New Options in Pest Control

Target Life Stages:

Knowing how different insecticides work and the life stages they affect is important to understanding how to use them in a management program. Ovicides are products that kill eggs. CM eggs are deposited on the upper surfaces of leaves or on developing fruit. Some CM ovicides (egg killers) work if they are applied over the top of the egg, that is, topically (Fig. 2). Examples of these products are mineral oil, Assail and Calypso. Other ovicides work if they are applied prior to egg deposition, that is, the CM egg is deposited on top of a residue. Esteem works in this way. Intrepid and Rimon are examples of ovicides that work either topically or as a residue.

Fig. 2

Larvicides are products that kill an insect’s larval stage. For CM, the window of opportunity to kill the larva is very short, after it has hatched and as it attempts to enter the fruit. Most CM eggs are deposited on leaves of fruiting clusters or directly on fruit. A CM larva hatching from an egg placed on a leaf has the ability to find a fruit and enter it within a few hours. Traditional insecticides (Guthion, Imidan, Sevin, Warrior, Danitol and Asana) are highly toxic by contact. That is, a CM larva can be killed by just walking across residues of these products. The newer insecticides (Assail, Calypso, Intrepid, Rimon and Proclaim) have very little contact activity. Their main effect comes when the CM larva consumes the insecticide as it attempts to enter the fruit. Some of these products allow more “stings” (shallow, unsuccessful entries) than traditional insecticides because the CM larva does not die until after it has partially or completely entered the fruit. This weakness is more of a problem in the second CM generation when scars left by “stings” are more evident.

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