Mark-recapture estimates of recruitment, survivorship and population growth rate for the screwworm fly, Cochliomyia hominivorax.

Pradel model mark-release-recapture estimates of survivorship, phi, recruitment, f, and the rate of density-independent population growth, lambda, are presented for eight mark-recapture studies of the screwworm Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) from Costa Rica, totalling 19 573 released and 4476 recaptured flies. Corroborative estimates of survivorship and the rate of population growth based on an extensive review of the literature are also reported. Weighted-mean +/- standard error of the mean (SEM) mark-release-recapture estimates of survivorship, recruitment and the rate of population growth were phi = 0.798 +/- 0.008, f = 0.193 +/- 0.008 and lambda = 1.005 +/- 0.002, respectively. Population doubling time was estimated from lambda at 139 days. Estimates of phi and lambda from the literature both exceeded those calculated by mark-recapture methods and estimates of population doubling times were consequently shorter.

A survey of diagnostic practices and the use of epoprostenol in patients with primary pulmonary hypertension.

STUDY OBJECTIVE: To obtain information about the diagnosis and management of primary pulmonary hypertension (PPH), especially about the use of epoprostenol (Glaxo-Wellcome; Research Triangle Park, NC) in this patient population. BACKGROUND: Long-term IV epoprostenol therapy was approved recently for use in patients with PPH who are unresponsive to conventional therapy. Although epoprostenol represents a major advance in the treatment of PPH, there is no published consensus regarding the optimal use of this therapy. METHODS: A five-page survey was mailed to 23 investigators at medical centers treating five or more patients with PPH with long-term epoprostenol therapy. RESULTS: Nineteen of 23 investigators responded to the survey. During the initial hemodynamic evaluation, 11 investigators used changes in pulmonary vascular resistance (PVR), pulmonary artery pressure (PAP), and cardiac output, 5 investigators considered PVR and PAP only, and 2 investigators analyzed PVR alone to define a short-term vasodilator response. During long-term therapy, two thirds of the investigators increased the dose at scheduled intervals, while all investigators increased the dose in response to worsening symptoms. Epoprostenol doses were reported to range from 0.5 to 270 ng/kg/min. Nine investigators routinely repeated right heart catheterization an average of 7.5+/-3.8 months after starting epoprostenol, and the mean decrease in pulmonary artery pressure was between 15 and 25%. CONCLUSION: This survey indicates that there is wide variation in the evaluation of patients with PPH and in the use of epoprostenol therapy. The lack of consensus suggests the need for multicenter collaborative studies in order to optimize the use of epoprostenol therapy for PPH.

Influence of habitat, season, and attractant on adult behavior of the screwworm (Diptera: Calliphoridae) in a tropical dry zone in Costa Rica.

Influence of attractant, season, habitat, temperature, and physiological state of the screwworm, Cochliomyia hominivorax (Coquerel), on daily activity and oviposition were examined during a 122 d study in a tropical dry forest in Costa Rica. Flies were marked and released. Numbers of flies visiting baits increased during the wet season and decreased during the dry season; 3 times more flies were observed at baits during the wet season than were observed during the dry season. An average of 33 females and 3 males was observed per day during the study. More flies (3.6 times) were attracted to liver than to sentinel sheep; many flies originally marked at liver failed to return and few of them oviposited on sentinel sheep. Females marked at sheep were recaptured more times and remained in the study area longer. More females marked at sheep sites were recaptured (51.4-54.1%) than those marked at liver sites (32.3-44.7). More than 6 times as many flies were observed at forest than at pasture sites. The physiological state of the female influenced daily activity. High temperatures during midday (> 31 degrees C) depressed activity and decreased the number of foraging hours available for flies during the dry season. Decreasing host resources and number of hours available for foraging may be factors that limit screwworm populations in the dry season.

Genetic relationships among three chlorophyll-deficient mutants in peanut, Arachis hypogaea L.

The genetic relationships of three chlorophyll-deficient mutant peanuts, lutescens (lu), aureus (au), and virescent (v) were studied under field and greenhouse conditions. The F1 plants from crosses between these mutants produced phenotypically normal green. In F2, aureus X virescent segregated 675 normal green : 225 virescent : 45 aureus : 15 virescent aureus : 64 seedling lethal, and lutescens X virescent segregated 45 normal green : 15 virescent : 3 lutescens : 1 seedling lethal. (Lutescens peanuts were seedling lethal in the field.) As previously reported, the F2 of aureus X lutescens gave 225 normal green : 15 aureus :15 lutescens : 1 seedling lethal. The three chlorophyll-deficient factors (au, lu, and v) show independent inheritance. The recessive combinations from the parental types between aureus and virescent and between aureus and lutescens would produce plants with a combination of their respective parental characteristics, but the recessive combination between lutescens and virescent was nearly albino. The v-au and lu-au seedlings have a longer life span than the v-lu seedling has. The genotypes for the three mutants are tentatively identified as lutescens VV Au 1 Au 1 Au 2 Au 2 lu 1 lu 1 lu 2 lu 2 L 1 L 1 L 2 L 2, aureus VV au1au1 au2au2 Lu1Lu1 Lu2Lu2 L1L1 l2l2, and virescent vv Au1Au1 Au2Au2 lu1lu1 Lu2Lu2 l1l1 L2L2.