Search results for "Parasitism"

Host detection and rate of parasitism by Acroricnus seductor (Hymenoptera: Ichneumonidae), a natural enemy of mud-dauber wasps (Hymenoptera: Sphecida…

2011

Abstract The behavioural ecology of ichneumonid wasps that attack aculeate Hymenoptera is still largely unknown. Field observations and morphological analyses were devoted to investigate host detection and rate of parasitism by Acroricnus seductor (Scopoli), a natural enemy of the black and yellow mud dauber wasp Sceliphron caementarium (Drury). At the study site, about half of the host nests suffered parasitism by A. seductor. No significant difference was found between the rate of parasitism in sheltered (inside human building) and unsheltered (outside building) nests. Larger nests did not suffer a higher rate of parasitism, and larger brood cells were not more likely to be parasitized. …

Parabiotic ants: the costs and benefits of symbiosis

2014

1. Mutualisms are important drivers of co-evolution and speciation. However, they typically imply costs for one or both partners. Each partner consequently tries to maximise benefits and minimise costs. Mutualisms can therefore develop towards commensalism or parasitism if one partner fails to provide sufficient benefits. This is particularly likely in diffuse interactions, where multiple species can associate with each other. If costs and benefits of a species vary with the identity of the partner species, this may result in a geographical mosaic of co-evolution. 2. In the present study, inter-specific interactions in two parabiotic associations of ants were studied (Hymenoptera: Formicida…

Parasite Infection and Host’s Behavior

2010

Animal behavior and parasitism are more tightly linked, from an ecological and evolutionary point of view, than commonly thought. In the past 30 years, the growing field of evolutionary parasitology has tackled both proximate and ultimate answers to the following question: Why and how should the behavior of hosts exposed to the risk of a disease or that of parasitized hosts be altered? Altered behavior may simply be a symptom of disease without obvious connection with host resistance or parasite-transmission strategies. However, natural selection may have shaped behavior to avoid infection, get rid of parasites, or limit their pathogenicity. Alternatively, manipulative parasites may alter t…

Build up of patches caused by Rhizoctonia solani

2010

Rhizoctonia solani is a complex species that is composed of different anastomosis groups (AG). Although these different AGs show differences in their host ranges, generally R. solani is a phytopathogenic species with a wide spectrum of hosts. It has the ability to grow as a saprotroph, which further complicates its behaviour as a parasite. The losses caused by R. solani are very important and need a sustainable management strategy. The patchy appearance of the disease caused by this pathogen is well-known. The patches show within and between season dynamics. The factors which affect the spread of the disease can be grouped into three main categories: host plant, pathogen and environment. Ho…

Interactive effects of parasitism and predation on the behaviour of the amphipod Pallasea quadrispinosa

2006

Collective defence portfolios of ant hosts shift with social parasite pressure

2014

Host defences become increasingly costly as parasites breach successive lines of defence. Because selection favours hosts that successfully resist parasitism at the lowest possible cost, escalating coevolutionary arms races are likely to drive host defence portfolios towards ever more expensive strategies. We investigated the interplay between host defence portfolios and social parasite pressure by comparing 17 populations of two Temnothorax ant species. When successful, collective aggression not only prevents parasitation but also spares host colonies the cost of searching for and moving to a new nest site. However, once parasites breach the host's nest defence, host colonies should resor…

First record of Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) parasitizing pupae of Ceratitis capitata (Wiedemann) (Diptera: Tephr…

2015

The Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) (Diptera : Tephritidae), isone of the most devastating pests of fruits and vegetables worldwide (Liquido et al. 1991; Chueca et al. 2007). It is the most invasive species of all members of the Tephritidae (Zucchi 2001) and a key pest of citrus and other fruits in the Mediterranean countries, including Tunisia (Enkerlin & Mumford 1997; Jerraya 2003). Serious economic damage is caused by this insect in Tunisia; in mixed fruit cultivation crop losses can be from 80 to 100% (Jerraya 2003). Citrus is the most affected host crop, with direct annual losses attributed to C. capitata of up to 38% of annual income from Tunisian citr…

Patterns of cercarial production from Diplostomum spathaceum: terminal investment or bet hedging?

2004

In the production of the infective cercariae of trematodes, the terminal investment hypothesis of life-history theory predicts that the rate of host exploitation and cercarial production should increase during the period of cercarial shedding since the reproductive value of the parasite decreases during this period. In contrast, a bet hedging hypothesis that focuses on the success of transmission when host contact rate is variable predicts that cercarial production should decrease in an attempt to keep the host alive for longer and thus would increase the probability of successful transmission. We examined these two hypotheses under laboratory conditions and recorded the production ofDiplos…

Investigationes on population dynamics and mortality of Phyllocnistis citrella in western Sicily (Italy)

2006

Population dynamics and mortality of P. citrella, and its natural enemies with parasitism levels in two different citrus orchards, sprayed and unsprayed, were investigated. The effect of host density on percentage parasitism and mortality was calculated by regression analyses. In both sites, over the 3-years period from 2002 to 2004, P. citrella was detected during the summer months and it was not found during the first flush. Population levels were low, never exceeding 3.0/leaf. P. citrella began to increase from June in 2002-2003 and from July in 2004. The monthly percentage parasitism of P. citrella in sprayed orchard fluctuated from 0 to 19%, while in unsprayed from 0 to 30%. High morta…

Learning can be detrimental for a parasitic wasp

2021

Animals have evolved the capacity to learn, and the conventional view is that learning allows individuals to improve foraging decisions. The parasitoid Telenomus podisi has been shown to parasitize eggs of the exotic stink bug Halyomorpha halys at the same rate as eggs of its coevolved host, Podisus maculiventris, but the parasitoid cannot complete its development in the exotic species. We hypothesized that T. podisi learns to exploit cues from this non-coevolved species, thereby increasing unsuccessful parasitism rates. We conducted bioassays to compare the responses of naïve vs. experienced parasitoids on chemical footprints left by one of the two host species. Both naïve and experienced …