Population studies and biological control of Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae) on passion fruit in Western Samoa

Abstract

AbstractThe development of infestations of Pseudaulacaspis pentagona (Targioni-Tozzetti) on passion fruit vines in Western Samoa was monitored at two sites over a period of 20 months, during which the aphelinid parasitoids Encarsia berlesei (Howard) and E. diaspidicola (Silvestri) were released. All vines were rated for P. pentagona infestations, and the female scale insects were counted on selected vines. At one site, the numbers of P. pentagona built up to over 10 000 adult females per vine before the parasitoids became established, and within one year 50% of the vines died. At the other site, where vines survived, an endemic coccinellid predator, Sticholotis quadrisignata Weise, kept populations below 3000 females per vine until the parasitoids became established. Biological control of P. pentagona was achieved at both sites eight months after the parasitoids were introduced. A model for interaction of P. pentagona and parasitoids predicted higher levels for parasitization than revealed by microscopic examination.