Life History of the Coconut Scale, Aspidiotus destructor Signoret (Hemiptera: Diaspididae), and the Natural Enemies of the Scale in Tea Fields

Abstract

We investigated the life history and the natural enemies of the coconut scale, Aspidiotus destructor Signoret (Hemiptera: Diaspididae), in some commercial tea fields from 2015 to 2017 in Shizuoka Prefecture, Japan. The periods of egg deposition and their hatching were observed three times a year: from late April to late May, one month in July, and from late August to late September, and most of overwintering stages were female adults. This result suggested that A. destructor occurs with three generations a year in tea fields. Total number of eggs per female of the overwintering generation was 58.7±2.8 (n=25). Four species of parasitoids emerged from the scale females collected in tea fields. The dominant species were two species, Encarsia citrine (Craw) and Aphytis diaspidis (Howard). It was observed that percentage parasitism by the dominant two species was sometimes over 90%, although it changed according to the season. We also found a kind of ladybird: Pseudoscymnus hareja (Weise) and predaceous gall midge (this species may be Dentifibula viburni (Felt) as predatory insects against the scale.