Effects of rearing density of survival, growth, and development of the ladybird Coleomegilla maculata in Culture

Authors: Riddick, Eric; Wu, Zhixin

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2015
Publication Date: 10/9/2015
Publication URL: http://handle.nal.usda.gov/10113/61786
Citation: Riddick, E.W., Wu, Z. 2015. Effects of rearing density of survival, growth, and development of the ladybird Coleomegilla maculata in Culture. Insects. 6:858-868.

Interpretive Summary: A major drawback to merging augmentative biological control into an IPM program is the high cost of rearing and purchasing natural enemies (predators). Cost-saving techniques that don’t sacrifice the quality of mass-reared predators are necessary. One way to reduce cost is to boost predator density per rearing cage. In this study, we evaluated the effects of rearing density (1, 5, 10, 15, and 20 larvae per arena) on survival, growth, and development of the pink-spotted ladybird beetle, Coleomegilla maculata, in arenas provisioned with powdered brine shrimp (Artemia franciscana) eggs as food. Although survival rate declined as rearing density increased, more than 80% of larvae and 100% of pupae achieved the adult stage at an initial rearing density of 20 first instars per 159 cm3 arena (i.e., 0.126 larvae/cm3). Development time, body size, and sex ratio were not affected by rearing density. This study is important because it documents the potential of rearing the pink-spotted ladybird in communal arenas. It suggests that scaling-up cage size-and ladybird density in these cages-to meet the demands of commercial mass production is possible.

Technical Abstract: Our research focuses on developing cost- and space-efficient techniques to rear ladybird beetles (Coleoptera: Coccinellidae). We evaluated the effects of rearing density on survival, growth and development of Coleomegilla maculata. The hypothesis that survival decreases as rearing density increases was tested. C. maculata first instars were reared to pupae at a density of 1, 5, 10, 15, or 20 individuals per arena (2.5 cm high, 9.0 cm diameter, and 159 cm3 volume) and fed powdered brine shrimp (Artemia franciscana) eggs. Results indicated that survival rate decreased as rearing density increased. More larvae survived at the 1 and 5 densities than the 10 density, but no differences were detected between the 10, 15, or 20 densities. Median survival rate was at least 90% for larvae and 100% for pupae at the 10, 15, and 20 densities. Development time, body weight, and sex ratio were unaffected by rearing density. Overall, this study suggests that C. maculata larvae can be reared effectively at a density up to 20 larvae/159 cm3 (˜ 0.126 larvae/cm3) in containers provisioned with powdered A. franciscana eggs. Scaling-up the size of containers, and C. maculata density in these containers, should be possible.