Clover root weevil: Observations on differences between 1997 and 1998 summer populations in the Waikato

Abstract

Field population studies of clover root weevil in the Waikato in 1996/97 showed that high levels of reproductive females in early summer were followed by a summer larval generation. However, in the 1997/98 summer, non-reproductive females predominated and a summer generation of larvae did not eventuate. Rainfall during the 1997/98 summer was less than in the preceding summer. The possibility that dry conditions inhibited the initiation of oviposition is supported by experimental evidence showing that females collected from irrigated pastures laid almost 100 times more eggs over a one month period than those from non-irrigated pastures.