Population dynamics, seasonality and aphid prey of Cheilomenes sexmaculata (Coleoptera: Coccinellidae) in an urban park in central Japan

Yasuko KAWAKAMI,Kazunori OHASHI,Kazuo YAMAZAKI

doi:10.14411/eje.2016.023

Yasuko KAWAKAMI, Kazunori OHASHI + Show 1 more

Open Access

https://doi.org/10.14411/eje.2016.023

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Abstract

The ladybird beetle, Cheilomenes sexmaculata (Fabricius), has been extending its distribution in and around urban areas at higher latitudes in Japan over the past 100 years. Between 2003 and 2011, we investigated the seasonal occurrence, aphid prey and population dynamics of this species in an urban park in Osaka City, central Japan. We found that C. sexmaculata completes three generations a year in Osaka. Overwintered adults emerge in March or April and produce two (or rarely one) generations by summer. Second-generation adults aestivate and subsequently produce another generation in autumn. This species feeds on five species of aphids that infest planted shrubs and alien weeds throughout the vegetative season. We analyzed the association between accumulated temperature and when overwintered adults first emerged. In addition, we determined the association between their time of emergence, peak abundance and last occurrence, and meteorological conditions. There was no association between the sum of effective temperatures and termination of adult overwintering. There was, however, an association between first occurrence and peak abundance, and climatic conditions, such as warm temperatures or low humidity. This species maintained a stable population in an urban park by becoming quiescent when climatic conditions were unfavourable or prey was scarce. We discussed these findings in relation to urban environmental factors, such as climate, food conditions and vegetation.

Highlights

The species diversity of some insect groups in urban areas increases while that of other insect groups decreases (Frankie & Ehler, 1978; McIntyre, 2000; Raupp et al, 2010)
Potential for regulating aphid abundance and ecological interest in its colour polymorphism and recent range extension the bionomics of C. sexmaculata have not been studied in detail; most studies on ladybirds are on five species and there is a need for studies on other species of ladybirds (Sloggett, 2005)
The numbers of larvae, all adults and teneral adults of C. sexmaculata recorded in 30 min of searching from 10 March to 10 December are shown in Fig. 1 for each year

Summary

Introduction

The species diversity of some insect groups in urban areas increases while that of other insect groups decreases (Frankie & Ehler, 1978; McIntyre, 2000; Raupp et al, 2010). The ladybird beetle, Cheilomenes sexmaculata (Fabricius), is a common predator of aphids and is widely distributed across intermediate and equatorial latitudes (Sasaji, 1971). It is polymorphic in terms of its elytral colour (Kawakami et al, 2013). The northward spread of this species between 1940 and 2010 is associated with the increase in areas in Japan where the annual mean temperature is more than 15°C (Kawakami et al, 2014). This ladybird has been mainly collected from urban areas in Japan (858/912 individuals, 30–36°N, Supplementary material; Kawakami et al, 2013) and is rare in suburban and mountainous areas. Potential for regulating aphid abundance and ecological interest in its colour polymorphism and recent range extension the bionomics of C. sexmaculata have not been studied in detail; most studies on ladybirds are on five species and there is a need for studies on other species of ladybirds (Sloggett, 2005)

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Conclusion