Development and Growth Ratio of Predaceous Coccinellid, Sasajiscymnus quinquepunctatus (Weise) on Papaya Mealybug, Paracoccus marginatus Williams & Granara de Willink

Abstract

The predaceous coccinellid, Sasajiscymnus quinquepunctatus (Weise) (Coleoptera: Coccinellidae) was identifi ed as a potential candidate for biological control of the papaya mealybug, Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae), which is native to the Neotropical region and in 2008 was detected as an invasive alien insect species in Thailand. It was subjected to laboratory investigation on its development, life history and growth ratio for its possible use in augmentative biological control. P. marginatus was cultured on Thai pumpkin (Cucurbita moschata) as an artifi cial host and was used as prey for the coccinellid. The development from egg stage to adult was described and their respective sizes measured. The development time (mean ± SD) from egg to adult was 29.96 ± 0.80 d. The incubation period, the duration of four larval instars, and the pupal stage, all reported as (mean ± SD), were 6.37 ± 1.03, 2.62 ± 0.64, 2.58 ± 0.56, 2.70 ± 0.59, 5.06 ± 0.80, and 10.58 ± 1.19 d, respectively. Adult longevity (mean ± SD) was 32.16 ± 10.56 d. The mean geometric growth ratio of 1.65 using the head capsule width in successive larval instars as a parameter was obtained and it conformed well to Dyar’s law. It was advocated that S. quinquepunctatus could be further evaluated for utilization in augmentative biological control of the papaya mealybug in Thailand.