# Adaptability of Yuanjiang River Valley Danaus genutia to Different Host Plants in Yunan

## TL;DR

This study identifies suitable host plants for the Danaus genutia butterfly in the Yuanjiang River Valley to aid in its conservation.

## Contribution

The study provides new insights into the adaptability of Danaus genutia to specific host plants and evaluates their impact on population dynamics.

## Key findings

- Cynanchum annularium and Cynanchum corymbosum are confirmed as suitable host plants for Danaus genutia.
- Larvae feeding on C. annularium showed shorter developmental periods and higher early survival rates.
- Population simulations confirmed the suitability of C. annularium and C. corymbosum for D. genutia conservation.

## Abstract

This research seeks to identify the local host plants of Yuanjiang River Valley Danaus genutia and assess the suitability of various host plants for the butterfly, thereby offering a scientific basis for the conservation of its population in the region. Two documented host plants, two plants with observed larval feeding, and two additional host plants recorded for other butterfly species were selected. Based on tests of adult oviposition and larval feeding preferences, Cynanchum annularium and Cynanchum corymbosum were found to be the most appropriate host plants. These species are also found locally in Yuanjiang. An age-stage, two-sex life table was created to examine physiological indicators after the butterfly uses these host plants, and population dynamics were simulated for the next 60 days. The results confirmed that C. annularium and C. corymbosum are local host plants for D. genutia, with C. annularium being the more suitable of the two.

This study aims to determine the local host plant range for Yuanjiang River Valley Danaus genutia (Cramer, 1779) and evaluate the effects of different host plants on its growth, development, and reproductive success. This research assesses adult oviposition preferences and larval feeding tendencies on various host plants. An age-stage, two-sex life table was constructed to analyze the butterfly’s growth, development, reproductive success, survival rates, and other physiological aspects on different host plants. Population dynamics over the next 60 days were simulated to offer a comprehensive evaluation of the host plant suitability for D. genutia. The results indicated that D. genutia adults preferred laying eggs on Cynanchum corymbosum, followed by C. annularium, C. rostellatum, and Asclepias curassavica, with very few eggs laid on Calotropis gigantea and Dregea volubilis. Larval feeding preferences were observed in the order of C. annularium > C. corymbosum > C. rostellatum, with A. curassavica consumed only by first-instar larvae, while C. gigantea and D. volubilis were avoided. Under identical room temperature conditions, larvae feeding on C. annularium and C. corymbosum completed a full generation. Larvae feeding on C. annularium exhibited shorter developmental periods and higher early survival rates compared to those feeding on C. corymbosum, with no significant differences in adult longevity, sex ratio, or number of eggs per female. Female adults did not die immediately after laying eggs. No significant differences in the intrinsic rate of increase (r), finite rate of increase (λ), net reproduction rate (R0), or doubling time (Td) were found between populations feeding on the two host plants. However, the gross reproductive rate (GRR) and mean generation time (T) were significantly lower in the population feeding on C. corymbosum. These results confirm C. annularium and C. corymbosum as host plants for D. genutia larvae and provide a theoretical and scientific basis for the conservation of the Yuanjiang River Valley D. genutia population.