Effects of Photofrin II on adults of Eretmapodites quinquevittatus.

This research was conducted to further assess the efficacy of photosensitizers as adult mosquito control agents. Fourth-stage larvae of Eretmapodites quinquevittatus were fed Photofrin porfimer sodium (PII) (< or = 3.75 microg/ml) and the resulting adults (parentals) were photoirradiated. These parentals were mated with untreated controls and resulting 1st generation (F1) progeny were inbred. Comparisons of fecundity and fertility were made between parentals and resulting F1 progeny. Interbred F1 adults survived significantly longer than parentals (P > 0.05). Parental females laid fewer eggs than F1 females, and parental eggs hatched at a significantly lower rate than eggs of F1 females (P < 0.01). Neither PII nor any effects of PII seem to be transferred from parent to offspring. Reduced fecundity and fertility may be due to reduced energy levels caused by exposure to PII. Experimental adults fed PII exhibited significantly reduced survivorship when compared to untreated controls (P < 0.001). Fertility did not differ when compared to controls, but experimental adult fecundity was significantly less than control fecundity for the constant photoirradiation group.

Site of Photofrin II photosensitization in larvae of Eretmapodites quinquevittatus Theobald.

Photofrin II (PII) accumulates and fluoresces in the alimentary canal, anal papillae, malpighian tubules, rectum, and gastric caeca at greater concentrations (>10 microg/ml) and accumulates (fluoresces) in (along) the alimentary canal only at lower concentrations (< or =10 microg/ml). Initial experiments with larvae exposed to different osmotic conditions and PII indicated that cells of osmoregulation were most susceptible to life-threatening cell damage. Larvae that lacked anal papillae and were exposed to different osmotic conditions and PII indicated that cells of osmoregulation may not be the most deleterious site for cell damage. Larvae ligated around the neck and exposed to PII survived significantly longer than larvae ligated after the 4th abdominal segment and after the 6th abdominal segment while also being exposed to PII. Pupae are unaffected by PII at any concentration and they do not ingest during their development. These experiments indicate the midgut gastric epithelia could be the most deleterious site for cell damage caused by PII.

Organophosphate and pyrethroid susceptibilities of Culex salinarius adults from Texas and New Jersey.

Susceptibilities of adults from newly established colonies of Culex salinarius from New Jersey and Texas to commonly used mosquito adulticides were assessed using the insecticide-coated vial bioassay technique. Females from both colonies were similar in their susceptibilities to naled, chlorpyrifos, resmethrin, and permethrin. However, females from the New Jersey colony (established from collections made in Cape May County, NJ) were found to be 9 times more tolerant to malathion than were those from the Texas colony (established from collections made in Chambers County, TX), with median lethal concentration values for malathion tested against these 2 colonies of 0.70 and 0.08 microgram malathion/vial, respectively. The differences between these 2 colonies with respect to their tolerances to malathion may be a product of the age of each colony at the time assessments were made and/or the degree to which the parent stock used to start each colony was previously exposed to malathion in the field.

Photosensitization of Eretmapodites quinquevittatus Theobald (Diptera: Culicidae) eggs and larvae with Photofrin II.

The susceptibility of Eretmapodites quinquevittatus eggs and larvae to photosensitization with Photofrin II (PII) was determined. Hatching rates of eggs (5 min to 2 h after oviposition with no PII exposure) exposed to solutions of PII (90 micrograms/ml) in the dark for 12 h, before photoirradiation for 72 h. were very similar to those of untreated controls (P > 0.05). Hatching rates of eggs (5 min after oviposition with no PII exposure) exposed to PII (90 micrograms/ml) and photoirradiated simultaneously for 72 h were significantly lower than for untreated controls (P < 0.05). Permeability of the egg to PII diminishes as the eggs age and the serosal cuticle becomes mature. Eretmapodites quinquevittatus larvae were killed after exposure to PII (90 micrograms/ml) that had been previously photoirradiated for 1-11 days. The effect was age and size related. First-instar to early 3rd-instar larvae were killed when exposed to PII (90 micrograms/ml) with no photoirradiation.

Fecundity, fertility, and developmental stage survivorship of Eretmapodites quinquevittatus.

This laboratory study analyzed fecundity, fertility (percentage hatched), and developmental stage survivorship of Eretmapodites quinquevittatus. Fecundity for females averaged 190.4 eggs, whereas paired (one male/female pair) females averaged 100.5 eggs. Fertility for autogenous eggs from paired females was 84.4%, which was significantly greater than percentage hatched of anautogenous eggs (67.3%). Percentage hatched of autogenous eggs from experimental groups (25 males/25 females) was 87.8%, whereas percentage hatched of anautogenous eggs was 74.5%. Developmental stage survivorship was significantly different for every stage of development of progeny from autogenous eggs, except the egg stage, when comparing experimental groups with pairs. Developmental stage survivorship of progeny from anautogenous eggs was significantly different only at the egg stage and 1st instar when comparing experimental groups and pairs.

Differences in male mating response and female flight sounds in Aedes aegypti and Ae. albopictus (Diptera: Culicidae).

Aedes aegypti (L.) and Ae. albopictus (Skuse) showed similar rates and timing of insemination in the laboratory. Laboratory attempts at interspecific mating were unsuccessful. Because Ae. aegypti males are known to locate females by flight sounds, male response to sound was compared in the two species. Ae. aegypti males responded to female flight sounds with stereotypical orientation and mating behavior, whereas Ae. albopictus males seldom responded. Recorded flight sounds of females were sampled via computer digitization and compared. Ae. aegypti females produced louder sounds with more harmonics than Ae. albopictus. Males were tested for their ability to discriminate between the sounds of the two species. Ae. albopictus males did not respond to recordings of either Ae. albopictus or Ae. aegypti females. Ae. aegypti males responded preferentially to the recorded sounds of Ae. aegypti females. Thus, males of the two species use different mechanisms in locating mates. Ae. aegypti males rely more on sound than do Ae. albopictus males.

A model for polygenic inheritance of abdominal tergal scale pattern in Aedes aegypti.

There is much variation in the amount of white scaling on the abdominal tergites of Aedes aegypti. The genetic basis for this white scale pattern was investigated in two laboratory strains established by selection from the CARN Strain of Ae. aegypti. These experimental strains were crossed in all possible directions in single pair matings. Based on analysis of their progeny it is proposed that genes at three separate independently assorting loci control abdominal tergal scale pattern. Correlation of observed data and expected data was high. Since the abdominal tergal scale pattern in Ae. aegypti appears to be controlled by one major polygenic system with modifiers, it is proposed that it is better to consider differences in ethology, physiology, and reproductive behavior as the bases for separation of the species into intraspecific groups.

Hybridization between Aedes simpsoni and Aedes woodi with observations on the genetic basis of morphological differences.

The public health importance of the genus Aedes makes it imperative that a better understanding of the genetic differences and isolating barriers between the species be developed. Aedes simpsoni and Aedes woodi from near Dar es Salaam, Tanzania, were used in this investigation. Analysis of F(1), F(2), and backcross progeny obtained from forced matings indicates that single factors form the genetic basis of some of the differences between the two species. There is evidence that Ae. simpsoni and Ae. woodi are separated by both premating and postmating reproductive isolating mechanisms.