Evidence for Semiochemical Divergence Between Sibling Bark Beetle Species: Dendroctonus brevicomis and Dendroctonus barberi.

We investigated geographic variation in the semiochemistry of major disturbance agents of western North American pine forests, Dendroctonus brevicomis Le Conte and Dendroctonus barberi Hopkins (Coleoptera: Curculionidae: Scolytinae), species separated by the Great Basin in the USA that until recently were synonymous. At 15 sites in the western USA and northern Mexico, beetle populations were examined to determine (1) pheromone production by solitary, mining females, (2) male electroantennogram amplitudes in response to known semiochemicals for the genus, or (3) relative attractiveness of two female-produced pheromone components (endo- and exo-brevicomin) and two host odors (alpha-pinene and myrcene) to beetles in the field. Compared to female beetles collected east of the Great Basin (D. barberi), western females (D. brevicomis) produced a consistently higher proportion of, and male antenna were correspondingly more sensitive to, the exo- than the endo-isomer of brevicomin. With the exception of one sampling location (where no preference was observed), beetles west of the Great Basin were more attracted to exo- than endo- brevicomin trap lures, whereas eastern beetles displayed the reverse preference. In contrast, there was not a consistent difference between these populations regarding relative attraction or olfactory response to myrcene or alpha-pinene, although some geographic variability was evident. These data show that the semiochemical systems of D. brevicomis and D. barberi have diverged and corroborate genetic and morphological evidence that they are distinct, allopatric species.

Stability of nifedipine in two oral suspensions stored at two temperatures.

OBJECTIVE: To determine the stability of nifedipine in two oral suspensions stored at 4 degrees C and 25 degrees C in plastic prescription bottles over a 3-month period. DESIGN: Two suspensions were prepared: 1% methylcellulose:simple syrup NF (1:13) stored in ten 2 oz bottles; and Ora Plus:Ora Sweet (1:1) at a nifedipine concentration of 4 mg/mL also stored in ten 2 oz bottles. Five bottles of each formulation were stored at 4 degrees C, and the rest of the bottles were stored at 25 degrees C. Three samples were collected from each bottle at 0, 7, 14, 28, 42, 56, 70, and 91 days and analyzed by a stability-indicating high-performance liquid chromatography analytic method (n = 15). SETTING: Laboratory. RESULTS: At 4 degrees C, the mean concentration of nifedipine was nearly 100% that of the original concentration in both the Ora Plus-Ora Sweet and the 1% methylcellulose-syrup formulations during the 3-month study period. At 25 degrees C, the mean +/- standard deviation concentration of nifedipine was 98.9% +/- 2.36% of the initial concentration in the Ora Plus-Ora Sweet and 97.4% +/- 2.48% in the 1% methylcellulose-syrup formulation over the 3-month period. No changes in pH or physical appearance were observed. CONCLUSION: Nifedipine can be prepared in two liquid dosage forms and stored for up to 3 months under refrigeration or at room temperature.