Assemblages of Hawkmoths (Sphingidae: Lepidoptera) in Kalinzu Forest South-western Uganda

Abstract

Intensification in anthropogenic activities has significantly lowered habitat quality, accelerated habitat loss and habitat isolation within forest ecosystems. However, there is less documentation on recovery of communities against reference landscapes in afrotropical forests. This study investigated the diversity and faunal composition of sphingid moths (Lepidoptera: Sphingidae) in old-growth and regenerating forest in Kalinzu Central Forest Reserve, South-western Uganda. The goal of the study was to generate information on how habitat recovery impacts insect fauna. The study was guided by the following questions: 1) how do sphingidae moth diversity patterns in regenerating forest compare with those in old-growth forest? 2) How does hawkmoth species diversity correlate with habitat vegetation variables? and 3) what phylogenetic relationships exist among hawkmoths in Kalinzu Forest? Sphingid moths were sampled between July 2019 and February 2020, using a combination of two 20W Ultraviolet light traps (FL20S-BLB and FL20-BL), operated on a battery. Habitat vegetation variables measured or estimated included: basal area of trees, understorey cover, tree density, understorey density and understorey complexity. Phylogenetic relationships among hawkmoths based on mt(CO1) gene were inferred using Maximum Likelihood method and General Time Reversible model in MEGA X. A total of 378 hawkmoth individuals belonging to 22 species were collected. Individual-based extrapolation curves did not reach asymptote implying that more species would be recorded with additional sampling effort. The overlap of curves at 95% CI indicated that richness between forest types did not differ significantly. Fisher’s α diversity was not significantly different between forest types (t(2.2) = 1.786, p > 0.05), also agreeing with very low beta diversity (βChao-Jaccard = 0.0499). Species dominance did not differ significantly between old-growth and regenerating forest (t(3.438) = -0.96). The highest proportion of species in both forest types were closed forest species. Analysis of similarity revealed no significant difference in hawkmoth community composition between forest types (R = -0.241, p > 0.05). Negative value of ANOSIM statistic signifies greater variability within a particular forest portion, than between forests. The genetic distances based on mt(CO1) between any two species of Hawkmoths ranged between 10% and 22%. The findings of this study add to the evidence that species richness does not always decrease with habitat modification. As a way of conserving biodiversity, natural regeneration of formerly degraded habitats should be considered.