Concentration and speciation of arsenic in an insect feeding on the leaves of Pteris vittata

Abstract

The development of an effective and green bioinsecticide is a research hotspot. This study demonstrated the possibility of using an arsenic (As) hyperaccumulator as a bioinsecticide. When the As concentration in the Pteris vittata fronds exceeded 138 mg kg -1 , the larva of the hawk moth (Theretra clotho) displayed apparent preference to lower-As-concentration P. vittata fronds. The As concentration in the larva body was as high as 850 mg kg -1 . Such high concentration of As in the larva body might have been the case that T. clotho lacks a process to exclude As. The larval frass showed an As concentration of only 1%-4% of that in the larva body. The predominant As species in the larva body and frass was As(III)-SH. The percentage of As(III)-SH was slightly higher in the frass than that in the larval body. Chelation with thiols may be a universal detoxification mechanism for As in both plants and insects. In general, the adoption of P. vittata as a bioinsecticide should be feasible. However, the exact processes to achieve this goal still need further study. The mechanism of different animals to detoxify As is another interesting research topic.