Relationship between the seasonal prevalence of the predacious coccinellid Pseudoscymnus hareja (Coleoptera: Coccinellidae) and the mulberry scale Pseudaulacaspis pentagona (Hemiptera: Diaspididae) in tea fields: Monitoring using sticky traps

Abstract

The relationship between the seasonal prevalence of the predacious coccinellid Pseudoscymnus hareja and the mulberry scale Pseudaulacaspis pentagona in tea fields was investigated using sticky traps set inside tea bushes. Crawlers (newly-hatched larvae) and winged adult males of P. pentagona and adults of P. hareja were captured in large numbers. The number of trapped P. hareja adults reached a peak 0 to 15 days (average: 6.9 days) after the peak in the number of P. pentagona crawlers in each tea field. P. hareja adults captured in this period are considered to have visited tea fields to prey on P. pentagona larvae and to deposit their offspring (larvae), which primarily consume P. pentagona larvae. Another relatively lower peak in P. hareja adults was found 0 to 14 days (average: 6.6 days) after the peak in the number of P. pentagona adult males. P. hareja adults trapped in this period are suggested to be those that had spent their larval period feeding on P. pentagona larvae and male pupae in tea fields. Thus, the seasonal occurrence of P. hareja adults in tea fields is associated with that of P. pentagona larvae as the main prey of P. hareja larvae.