), insulin-like growth factor binding protein-5 (IGFBP-5), a key transcription factor in lipid biosynthesis (SREBP-1c), and enzymes of lipid metabolism (FASN, ACACA, and ACADVL) by real-time quantitative PCR. Heat stress increased rectal temperatures (39.2 vs. 38.8°C), plasma prolactin concentrations at −1 (171 vs. 79 ng/mL) and 0 d (210 vs. 115 ng/mL) relative to calving, and decreased dry matter intake at 0 and +14 d relative to calving and 3.5% fat-corrected milk postpartum (26.1 vs. 35.4kg/d) compared with CL cows. Relative to CL cows, hepatic mRNA expression of SOCS-2 and IGFBP-5 was downregulated in HT cows. Expression of ACADVL was upregulated in CL cows at d +2 but downregulated at d +20 relative to HT cows. Concentrations of C16:0 and cis C18:1 were greater in the milk and liver of CL cows compared with HT cows, which reflects greater lipid mobilization. These results suggest that heat-stress abatement in the dry period improves subsequent lactation, possibly via suppression of plasma prolactin surge around calving, SOCS-2 expression, and regulation of hepatic lipid metabolism.

Temperature at immature and adult stages differentially affects mating duration and egg production of Neoseiulus californicus females mated once (Acari: Phytoseiidae)

A series of experiments was conducted to investigate whether temperatures of 18 °C, 25 °C, 30 °C, and 35 °C and a photoperiod of 16L:8D at immature and adult stages would differentially affect the mating duration and egg production of Neoseiulus californicus females mated once. Mating duration was strictly determined by ambient temperature at the time of mating, regardless of the temperatures under which they were raised. Compared with a consistent 25 °C condition, total fecundity of females decreased when temperature conditions of 18 °C, 30 °C, and 35 °C were applied during any life stage (immature, mating, and oviposition periods) or a combination of different stages. In general, however, if mites were raised in conditions of ≤ 25 °C, and mated and oviposited at conditions of ≥ 25 °C, total egg production was relatively high. Based on these results, the adaptation of mites to thermal environments was discussed.

CONSUMO DE VITELO DURANTE O DESENVOLVIMENTO EMBRIONÁRIO DE MELANOTÊNIA-MAÇÃ, Glossolepis incisus, WEBER 1907 (Melanotaeniidae)

The consumption of yolk on development of embryos of the salmon-red rainbowfish (Glossolepis incisus) was examined under controlled hatchery conditions. Naturally-fertilized eggs, obtained by natural spawning of cultured adults, were stocked into floating sieves in 40L flow-through aquaria at temperature of 28°C. A photoperiod of 16L: 8D was maintained. The embryos have a long period of hatching about 7 days at 28oC, consuming almost all yolk during the early stages into the eggs. At hatching the newly-hatched larvae yolk-sac is reduced, but still present and the larvae are strongly swimmers and have a functional mouth, enteric peristaltic movement and anus opened suggesting an initial exogenous feeding stage. Differently to others species of tropical fishes that have a long time for the weaning, larvae of salmon-red rainbowfish are already for becoming first-feeding larvae in few hours after eclosion. KEY WORDS: Early development, ontogeny, ornamental fish.

Mating duration and egg production of the predaceous mite Neoseiulus californicus (Acari: Phytoseiidae) vary with temperature

Effects of constant temperature on mating duration and total fecundity of Neoseiulus californicus females mated once were investigated at 18 °C, 25 °C, 30 °C, and 35 °C with a photoperiod of 16L:8D. Adult mites grown and maintained at 25 °C mated for 315.3 min on average and produced 46.1 eggs per female. These values varied significantly by temperature: 553.6 and 13.9 (18 °C), 261.2 and 26.6 (30 °C), and 253.6 and 23.9 (35 °C), respectively. Duration of copulation was negatively correlated with temperature. However, total egg production peaked at 25 °C and decreased at lower and higher temperatures. Reduced sperm transfer and/or survival rate of sperm in the female body may account for decreased egg production when temperatures are not optimal.

Immune responses of Indian Jungle Bush Quail, P. asiatica, to different photoperiodic regimens during the reproductively inactive phase

Effects of different photoperiod regimens: Natural Day Length (NDL), Constant Light (LL), Constant Dark (DD), 16 h Light:8 h Dark (16L:8D), 14 h Light:10 h Dark (14L:10D), 12 h Light:12 h Dark (12L:12D) on immunity was noted during the reproductively inactive phase of a tropical bird, Perdicula asiatica. Extreme exposure of photoperiod i.e. LL and DD has a drastic effect on the immune status of the birds while two long photoperiods 16L:8D and 14L:10D have a significant effect when compared with the immune status of NDL birds. The immune status and melatonin level had a direct relationship but shared an inverse relationship with that of the gonadal activity of the birds. Thus, even in the tropical zone (where the photoperiod is having slight difference) the immunity relies on photoperiodic time measurement mechanisms that include the pineal gland and melatonin to relay photoperiodic changes in physiological and behavioural components of immune function.

Effect of combined photoperiod, water calcium concentration and pH on survival, growth, and moulting of juvenile crayfish (Procambarus clarkii ) cultured under laboratory conditions

The red swamp crayfish, Procambarus clarkii (Girard), is one of the most commonly farmed freshwater species in inland China due to its high market value and consumer demand. The aim of this study was to determine the optimum combinations of photoperiod, water calcium concentration and pH for juvenile survival, growth and moulting. In our orthogonal experiment, the three environmental factors were varied at three levels (photoperiod: 16L:8D, 12L:12D and 8L:16D; calcium concentration: 45.5, 65.5 and 85.5 mg L−1; and pH: 6.8, 7.8 and 8.8). Range analysis showed that the maximum survival of juvenile crayfish occurred at photoperiods of 16L:8D or 8L:16D, water calcium concentration of 45.5 mg L−1 and pH of 7.8; maximum weight gain at photoperiod 16L:8D, water calcium concentration 65.5 mg L−1 and pH 7.8; maximum length increase at photoperiod 16L:8D, water calcium concentration 65.5 mg L−1 and pH 7.8; and the highest moult frequency at photoperiod 12L:12D, water calcium concentration 65.5 mg L−1 and pH 7.8. Analysis of variance indicated that photoperiod, water calcium concentration and pH significantly influenced only the weight gain of juvenile crayfish (P<0.05). Taking growth into consideration, we suggest that a photoperiod of 16L:8D, calcium concentration of 65.5 mg L−1 and pH 7.8 might be optimal conditions for rearing juvenile P. clarkii.

The model anti-androgen flutamide suppresses the expression of typical male stickleback reproductive behaviour

Over the past 15 years considerable attention has been given to the presence in the environment of endocrine disrupting chemicals (EDCs) that may have harmful effects on organisms. Specific test guidelines for the detection of EDCs used for short-term fish screening assays have been developed by the Organisation for Economic Cooperation and Development (OECD). Compared to the core species used in the OECD guidelines, the three-spined stickleback ( Gasterosteus aculeatus) has an additional and unique endpoint for (anti-)androgenic substances through the androgen-dependent glue protein (spiggin) used in the nest building. Here we describe a specific behavioural assay that was developed in parallel to the OECD protocol, utilising unique behavioural features of sticklebacks. In the assay, a photoperiod of 16L:8D (light:dark) and a temperature of 17 ± 1 °C was used to induce breeding in quiescent male sticklebacks that were simultaneously exposed for a 21-day period to the mammalian anti-androgen flutamide (FL) at 100, 500 and 1000 μg/l (plus a water control). Spiggin production and the reproductive behaviour (nest building and courtship) of male sticklebacks were the main measured endpoints. The control fish entered an active breeding cycle including nest building and courtship behaviours as expected due to the stimulating temperature and photoperiodic conditions. The FL-exposed males showed significantly lower spiggin levels at 500 and 1000 μg/l. In addition, there was a significant decrease in the number of nests built by the FL-treated males at 100 μg/l with no nest built at 500 and 1000 μg/l. Finally, FL affected the courtship behaviour of the males with a significant reduction of the number of zigzags towards the female. When the breeding status of the stickleback males is controlled, the behavioural assay developed here is a suitable tool for the detection of androgen antagonists.

The role of temperature and photoperiod in diapause induction in the brassica leaf beetle, Phaedon brassicae (Coleoptera: Chrysomelidae)

The brassica leaf beetle, Phaedon brassicae Baly (Coleoptera: Chrysomelidae), one of the pests infesting cruciferous vegetables in China and Japan, is a multivoltine species that oversummers and overwinters as an adult. The effects of both temperature and photoperiod on reproductive diapause induction were systematically investigated in this beetle. Under 16L : 8D, most of the beetles entered reproductive diapause at 12-30°C, indicating that photoperiod played a crucial role in estivation diapause induction. Under 12L : 12D, all adults developed without diapause at 28 and 30°C; less than 25% of the individuals entered reproductive diapause at 16-24°C; however, 46.1% of the individuals entered diapause at 12°C, suggesting that low temperature also had a relatively important influence on the determination of diapause. The photoperiodic response curves indicate that this species is a typical short-day species. The critical day-lengths at 20, 24 and 28°C were 13.2, 13.6 and 13.8 h, respectively. Transferring them from 16L : 8D to 12L : 12D or vice versa at different ages and/or stages during their development revealed that the photoperiod experienced by adults during the first 11 days might be important for diapause determination, even though an effect of photoperiod on the larval and pupal stages can not be excluded. Transferring individuals kept at a photoperiod of 12L : 12D from 25°C to 12°C or vice versa at different ages and/or stages during their development revealed that the temperature cue for diapause is mainly perceived by the late instar larvae and pupae.

보리두갈래진딧물 [Schizaphis graminum (Rondani)]의 온도발육과 발육모형

The development of Schizaphis graminum (Rondani) was studied at various constant temperatures ranging from 15 to , with RH, and a photoperiod of 16L:8D. Mortality of the stage nymphs were similar at most temperature ranges while at high temperature of , more stage individuals died. The total developmental time ranged from 13.8 days at to 4.9 days at suggesting that the higher the temperature, the faster the development. However, at higher end temperature of the development took 6.4 days. The lower developmental threshold temperature and effective accumulative temperatures for the total immature stage were and 105.9 day-degrees, respectively and the nonlinear shape of temperature related development was well described by the modified Sharpe and DeMichele model. The normalized cumulative frequency distributions of developmental period for each life stage were fitted to the three-parameter Weibull function. The attendance of shortened developmental times was apparent with nymph, and total nymph stages in descending order. The coefficient of determination ranged between 0.80 and 0.87.

벼 시골가시허리노린재, 우리가시허리노린재의 온도별 발육 및 산란반응

휴경지 인근 벼에 발생하여 반점미를 유발하는 등 미질에 영향을 주는 시골가시허리노린재와 우리가시허리노린재의 생물학적 특성을 구명하였다. 시골가시허리노린재와 우리가시허리노린재 알의 부화율은 20, 25 및 <TEX>$30^{\circ}C$</TEX>에서 각각 80.6/88.0, 91.7/96.3 및 96.4/96.2%이며, 평균발육기간은 각각 16.4/18.4, 9.4/10.2 및 6.4/7.3일이었다. 약충의 발육기간은 <TEX>$30^{\circ}C$</TEX>에서 1령, 2령, 3령, 4령 및 5령이 각각 평균 2.1/2.0, 3.5/4.0, 3.3/5.6, 3.2/4.8 및 5.8/6.9일이었으며, 시골가시허리노린재가 우리가시허리노린재에 비하여 약충의 발육기간이 짧았다 시골가시허리노린재의 산란전기간은 <TEX>$25^{\circ}C$</TEX>에서 8.1일, 성충수명은 암컷이 120.0일, 수컷이 117.3일로 약 4개월 정도였고, 암컷이 수컷에 비하여 수명이 약간 길었다. 성충 한 마리의 총 산란수는 245.5개였고, 일일 산란수는 평균 2.2개였다. 시골가시허리노린재는 산란기간 중 여러 번 교미하며, 교미한 후 90일이 경과한 뒤 산란된 알의 부화율은 수컷과 같이 넣어둔 경우에는 92.1%였으나, 30일 동안 수컷을 넣어주지 않은 경우에는 9.6%로 낮게 나타났다. 또한 두 종의 형태적 특징을 현미경하에서 관찰하여 기술하였다. The two species of rice bugs causing pecky rice, Cletus punctiger and Cletus schmidti are often observed coexisting in the rice fields of nearby fallow land. Direct feeding damage to rice by C. punctiger and C. schmidti can lead to a reduction in grain quality and quantity. These studies were carried out to investigate the development of C. punctiger and C. schmidti at various constant temperatures ranging from 20 to <TEX>$30^{\circ}C$</TEX>, 65% RH, and a photoperiod of 16L:8D. Egg hatchability of C. punctiger/C. schmidti at the temperatures of 20, 25 and <TEX>$30^{\circ}C$</TEX> were 80.6/88.0, 91.7/96.3, 96.4/96.2%, respectively. The development periods of eggs of C. punctiger/C. schmidti at the temperatures of 20, 25, and <TEX>$30^{\circ}C$</TEX> were 16.4/18.4, 9.4/10.2 and 6.4/7.3 days, respectively. Mean developmental periods of 1 st, 2nd, 3rd, 4th and 5th nymphs of C. punctiger/c. schmidti at <TEX>$30^{\circ}C$</TEX> were 2.1/2.0, 3.5/4.0, 3.3/5.6, 3.2/4.8 and 5.8/6.9 days, respectively. Oviposition began 8.1 days after emergence at <TEX>$25^{\circ}C$</TEX>, and the longevity of female and male were 120.0 and 117.3 days, respectively. Total number of eggs through the life of female were 245.5 laying 2.2 eggs a day in average at <TEX>$25^{\circ}C$</TEX>. The development periods of egg and nymphs of C. punctiger were relatively shorter than those of C. schmidti. Availability of male had affected the egg hatchability greatly that laid at 30th day after 60 days period of oviposition in the presence of adult male of C. punctiger. The fertile eggs laid by the female together with male was 92.1% but those without male was only 9.6%.

보리를 기주로 한 보리두갈래진딧물[Schizaphis graminum (Rondani)]의 생명표

To construct a life table and development model Schizaphis graminum (Rondani), its adult longevity and fecundity were studied at various constant temperatures ranging from 15 to , with RH, and a photoperiod of 16L:8D. Adult longevity of the greenbug gradually increased with decreasing temperature below . Total fecundity was not significantly different at all temperatures except at . Daily fecundity gradually increased from . It was 3.6 at and as temperatures either went down or up, it decreased to 1.4 at and 0.4 at Net reproduction rate (Ro) was highest with 47.6 at . The intrinsic rate of increase per day and the finite rate of increase per day were highest with 0.4 and 1.5 at , respectively and the doubling time (Dt) was shortest with 0.98 at . The mean generation time (T) was 8.41 at

Controle biológico de Culex (Culex) saltanensis Dyar, (Diptera, Culicidae) através de Bacillus thuringiensis israelensis em condições de laboratório e campo

Culex ( Culex ) saltanensis Dyar, 1928 can become a problem in urban centers because they reproduce abundantly in ponds organically enriched. It is vector of the Plasmodium spp. and Crithidia ricadoi Sibajev et al. 1993. This research verifies the efficacy of Bacillus thuringiensis israelensis on C. saltanensis in two temperature situations, both in laboratory and field conditions. LC 50 for C. saltanensis immatures fourth instar, was 0.154 ppm and the LC 95 was 0.248 ppm an average temperature of 25.7oC. When exposed at a constant temperature of 12±1oC and a photoperiod of 14L:10D, had its susceptibity decreased in 1.50 times in reation to LC 50 , when compared to room temperature. B. thuringiensis israelensis is highly efficient in the control of this mosquito in natural environment with a high level of polluants using the concentration of 2 liters/hectare, with applications every 15 days.

Biological control of Culex (Culex) saltanensis Dyar, (Diptera, Culicidae) through Bacillus thuringiensis israelensis in laboratory and field conditions

Culex (Culex) saltanensis Dyar, 1928 can become a problem in urban centers because they reproduce abundantly in ponds organically enriched. It is vector of the Plasmodium spp. and Crithidia ricadoi Sibajev et al. 1993. This research verifies the efficacy of Bacillus thuringiensis israelensis on C. saltanensis in two temperature situations, both in laboratory and field conditions. LC50 for C. saltanensis immatures fourth instar, was 0.154 ppm and the LC95 was 0.248 ppm an average temperature of 25.7ºC. When exposed at a constant temperature of 12±1ºC and a photoperiod of 14L:10D, had its susceptibity decreased in 1.50 times in reation to LC50, when compared to room temperature. B. thuringiensis israelensis is highly efficient in the control of this mosquito in natural environment with a high level of polluants using the concentration of 2 liters/hectare, with applications every 15 days.

Morphometry of eggs and immatures of Culex (Culex) saltanensis Dyar (Diptera, Culicidae) obtained in the laboratory and on the field

The objectives of this morphometric study of Culex (Culex) saltanensis Dyar, 1928 larvae were to observe the continuous growth of siphon and cephalic capsule length and width in each instar, and to propose a linear equation to differentiate instars according to the size of both structures. Larvae obtained in laboratory at 27 ± 1ºC, photoperiod 14L:12D were studied. Larvae of the forth instar were collected on the field and compared with same instar larvae reared in the laboratory. Egg size and pigmentation pattern, first instar continuous growth, and differentiation of larval stages measurements were studied. Egg pigmentation patterns and the shapes of raft eggs differentiated specimens of C. saltanensis from Culex (Culex) quinquefasciatus Say, 1823 found in polluted pond water.