0000000000138656
AUTHOR
E. Peri
Gli stimoli chimici indiretti dell'ospite nel processo di localizzazione da parte degli oofagi: conviene sintonizzarsi?
Tra gli stimoli indiretti che un parassitoide può utilizzare per ritrovare l'ospite, particolare importanze rivestono per i parassitoidi oofagi le tracce chimiche depositate dai Pentatomidi mentre si muovono su un substrato. Questo segnale chimico induce nelle femmine del parassitoide un comportamento di arresto che ne delimita la ricerca e ne aumenta le possibilità di ritrovamento delle uova. Nel sistema Murgantia histrionica (Heteroptera: Pentatomidae) - Trissolcus brochymenae (Hymenoptera: Scelionidae) si è voluto verificare se lo stato fisiologico dell’ospite influenza lo sfruttamento delle tracce da parte del parassitoide. I biosaggi sono stati condotti in arena aperta, e registrati me…
Foraging behaviour of a scelionid egg parasitoid exploiting chemical footprints from associated and non-associated host
Chemical footprints deposited by herbivorous pentatomid host bugs hosts when walking on the plant are adsorbed by leaf surfaces and perceived as substrate borne semiochemicals by scelionid egg parasitoids during host selection process. They act as indirect host-related cues, as they are not able to “promise” to parasitoid females the presence of the suitable host stage, but they drive them in the areas where their hosts are potentially present. Once in contact with host chemical footprints, scelionid wasps evidence an innate arrestment response characterized by an intense searching behaviour on host-contaminated areas. Exploiting of these cues allows the parasitoids to optimize their search…
Contrasting behavioural responses of two egg parasitoids to buckwheat floral scent is reflected in field parasitism rates
The use of food supplements in conservation biological control (CBC) programmes is considered an essential element for increasing parasitoid fitness and their population density leading to an increase in overall parasitism levels. However, non-crop habitats that substitute the necessary resources for natural enemies have not always achieved the desired effects. It is suggested that the composition of flower strips in agricultural systems around/in agricultural fields plays an important role because not all plant species are equally suitable and the consumption of food resources by parasitoids can shape direct and indirect interactions with other arthropods and the community complex. We deve…
Role of VOCs from Brassica oleracea in host location processes of Bagrada hilaris: electrophysiological and behavioral studies
The Painted bug, Bagrada hilaris Burmeister is an herbivorous insect native of Asia and Africa, invasive in Southern Europe and North America where it causes major damage on various vegetable crops mainly belonging to Brassicaceae family. Young plants at cotyledon stage of B. oleracea are particularly attractant and susceptible to B. hilaris feeding activity. To elucidate the main volatile organic compounds (VOCs) involved in the attraction of B. hilaris individuals toward the host plant B. oleracea, laboratory experiments were carried out using vertical Y-shaped olfactometer and electroantennographic techniques (EAG). Both adults and late nymphal instars were used in these experiments. Olf…
Environmental Noise and Nonlinear Relaxation in Biological Systems
We analyse the effects of environmental noise in three different biological systems: (i) mating behaviour of individuals of 'Nezara viridula' (L.) (Heteroptera Pentatomidae); (ii) polymer translocation in crowded solution; (iii) an ecosystem described by a Verhulst model with a multiplicative Lèvy noise. Specifically, we report on experiments on the behavioural response of 'N. viridula' individuals to sub-threshold deterministic signals in the presence of noise. We analyse the insect response by directionality tests performed on a group of male individuals at different noise intensities. The percentage of insects which react to the sub-threshold signal shows a non-monotonic behavior, charac…
Sexual communication in the egg parasitoid Trissolcus brochymenae
The males of the egg parasitoid Trissolcus brochymenae (Hymenoptera Scelionidae) exploit a short range pheromone for recognition of the other gender. To evaluate the role of this pheromone, the behavior of virgin males has been studied in closed arena when exposed to the following cues: 1) virgin females (alive, dead "washed" with solvents, dead" unwashed"); 2) dissected and re-assembled virgin females (females dissected into head, mesosoma, and gaster, then reassembled using two solvent "washed" parts and an "unwashed” part, or "unwashed" legs assembled with entire" washed" body); 3) "washed" females treated with acetone extracts (of virgin females and of legs). Males antennate and mount v…
Lures for red palm weevil trapping systems: aggregation pheromone and synthetic kairomone
[EN] BACKGROUNDThe optimisation of the lure is essential for the implementation of trapping systems to control insect pests. In this work, the response of the red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, to increasing emission rates of its aggregation pheromone (ferrugineol) and the efficacy of a convenient synthetic kairomone based on fermentation odours (ethyl acetate and ethanol) have been evaluated in different years and locations along the Mediterranean basin. RESULTSIn general, although capture data and emission had noticeable variability among locations, significantly fewer RPW were captured in pyramidal Picusan (R) traps with the lowest ferrugineol emission rates tested…
Il feromone sessuale a breve raggio del parassitoide oofago Trissolcus brochymenae
Il comportamento sessuale dei parassitoidi presenta una fase di pre-copula, in cui si ha ricerca, corteggiamento e riconoscimento dell’altro sesso, alla quale seguono le fasi di copula ed eventualmente post-copula. Durante la pre-copula, la localizzazione e il riconoscimento sono per lo più stimolati da composti feromonali con diversa volatilità. I composti feromonali ad alta volatilità, rilasciati dalle femmine, sono utilizzati dai maschi per l’orientamento a lunga distanza, mentre quelli scarsamente volatili mediano il comportamento di corteggiamento. In questo lavoro si riportano dati sperimentali sul feromone sessuale a breve raggio emesso dalle femmine di Trissolcus brochymenae (Hymeno…
The ovipositing female of Ooencyrtus telenomicida relies on physiological mechanisms to mediate intrinsic competition with Trissolcus basalis
Ongoing studies by our group showed that the outcome of the intrinsic competition between two solitary egg parasitoids, Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae), is dominated by O. telenomicida. In this article we investigated the role played by the ovipositing O. telenomicida female in the suppression of a T. basalis competitor. Laboratory experiments were conducted by allowing an O. telenomicida female to puncture the eggs of Nezara viridula (L.) (Heteroptera: Pentatomidae) with her ovipositor (= no oviposition) or to parasitize them. The results show that O. telenomicida relies on some physiological mechan…
Effetto del grado di coevoluzione e di specializzazione nella capacità di ooparassitoidi ad utilizzare le impronte chimiche dell'ospite
Le impronte chimiche lasciate sul substrato dai Pentatomidi stimolano nei parassitoidi oofagi la ricerca dell’ospite nell’area contaminata e consentono loro di distinguerne il sesso. Le impronte chimiche delle femmine sono preferite poiché risultano più affidabili in quanto nei dintorni è maggiore la probabilità di ritrovare l’uovo ospite. In questo lavoro è stato ipotizzato che l’abilità di discriminare il sesso degli ospiti da parte degli ooparassitoidi è stata acquisita solo nei confronti di quelli coevoluti. Sono state quindi considerate due associazioni di ospite-parassitoide coevoluti quali Nezara viridula-Trissolcus basalis e Murgantia histrionica-Trissolcus brochymenae e come ospite…
Single sensillum responses in Trissolcus basalis females to companion plant volatiles
In food resources location and selection, parasitoid females spend considerable time examining the substrate with their antennae, where chemosensory, mechanosensory and thermo-hygroreceptive sensilla exist. Olfaction and perception of plant volatiles play a basic role in recognition of nutritional resources. For Trissolcus basalis, an egg parasitoid of the green stink bug Nezara viridula, previous electroantennography and behavioural experiments tested the parasitoid’s response to extracted headspace volatiles and a synthetic blend of buckwheat volatiles indicated that T. basalis females have sensitive and selective olfactory responses some major buckwheat, Fagopyrum esculentum, flower vola…