The Agrarian Economy of Oman (132-280/749-893) in Arabic Sources

Abstract

The effect of age and dietary factors of Anopheles gambiae (Diptera: Culicidae) on the infectivity of natural Plasmodium falciparum parasites was studied. Mosquitoes of various ages (1–3, 4–7 and 8–11 day old) and those fed blood (either single or double meals) and sugar meals were experimentally co-infected with P. falciparum gametocytes obtained from different naturally infected human volunteers. On day 7, midguts were examined for oocyst infection to determine whether mosquito age or diets have significant effects on parasite infectivity. The age of the mosquitoes did not significantly influence the oocyst infection rates (χ2 = 48.32, df = 40, P = 0.172) or oocyst load (# of oocysts/midgut) (P = 0.14) observed. Oocyst load between groups was not significantly different. Similarly, the type of diet (either blood or sugar) did not influence oocyst infection rates (χ2 = 16.52, df = 19, P = 0.622). However, an increase in oocyst infection rates resulted after previous feeding on double blood meals (35%) compared to single blood meals (25%), with comparable oocyst load. These observations are in agreement with those reported in previous studies suggesting that increased mosquito nutritional reserves resulting from increased dietary resources is favorable for malaria infectivity. This field-based study indicates that vector competence of An. gambiae to natural P. falciparum parasites does not vary with age and that nutritional resources acquired prior to an infectious blood meal plays a crucial role in mosquito-parasite relationships.Abbreviation:oocyst loadnumber of oocysts per midgutoocyst infection ratespercent of midguts with oocysts

Mosquito age and avian malaria infection

“…aegypti age they become more resistant to a P. gallinaceum infection. More recently, however, Okech et al [ 57 ] found no effect of age on the prevalence of Plasmodium falciparum infections in An. gambiae , although the low infection rates in these experiments (<4 % of the membrane-fed mosquitoes became infected) may have significantly reduced the statistical power of their experiments.…”

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

“…Emerging adults were fed on 5% glucose, and adults emerging on days 2–4 were pooled in an age-matched group for blood feeding. An age spread this small does not influence infection susceptibility [32]. …”

Non-Genetic Determinants of Mosquito Competence for Malaria Parasites

“…Studies on diet effects in mosquito- Plasmodium interactions have lagged behind, but a handful of findings indicate that nutrition can influence mosquito competence [28], [42]–[46]. These studies have proven difficult to reconcile however, as the competence and immune response of food-deprived larvae or adult mosquitoes was reported to be higher in some instances [28], [43], [46] but lower in others [42], [44] ( Table 1 ). It remains unclear whether these discrepancies are due to species-specific differences or to the type and degree of nutritional stress.…”

“…gambiae to melanize foreign entities was reduced in old females [64], recent findings revealed no age effect on An. gambiae competence for fungi [65] or P. falciparum [44].…”