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Volume 2012, Article ID 173482, 5 pages
Research Article

Effect of Air Humidity on Sex Ratio and Development of Ladybird Harmonia axyridis (Coleoptera: Coccinellidae)

1Faculty of Biological Sciences, University of South Bohemia, 370 05 České Budějovice, Czech Republic
2Institute of Entomology, Biology Center, Academy of Sciences of the Czech Republic, Branišovská 31, 370 05 České Budějovice, Czech Republic
3Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Boulevard Tzar Osvoboditel, 1000 Sofia, Bulgaria

Received 30 September 2011; Accepted 19 November 2011

Academic Editor: D. Bruce Conn

Copyright © 2012 Oldřich Nedvěd and Plamen Kalushkov. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Length of development of larvae and pupae of the invasive alien ladybird beetle Harmonia axyridis, their survival rates, sex ratio, and fresh mass of the emerged adults were measured at three contrasting levels of relative air humidity: 30, 60, and 90%, 25°C and photoperiod 16L : 8D. Overall sex ratio was 51%, but there was a strong trend for higher proportion of males at low humidity and higher proportion of females at high humidity. Survival rate, larval developmental time, and adult mass were all differently influenced by air humidity depending on the food type. In individuals fed with aphid Acyrthosiphon pisum there was a trend for better survival, shorter development, and higher mass gained at higher humidity. These trends were opposite or nonsignificant in individuals fed with frozen eggs of moth Ephestia kuehniella.