Explaining variations in the diversity of parasitoid assemblages in a biosphere reserve of Mexico: evidence from vegetation, land management and seasonality.

Insect fauna biodiversity in natural protected areas has not been thoroughly studied. Therefore, the aim of this work was to assess whether and how vegetation types, land management and seasonality influence the diversity of Ichneumonidae (Hymenoptera) in the Ría Lagartos Biosphere Reserve (Mexico). A sampling programme was conducted using Malaise traps from 2008 to 2009 in three vegetation types, each with two conservation zones (core and buffer zones). Three seasons were considered: rainy, dry and north-winds (isolated storms from November to February). A total of 336 species were identified. Rarefaction and Generalized Linear Model indicated higher species richness and abundance, respectively, in the buffer zone of the dry forest; possible explanations for this finding include the intermediate disturbance hypothesis, wherein diversity can be higher in sites where disturbance is not very frequent or very intense, and the 'enemies hypothesis', wherein structural complexity and high plant diversity favour increased predators or, in this case, parasitoids. Diversity was higher during the rainy season, which may have been due to the higher availability of resources. Vegetation and management had a positive impact on the Coc (attack cocoons and pupae) and Myc (attack concealed larvae living in the fruiting bodies of mushrooms) parasitoid guilds. Members of the Coc guild are generalist parasitoids, which may be favoured in complex vegetation with a high richness of potential hosts and non-hosts. The Myc guild requires certain environmental conditions that promote fungal growth, such as humidity, that is absent in the other vegetation types of savannah and coastal dune scrubland.

Diurnal flight behavior of Ichneumonoidea (Insecta: Hymenoptera) related to environmental factors in a tropical dry forest.

The biology and behavior of insects are strongly influenced by environmental conditions such as temperature and precipitation. Because some of these factors present a within day variation, they may be causing variations on insect diurnal flight activity, but scant information exists on the issue. The aim of this work was to describe the patterns on diurnal variation of the abundance of Ichneumonoidea and their relation with relative humidity, temperature, light intensity, and wind speed. The study site was a tropical dry forest at Ría Lagartos Biosphere Reserve, Mexico; where correlations between environmental factors (relative humidity, temperature, light, and wind speed) and abundance of Ichneumonidae and Braconidae (Hymenoptera: Ichneumonoidea) were estimated. The best regression model for explaining abundance variation was selected using the second order Akaike Information Criterion. The optimum values of temperature, humidity, and light for flight activity of both families were also estimated. Ichneumonid and braconid abundances were significantly correlated to relative humidity, temperature, and light intensity; ichneumonid also showed significant correlations to wind speed. The second order Akaike Information Criterion suggests that in tropical dry conditions, relative humidity is more important that temperature for Ichneumonoidea diurnal activity. Ichneumonid wasps selected toward intermediate values of relative humidity, temperature and the lowest wind speeds; while Braconidae selected for low values of relative humidity. For light intensity, braconids presented a positive selection for moderately high values.