Spatial patterns of the parasitic mite Hemisarcoptes coccophagus (Astigmata: Hemisarcoptidae): Host effect, density-dependence of aggregation, and implications for biological control

The spatial distribution of the parasitic mite Hemisarcoptes coccophagus Meyer on two armoured scale insects (Homoptera: Diaspididae) was highly aggregated in the field. Mites were more aggregated on young than on ovipositing host scale females. No differences in the mite's distribution pattern were found between latania scale (Hemiberlesia lataniae (Signoret)) and oleander scale (Aspidiotus nerii (Bouché)). Mite aggregation was density-dependent on ovipositing host females (the degree of overdispersion decreased as mite abundance increased), but density-independent on young females. The effect of density-dependent and independent mite aggregation on the proportion of hosts escaping attack at different parasite abundances was simulated, and its relevance to biological control of Diaspididae is discussed.