Reproductive Activity of Socorro Island Merino Ewes and Their Crosses with Pelibuey under Heat Stress Conditions.

An experiment was carried out to evaluate the effect of spring and autumn seasons on the reproductive activity of Merino Socorro Island ewes and their crosses with Pelibuey under heat stress (HS) conditions in the tropics. All ewes (n = 80) were randomly assigned to one of two breeds during the first and second periods, respectively: (1) Twenty Socorro Island Merino ewes (SIM) and (2) 20 Pelibuey Crossbred ewes (PBC). Animals were fed the same diet and given water ad libitum. All statistical analyses were performed using SAS statistical software 9.12 procedures. In both seasons, a mean of more than 80 U of maximum THI was obtained, while in spring and autumn, the minimum THI exceeded 30 and 40 U, respectively. All animals were in oestrus and ovulated in both seasons. The frequency of animals in spring during the first 48 h of oestrus expression was greater (p < 0.05) than 48-55 h but similar (p > 0.05) than 55-65 h; in autumn during the first 48 h and 48-55 h were similar (p > 0.05), but different (p < 0.05) than 55-65 h. The duration of oestrus expression was longer in the spring than in the autumn (p < 0.05). The frequency of animals was higher (p < 0.05) in SIM than in PBC ewes during the first oestrus cycle (1-17 d) and was also higher (p < 0.05) in PBC than in SIM ewes during the second oestrus cycle (18-35 d). The SIM ewes produced more (p < 0.05) progesterone (P4) than the PBC ewes. During the sampling days of the oestrus cycle, more P4 was created in autumn than in spring (p < 0.05). Both breeds showed severe HS. In the future, ewes treated under assisted reproductive programs in the tropics may improve reproductive efficiency.

Effect of Metarhizium anisopliae (Ascomycete), Cypermethrin, and D-Limonene, Alone and Combined, on Larval Mortality of Rhipicephalus sanguineus (Acari: Ixodidae).

The effect of the fungus Metarhizium anisopliae Ma14 strain, D-limonene, and cypermethrin, alone and combined, on the mortality of Rhipicephalus sanguineus Latreille larvae was evaluated. Eight separate groups with 25 tick larvae were inoculated with the fungus, cypermethrin, and D-limonene, and four groups were used as untreated controls. The groups were inoculated with serial dilutions of each treatment material: for example, conidial concentrations were 1 × 101, 1 × 102, 1 × 103, 1 × 104, 1 × 105, 1 × 106, 1 × 107, and 1 × 108. A complete randomized experimental design was used. Significant differences were obtained between fungal concentrations, with larval mortalities ranging from 29 to 100%; the D-limonene concentrations showed significant differences, with mortalities that ranged from 47.9 to 82.6%, and cypermethrin mortalities ranged from 69.9 to 89.9% when each was applied alone. In the combined application, the serial dilution of the Ma14 fungus plus cypermethrin at 0.1% concentration caused mortalities ranging from 92.9 to 100%; the mix of serially diluted Ma14 plus D-limonene at 0.1% caused mortalities from 10.3 to 100%; and the mix consisting of serially diluted D-limonene plus cypermethrin at 0.1% caused mortalities from 7.4 to 35.9%. Further laboratory and field research could show that these materials, alone and in combinations, are useful in future tick management and control programs.

Neumonía lipídica endógena en tlacuaches (Didelphis virginiana) capturados en el estado de Colima, México / Endogenous lipid pneumonia in opossum (Didelphis virginiana) captured in the state of Colima, Mexico

Endogenous lipid pneumonia was found in 11 out of 15 (73.3%) opossums (Didelphis virginiana) captured in six municipalities from the state of Colima, Mexico. Macroscopically, multifocal yellow white subpleural plaques were found in the dorsocaudal region of both lungs. These lesions were extended to the pulmonary parenchyma. Microscopically, they were characterized by aggregates of macrophages in the alveolar walls and spaces. These macrophages had small lipid vacuoles in the cytoplasm. Also, hyperplasia of pneumocytes type II, perivascular lymphoid hyperplasia, emphysema and fibrosis were discovered. Based on these findings, endogenous lipid pneumonia was diagnosed, which seemed to be associated in 11 (73.3%) opossums with the presence of Didelphostrongylus hayesi in lungs.

Se encontró neumonía lipídica endógena en 11 (73.3%) de 15 tlacuaches (Didelphis virginiana) capturados en seis municipios del estado de Colima, México. Macroscópicamente se observaron placas subpleurales multifocales (1-5 mm) de color amarillo pálido en la región dorso caudal de ambos pulmones. Estas lesiones se extendían al parénquima pulmonar. Microscópicamente se caracterizaban por agregados de macrófagos en los espacios y paredes alveolares. Los macrófagos tenían abundantes vacuolas pequeñas lipídicas en el citoplasma. También se observó hiperplasia de neumocitos tipo II, hiperplasia linfoide perivascular, enfisema y fibrosis. Con base en estos hallazgos se diagnosticó neumonía lipídica endógena, la cual parecía estar asociada en 11 de los tlacuaches, con la presencia de Didelphostrongylus hayesi en los pulmones.