BackgroundThe abundance, richness and diversity of mosquitoes and aquatic insects associated with their oviposition sites were surveyed along eight states of the Pacific coast of Mexico. Diversity was estimated using the Shannon index (H’), similarity measures and cluster analysis.MethodsOviposition sites were sampled during 2–3 months per year, over a three year period. Field collected larvae and pupae were reared and identified to species following adult emergence. Aquatic insects present at oviposition sites were also collected, counted and identified to species or genus.ResultsIn total, 15 genera and 74 species of mosquitoes were identified: Anopheles pseudopunctipennis, An. albimanus and Aedes aegypti were the most abundant and widely-distributed species, representing 47% of total mosquito individuals sampled. New species records for certain states are reported. Anopheline diversity was lowest in Sinaloa state (H’ = 0.54) and highest in Chiapas (H’ = 1.61) and Michoacán (H’ = 1.56), whereas culicid diversity was lowest in Michoacán (H’ = 1.93), Colima (H’ = 1.95), Sinaloa (H’ = 1.99) and Jalisco (H’ = 2.01) and highest in Chiapas (H’ = 2.66). In total, 10 orders, 57 families, 166 genera and 247 species of aquatic insects were identified in samples. Aquatic insect diversity was highest in Chiapas, Oaxaca and Michoacán (H’ = 3.60-3.75). Mosquito larval/pupal abundance was not correlated with that of predatory Coleoptera and Hemiptera.ConclusionThis represents the first update on the diversity and geographic distribution of the mosquitoes and aquatic insects of Mexico in over five decades. This information has been cataloged in Mexico’s National Biodiversity Information System (SNIB-CONABIO) for public inspection.

BackgroundThe larvicidal efficacy of the naturally derived insecticide spinosad, for control of immature stages of Anopheles albimanus and associated culicids, was compared to that of synthetic and biological larvicides. Effects on non-target insects were also determined.MethodsA field trial was performed in replicated temporary pools during the rainy season, in southern Mexico. Pools were treated with 10 ppm a.i. spinosad (Tracer 480SC), Bti granules applied at 2 kg/ha (VectoBac WDG, ABG-6511), and 100 ml/ha temephos (50 EC), or an untreated control. Numbers of immature mosquitoes, and aquatic insects in pools were monitored for 20 weeks.ResultsSamples of immature mosquitoes comprised approximately 10% An. albimanus, 70% Culex spp. (mostly Cx. melanoconion and Cx. coronator) and 20% Uranotaenia lowii. The most effective larvicides were spinosad and temephos that eliminated An. albimanus in 16 out of 20 post-treatment samples, or 9 weeks of continuous control of immature stages, respectively. These larvicides resulted in 15 and 5 weeks of elimination of Culex spp., respectively, or 20 and 4 weeks of continuous elimination of U. lowii, respectively. Bti treatment provided little consistent control. Aquatic insects were recorded comprising 3 orders, 20 families, 40 genera and 44 species. Shannon diversity index values (H’) for aquatic insects were highest in the control (0.997) and Bti (0.974) treatments, intermediate in the spinosad treatment (0.638) and lowest in the temephos treatment (0.520). Severely affected non-target insects in the spinosad and temephos treated pools were predatory Coleoptera, Hemiptera and Odonata, which in the case of spinosad was likely due to the high concentration applied. Bti had little effect on aquatic insects.ConclusionsThe spinosad treatment retained larvicidal activity for markedly longer than expected. Spinosad is likely to be an effective tool for control of anopheline and other pool-breeding mosquitoes in tropical regions. Non-target effects of spinosad on aquatic insects merit further study, but were likely related to the concentration of the product used.

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Odonate diversity in the Coalcomán Mountain Range (CMR), Michoacán State, Mexico, was surveyed, and samplings were made during 2 years in eight streams along an altitudinal gradient. Presence-absence data were analyzed using non-parametric and parametric methods. Beta and gamma diversities were estimated using Whittaker's and Lande's formulae, respectively. A total of 2,526 adults and 489 larvae were captured, yielding 116 species (c diversity), 44 genera and 9 families. Five new species were discovered. The genus Argia was the most important contributor to Zygoptera diversity and total richness (c diversity), yielding 40.4 and 14.7%, respectively. The non-parametric estimator Chao2 provided the closest theoretical estimate of species richness, and Clench's model fit the data well (R 2 ranged from 99.44 to 99.99) to explain a high proportion of the variance (98.8). We conclude that beta diversity is important at the landscape scale, supporting the hypothesis that Mexico is a beta diverse country. Our results triple the number of known species of Odonata for Michoacán. Given the considerable richness of odonates at local and landscape scales, our results support the proposal of the Coalcomán Mountain Range as a priority area for conservation and related research.

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1. Assessing species richness (SR) and diversity along environmental gradients is important to see whether abiotic differences alter patterns of species distribution and composition.2. We examined distributions of odonate SR, average taxonomic distinctness (ATD) and functional diversity (FD) (using the Shannon Index on proportions of plant-dependent and non-dependent species) with elevation and slope provided from an exploratory survey along a transect in the Sierra de Coalcoma´n Mountains, Michoaca´n State, Mexico. Adults were collected along both sides of a 500 m stream segment for 6 h day )1 site )1 in each of eight sites, and these species lists were complemented by collecting mature larvae.3. Species richness and FD declined with elevation among windward sites, while ATD increased. Among leeward sites, SR peaked at mid-elevation, and there was no trend for FD or ATD with elevation. Leeward sites were similar in species composition, whereas windward sites were dissimilar. Slope was correlated with elevation among windward sites, and influenced most variables, but not among leeward sites. FD was negatively correlated with ATD among sites along both aspects. Mean values of SR, ATD and FD between aspects were similar.4. The Energy-Richness Hypothesis best explained the species distributions along the windward aspect. Local abiotic influences appeared more important in community assembly among windward sites. Among leeward sites, the potential for Mid-Domain and Rapoport Effects suggest interspecies interactions control community assembly; providing greater potential for expansion of species elevational ranges, and an increase in range expansion of alien and non-endemic species along this aspect.

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