Effect of fruit and host fly species on the associative learning by Fopius arisanus.

Parasitoids, released in augmentative biological control programmes, which display a rapid host-location capacity, have a higher likelihood of successfully controlling target pest species. By learning to associate sensory cues to a suitable oviposition site, might parasitoids used as biological control agents, locate hosts more rapidly, and perhaps increase the efficacity of e.g. Tephritidae fruit fly management. We studied associative learning of Fopius arisanus (Hymenoptera: Braconidae) and tested its range of learning in natural and conditional hosts and host fruits, i.e. Bactrocera dorsalis, Zeugodacus cucurbitae, Ceratitis capitata and Ceratitis cosyra (Diptera: Tephritidae) and on fruits (papaya, tomato, banana). Naïve female F. arisanus were compared with experienced wasps, which had been offered infested and non-infested fruit, and been allowed to oviposit. Preferences for olfactory cues from infested fruits were thereafter assessed in a two-choice olfactometer. Naïve and trained parasitoids preference differed in general and non-responders to infested fruits were higher among naïve parasitoids. The trained wasps preferred the fruit infested in the training more than the control fruit, for all combination, except when C. cosyra infested the fruits, hence avoidance behavioural response was observed towards the odour of the infested fruit. Fopius arisanus was capable of behaviourally respond to the learned information, e.g. associative odour learning was achieved, yet limited depending on interaction level, fruit fly and fruit combination. To create F. arisanus preference of an associated odour, it might hence be needed to ensure oviposition in perceived suitable host and host fruit, for the parasitoid learning to become favourable in a biological control setup.

Signal detection via residence-time asymmetry in noisy bistable devices.

We introduce a dynamical readout description for a wide class of nonlinear dynamic sensors operating in a noisy environment. The presence of weak unknown signals is assessed via the monitoring of the residence time in the metastable attractors of the system, in the presence of a known, usually time-periodic, bias signal. This operational scenario can mitigate the effects of sensor noise, providing a greatly simplified readout scheme, as well as significantly reduced processing procedures. Such devices can also show a wide variety of interesting dynamical features. This scheme for quantifying the response of a nonlinear dynamic device has been implemented in experiments involving a simple laboratory version of a fluxgate magnetometer. We present the results of the experiments and demonstrate that they match the theoretical predictions reasonably well.