Published online by Cambridge University Press: 10 July 2009
Males of Phthorimaea operculella (Zell.) less than 24 h old were sterilised with thiotepa by circulatory fumigation in the laboratory and then released in cages in a potato field in New Zealand. Laboratory-reared sterile males, normal males and females were released in different ratios. Sterile males competed successfully in mating to suppress reproduction between laboratory-reared normal males and females. Laboratory-reared sterile males were also released in different numbers into field cages containing the resident population and additional field-collected males and females. The results showed that the sterile males were slightly less competitive than normal ones, but they were effective in suppressing the population in the cages.