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The effects of 2 growth regulators, diflubenzuron (DFB) and OMS 2017, on the ability of females Aedes aegypti to become infected with Molinema dessetae was studied under laboratory conditions. OMS 2017 and DFB had no effect on either the amount of blood ingested or the microfilarial load. The infective potential of females that survived DFB treatment was significantly greater than untreated females, but there was no difference between OMS 2017-treated and control females. The percentage of infective larvae in the head after OMS 2017 and DFB treatments was significantly greater than for control females. Insect growth regulators appear to affect the vectorial competence of mosquitoes, and these results indicate the need for preliminary studies before these compounds are used in large-scale control programs.

Lactate dehydrogenase (Ldh) electrophoresis showed the presence of Plasmodium yoelii yoelii in Anopheles stephensi and An. gambiae. The Ldh appeared as an additional band (pLdh) whose activity was more intense with 3-acetyl pyridine adenine dinucleotide as coenzyme than with beta nicotin-amide adenine dinucleotide. Several allelic forms occurred both in the vector and the host. The isoelectric point of Ldh, similar in the vector and host, differed from those of Ldh from mosquito and mouse. The presence of pLdh was detected from the 2nd to the 28th day of infection. The pLdh appeared to be proportional to the number of sporozoites present in infected salivary glands. However, pLdh was not found in salivary glands or midguts, but it was detected in the rest of the corresponding mosquito. The origin and use of pLdh as a marker of Plasmodium in its vector is discussed.

Diflubenzuron and OMS 2017 are insect growth regulators that affect larval to adult development in Aedes aegypti (L.) by altering ecdysis. When larvae were exposed to sublethal concentrations, surviving adults express reduced reproductive potential. In mosquitoes, ecdysteroids are important in larval and adult ovarian development. We applied 30% emergence reduction concentrations (EI30) of OMS 2017 and diflubenzuron to 4th-instar Ae. aegypti to determine if changes in ecdysteroid production may explain these physiological effects. Ecdysteroid concentrations were measured in the larvae, pupae, and adults after treatment with both IGRs. After treatment with OMS 2017, the 1st peak of ecdysteroid production in larvae was totally inhibited, but after pupation, ecdysteroid concentrations were the same as in untreated controls. In diflubenzuron-treated larvae, the second peak of production was delayed and the ecdysteroid concentrations of the larvae, pupae, and adults were depressed slightly when compared with untreated controls. The production of ecdysteroids by the ovaries was not altered by sublethal larval treatment with both IGRs. Although OMS 2017 and diflubenzuron belong to the same chemical family, their mode of action apparently is different.

The electrophoretic analysis of five natural populations of Aedes detritus has shown that the two sibling species A and B of the complex, described in 1977 in an other geographical area by Pasteur et al., cohabit on Atlantic coastline in France.

The effects of 2 benzoylphenylurea insect growth regulators, OMS 2017 and diflubenzuron, on 4th instar larvae of Aedes aegypti were investigated in the laboratory. Apart from delayed lethal action, possible effects on the reproductive potential were also studied. A baseline concentration of each compound causing 30% emergence inhibition was determined. At this concentration, OMS 2017 affected fecundity of the mosquito but diflubenzuron did not. The fertility of females that survived OMS 2017 exposure also was decreased; 23% of the eggs reached the 4th larval instar. Diflubenzuron did not cause any reduction in fertility. The basal follicle number showed great variability after both treatments as it was alternatively equal, lower, or higher than in the control.

In vitro tests, deltamethrin reduced the parasitemic index of Plasmodium falciparum on human red blood corpuscles. In vivo tests, at sublethal doses, deltamethrin limited the development of the sporogonic cycle of Plasmodium yoelii yoelii in Anopheles stephensi. This novel type of antiplasmodic activity involve an intravectorial route and gives an explanation about surprising antimalaria effects observed several months after treatment.