Search results for "BASAL"

Impact of an invasive pest in local semiochemical networks

During the host location process, egg parasitoids rely on a series of chemical stimuli from the host/plant complex. In particular, in tritrophic systems consisting of plants, herbivorous stink bugs and their egg parasitoids, previous studies demonstrated that wasps are attracted by oviposition-induced plant volatiles (OIPVs). These compounds act as indirect plant defence mechanism allowing plants to recruit egg parasitoids, which are in general the most important natural enemies of stink bugs. Moreover, when wasps land on a plant, they can exploit chemical footprints left by male and female stink bugs walking on the leaves as indirect host-related cues, since chemicals lead them in an area …

Foraging behaviour of a scelionid egg parasitoid exploiting chemical footprints from associated and non-associated host

2017

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…

How can two competing egg parasitoid species coexist in a host patch?

2013

Interspecific competitions among parasitoids can affect community structures, and, as a consequence at applicative level, biological control programs. For example, competitions can cause local displacement of inferior species or niche separation. However, the coexistence of species attacking the same host is possible when they adopt different strategies to exploit the resource. In this work we evaluated in field and semi-field conditions intraguild interactions between two egg parasitoids, Trissolcus basalis and Ooencyrtus telenomicida exploring egg masses of Nezara viridula. In semi-field trials, pepper plants were covered with mesh net creating small cages with five plants inside. In each…

Leaf epicuticular waxes effects egg parasitoid’s response to host adult footprint contact kairomone

2009

Chemical footprints left behind by true bugs are perceived as a contact kairomones by scelionid egg parasitoids. In the system Nezara viridula and its egg parasitoid Trissolcus basalis, previous studies have shown that the kairomone mediating such behavior is part of N. viridula’s cuticular hydrocarbons. In this study, the effect of epicuticular waxes of leaves of broad bean, Vicia faba, on wasp response to footprints of N. viridula females are investigated. Plants with intact waxes layer were used (1) without host chemical contamination, or (2) contaminated by host female footprints. Mechanically de-waxed plants were tested (3) without host chemical contamination, or (4) de-waxed a few min…

Plant surface mediates interaction between true bug chemical footprints and scelionid egg parasitoids

2009

Chemical footprints left behind by true bugs act as contact kairomones inducing an arrestment response in scelionid egg parasitoids. Once in contact with contaminated substrates, female wasps display a characteristic arrestment posture followed by an increase of the host searching time. Previous studies were conducted on artificial substrates as filter papers, so that little is known about the effects of natural substrates on behavioural response by wasps. In field, the substrate where these interactions occur, i.e. the surface of plants, is covered by wax layers that can have a role in trophic interactions between insects. In this study, we investigated the influence of plant surfaces on a…

I semiochimici utilizzati nella localizzazione dell’ospite da parte del parassitoide oofago Ooencyrtus telenomicida

2009

Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) è un parassitoide oofago di Nezara viridula (L.) (Heteroptera: Pentatomidae) di origine paleartica frequentemente diffuso in Sicilia. Scopo del presente lavoro è stato quello di investigare il processo di localizzazione dell’ospite nel sistema tritrofico Solanum lycopersicum L. – N. viridula – O. telenomicida. In particolare sono stati condotti esperimenti in olfattometro a Y, per valutare il ruolo attrattivo dei composti volatili emessi sia dalle piante, sia dagli adulti della cimice verde, e in arena aperta, per biosaggiare. la risposta delle femmine del parassitoide alle tracce lasciate sul substrato dagli adulti di N. viridul…

Endogenous and exogenous factors affecting the host chemical footprint’s exploitation of an egg parasitoid

2013

During the host location process, parasitoids encounter and explore a great variety of volatile and contact semiochemicals from the host-plant complex. In the system Nezara viridula and its egg parasitoid Trissolcus basalis, when wasps land on a plant, they can taste chemical footprints left by walking adult hosts. These cues represent a set of indirect host-related contact kairomones that induce arrestment and motivated searching behavior, as they drive wasps in an area where there is a high probability of finding hosts but are not able to “promise” the presence of the suitable host stage. Patch time allocation is strongly modified by experience gained during foraging on host traces. In fa…

Intraguild interactions between two egg parasitoids of a true bug: from laboratory to field investigations

2011

Intraguild interactions can play a role in species coexistence and in sizing and shaping community structures. In addition, understanding how competitive interactions between parasitoid guilds can affect pest suppression may improve biological control. Interspecific competitive effects can be divided in “extrinsic competition”, the indirect interactions between adult females searching for or exploiting hosts, and “intrinsic competition”, the competition that occurs between larvae developing in the same host. In this work we performed both laboratory and field investigations to address on intraguild interactions occurring between Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus t…

Gli stimoli chimici indiretti dell'ospite nel processo di localizzazione da parte degli oofagi: conviene sintonizzarsi?

2008

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…

Semiochemical exploitation by two egg parasitoids,Trissolcus basalis and Trissolcus brochymenae (Hymenoptera: Scelionidae)

Chemo-orientation in egg parasitoids, a self-controlled movement in time and space, is led by volatile or substrate-borne chemicals distribution in the environment for purposes of locating host, food, mates and other resources. The perception of these chemical stimuli can be either from a distance by exploiting long-range infochemicals in the case of volatile chemoreception and/or upon contact with the cues when wasps are relatively close to the host in the case of contact chemo-reception by perceiving short-range infochemicals. In the present thesis, two different examples of chemo-orientation were treated. The first is an olfactory chemo-reception concerning Trissolcus basalis (Wollaston)…