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

Abstract

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.

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

“…It is also interesting to note that we classified Mycalesis terminus as a forest specialist while two other Mycalesis species ( M. perseus and M. sirius ) are mainly found in sugarcane plantations. This evidence, which has also been found for other sister species in Guyana by Sambhu et al (), is contrary to the notion that similar species behave or live in similar areas (Francesconi et al, ). Nonetheless, the unique compositions of forest habitats suggest that conservation of these habitats may target different species than conservation of human‐modified habitats.…”

“…These forests are very old (Turton, 2016) and, as such, have established species adapted to the rainforest. Three species were identified as forest habitat specialists ( This evidence, which has also been found for other sister species in Guyana by Sambhu et al (2017), is contrary to the notion that similar species behave or live in similar areas (Francesconi et al, 2013).…”

“…The traps were placed approximately 1.5 m above ground to ensure easy access and baited with approximately 100 g of a fermented mixture of bananas ( Musa sp. L., 1753), 4.7 percent alcohol per volume of 275 ml beer and brown sugarcane sugar (4.5 kg of banana +4 beers +1 kg of sugar) (Nyafwono, Valtonen, Nyeko, & Roininen, ; Sambhu, ; Sambhu et al, ). They were checked daily between 08:00 hr and 16:00 hr over a three‐day period every month to reduce the bias of daily temperature fluctuation (Sands & New, ).…”

“…Additionally, monoculture plantations are known to be highly dissimilar from natural habitats in both composition and structure (Anand, Krishnaswamy, Kumar, & Bali, 2010). However, field margins within this landscape may help to support butterflies (Sambhu, Northfield, Nankishore, Ansari, & Turton, 2017), as has been found in other agricultural landscapes (Fahrig et al, 2015;Feber, Smith, & Macdonald, 1996;Hodgson, Kunin, Thomas, Benton, & Gabriel, 2010;Sybertz, Matthies, Schaarschmidt, Reich, & Haaren, 2017). We were interested in the conservation implications of the Wet Tropics management system, which allows for both ecosystem protection and landscape modification for livelihood and/or economic gains.…”

Year-round temporal stability of a tropical, urban plant-pollinator network

“…Indeed, of the 136 plant taxa observed in this study, 73 species were exotic and 47 were native; the remaining 16 could not be verified (S2 Table ). The benefits of reliable floral resources in urban habitats have also been demonstrated in temperate bees [23] and tropical butterflies [39], where the abundance and richness of these taxa were less variable in urban environments than natural habitats.…”