The chemical ecology of Harmonia axyridis

Abstract

In the recent SI of BioControl and resultant book from this working group (Roy et al., 2012), we contributed a review paper on the chemical ecology of the invasive aphidophagous ladybird Harmonia axyridis (Sloggett et al., 2011). This paper focused on both the pure and applied aspects of this subject, including sections on: (1) chemical defence; (2) foods, feeding and reproduction; (3) H. axyridis chemistry, humans and human activity, and (4) future research perspectives.Harmonia axyridis' chemical defence is comprised of two alkaloids (harmonine and 3-hydroxypiperidin-2-one) and four methoxypyrazines. Based on assays of palatability and toxicity, it appears to be one of the most powerful chemical defence blends amongst ladybirds. There is some evidence that both harmonine and methoxypyrazine concentrations vary predictably with ladybird colour and pattern, although no such work has been carried out for 3-methoxypiperidin-2-one. Since our original review was published, the alkaloid harmonine has been shown to be a broad spectrum anti-microbial and powerful anti-malarial compound (Rörich et al., 2012).Our knowledge of food location in H. axyridis remains poor, although the ladybird appears to use multimodal cues, probably including chemical ones from both host plant and aphid prey. Like many other ladybirds, H. axyridis is deterred from oviposition by conspecific larval chemical cues. It is not deterred from oviposition by chemical cues from allospecifics, although in its native range other ladybird species avoid such cues from H. axyridis. This behaviour probably serves these species as a means of avoiding H. axyridis intraguild predation. Generally, H. axyridis ignores the deterrent hydrocarbon cues on the surface of ladybird egg intraguild prey and is little affected by intraguild prey defensive alkaloids, although a number of exceptions are known, especially in its invasive range.The habit of H. axyridis overwintering in large aggregations in buildings is not limited to its invasive range, although in its native range, such aggregations tend to be of very limited duration. Aggregations in buildings cause numerous problems, including the spotting of furnishings from reflex blood, allergic reactions in humans using the buildings and risks posed to pets or even children that may eat the ladybirds. Another problem caused by the abundance of H. axyridis is "wine taint", predominantly from methoxypyrazines, when the ladybirds are attracted to grape crops in autumn and are harvested and processed with the

Role of long-chain hydrocarbons in the aggregation behaviour of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)

“…Infestations of H. axyridis in dwellings have become increasingly problematic (Goetz, 2006;Dutau and Rancé, 2008), causing both annoyance from their number and allergic reactions (Nakazawa et al, 2007;Sloggett et al, 2011). Until now, the only recommended way to avoid these problems was physical removal of the aggregation.…”

“…Until now, the only recommended way to avoid these problems was physical removal of the aggregation. The use of attractants in traps would be more appropriate to control populations of this invasive species and easier to handle for householders (Sloggett et al, 2011). The blends collected during these experiments could be used in the design of such a trap.…”

Predators and parasitoids of the harlequin ladybird, Harmonia axyridis, in its native range and invaded areas

“…Potential of predators and parasitoids to limit H. axyridis numbers Harmonia axyridis is protected chemically against predation and more so than many other coccinellids (Sloggett et al 2011). Many laboratory assays indicate its higher toxicity and/or unpalatability compared to other members of aphidophagous guilds (ladybirds, lacewings) (Phoofolo and Obrycki 1998;Cottrell 2004;Sato and Dixon 2004;Kajita et al 2010;Nedvȇd et al 2010).…”

Detecting arthropod intraguild predation in the field

“…In GC-MS, distinctive prey chemicals or suites of chemicals are isolated from the predator in order to identify diet components (Knutsen and Vogt 1985;Becerro et al 2006). Because ladybirds possess taxonomically-specific defensive alkaloids (Daloze et al 1995), GC-MS of prey alkaloids in predator bodies is particularly appropriate for studying IGP of other ladybird species by H. axyridis (Hautier et al 2008;Sloggett et al 2009;Sloggett et al 2011) and to date are used in the only two published field studies on the ecological impact of H. axyridis (Hautier et al 2008;Hautier et al 2011). In addition to the above technique, the last decade has seen the development of a PCR DNA based approach to identifying the gut contents of predatory invertebrates (King et al 2008).…”

“…In general, DNA detection times are a few to many hours (McMillan et al, 2007;Greenstone et al, 2007), while detection using ELISA, can extend to days (Sopp and Sunderland, 1989;Symondson and Liddell, 1995). Results from GC-MS are highly variable, because target chemicals, especially defensive ones, can be broken down (Sloggett and Davis 2010;Sloggett et al 2011), sequestered or may remain in the predator as unmetabolised compounds. While Sloggett et al (2009) found that hippodamine from single H. convergens eggs persisted on average for 13.5 h in H. axyridis intraguild predators, Hautier et al (2008) found that adaline from a single A. bipunctata first instar larva could persist for many days.…”