Avoidance responses of an aphidophagous ladybird, Adalia bipunctata, to aphid‐tending ants

Abstract

1. Insect predators often aggregrate to patches of high prey density and use prey chemicals as cues for oviposition. If prey have mutualistic guardians such as ants, however, then these patches may be less suitable for predators. 2. Ants often tend aphids and defend them against predators such as ladybirds. Here, we show that ants can reduce ladybird performance by destroying eggs and physically attacking larvae and adults. 3. Unless ladybirds are able to defend against ant attacks they are likely to have adaptations to avoid ants. We show that Adalia bipunctata ladybirds not only move away from patches with Lasius niger ants, but also avoid laying eggs in these patches. Furthermore, ladybirds not only respond to ant presence, but also detect ant semiochemicals and alter oviposition strategy accordingly. 4. Ant semiochemicals may signal the extent of ant territories allowing aphid predators to effectively navigate a mosaic landscape of sub‐optimal patches in search of less well‐defended prey. Such avoidance probably benefits both ants and ladybirds, and the semiochemicals could be regarded as a means of cooperative communication between enemies. 5. Overall, ladybirds respond to a wide range of positive and negative oviposition cues that may trade‐off with each other and internal motivation to determine the overall oviposition strategy.

Effect of Formica aserva Forel (Hymenoptera: Formicidae) on ground dwelling arthropods in central British Columbia.

“…These behavioural patterns may support the findings of other studies that have found negative associations between ants and some carabids (Niemela et al, 1992;Koivula et al, 1999;Reznikova & Dorosheva, 2004;McColl, 2010). Our findings are also in agreement with other studies that have found that some insects are able to perceive and respond to signals o f ant presence (Offenberg et al, 2004;Oliver et al, 2008;Van Mele et al, 2009). …”

“…The mechanisms of such effects, however, are not known. Aggressive behaviour, e.g., as shown for the negative effect of Lasius niger L. ants on cocinellid beetles (Adalia bipunctata L.) (Oliver et al, 2008), is one possible mechanism. Some insects may also have the ability to detect the chemical signals associated with ants.…”

“…Some insects may also have the ability to detect the chemical signals associated with ants. For example, A. bipunctata beetles are able to adjust their behaviour in response to L. niger semiochemicals (Oliver et al, 2008), and Offenberg et al (2004) found that chrysomelid beetles (Rhyparida wallacei Baly) preferentially fed on leaves collected from trees absent of Oecophylla smaragdina …”

“…Gonsalves et al (2005) also found that predatory ants had a negative effect on termite activity, while non-predatory ants did not, suggesting that predation by ants may be an important disturbance factor in some ecosystems. In some cases, direct interactions with ants may not be required for them to influence other arthropods (Offenberg et al, 2004;Oliver et al, 2008). Artificially low Formica aquilonia Yarrow ant densities created by Laakso and Setala (2000) also resulted in increased activity of other predatory arthropods, which they described as a compensatory shift in the predatory invertebrate guild.…”

Intraguild Interactions

“…Consequently, non -myrmecophilous coccinellids frequently leave ant -attended aphid colonies, and may also avoid laying eggs in these patches (Oliver et al 2008 ).…”