Reproduction of Omalonyx matheroni (Gastropoda: Succineidae) under laboratory conditions

The life histories of succineids have received relatively little attention. To evaluate life history characteristics of Omalonyx matheroni, we studied a Brazilian population (Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala, in Caratinga, Minas Gerais, Brazil) under laboratory conditions. The aims of the present study were (1) to describe in detail an appropriate rearing method; (2) to investigate the effects of different temperature and photoperiod conditions; and (3) to assess the effects of self and cross-fertilization on the reproductive biology of these mollusks. We studied the oviposition site, the time to sexual maturity and the influences of photoperiod and temperature on reproductive parameters of O. matheroni reared under laboratory conditions. We tested three combinations of temperature and photoperiod, designated A, B and C (A: 25ºC, 24 hours of light; B: environmental conditions of temperature and photoperiod, characterized as follows: average máximum temperature=27.1ºC, average minimum temperature=18.3ºC, average day length=12.06 hours; and C: 25ºC, zero hours of light) and two rearing densities (I: isolated and G: grouped) on reproductive parameters (number of eggs per egg mass, number of unviable eggs per mass, egg mass incubation period, and duration of the hatching period). A total of 186 individuals and 565 egg masses were studied. Data were analyzed by Student’s t-test, two-way ANOVA and Chi-Square test. Eight generations were produced (March/2004-March/2006), from 35 field specimens, 91% of 3 197 eggs hatched. The time to sexual maturity was approximately three months for individuals reared in groups or in isolation (Student’s t-test: t=1.41, df=31, p=0.16); however, they differed significantly in weight (Student’s t-test: t=3.6, df=31, p<0.001). Regarding the influences of temperatura and photoperiod on reproductive parameters, under natural environmental conditions, individuals produced a greater number of eggs per mass (ANOVA: F2,573=84.15, p<0.001), with a longer incubation period (ANOVA: F2;559=170.05, p<0.001). The extreme photoperiod conditions of 24 hours of light or zero hours of light likely imposed stress and could be related to the significant reductions in the number of eggs per mass, and egg incubation period as well as the increased synchrony in egg hatching. No correlations were observed between the number of unviable eggs per mass and the temperature, photoperiod (ANOVA: F2,573=0.87, p=0.92) or rearing density (ANOVA: F1,573=0.21, p=0.64). Individuals reared in isolation under natural conditions produced more eggs per mass and did not presented any disadvantage with respect to the variables analyzed as compared to the animals reared in groups. These results indicate that O. matheroni can successfully reproduce by selfing. Rev. Biol. Trop. 60 (2): 553-566. Epub 2012 June 01.

How to increase the population of a Phlebotomus perniciosus (Diptera: Psychodidae) colony: a new method

The sandfly Phlebotomus perniciosus is the most widespread vector of Leishmania infantum in Spain. Laboratory colonisation represents the most feasible source of information on the biology of these insects, but in conducting any study, the density of individuals in the colony may drop to such an extent that it is sometimes difficult to recover the initial population levels. A new technique was tested for the recovery of sandfly eggs in three different colonies; the recovery rate was studied by comparing the standard method of mass rearing with this new method of colony management. The results demonstrate a mean increase of 18.4 percent in adult production, a growth in colony productivity that justifies the inclusion of this process in the routine maintenance of any colony of sandflies.

Embrytoxic effects of 2-methoxyethanol in albino rats

2-Methoxyethanol [2-M.E.] is an alkyl derivative of ethyleneglycol. It is used widely as a solvent in many industrial and domestic products as industrial coating, liquid soap, fingernail polish and an antifreeze additive in hydraulic fluids and jet fuel. So, the present study was conducted on mature female rats to assess the embryotoxic effects of 2-M.E. Sixty mature pregnant rats were randomly divided into six groups each often rats. The first group was used as a control. The second, third and fourth groups were given 250, 500 and 1000 mg/kg of 2-M.E, applied topically on the skin from the 6 th to 15 th day of pregnancy. The fifth group was given 1000 mg/kg 2-M.E. applied topically on the skin from the day 10 th to 12 th day [3 repeated doses]. The sixth group was given 2000 mg/kg 2-M.E applied topically on the skin in the 12 th day of gestation as a single dose. All foeti of the treated dams were subjected to morphological, skeletal and histopathological study. The study revealed a significant decrease in foetal body weight and crown-rump length of all treated groups as compared to control group. As regard to the reproductive outcome of the present study, there was a significant increase of resorped foeti per litter, which reached the maximal degree of resorption in-group IV [1000 mg/kg as a repeated dose from the 6th to 15 th day of gestation]. The present study revealed a significant increase in congenital malformation as absence of anterior abdominal wall, skull defects, exencephaly and kinked tail in-group III that received 500 mg/kg as compared to control and other treated groups. Subcutaneous haemorrhage was observed in groups II, III and VI. Also, limb hyperflexion was obvious in groups V. VI and II. However, protruded tongue was found in groups II and III only. Skeletal abnormalities detected in this study included polydactly, brachydactly, incomplete ossification of all body bone with skull defect, decrease number of ribs and decrease number of bones of sternum. The present study demonstrated histopathological changes in both liver and kidney in the form of marked dilatation of blood vessels, degeneration and necrosis of some cells with marked congestion between the cells. Finally this study concluded that 2-M.E has high dermal absorption with a wide variety of embryotoxicity. Also, the morphological, reproductive variables and skeletal abnormalities as well as the histopathological changes induced by 2-M.E vary according to the dose, duration of exposure and the period of organogenesis. Women in reproductive age ought to be restricted from working areas of 2-M.E. exposure to avoid its embryotoxic effect

Morfometría, patrones de crecimiento y ganancia de peso de venados cola blanca (Odocoileus virginianus) en cautiverio en Durango y Toluca, México / Morphometrics, growth and weight gain patterns in White-Tailed deer (Odocoileus virginianus) in captivity in Mexico

Las tasas de crecimiento, ganancias diarias de peso y medidas corporales fueron estudiadas en venados cola blanca (O. virginianus) (n = 35) en Durango y Toluca, México, de 1989 a 1994. Los cervatillos pesaron al nacer 2.3 kg en promedio (ee = 0.873, n = 14), tienen una ganancia de peso promedio de 225.5 g/día (ee = 25.7, n = 4) y de 107.0 g/día (ee = 38.4, n = 7), el promedio de días de lactancia fue de 112.2 y 88.5 días y el peso promedio al destete fue de 14.5 y 12.6 kg para cervatillos en lactancia natural y artificial, respectivamente. Se notifican las medidas corporales tomadas semanalmente, desde el nacimiento al destete; los largos total del cuerpo, de las patas traseras, de las patas delanteras y de las orejas de cervatillos en lactancia artificial. Los machos adultos (n = 10) continúan su crecimiento hasta después de los cinco años de edad y las hembras (n = 11) estabilizan su peso al tercer año de edad. Se discuten los efectos de la dieta, productividad primaria del hábitat y variaciones entre subespecies como factores reguladores del crecimiento. Los patrones de crecimiento de esta especie en México son similares a lo descrito en Estados Unidos de América y Canadá, para la familia Cervidae y para otros ungulados silvestres y domésticos de climas templados

Condiçöes de sobrevivência em laboratório de Haemagogus janthinomys dyar, 1921 (Diptera: Culicidae) / Laboratory survival conditions of Haemagogus janthinomys dyar, 1921 (Diptera: Culicidae)

A little modification was made on the classical Borel tube, used for rearing isolated females of mosquitoes. The first studies were realized with the main Yellow fever vector, Haemagogus janthinomys, in Brazil. The results are: a better survival, as far as 72 days, a greater number of eggs, up to 80, and a shorter trophogonic cycle of 7-8 days. So, one can imagine more easily further studies about the vertical transmission of the YF virus by this important neo-tropical mosquito.