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Recognition of the importance of debilitating effects of insect virus diseases is currently growing. Commonly observed effects of sublethal infection at the individual level include extended development times, reduced pupal and adult weights, and lowered fecundity. However, for the most part, sublethal infections are assumed to be present in survivors of an inoculum challenge, rather than demonstrated to be present by microscopy or molecular techniques. Invertebrate iridescent viruses are dsDNA viruses capable of causing disease with symptoms obvious to the naked eye, a "patent" infection, that is lethal. Furthermore, inapparent "covert" infections may occur that are non-lethal and which can only be detected using bioassay or molecular techniques. In this study, replication of Invertebrate iridescent virus 6 in Aedes aegypti larvae was demonstrated in the absence of patent disease. A sensitive insect bioassay (using Galleria mellonella) allowed the detection of covert infections, which were more common than patent infections. A concentration-response relationship was detected for the incidence of patent infections. Covert infections were up to 2 orders of magnitude commoner than patent infections, but the prevalence of covert infections did not appear to be related to virus inoculum concentration. Exposure of larvae to virus inoculum resulted in extended juvenile development times. A reduction in the mean and an increase in the variability of fecundity and adult progeny production was observed in females exposed to an inoculum challenge, although formal analysis was not possible. Males appeared capable of passing virus to uninfected females during the mating process. Covertly infected females were smaller and had shorter lifespans than control or virus-challenged females. A conservative estimate for the reduction in the net reproductive rate (R 0) of such insects was calculated at slightly more than 20% relative to controls.

Venezuelan equine encephalitis virus (VEEV) continues to circulate enzootically in Mexico with the potential to re-emerge and cause disease in equines and humans in North America. We infected two geographically distinct mosquito populations of eastern Psorophora columbiae form columbiae (Chiapas, Mexico and Texas, United States) and one mosquito population of western Psorophora columbiae form toltecum (California, United States) with epizootic and enzootic IE VEEV and epizootic IAB VEEV. We detected no differences between epizootic and enzootic IE viruses in their ability to infect any of the mosquito populations analyzed, which suggested that neither species selects for epizootic IE viruses. Psorophora columbiae f. columbiae (Texas) were significantly less susceptible to infection by epizootic IE than Ps. columbiae f. columbiae (Mexico). Psorophora columbiae f. toltecum populations were more susceptible than Ps. columbiae f. columbiae populations to epizootic IE and IAB viruses.

We assessed the efficacy of commercial repellents available in Yucatan against Aedes aegypti, vector of dengue, Chikungunya and Zika.Protection time was determined based on WHO/CTD/ WHOPES/IC y la NOM-032-SSA2-20I4.Products with DEET (N, N-diethyl-3-methylbenzamide) at 25% met the recommended protection. Efficacy was directly proportional to the concentration of DEET; botanicals repellents resulted no protective.Repellents with DEET provided more protection against Ae. aegypti and botanical repellents, including impregnated wristbands, provided no protection.

Background \ud Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013.\ud \ud Methods \ud Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment.\ud \ud Results \ud LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention.\ud \ud Conclusions \ud These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide.

The transmission of insect pathogens cannot be adequately described by direct linear functions of host and pathogen density due to hetero- geneity generated from behavioural or physiological traits, or from the spatial distribution of pathogen particles. Invertebrate iridescent viruses (IIVs) can cause patent and lethal infection or a covert sub-lethal infection in insects. Aedes aegypti larvae were exposed to suspensions of IIV type 6 at two densities. High larval density increased the prevalence of aggression resulting in potentially fatal wounding. 2. The overall prevalence of infection (patent þ covert) was positively influ- enced by host density and increased with exposure time in both densities. The survival time of patently infected insects was extended by & 5 days compared with non-infected insects. 3. Maximum likelihood models based on the binomial distribution were fitted to empirical results. A model incorporating heterogeneity in host susceptibility by inclusion of a pathogen-free refuge was a significantly better fit to data than an all-susceptible model, indicating that transmission is non-linear. The transmission coefficient (u) did not differ with host density whereas the faction of the popula- tion that occupied the pathogen-free refuge (PR) was significantly reduced at high host density compared with the low density treatment. 4. The transmission of free-living infective stages of an IIV in Ae. aegypti larvae is non-linear, probably because of density-related changes in the frequency of aggressive encounters between hosts. This alters host susceptibility to infection and effectively reduces the proportion of hosts that occupy the pathogen-free refuge.

The insecticidal properties of certain entomopathogenic viruses can be greatly improved in mixtures with substances that affect the integrity of the insect peritrophic membrane, particularly optical brighteners. We aimed to determine the effect of an optical brightener, Blankophor BBH, and an abrasive compound, silicon carbide, alone and in mixtures, on the prevalence of patent and covert infection of Aedes aegypti (L.) (Diptera: Culicidae) by Invertebrate iridescent virus 6 (IIV-6) (Iridoviridae). The prevalence of patent infection by IIV-6 was < 1.5% in all treatments involving virus. Contrary to predictions, there were significantly fewer patent infections in virus treatments involving Blankophor with or without silicon carbide compared with controls. Covert infection of adults detected by insect bioassay was between 6.7 and 12.2%, although no significant differences were observed between treatments. Exposure to IIV-6 alone or silicon carbide alone did not significantly increase larval mortality compared to the controls, whereas exposure to Blankophor alone, or in any combination with IIV-6 or silicon carbide, clearly increased larval mortality. These effects did not carry-over to the pupal stage. Adult females emerged ∼ 1.5 days later than males. Compared to control insects, female development rate was extended by 11.4 and 12.6% in the treatments involving IIV-6 alone and silicon carbide alone, respectively. The sex ratio at adult emergence did not differ significantly between control insects and those of other treatments. These results support the hypothesis that the gut is unlikely to represent the principal point of infection of mosquito larvae by iridescent viruses.

Sublethal viral infections can cause changes in the body size and demography of insect vectors, with important consequences for population dynamics and the probability that individual mosquitoes will transmit disease. This study examined the effects of covert (sublethal) infection by Invertebrate iridescent virus 6 (IIV-6) on the demography of female Aedes aegypti and the relationship between key life history parameters in covertly infected female insects compared with healthy ( control) insects or non-infected mosquitoes that had survived exposure to virus inoculum without becoming infected. Of the female mosquitoes that emerged following exposure to virus inoculum and were offered blood meals, 29% (43/150) proved positive for covert IIV-6 infection. The net reproductive rate ( R 0) of covertly infected females was 50% lower for infected females compared to control mosquitoes, whereas non-infected exposed females had an R 0 approximately 15% lower than that of controls. Reproduction caused a significant decrease of about 13 days in mosquito longevity compared to females that did not reproduce (P < 0.001). Infected females lived 5-8 days less than non-infected exposed females or controls, respectively (P = 0.028). Infected females and non-infected exposed females both had significantly shorter wings than control insects ( P < 0.001). There was a significant positive correlation between wing length and longevity in covertly infected female mosquitoes but not in control or non-infected exposed mosquitoes. Longer lived females produced more eggs in all treatments. There were no significant correlations between body size and fecundity or the production of offspring. There was also no correlation between fecundity and fertility, suggesting that sperm inactivation was a more likely cause of decreased fertility in older mosquitoes than sperm depletion. We conclude that covert infection by iridescent virus is likely to reduce the vectorial capacity of this mosquito.

Dengue prevention efforts rely on control of virus vectors. We investigated use of insecticide-treated screens permanently affixed to windows and doors in Mexico and found that the screens significantly reduced infestations of Aedes aegypti mosquitoes in treated houses. Our findings demonstrate the value of this method for dengue virus vector control.

Cyanobacteria associated with Anopheles albimanus Wiedemann larval habitats from southern Chiapas, Mexico, were isolated and identified from water samples and larval midguts using selective medium BG-11. Larval breeding sites were classified according to their hydrology and dominant vegetation. Cyanobacteria isolated in water samples were recorded and analyzed according to hydrological and vegetation habitat breeding types, and mosquito larval abundance. In total, 19 cyanobacteria species were isolated from water samples. Overall, the most frequently isolated cyanobacterial taxa were Phormidium sp., Oscillatoria sp., Aphanocapsa cf. littoralis, Lyngbya lutea, P. animalis, and Anabaena cf. spiroides. Cyanobacteria were especially abundant in estuaries, irrigation canals, river margins and mangrove lagoons, and more cyanobacteria were isolated from Brachiaria mutica, Ceratophyllum demersum, and Hymenachne amplexicaulis habitats. Cyanobacteria were found in habitats with low to high An. albimanus larval abundance, but Aphanocapsa cf. littoralis was associated with habitats of low larval abundance. No correlation was found between water chemistry parameters and the presence of cyanobacteria, however, water temperature (29.2-29.4 degrees C) and phosphate concentration (79.8-136.5 ppb) were associated with medium and high mosquito larvae abundance. In An. albimanus larval midguts, only six species of cyanobacteria were isolated, the majority being from the most abundant cyanobacteria in water samples.

The influence of predacious Mesocyclops longisetus Thiebaud on the selection of oviposition sites by prey Aedes aegypti (L.) was studied under laboratory and field conditions. In both cases, gravid Ae. aegypti females were significantly more attracted to ovitraps containing copepods or to ovitraps with water in which copepods were held previously than to distilled water. Monoterpene and sesquiterpene compounds including 3-carene, α-terpinene, α-copaene, α-longipinene, α-cedrene, and δ-cadinene were found in hexane extracts of copepods by gas chromatography and mass spectrometry analyses. These compounds may be responsible for attracting gravid Ae. aegypti females and may increase the number of potential prey for the copepod.

The availability of flowering plants affected the sugar feeding rates of female Aedes aegypti (L.) in 4 areas of a small city in southern Mexico. The proportion of mosquitoes containing sugar varied from 8 to 21% in 4 areas in direct relation to blooming plant abundance. Human density was similar in the 4 areas (range, 3.9-5.4 per house), whereas the number of flowering plants per house increased on the outskirts (range, 3.1-5.4 plants per house). Equal proportions of sugar positive females were nulliparous or parous, indicating similar sugar feeding at any age. In addition, nearly 60% of positive females were at the Christophers stage II, indicating a greater need for flight fuel during the early stages of egg development. We conclude that Ae. aegypti feeds frequently on nectar and that this activity is modulated by nectar availability.

Aquatic Coleoptera, Hemiptera, and Odonata associated with Anopheles albimanus Wiedemann larval habitats (defined by dominant plant vegetation) were investigated in various hydrological types along the coastal plain of southern Chiapas, Mexico. Aquatic insects were sampled by manual dragging nets, and mosquito larvae were sampled with standard dippers. Aquatic Coleoptera were the most abundant and diverse group, represented by 20 genera, followed by Hemiptera and Odonata, each with 16 genera. Aquatic insects were more abundant in permanent and temporary lagoons in Hymenachne amplexicaulis (Rudge) Nees and Lippia nodosa (L.) Michx. habitats, whereas mosquito larvae were most abundant in Ceratophyllum demersum L. and Crinum erubescens Soland. habitats, where aquatic insects were moderately abundant. Significant association in regression models with the addition of quadratic terms were found in aquatic Coleoptera and Odonata with respect to mosquito larvae. However, adjusted models that included environmental parameters proved these associations to be nonsignificant.

We compared the number of adult Aedes aegypti emerging from subsurface catch basins located in the streets against the number of pupae (as a proxy of adults emerging) from the entire container larval habitats found at residential premises within 1 ha of a neighborhood in the Mexican city of Merida during 8 days in the dry season of 2012. Aedes aegypti adults were collected from 60% of the subsurface catch basins. They produced 12 adults/day/ha (95% confidence interval [CI], 6.4 to 17.9), 5 females (95% CI, 2.1 to 7.7), and 7 males (95% CI, 3.8 to 10.7). In contrast, only 7 containers holding water were identified in 30 premises inspected, 1 bucket was positive for Ae. aegypti larvae, but no pupae-positive containers were found. No other mosquito species were found. This study revealed the importance of this type of nonresidential and subterranean aquatic habitat for Ae. aegypti adult production in this neighborhood of Merida during the dry season.

We report the collection of Aedes aegypti, Culex quinquefasciatus, Cx. interrogator, Cx. thriambus, Cx. coronator, and Cx. salinarius larvae from storm sewers within an endemic area for dengue transmission in Merida, Mexico, during the rainy season of 2011. This is the first record of the dengue vector Ae. aegypti breeding in storm sewers in the southeast of Mexico.

Background The Southern Chiapas focus of onchocerciasis in Southern Mexico represents one of the major onchocerciasis foci in Latin America. All 559 endemic communities of this focus have undergone semi-annual mass treatment with ivermectin since 1998. In 50 communities of this focus, ivermectin frequency shifted from twice to four times a year in 2003; an additional 113 communities were added to the quarterly treatment regimen in 2009 to achieve a rapid suppression of transmission. Methodology/Principal findings In-depth epidemiologic and entomologic assessments were performed in six sentinel communities (which had undergone 2 rounds of ivermectin treatment per year) and three extra-sentinel communities (which had undergone 4 rounds of ivermectin treatment per year). None of the 67,924 Simulium ochraceum s.l. collected from this focus during the dry season of 2011 were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the 95% confidence interval (95%-ULCI) of the infective rate in the vectors of 0.06/2,000 flies examined. Serological assays testing for Onchocerca volvulus exposure conducted on 4,230 children 5 years of age and under (of a total population of 10,280 in this age group) revealed that 2/4,230 individuals were exposed to O. volvulus (0.05%; one sided 95% confidence interval = 0.08%). Conclusions/Significance The in-depth epidemiological and entomological findings from the Southern Chiapas focus meet the criteria for interruption of transmission developed by the international community., Author Summary The absence of infective larvae of Onchocerca volvulus in the black fly vector of this parasite and reduction of exposure to and new infections with O. volvulus are the criteria currently used to certify focal interruption of parasite transmission. In the present study, we report entomological and epidemiological assessments in the Southern Chiapas focus of Mexico that together indicates that transmission of O. volvulus has been interrupted in this focus. None of the Simulium ochraceum s.l. vector black flies collected from sentinel and extra-sentinel communities in this focus during the 2011 transmission season was found to contain parasite DNA when tested by PCR-ELISA, suggesting vector parasite contact was nearly nonexistent. In addition, there was a minimal exposure to the parasite in children 5 years of age and under, as measured by circulating antibody to a parasite-specific antigen. The Southern Chiapas focus was the major focus in Mexico and one of the largest in Latin America, with well-documented history of active transmission prior to the commencement of Mectizan mass distribution. This study demonstrates the interruption of transmission in geographically large focus in Latin America with a historically high intensity of transmission.

Aedes albopictus, Culex corniger, Cx. restuans, and Toxorhynchites theobaldi are reported for the first time for the Mexican State of Morelos. The updated list of species reported is also presented.

All endemic communities of the Oaxaca focus of onchocerciasis in southern Mexico have been treated annually or semi-annually with ivermectin since 1994. In-depth epidemiologic assessments were performed in communities during 2007 and 2008. None of the 52,632 Simulium ochraceum s.l. collected in four sentinel communities was found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the infection rate in the vectors of 0.07/2,000. The prevalence of microfilariae (mf) in the cornea and/or anterior chamber of the eye was also zero (0 of 1,039 residents examined; 95%-UL = 0.35%). Similarly, all 1,164 individuals examined by skin biopsy were mf negative (95%-UL = 0.31%), and sera collected from 3,569 children from 25 communities did not harbor Ov16 IgG4-antibodies (95%-UL = 0.09%). These meet the criteria for absence of morbidity and parasite transmission in the Oaxaca focus. As a result mass treatments with ivermectin were halted in 2009.

The existence of sympatric populations within Anopheles albimanus Wiedemann with specific host preferences and the question of whether host selection has a genetic basis or is a learned characteristic were investigated. Progeny of wild females collected from corrals or human bait were reared in an insectary. F1 females were fed on a cow or on a human host, allowed to oviposit, and then were released in an experimental hut divided into three compartments. The side rooms occupied by two human or one calf baits were connected by a "funnel-like" cone with the central room in which mosquitoes were released. Females were released at 2000 hours and recaptured the next morning at 0600 hours. A fixed proportion of mosquitoes selected either host (approximately 65% cow and 35% human), irrespective of their parental origin or source of the first blood meal. The data indicate that the existence of cryptic populations with anthropophilic habits is unlikely and that a "learned" host selection also may be ruled out.

We studied the efficacy of space ultra-low volume treatments of 3 insecticides for the control of the dengue virus vector Aedes aegypti in southern Mexico. Insecticides tested were permethrin (Aqua-Reslin® Super), d-phenothrin (Anvil®), and cyfluthrin (Solfac®), applied at rates of 10.87, 7.68, and 2 g/ha, respectively, by using London Fog®, HP910-PHXL®, or Micro-Gen® pumps mounted on vehicles. Studies included 1) open field penetration tests and 2) house penetration tests. Open field tests indicated that Anvil and Solfac were more effective than Aqua-Reslin Super. In house tests, Anvil yielded the highest mosquito mortalities (≥ 88%) of the three insecticides in the front porch, living room, bedroom, and backyard. Therefore, Anvil proved to be better than other insecticides evaluated to control Ae. aegypti in Chiapas, Mexico.

A method has been developed for estimating the sample sizes needed to identify categories that comprise a large proportion of a compositional data-set. The method is to be used in the design of surveys of mosquito pupae, for identifying the key container types from which the majority of adult dengue vectors emerge. Although a finite-population correction was devised for estimating the mean of a negative binomial distribution, other complications of parametric approaches make them unlikely to yield methods simple enough to be practically applicable. The Shannon-Wiener index was therefore investigated as a more useful alternative, at the cost of theoretical generalizability, in an approach based on re-sampling methods in conjunction with the use of entropy. This index can be used to summarize the degree to which pupae are either concentrated in a few container types, or dispersed among many. An empirical relationship between the index and the repeatability of surveys of differing sample sizes was observed. A step-wise rule, based on the entropy of the cumulative data, was devised for determining the sample size, in terms of the number of houses positive for pupae, at which a pupal survey might reasonably be stopped.

Oviposition response of gravid Anopheles albimanus Wiedemman (Diptera: Culicidae) females to water containing Brachiaria mutica, Cynodon dactylon, Jouvea straminea, Fimbristylis spadicea, and Ceratophyllum demersum was investigated. Gravid An. albimanus females deposited similar egg numbers in cups containing natural plants in water from natural breeding sites and in cups containing natural plants in distilled water. Gravid mosquitoes deposited significantly more eggs in cups containing natural plants in water from natural breeding sites than in cups containing artificial plants in water from the corresponding natural breeding sites. These results were confirmed in experiments conducted in a wind tunnel, indicating that female response is mediated by chemical cues from plants. Bioassays with organic extracts of all 5 plant species indicated that these extracts at 100%, 10%, and 1% concentrations had an oviposition repellent effect, while attractiveness was observed at 0.1%, 0.01%, and 0.001%. Gas chromatography and mass spectrometry analysis of the organic extracts found in all 5 plants showed a mixture of terpenoid and alcohol compounds, among them: guaiacol, phenol, isoeugenol, longifolene, caryophyllene, phenyl ethyl alcohol, and p-cresol. These results suggest that middle-range volatiles from plants may function as chemical cues for the female's oviposition response in this mosquito species.

We assessed the degree of host specificity of the purported anthropophilic and zoophilic populations of Anopheles vestitipennis. A series of experiments were conducted in an experimental hut with 3 compartments lined with nylon netting. A central release compartment and 2 side compartments were each baited with equivalent surface area of human and animal baits. Wild An. vestitipennis collected on each host, as well as corresponding F1 mosquitoes, were released in the central compartment. Overall, 22% (166/748) of all mosquitoes collected on humans were recaptured in the human compartment, whereas 23% of mosquitoes originally collected on animals were recaptured in this compartment. Experiments with F1 females resulted in 59% human selection rates, a 2.6 times increase compared with wild anthropophilic females, while a 1.2 times decrease in human selection rates (from 24% to 20%) was observed in F1 of wild zoophilic females. Host selection experiments in the Lacandón Forest revealed the same trend. These findings suggested that the complex mode of inheritance that resulted in female mosquitoes showing a stronger tendency to return to their preferred host was obscured by the nature of the method of collection, i.e., wild parental females selecting a host either innately or opportunistically, the majority of which were likely innately attracted. This was revealed by F1 females, of which, when given the choice to select a host, a higher proportion opted for the preferred one. The results presented here are in accordance with other studies that identified a subpopulation of An. vestitipennis in southern Mexico with higher anthropophily.

The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region.

A serologic survey in domestic animals (birds and mammals) was conducted in four communities located in the Lacandón Forest region of northeastern Chiapas, Mexico, during June 29 to July 1, 2001, with the objective to identify zoonotic arboviruses circulating in this area. We collected 202 serum samples from healthy domestic chickens, geese, ducks, turkeys, horses and cattle. The samples were tested by plaque-reduction neutralization test for antibodies to selected mosquito-borne flaviviruses (family Flaviviridae), including St. Louis encephalitis (SLE), Rocio (ROC), Ilheus (ILH), Bussuquara (BSQ), and West Nile (WN) viruses, and selected alphaviruses (family Togaviridae), including Western equine encephalitis (WEE), Eastern equine encephalomyelitis (EEE), and Venezuelan equine encephalitis (VEE) viruses. Neutralizing antibodies to SLE virus were detected in two (8%) of 26 turkeys, 15 (23%) of 66 cattle, and three (60%) of five horses. Antibodies to VEE virus were detected in 29 (45%) of 65 cattle. Because some of these animals were as young as 2 months old, we demonstrated recent activity of these two viruses. Sub-typing of the VEE antibody responses indicated that the etiologic agents of these infections belonged to the IE variety of VEE, which has been reported from other regions of Chiapas. WN virus-neutralizing antibodies were detected in a single cattle specimen (PRNT(90) = 1:80) that also circulated SLE virus-neutralizing antibodies (PRNT(90) = 1:20), suggesting that WN virus may have been introduced into the region. We also detected weak neutralizing activity to BSQ virus in four cattle and a chicken specimen, suggesting the presence of this or a closely related virus in Mexico. There was no evidence for transmission of the other viruses (ROC, ILH, EEE, WEE) in the study area.

The egg of Anopheles (Anopheles) punctimacula is described from scanning electron micrographs. Eggs of An. punctimacula are boat shaped, with lateral floats extending 70% of the length of the egg. Plastronlike polyhedral chorionic cells with distinctive boundaries and round tubercles in the cell field cover the dorsal, lateral, and ventral surfaces. Narrow decks enclosing a field of irregular jagged tubercles and 2-4 lobed tubercles are present at both egg poles.

We present herein the results of a series of mark-recapture experiments with female Anopheles vestitipennis. Theses experiments used human and animal hosts to assess the degree of anthropophily of field-caught specimens, originally collected on either host, and of their offspring. Fidelity of mosquitoes to particular hosts was estimated by recapturing marked host-seeking mosquitoes returning for a 2nd blood meal. Results indicated that mosquitoes seeking animal hosts were more faithful (80.48%; 33 of 41) in returning to their original host than were those seeking human hosts (63%; 49 of 78).

Light and scanning electron microscopy were used to compare the eggs of Anopheles vestitipennis Dyar & Knab females collected from human and animal baits in 9 villages of southern Mexico. An. vestitipennis eggs are boat-shaped, with lateral floats extending the length of the egg. Both the deck and dorsal surface are covered with hexagonal and pentagonal chorionic cells that contain round tubercles in the cell field. Crowns that enclose 3–5 lobed tubercles are present at both egg poles. By light microscopy, the mean length/width ratio of eggs of females caught at human bait were statistically different from those of females caught in horse-baited animal traps. In a regression tree model that included 19 egg attributes, the same egg groups could be separated by their posterior crown length/width ratio and mean anterior cell deck form factor (an index of their roundness). These findings support of the possible existence of 2 An. vestitipennis subpopulations with different host preferences in southern Mexico.

The duration of the gonotrophic cycle and survivorship of Anopheles vestitipennis Dyar & Knab was estimated in 2 malarious areas of Chiapas, Mexico: the Lacandon Forest and the Pacific Ocean Coastal Plain. Blood-engorged females held in an outdoor cage required 2.75 d for egg maturation, and 3.75 d for the duration of the gonotrophic cycle. Duration of the gonotrophic cycle also was estimated by parous-nulliparous dynamics for 20 consecutive days and autocorrelation time-series analysis, and by mark-recapture techniques. These methods depicted differences between the Lacandon Forest (3-d cycle) and the Coastal Plain (2–3 d cycles). Daily survival rates were estimated vertically and were generally higher in the Lacandon Forest (0.68) than in the Coastal Plain (0.45–0.58). The probability of mosquitoes surviving the sporogonic cycle was 10–100 times greater in the Lacandon Forest. The pregravid rate was 8.2%, and 29.3% of females with primary follicles beyond Christophers’ stage III had traces of red blood in the gut. The 1st statistic indicated that 8.2% of females required >1 blood meal for initial egg development, the 2nd statistic indicated that 29.3% of females take >1 blood meal during a gonotrophic cycle. In summary, the enhanced vectorial role of this species is explained partially by high longevity and multiple blood-feeding habits.

ResumenCon el fin de actualizar el listado de mosquitos selváticos en Colima, ubicada en la costa oeste de México, se llevó a cabo una colecta entomológica en 33 sitios de muestreo con cebo humano, trampas CDC cebadas con CO2 y aspirador mecánico durante el año 2007. En total se recolectaron 3 076 mosquitos, de los cuales las especies más abundantes fueron Aedes taeniorhynchus, A. trivittatus y Deinocerites pseudes. Los sitios costeros, con clima más cálido y menor altura sobre el nivel del mar mostraron mayor densidad de mosquitos. Las especies más abundantes presentaron una distribución de tipo agregado y se encontraron 18 especies no registradas en Colima. Algunas de las especies encontradas son de importancia en salud pública, por lo que se sugiere incluir la vigilancia entomológica en zonas silvestres y localidades escasamente pobladas.AbstractIn order to update the checklist of wild mosquitoes in the state of Colima, in the western coast of Mexico, an entomological survey was conducted in 33 sampling sites using human bait, CDC traps with CO2 and mechanical aspirator during 2007. A total of 3 076 mosquitoes were collected, of which the most abundant species were: Aedes taeniorhynchus, A. trivittatus and Deinocerites pseudes. Coastal sites, with higher temperature and lower elevation above sea level showed the highest densities of mosquitoes. The most abundant species had an aggregated distribution and there were 18 species previously unrecorded for Colima. Some of the species found are of public health importance, therefore, it is suggested to include undisturbed places and sparcely populated settlements in entomological surveillance.