Agnieszka Bugaj-Nawrocka

Invasive aphids of the tribe Siphini: a model of potentially suitable ecological niches

Sipha (Rungsia) maydis, Sipha (Rungsia) elegans, Sipha (Sipha) glyceriae and especially Sipha (Sipha) flava are considered to be virus vectors and serious pests of crops and pasture grasses. Ecological niche modelling, a useful tool for assessing potential geographical distributions of species, was used to predict the risk of invasion of these four species of the Siphini (Hemiptera, Aphididae) on a global scale. The maximum entropy model based on associations between unique occurrence localities and a set of environmental variables was used. Obtained models of potentially suitable habitats, based only on climatic variables, suggest that favourable conditions for each species may be present on every continent. However, S. (S.) flava appears to be potentially the most widespread species. Moreover, the resulting maps provide important information on the corridors by which invasive species are able to penetrate into new areas. A mean of the area under the receiver operating characteristic curve at the levels of 0.937, 0.947, 0.968, 0.937 for S. (R.) maydis, S. (R.) elegans, S. (S.) glyceriae and S. (S.) flava, respectively, indicated a high level of discriminatory power of the maximum entropy model. A jackknife test indicated that the precipitation of the coldest quarter with the highest gain value was the most important environmental variable restricting the expansion of the studied species.

Model of Potential Distribution of Platymeris rhadamanthus Gerstaecker, 1873 with Redescription of Species

BackgroundThe redescription of Platymeris rhadamanthus Gerstaecker, 1873 as well as the designation of lectotype and paralectotype, plus the prediction of the potentially suitable habitat was the main goal of this study. Our research were based on 262 specimens of museum collections of P. rhadamanthus species and a set of 23 environmental predictor variables, all recorded in a 1x1 km grid covering Africa. Ecological niche modelling was performed using the MAXENT analyses to produce predictive potential distribution maps for this species and its colour forms separately.ResultsThe results suggested the most suitable areas of distribution of P. rhadamanthus, both for species as a whole and also for the colour forms. A jackknife test showed that the precipitation of coldest quarter and herbaceous vegetation were the most important environmental variables affecting the distribution of P. rhadamanthus. After analyzing the climatic preferences, this species seems to be related mainly to the tropical savanna climate, subtropical highland variety of the oceanic climate and humid subtropical climate. An analysis of environmental variables also showed that this species prefers areas with herbaceous vegetation, with a small participation of trees, which is probably caused by food preferences of its victims.ConclusionsP. rhadamanthus so far was only known that it occurs in widely understood tropical Africa. On the base of the museum data on the occurrence of the species and ecological niche modelling methods we provided new and valuable information of the potentially suitable habitat, the possible range of distribution of the species and its climatic preferences.

Current and potential geographical distribution of Platymeris biguttatus (Linnaeus, 1767) with description of nymphs

BackgroundThe description of Platymeris biguttatus (Linnaeus 1767) nymphal instars as well as the prediction of the potentially suitable ecological niche was the main goal of this study. Our research was based on 258 specimens of P. biguttatus species of museum collections. A set of 23 environmental predictor variables covering Africa was used at ecological niche modeling - a method performed using the Maxent software to prepare potential distribution maps for this species.ResultsThe results suggested the most suitable areas seen as potentially suitable ecological niche for P. biguttatus in Africa. A jackknife test showed that temperature seasonality and percentage of tree cover were among the most important environmental variables affecting the distribution of the species. The analysis of climate preferences shows that most of the potentially suitable niches for this species were located in the area of tropical savanna climate, with a small participation of tree vegetation.ConclusionsP. biguttatus was only known to be widely distributed in the tropical part of continental Africa. Thanks to the ecological niche modeling methods and the museum data on the occurrence of the species, we introduced new information about potentially suitable ecological niches and the possible range of distribution.

Pine pest aphids of the genusEulachnus(Hemiptera: Aphididae: Lachninae): how far can their range extend?: Pine pest aphids of the genusEulachnus

Species of the aphid genus Eulachnus (Hemiptera, Aphididae), associated with pine trees, are an example of insects reported as rare over their native geographical range in Europe and serious pine pests far from their natural distribution. To predict the risk of invasion of spotted pine aphid Eulachnus agilis (Kaltenbach, 1843), green pine aphid Eulachnus brevipilosus Börner, 1940 and narrow brown pine aphid Eulachnus rileyi (Williams, 1911) on a global scale, ecological niche modelling was applied. We used the maximum entropy model, based on associations between unique occurrence localities and a set of environmental variables. We obtained models of potentially suitable habitats, based on climatic variables and distribution of host plants, suggesting that favourable conditions for each species may be present on every continent. However, E. agilis and E. rileyi appear to be potentially the most widespread species. In Europe, models showed that the potential distribution of the representatives of the genus Eulachnus overlapped with that of the host plants. In places where they have been introduced, these aphid species have readily adapted to indigenous or introduced pines, including trees grown commercially for timber. A jackknife test indicated that annual mean temperature and mean temperature of the coldest quarter were the most important environmental variables restricting the expansion of the species under investigation. Moreover, the most important factor in the decrease in population density of the feeding aphids is the rainy season and, on a smaller scale, the presence of their natural enemies.

Distribution Pattern and Climate Preferences of the Representatives of the Cosmopolitan Genus Sirthenea Spinola, 1840 (Heteroptera: Reduviidae: Peiratinae).

The main goal of this study was to predict, through the use of GIS tool as ecological niche modelling, potentially suitable ecological niche and defining the conditions of such niche for the representatives of the cosmopolitan genus Sirthenea. Among all known genera of the subfamily Peiratinae, only Sirthenea occurs on almost all continents and zoogeographical regions. Our research was based on 521 unique occurrence localities and a set of environmental variables covering the whole world. Based on occurrence localities, as well as climatic variables, digital elevation model, terrestrial ecoregions and biomes, information about the ecological preferences is given. Potentially useful ecological niches were modelled using Maxent software, which allowed for the creation of a map of the potential distribution and for determining climatic preferences. An analysis of climatic preferences suggested that the representatives of the genus were linked mainly to the tropical and temperate climates. An analysis of ecoregions also showed that they preferred areas with tree vegetation like tropical and subtropical moist broadleaf forests biomes as well as temperate broadleaf and mixed forest biomes. Therefore, on the basis of the museum data on the species occurrence and ecological niche modelling method, we provided new and valuable information on the potentially suitable habitat and the possible range of distribution of the genus Sirthenea along with its climatic preferences.

Geographical variation in morphology of Chaetosiphella stipae stipae Hille Ris Lambers, 1947 (Hemiptera: Aphididae: Chaitophorinae)

Chaetosiphella stipae stipae is a xerothermophilous aphid, associated with Palaearctic temperate steppe zones or dry mountain valleys, where there are grasses from the genus Stipa. Its geographical distribution shows several populations that are spread from Spain, across Europe and Asia Minor, to Mongolia and China. Geographical variation in chaetotaxy and other morphological features were the basis to consider whether individuals from different populations are still the same species. Moreover, using Ch. stipae stipae and Stipa species occurrences, as well as climatic variables, we predict potential geographical distributions of the aphid and its steppe habitat. Additionally, for Stipa species we projected current climatic conditions under four climate change scenarios for 2050 and 2070. While highly variable, our results of morphometric analysis demonstrates that all Ch. stipae stipae populations are one very variable subspecies. And in view of predicted climate change, we expect reduction of Stipa grasslands. The disappearance of these ecosystems could result in stronger separation of the East-European and Asian steppes as well as European ‘warm-stage’ refuges. Therefore, the geographic morphological variability that we see today in the aphid subspecies Ch. stipae stipae may in the future lead to speciation and creation of separate subspecies or species.

Are we witnessing speciation? A case study of the species Sirthenea flavipes (Stål, 1855) (Heteroptera: Reduviidae): Speciation of Sirthenea flavipes

During our previous morphological and molecular studies, as well as modelling the environmental niche preferences of the genus Sirthenea Spinola, (Peiratinae), the distribution of the species S. flavipes (Stål, ) became one of the most interesting issues. This species has a very broad distribution range covering the southern part of western, central and eastern Asia. We observed two distinct types of colouration, each also exhibiting a certain degree of variability. Although both colour forms of the studied species show similar variability, the differences between them are so clear that they allow distinction of two populations that are separated by a geographical barrier. Morphology and colour variability are described for representatives of both populations. Genetic studies support the use of the distributional model for individuals in both populations, as well as a characteristic distribution of colour forms. Models which identified potentially suitable habitats based solely on climatic variables are prepared for both populations, as well as for the entire species, and predicted for the Last Glacial Maximum period. An analysis of ecoregions shows that both populations prefer areas with tree vegetation, such as tropical and subtropical moist broadleaf forest biomes. Our studies show morphological divergence of these two discrete populations, reflecting an incipient stage of speciation.

Assassin bugs of the subfamily Diaspidiinae (Heteroptera: Reduviidae): distribution and potential ecological niches

The prediction and definition of the conditions for the potentially suitable ecological niche of the subfamily Diaspidiinae was the main goal of this study. Our research was based on 283 specimens of all known species of assassin bugs belonging to the subfamily Diaspidiinae stored in European museum collections and a set of 21 environmental variables in the form of a 1 × 1 km grid covering Africa and Madagascar. Based on occurrence localities, as well as a digital elevation model and layer of the tree cover‐continuous fields, information about the distribution of each species is given. Using Maxent software, potentially useful ecological niches were modeled, which allowed for the creation of a map of the potential distribution of the members of this subfamily and for determining their climatic preferences. A jackknife test showed that annual precipitation, annual temperature range and tree cover‐continuous fields were the most important environmental variables affecting the distribution of the subfamily Diaspidiinae. An analysis of climatic preferences suggested that the representatives of the subfamily were linked mainly to the tropical climate. An analysis of environmental variables also showed that the subfamily preferred areas with herbaceous vegetation and some trees, and this preference is probably caused by the food preferences of their prey. On the basis of the museum data on the species occurrence, as well as ecological niche modeling methods, we provided new and valuable information on potentially suitable habitat and the possible range of distribution of the subfamily Diaspidiinae along with its climatic preferences.