Life history and host range characteristics of Paracles azollae Berg, 1877 (Lepidoptera: Erebidae), an herbivore considered for biological control of invasive species of Ludwigia L. (Onagraceae) in the United States

Abstract

Exotic water primroses in the genus Ludwigia L. (Onagraceae) invade aquatic ecosys-tems worldwide. Management of these plants has been limited to physical and chemical controlmethods, but alternative approaches are needed, including classical biological control. Herein,the biology and host range of Paracles azollae Berg, 1877 (Lepidoptera: Erebidae), a mothassociated with Ludwigia spp. in Uruguay, was studied to determine its suitability as a biologicalcontrol agent of exotic water primroses in the U.S.A. Larval no-choice and multi-choice testswere conducted using four exotic Ludwigia species and seven species native to the U.S.A. Whenfed the optimal host plant, Ludwigia hexapetala (Hook. & Arn.) Zardini, Gu & P. H. Raven,the number of larval instars ranged from 6–8 and generation time from egg to adult was 51.1 ±5.9 days at 25 °C. Females are short-lived (9.0 ± 2.3 days) but highly fecund, with a lifelongfecundity of 597.3 ± 338.8 eggs. Paracles azollae did not exhibit a high level of host specificityamong test plants; larvae completed development on all target weeds and four of seven nativespecies. Additionally, larvae did not differentiate between exotic weeds and most native speciesin multiple-choice tests. Results indicate that the host range of P. azollae is unacceptably broadto be considered for biological control of exotic Ludwigia spp. in the U.S.A. and further consid-eration is not warranted.