Record of the invasive alien ladybird Harmonia axyridis (Coleoptera, Coccinellidae) from Kenya

Abstract The biological control agent and alien invasive ladybird Harmonia axyridis (Pallas, 1773) was recorded for the first time in Kenya, and in equatorial Africa, in 2010.


Introduction
The multicolored Asian lady beetle or harlequin ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is native to temperate (and mountain subtropical) Central and East Asia: China, Taiwan, Japan, Korea, Mongolia, Kazakhstan and eastern Rus sia (Kuznetsov 1992). It was introduced in many regions of the world as a biological control agent against aphids, and later became an invasive species, spreading 100-500 km each year. It is established in at least 37 countries in four continents (Brown et al. in press). In Africa, this species was intentionally introduced in two Mediterranean countries: Tunisia, where it did not survive, and Egypt (Ferran et al. 2000), where it established a limited population (Brown et al. in press). Conversely, it has invaded and established in South Africa (Stals and Prinsloo 2007)  We observed the beetles on the plant Ipomoea pescapre (Convolvulaceae) on the sea coast ( Fig. 1). All individuals belonged to the colour morph succinea (Hope), with 19 welldeveloped spots on the elytra and welldeveloped elytral ridges (Fig. 2). Like a previous record of H. axyridis in Uruguay (Nedvěd and Krejčík 2010), this finding was done by chance by a nonprofessional entomologist.

Discussion
Because Kikambala is a holiday centre, but not a port or transport node, we consider the occurrence of H. axyridis here to be the result of a wider and lasting invasion, rather than a singular incidental and ephemeral introduction with goods.
The observed colour morph succinea is the most common morph in the eastern part of its natural range (Blekhman et al. 2010) and in the invasive European popula tion (Brown et al. 2008). The size of the spots suggests that the individuals recorded emerged from pupae at temperatures of around 25°C -the spots would be smaller or missing at higher temperatures (Michie et al. 2010).
High temperature may be limiting the continued spread of H. axyridis, at least at a local scale. The American (Acar et al. 2001) and European (Fois et al., unpublished) invasive populations do not survive temperatures above 33°C. However, the CLIMEX model that used known physiological limits of H. axyridis indicated that this species may tolerate most southern and eastern African countries, including Kenya (Poutsma et al. 2008). The coastal climate near Mombasa is rather hot (average annual tem perature 26°C, Climate & Temperature 2011), while at higher elevations inland, mild temperatures (e.g. 18°C in the capital, Nairobi) are more favourable for H. axyridis. Although there were several independent introductions of H. axyridis in Europe and North America, with different source populations from East Asia, there is a single main invasive population/strain in several continents . Thus in future the origin of the population in Kenya should be compared with known populations from both the native and invasive ranges, using molecular genetic methods (Blekhman et al. 2010, Thomas et al. 2010 to determine if it is the same strain, or a different one that might have higher temperature requirements.

Conclusion
We consider that H. axyridis has established in Kenya, the first fully tropical country to be invaded, but that its further spread may be hampered by high temperature and low prey availability. In this region we suggest that H. axyridis may pose a low threat to biodiversity, such as the native ladybird beetles, which are mostly coccidophagous.