ABSTRACT
Gibellula (Cordycipitaceae, Hypocreales) is frequently observed growing on spiders, but little is known about their host range. One of the greatest challenges in describing these interactions is identifying the host, since the fungus often rapidly consumes the parasitised spiders and destroys important diagnostic taxonomic traits. Additionally, the global diversity of Gibellula remains unclear, as does the natural history and phylogenetic relationships of most of the species. Herein, we performed an extensive investigation on the species of Gibellula, reconstructed the most complete molecular phylogeny of the genus in the context of Cordycipitaceae, and performed a systematic review in order to provide the foundations towards a better understanding of the genus. Therefore, we have performed an integrative study to investigate the life history of the genus and to disentangle the questionable number of valid species proposed over time. We provided novel molecular data for published species that had not been sequenced before, such as G. mirabilis and G. mainsii, and evaluated all the original and modern morphological descriptions. In addition, we presented its global known distribution and compiled all available molecular data. We suggested a set of terms and morphological traits that should be considered in future descriptions of the genus and that a total of 31 species should be considered as accepted.
ABSTRACT
Strategies to invade and exploit hosts for survival are an essential part of the parasitic lifestyle. Species of the Polysphincta genus group (Hymenoptera: Ichneumonidae), which utilize spiders as hosts, are examples of parasitoids that present several behavioral strategies in host immobilization and egg laying. In this study, we characterized the oviposition behavior of the Darwin wasp Hymenoepimecis cameroni Townes, 1966 (Hymenoptera: Ichneumonidae) on their host spider, performed the taxonomic description of the female, and redescribed the male parasitoid. We observed eight H. cameroni females endeavoring to parasitize young Leucauge volupis (Keyserling, 1893) spiders. Each female made up to 12 successive attempts at oviposition, totaling 36 observed attacks, with only two successful attacks. The main oviposition behavior of H. cameroni individuals consists of flying close to the web and performing a direct attack on the spider, which often results in the spider escaping into the vegetation. We observed that in seven events where the spiders fled into the vegetation, the individuals of H. cameroni adopted a second strategy, which consisted of hanging from the hind legs in the web hub. This observation showed that the females of H. cameroni have the ability to modulate the oviposition strategy after a failure in the initial attack. The pattern observed for the attack of H. cameroni indicates that the ability to adjust the approach could be specific to the behavioral habits of L. volupis.
Subject(s)
Parasites , Spiders , Wasps , Animals , Female , Habits , Male , OvipositionABSTRACT
Some ichneumonid wasps of the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae) induce behavioral modifications in their host spiders during a specific moment of their development, resulting in the construction of webs that differ in several aspects from those constructed by unparasitized individuals. In this study, we describe the parasitoid wasp Hymenoepimecis pinheirensis sp. n. (Ichneumonidae: Pimplinae) and present information on behavioral modifications in the orb-web structure of its host, the spider Leucauge volupis (Keyserling 1893). Previously, reported observation on this host/parasitoid interaction was restricted to one locality, and the wasp species was misidentified as Hymenoepimecis jordanensis Loffredo and Penteado-Dias 2009. Modified webs built by parasitized spiders lack adhesive spirals and have several radii that converge to the web hub. The cocoon built by the wasp larvae is attached to the web hub, suspended by horizontal radial lines, and surrounded by a tridimensional tangle positioned below the hub. This modified web structure is similar to the most frequent architecture of webs constructed by individuals of Leucauge mariana (Taczanowski 1881) parasitized by Hymenoepimecis tedfordi Gauld 1991. However, cocoon webs built by L. volupis parasitized by H. pinheirensis sp. n. differ from the cocoon webs described for the other Leucauge species parasitized by Hymenoepimecis wasps. This evidence suggests that the modified web pattern in Leucauge species is determined by specific responses of each spider species to the behavioral manipulation mechanism displayed by the wasps.
Subject(s)
Host-Parasite Interactions , Spiders , Wasps , Animals , Larva , Spiders/parasitology , Wasps/physiology , Species Specificity , Behavior, AnimalABSTRACT
Eusocial insects interact with a diversity of parasites that can threaten their survival and reproduction. The amount of harm these parasites cause to their hosts (i.e., their virulence) can be influenced by numerous factors, such as the ecological context in which the parasite and its host are inserted. Leaf-cutting ants (genera Atta, Acromyrmex and Amoimyrmex, Attini: Formicidae) are an example of a eusocial insect whose colonies are constantly threatened by parasites. The fungi Escovopsis and Escovopsioides (Ascomycota: Hypocreales) are considered a highly virulent parasite and an antagonist, respectively, to the leaf-cutting ants' fungal cultivar, Leucoagaricus gongylophorus (Basidiomycota: Agaricales). Since Escovopsis and Escovopsioides are common inhabitants of healthy colonies that can live for years, we expect them to have low levels of virulence. However, this virulence could vary depending on ecological context. We therefore tested two hypotheses: (i) Escovopsis and Escovopsioides are of low virulence to colonies; (ii) virulence increases as colony complexity decreases. For this, we used three levels of complexity: queenright colonies (fungus garden with queen and workers), queenless colonies (fungus garden and workers, without queen) and fungus gardens (without any ants). Each was inoculated with extremely high concentrations of conidia of Escovopsis moelleri, Escovopsioides nivea, the mycoparasitic fungus Trichoderma longibrachiatum or a blank control. We found that these fungi were of low virulence to queenright colonies. The survival of queenless colonies was decreased by E. moelleri and fungus gardens were suppressed by all treatments. Moreover, E. nivea and T. longibrachiatum seemed to be less aggressive than E. moelleri, observed both in vivo and in vitro. The results highlight the importance of each element (queen, workers and fungus garden) in the leaf-cutting ant-fungus symbiosis. Most importantly, we showed that Escovopsis may not be virulent to healthy colonies, despite commonly being described as such, with the reported virulence of Escovopsis being due to poor colony conditions in the field or in laboratory experiments.
ABSTRACT
A new species of Cladochaeta Coquillett (Diptera: Drosophilidae) is described, C. caxiuana sp. nov. from the Brazilian Amazon, based on 10 male and 10 female specimens obtained from nymphs of Sphodroscarta trivirgata (Amyot Serville, 1843) (Hemiptera: Auchenorrhyncha: Aphrophoridae). The female of Cladochaeta atlantica Pirani Amorim, 2016 is described based on specimens reared from spider egg sacs of the spider Cryptachaea migrans (Keyserling, 1884) (Araneae: Theridiidae) obtained in the state of Espírito Santo, Brazil. This is the first record of this fly genus attacking a spider egg sac. The species Cladochaeta sororia (Williston, 1896) is recorded for the first time from Brazil, based on specimens collected in an urban garden in the Amazon. In addition, an unidentified female specimen of Cladochaeta Coquillett, 1900 was obtained from the cocoon of a spider wasp of the genus Notocyphus Smith (Hymenoptera: Pompilidae).
Subject(s)
Drosophilidae , Animal Structures , Animals , Brazil , Diptera , Female , Male , Spiders , WaspsABSTRACT
Some ichneumonid wasps induce modifications in the web building behavior of their spider hosts to produce resistant "cocoon" webs. These structures hold and protect the wasp's cocoon during pupa development. The mechanism responsible for host manipulation probably involves the inoculation of psychotropic chemicals by the parasitoid larva during a specific developmental period. Recent studies indicate that some spiders build cocoon webs similar to those normally built immediately before ecdysis, suggesting that this substance might be a molting hormone or a precursor chemical of this hormone. Here, we report that Cyclosa spider species exhibiting modified behavior presented higher 20-OH-ecdysone levels than parasitized spiders acting normally or unparasitized individuals. We suggest that the lack of control that spiders have when constructing modified webs can be triggered by anachronic activation of ecdysis.
