The corresponding larval data show that for some insecticides,
such as malathion, the reduction in adult mortality over the period
of these assays corresponded to an increase in the number of
D. suzukii larvae in the berries. Other compounds, such as
methomyl and acetamiprid, continued to cause high larval control
in the fruit even with corresponding low adult mortality. These
differences between effects on adult mortality and on larval
infestation of the fruit highlight the difficulties in assessing how
well insecticides are able to protect fruit from D. suzukii in the field,
unless larval infestation measurements are taken. Further research
is needed on insecticide performance against the main life stages to
elucidate whether low larval infestation (despite high adult survival)
is due to lack of egg laying, eggs not hatching, or young larvae
dying in the fruit as suggested by some recent laboratory studies (J.
Wise, unpublished data). It will also be essential to determine how
these results from controlled semi-field assays in which bushes
were treated with a high degree of coverage translate into real
world settings where coverage may not be as complete and surviving
flies can choose where they fly and lay eggs