Phenotypic matching in ovipositor size in the parasitoid Galeopsomyia sp. (Hymenoptera, Eulophidae) attacking different gall inducers

ABSTRACT Parasitoid ovipositor size importantly affects host choice; those attacking exposed hosts usually have shorter ovipositors compared to those needing drilling deeper through substrates such as plant tissue and gall tissue. Most studies treat this theme at the interspecific level, and the aim of this work was to test for intraspecific variation and phenotypic matching in ovipositor size for Galeopsomyia sp. attacking galls. Galls were sampled from Guapira opposita(Nyctaginaceae), a host plant to five species of Bruggmannia gallers (Diptera, Cecidomyiidae) in southern Brazil: Bruggmannia elongata, B. robusta, B. acaudata, and two undescribed species of Bruggmannia (sp. 1 and sp. 2). On forest transects, all galls from the 30 first galled plants found were sampled and kept in sealed plastic bags until parasitoid emergence. A total of 15 samples were done along two years. We measured galler last instar larvae length and gall thickness for each galling species, and ovipositor length for all Galeopsomyia sp. individuals emerging from the galls. There were no differences in larval length among galler species. However, Bruggmannia sp. 1 and sp. 2 galls were significantly thicker than those of B. acaudata, and the latter thicker than both B. elongata and B. robusta galls. Wasp ovipositor size differed significantly between those coming from Bruggmannia sp. 1 and sp. 2 galls relative to all others. Host extended phenotype size is thus fundamental to determine parasitoid size, but in this case host (larval) size does not change among species, although gall thickness was different. Thicker galls were attacked by larger parasitoids with longer ovipositors, denoting phenotypic matching. Thicker galls appear to be selecting larger parasitoid individuals, which in the long run can lead to important evolutionary change as well.

Philogenia gaiae sp. nov. (Zygoptera: Philogeniidae) and description of the female of P. macuma Dunkle, 1986, two species from the Ecuadorean lowland rainforest

Philogenia gaiae sp. nov. (Holotype ♂, Ecuador, Orellana, Tiputini Biodiversity Station, -0.6349, -76.1501, 241 m, 13 xii 2012, A. Cordero-Rivera & M. Sánchez-Herrera leg., in MUAE) from the helena group is described, illustrated, diagnosed and compared with morphologically close species of the genus. Philogenia gaiae can be distinguished from its most similar congener P. minteri Dunkle, 1986 by the enlarged cerci and the club-like paraprocts. We also describe the female of P. macuma Dunkle, 1986, from a pair collected at Jatún Sacha Biological Reserve, which is also similar to P. gaiae and can be distinguished by the intersternite morphology, ovipositor length and vulvar lamina shape.

Influence of Distance from the Host on Parasitisation by Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae)

The olive fruit fly, Bactrocera oleae, is considered the main olive pest worldwide, and has been the target of biological control programmes through the release of the braconid parasitoid Psyttalia concolor. Laboratory tests were performed to evaluate the influence of distance from the host on parasitisation, placing larvae of the substitute host Ceratitis capitata at seven distances (0, 0.5, 1, 1.5, 2, 2.5, 3 mm) and four different time periods (7, 15, 30, 60 min). Moreover, field collected olives of Ogliarola Barese cultivar infested by B. oleae were exposed to P. concolor females to confirm its ability to parasitise B. oleae in small olives. Psyttalia concolor oviposition was inhibited at 2.5 and 3 mm due to the ovipositor length of the parasitoid females (2.7 mm). Hosts were easily parasitised at distances between 0 and 1.5 mm. The thin fruit pulp (up to 3.5 mm) of field collected olives allowed the parasitisation to occur also in mature fruits. At the best combination distance/time (0 mm, 30 min), tests performed with different larvae/parasitoid female ratio showed an increasing emergence of P. concolor (from 20% to 57%) with larvae/parasitoid ratio increasing from 0.11 to 0.74. The results of the present study might optimise the mass rearing of P. concolor, through a proper setting of its parameters, such as the host/parasitoid ratio, exposure distances, and interaction time.

Evolution of ovipositor length in Drosophila suzukii is driven by enhanced cell size expansion and anisotropic tissue reorganization

Morphological diversity is dominated by variation in body proportion. Yet the cellular processes underlying differential growth of morphological traits between species remain largely unknown. Here we compare the ovipositors of two closely related species, Drosophila melanogaster and D. suzukii. D. suzukii has switched its egg-laying niche from rotting to ripe fruit. Along with this shift, the D. suzukii ovipositor has undergone a significant change in size and shape. Using an allometric approach we find that, while adult ovipositor width has hardly changed between the species, D. suzukii ovipositor length is almost double that of D. melanogaster. We show that this size difference mostly arises during a 6-hour time window in the middle of pupal development. We observe that the developing ovipositors of the two species comprise an almost identical number of cells, with a very similar profile of cell shapes and orientations. After cell division stops, we find that the ovipositor area continues to grow through the isotropic expansion of cell apical area. Remarkably, at one point, the rate of cell apical area expansion is more than 4 times faster in D. suzukii than in D. melanogaster. In addition, we find that an anisotropic cellular reorganization of the developing ovipositor results in a net elongation of the tissue, despite the isotropic expansion of cell size, and is enhanced in D. suzukii. Therefore, the quantitative fine-tuning of shared, morphogenetic processes -the rate of cell size expansion and the cellular rearrangements–can drive macroscopic evolutionary changes in organ size and shape.

Biased parasitoid sex ratios: Wolbachia, functional traits, local and landscape effects

Adult sex ratio (ASR) is a demographic key parameter, being essential for the survival and dynamics of a species populations. Biased ASR are adaptations to the environment on different scales, resulted by different mechanisms as inbreeding, mating behaviour, resource limitations, endosymbionts such as Wolbachia, and changes in density or spatial distribution. Parasitoid ASRs are also known to be strongly biased. But less information is available on large scale variable effects such as landscape composition or fragmentation. We aimed to study whether the landscape scale does affect the ASR of parasitoids belonging to the same tritrophic gall inducer community. We examined effects of characteristics on different scales as functional trait, local and landscape scale environment on parasitoid ASR. On species level ovipositor length, on local scale resource amount and density, while on landscape scale habitat amount, land use and landscape history were the examined explanatory variables. We controlled for the incidence and prevalence of Wolbachia infections. Parasitoid ASR is best explained by ovipositor length: with which increase ASR also increases; and available resource amount: with the gall diameter increase ASR decreases. On large scale the interaction of functional traits with habitat size also explained significantly the parasitoid ASRs. Our results support the hypothesis that large scale environmental characteristics affect parasitoid ASRs besides intrinsic and local characteristics.

Genetic and morphometric variations in the Lebanese populations of the flower-head-infesting fruit fly, Terellia serratulae (Diptera: Tephritidae)

The polyphagous fruit fly, Terellia serratulae (Linnaeus) (Diptera: Tephritidae), exploits hosts belonging to three genera of thistles: Carduus Linnaeus, Cirsium Miller, and Picnomon Adanson (Asteraceae). The difference in phenology among its hosts suggests intraspecific variation. Comparative morphometric and genetic studies revealed differences among its populations. Adults reared from different hosts showed intraspecific morphological variations. Canonical discriminant analysis based on two head and four wing measurements divided the adults into four distinct clusters with 70% accuracy, reflecting four host-associated populations. The most useful predictors in distinguishing adults associated with the different host plants were wing width and head length, in addition to ovipositor length for females. Only the ovipositor tip in females reared from Picnomon acarna (Linnaeus) Cassini was clearly distinct. Mitochondrial DNA sequencing revealed genetic differentiation among the different populations of T. serratulae with the P. acarna-associated population being most distinct. Sequencing a region of the mtND1 gene and mtCOXI gene revealed nine and seven haplotypes, respectively. Surprisingly, haplotype sequences of flies emerging from P. acarna showed a sequence divergence of over 3% for both genes. This study provides morphometric and molecular evidence supporting that the Lebanese T. serratulae population associated with P. acarna most likely constitutes a distinct host race.