An integrated view of entomological and parasitological observations on falciparum malaria in Gambela, Western Ethiopian Lowlands

A 14-month longitudinal malaria survey was performed among the Nilote inhabitants of Gambela, a small garrison town in Illubabor Province, Ethiopia. The results are integrated with a simultaneously performed entomological study. Monthly variation in Plasmodium falciparum prevalence was primarily a result of seasonal fluctuation in risk of sporozoite inoculation from Anopheles arabiensis (= gambiae species B), A.funestus, and A. nili. The proportion of sporozoite inoculations actually infective was estimated, assuming a constant recovery rate, by employing Macdonald's formulae. Inoculation (incidence) rates calculated from progressive increase and decrease in P. falciparum prevalence were then taken as fractions of entomologically measured ‘crude’ inoculation rates. Among children, values of 7 to 27% were obtained, the higher occurring in the first quarter of the wet season. Estimates among adults were approximately half those for children, illustrating the more competent immune state of the older age group. Using the methods of Bekessyet al. (1976), incidence and recovery were estimated on the basis of transition rates (parasite negative to positive; positive to negative) derived from a group of inhabitants examined at 28-day intervals. Incidence rates were estimated to be two-fold greater among children than adults; recovery rates were about three-fold greater among adults than children.This article is published as Krafsur, E. S., and J. C. Armstrong. "An integrated view of entomological and parasitological observations on falciparum malaria in Gambela, Western Ethiopian Lowlands." Transactions of the Royal Society of Tropical Medicine and Hygiene 72, no. 4 (1978): 348-356. doi: 10.1016/0035-9203(78)90125-6.</p

Cuticular lipid mass and desiccation rates in Glossina pallidipes : interpopulation variation

Tsetse flies, Glossina pallidipes (Diptera: Glossinidae) are said to have strong dispersal tendencies. Gene flow among these populations is estimated to be the theoretical equivalent of no more than one or two reproducing flies per generation, thereby raising the hypothesis of local regimes of natural selection. Flies were sampled from four environmentally diverse locations in Kenya to determine whether populations are homogeneous in desiccation tolerance and cuticular lipids. Cuticular hydrocarbon fractions known to act as sex pheromones do not differ among populations, thereby eliminating sexual selection as an isolating mechanism. Cuticular lipid quantities vary among populations and are not correlated with prevailing temperatures, humidities, and normalized density vegetation indices. Females demonstrate a stronger correlation than males between cuticular lipid mass and body weight. Desiccation rates also vary among populations, but are not correlated with the amounts of cuticular lipid. Chemical analysis of cuticular hydrocarbons by gas chromatography – mass spectroscopy shows that one of the four populations has more 11,15- and 11,21-dimethyl-31 hydrocarbon on females. These results are discussed in the context of population differences and estimates of gene flow.Centre of Excellence for Invasion Biolog

Cold treatment enhances low‐temperature flight performance in false codling moth, Thaumatotibia leucotreta

1 In sterile insect technique programmes, temperatures experienced by insects during rearing and handling, along with cool temperatures after release, can negatively affect performance and activity levels. Phenotypic plasticity (trait modifications caused by prior stress exposure) can offset these effects but is poorly understood in many species and traits. 2 We investigated the effects of a cold treatment (2 ∘C for 16 h) on flight performance in adult false codling moth, Thaumatotibia leucotreta. Using diverse methods, flight performance was tested using flight assays in the laboratory and in the field under varying environmental conditions. 3 The flight performance of T. leucotreta in the laboratory was affected by cold treatment (relative to a 25 ∘C control group), test temperature and their interaction. Field recapture of released moths was significantly affected by the interaction between cold treatment and environmental conditions. 4 Field recapture counts depended on the ambient temperature upon release. For example, under warmer conditions (>17 ∘C), the recapture count of cold-treated moths was lower than that of the untreated control group, whereas the recapture count of cold-treated moths at cooler temperatures was significantly higher. 5 Our results suggest a temperature-dependent interaction between acute cold exposure and flight performance in adult T. leucotreta, which may be used to enhance the efficacy of the sterile insect technique under cooler environmental conditions