The Effects of Three Folic Acid Antagonists on Reproduction of Habrobracon juglandis1,2

Abstract

Following ingestion of the folic acid antagonists methotrexate, aminopterin, and trimethoprim, reproductive performance was studied in the parasitic wasp Habrobracon juglandis Ashmead (= Bracon hebetor Say). Methotrexate produces a severe decrease in egg production and hatchability of eggs 2–4 days posttreatment. Aminopterin produces a moderate decline in egg production 3 days posttreatment and a dramatic decline in hatchability on days 2–4. Trimethoprim produces only a very weak decline in egg production for the 1st 3 days posttreatment and a sharp decrease in hatchability on day 1. The number of larvae obtained per female is reduced only moderately by trimethoprim. All 3 drugs demonstrate an excellent dose-response relationship. Methotrexate and aminopterin can be classified as antivitellogenic agents while trimethoprim does not appear to affect vitellogenesis.