Butterflies (Lepidoptera) of Guyana: A compilation of records.

An examination of the available literature shows that a total of 1,205 butterfly species from 457 genera, 22 subfamilies and six families have been recorded in Guyana. Specimens that are unidentified above genus level and those that require further verification are excluded from this checklist. Although investigations have been conducted in all of the natural regions and administrative regions of Guyana, additional research is required on a number of aspects including species biology and behavioral ecology. It is hoped that this list will facilitate research on such data gaps.

Trade-offs for butterfly alpha and beta diversity in human-modified landscapes and tropical rainforests.

The accelerating expansion of human populations and associated economic activity across the globe have made maintaining large, intact natural areas increasingly challenging. The difficulty of preserving large intact landscapes in the presence of growing human populations has led to a growing emphasis on landscape approaches to biodiversity conservation with a complementary strategy focused on improving conservation in human-modified landscapes. This, in turn, is leading to intense debate about the effectiveness of biodiversity conservation in human-modified landscapes and approaches to better support biodiversity in those landscapes. Here, we compared butterfly abundance, alpha richness, and beta diversity in human-modified landscapes (urban, sugarcane) and natural, forested areas to assess the conservation value of human-modified landscapes within the Wet Tropics bioregion of Australia. We used fruit-baited traps to sample butterflies and analyzed abundance and species richness in respective land uses over a one-year period. We also evaluated turnover and spatial variance components of beta diversity to determine the extent of change in temporal and spatial variation in community composition. Forests supported the largest numbers of butterflies, but were lowest in each, alpha species richness, beta turnover, and the spatial beta diversity. Sugarcane supported higher species richness, demonstrating the potential for conservation at local scales in human-modified landscapes. In contrast, beta diversity was highest in urban areas, likely driven by spatial and temporal variation in plant composition within the urban landscapes. Thus, while improving conservation on human-modified landscapes may improve local alpha richness, conserving variation in natural vegetation is critical for maintaining high beta diversity.

Tropical Rainforest and Human-Modified Landscapes Support Unique Butterfly Communities That Differ in Abundance and Diversity.

Tropical forests account for at least 50% of documented diversity, but anthropogenic activities are converting forests to agriculture and urban areas at an alarming rate, with potentially strong effects on insect abundance and diversity. However, the questions remain whether insect populations are uniformly affected by land conversion and if insect conservation can occur in agricultural margins and urban gardens. We compare butterfly populations in tropical secondary forests to those found in sugarcane and urban areas in coastal Guyana and evaluate the potential for particular butterfly communities to inhabit human-modified landscapes. Butterflies were sampled for 1 yr using fruit-baited traps in three separated geographical locations on the coast. We used nonmetric multidimensional scaling to assess differences in species assemblages and a generalized linear mixed model to evaluate abundance, species richness, evenness, and diversity. The secondary forests in all three locations supported higher butterfly abundance and diversity than other human-modified areas, although the magnitude of this effect varied by season and location. However, each land use supported its own type of butterfly community, as species composition was different across the three land uses. Sugarcane field margins and urban gardens supported populations of butterflies rarely found in our tropical secondary forest sites. Land management practices that encourage forest conservation along with butterfly-friendly activities in human settlements and agricultural areas could improve butterfly conservation. To this end, butterfly conservation in Guyana and other tropical landscapes would benefit from a shift from inadvertently to actively making the landscape attractive for butterflies.

The response of contrasting tomato genotypes to combined heat and drought stress.

Efforts to maximize yields of food crops can be undermined by abiotic stress factors, particularly those related to climate change. Here, we use a range of physiological methods to detect the individual and combined effects of heat and drought stress on three contrasting varieties of tomato: Hybrid 61, Moskvich, and Nagcarlang. Seedlings were acclimated under the following treatment regimes: CONTROL (25-36°C; well-watered), DRY (25-36°C; 20% field capacity), HOT (25-42°C; well-watered) and HOT+DRY (25-42°C; 20% field capacity). In each treatment, stomatal conductance, leaf temperature, chlorophyll content, and several chlorophyll fluorescence variables (both in situ and in vitro following a heat shock treatment) were measured. Plants from the HOT treatment remained statistically similar to the CONTROL plants in most of the measured parameters, while those from the DRY treatment and especially the HOT+DRY treatment showed clear effects of abiotic stress. Hybrid 61 showed considerable resilience to heat and drought stress compared to the other varieties, with significantly cooler leaves (one day after treatments imposed) and significantly higher Fv/Fm values both in situ and in vitro. The genotypic differences in resilience to heat stress were only apparent under water-limited conditions, highlighting the need to consider leaf temperature rather than air temperature when testing for tolerance to heat stress. The most effective parameters for discriminating genotypic variation in heat and drought stress were in vitro Fv/Fm and chlorophyll content.