Variation in Rotenone and Deguelin Contents among Strains across Four Species and Their Activities against Aphids and Whiteflies.

Botanical pesticides have received increasing attention for sustainable control of insect pests. Plants from the genus are known to produce rotenone and deguelin. Rotenone is known to possess insecticidal activities against a wide range of pests, but deguelin's activities remain largely inconclusive. On the other hand, the biosynthesis of rotenone and deguelin may vary in species. This study analyzed the rotenone and deguelin contents in 13 strains across 4 species over 4 growing seasons using HPLC. Our study shows that the species and even the strains within a species vary substantially in the biosynthesis of rotenone and deguelin, and their contents can be affected by the growing season. After identification of the LC values of chemical rotenone and deguelin against (Glover) and (Gennadius), leaf extracts derived from the 13 strains were used to test their insecticidal activities against the 2 pests. The results showed that the extracts derived from 2 strains of . had the highest insecticidal activity, resulting in 100% mortality of and greater than 90% mortality of . The higher mortalities were closely associated with the higher contents of rotenone and deguelin in the two strains, indicating that deguelin also possesses insecticidal activities. This is the first documentation of leaf extracts derived from 13 strains against 2 important pests of and . The strain variation and seasonal influence on the rotenone and deguelin contents call for careful attention in selecting appropriate strains and seasons to produce leaf extracts for the control of insect pests.