Search results for "Trissolcus basalis"

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)…

Outcomes of intraguild interactions between two egg parasitoids in field and semi-field conditions

2012

Intraguild interactions between two egg parasitoids, Trissolcus basalis (Wollaston) and Ooencyrtus telenomicida (Vassiliev) exploring egg masses of the Southern Green Stink Bug Nezara viridula (L.) were investigated in field and semi-field conditions. Field trials were conducted in tomato fields by using sentinel and naturally laid egg masses in 2010 and 2011. Egg parasitoids monitoring, by sentinel egg masses placed weekly on plants during the tomato growing season and recollected one week later, showed that T. basalis occurs from June to October, whereas O. telenomicida occurs mainly in July and August. In the same fields, collections of naturally laid egg masses display different types o…

Effect of dual biotic stress on plant volatile synomones used by egg parasitoids

2014

Studies on semiochemical communication have demonstrated that broad bean plant, Vicia faba, emits volatile synomones induced by feeding and oviposition activities of the southern green stink bug, Nezara viridula, which recruit the egg parasitoid Trissolcus basalis. However plants growing in agro-ecosystems can be attacked by several herbivore species that could affect both above and belowground plant tissues with possible consequences for parasitoid recruitment. For example, broad bean plants can also be attacked by the leaf weevil, Sitona lineatus, and simultaneous attacks by the southern green stink bug and the leaf weevil can occur in agro- ecosystems. The purpose of this work was to inv…

Sub-lethal effects of deltamethrin on walking behaviour and response to host kairomone of the egg parasitoid Trissolcus basalis.

2002

The lethal doses of the pyrethroid deltamethrin were estimated for the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae), and the sub-lethal effects of an LD25 on female walking behaviour were evaluated. Linear speed of treated parasitoids was reduced compared with that of untreated ones for a period of up to 24 h. The sub-lethal effects of deltamethrin on parasitoid response to patches contaminated by a contact kairomone from its host, Nezara viridula L (Heteroptera: Pentatomidae), was also evaluated. Both treated and untreated parasitoids responded to host-contaminated patches by increasing residence time and decreasing linear speed. However, treated females showed …

Intraguild interactions between two egg parasitoids exploring host patches

2010

Intraguild interactions between two egg parasitoids, Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Hymenoptera: Encyrtidae), exploring egg masses of the Southern Green Stink Bug (SGSB) Nezara viridula (Heteroptera: Pentatomidae), were investigated in laboratory conditions by single, simultaneous and sequential host attack experiments. Mortality of N. viridula eggs was higher in simultaneous and sequential releases compared to single species releases. In simultaneous host exploitations, T. basalis females displayed an aggressive behavior against O. telenomicida females. The outcome of multiparasitism showed that interspecific larval competition was dominated by O…

Host chemical footprints induce host sex discrimination ability in egg parasitoids

2013

Trissolcus egg parasitoids, when perceiving the chemical footprints left on a substrate by pentatomid host bugs, adopt a motivated searching behaviour characterized by longer searching time on patches were signals are present. Once in contact with host chemical footprints, Trissolcus wasps search longer on traces left by associated hosts rather than non-associated species, and, in the former case, they search longer on traces left by females than males. Based on these evidences, we hypothesized that only associated hosts induce the ability to discriminate host sex in wasps. To test this hypothesis we investigated the ability of Trissolcus basalis, T. brochymenae, and Trissolcus sp. to disti…

The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes.

2009

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves…