Egg Mortality of German Cockroaches Exposed to Fenitrothion MC Bait and Hydramethylnon Bait

Abstract

The viability of the oothecae (eggs) of Blattella germanica females which were killed by ingesting fenitrothion MC bait and hydramethylnon bait was studied under the high humidity condition (75 % RH). In case of the females treated with fenitrothion MC bait, 17 oothecae out of 25 (68%) and 520 eggs out of 807 (64.4%) were hatched during the period of 4-24 days after treatment. In case of the females treated with hydramethylnon bait, 15 oothecae out of 25 (60%) and 499 eggs out of 842 (59.3%) were hatched during the period of 1-28 days after treatment. In the control group (decapitated females), 21 oothecae out of 25 (84%) and 728 eggs out of 835 (87.2%) were hatched during the period of 1-24 days after decapitation, which was significantly different from those of the eggs of the females treated with both fenitrothion MC bait and hydramethylnon bait (P<0.05). Neither the degree of maturity of oothecae, nor detachment/attachment of oothecae from/to female abdomens were correlated to the hatching (viability) of the oothecae.