THE EFFECT OF LABORATORY COLONY CONDITION ON THE TROPHALLACTIC INTERACTIONS OF CAMPONOTUS VAGUS (HYMENOPTERA: FORMICIDAE)

In this study, our aim was to give a detailed evaluation of the trophallactic interactions among foragers of Camponotus vagus in outside-nest situation, and to find out which properties of trophallaxis may have a role in the information-flow among workers about current nutritional state of the colony. Measured parameters were the number and frequency of trophallactic interactions, the duration of trophallaxes, the frequency of different duration interactions, and the number and size-class of workers participating in trophallactic events outside the nest. Experiments were conducted both with starved and satiated colonies to examine the effect of feeding condition. We demonstrated that the dynamics of trophallaxis is a stable parameter; it was independent from the starvation level. Similarly,the number of partners and the size class distribution of the different sized worker pairs did not differ between the two colony states. Starvation level influenced both the frequency and mean duration of trophallactic interactions. The frequency-distribution of the duration of trophallactic events showed an exponential trend, i.e., the short term interactions were more frequent than the prolonged ones in both colony states. However, the rate of these two distinguished types of trophallaxis was different in the case of the two colony conditions. Different rates of the short term and prolonged interactions may provide information about the current nutritional requirements of the colony, enhancing the speed and efficiency of colony responses to feeding stress. Frequent short term trophallaxis may not only contribute to a high level of cooperation during retrieval of food among foragers, but also maintain the integration of colony members even outside their nest

CLOSE NESTING ASSOCIATION OF TWO ANT SPECIES IN ARTIFICIAL SHELTERS: RESULTS FROM A LONG-TERM EXPERIMENT

Close nesting (real or quasi plesiobiosis) is the simplest form of spatial associations of heterospecific ant colonies that share the same microhabitat, but remain separate as individual units. We studied the tendency to close nesting between two ant species, Lasius psammophilus and Plagiolepis taurica, under slate plates used as artificial nesting sites during a 34 years long study period. 2410 nest records of 11 ant species were made under the plates, and a total of 181 close nesting associations were observed, most of which between L. psammophilus and P. taurica. The hypothesis of the weak antagonism between the two species was supported by (1) the rate of nesting associations, which was lower than expected from random probabilities; (2) the maximum of the index of avoidance, at intermediate densities; (3) the negative relationship between the unoccupied nesting shelters and the frequency of close nesting; (4) the tendency of individual and group level avoidance and (5) the low rate of interspecific aggression. The benefit of choosing favorable nesting sites and the risk of interspecific competition are in trade-off relation and the attractiveness of nesting shelters is the stronger constraint; therefore it can be regarded as the primary driver of the formation of spatial associations between the colonies of the two studied species

The Influence of Illumination Regimes on the Structure of Ant (Hymenoptera, Formicidae) Community Composition in Urban Habitats

The reliance on visual cues can vary among ant species living in different habitats, and is mostly influenced by the level of ambient illumination and the morphological adaptations of ant species that can determine their period of daily activity. Thus, different illumination regimes might affect ant community composition in habitats with different ambient illumination intensities. Despite this, in the literature, information is scarce about the effects of ambient illumination on ant activity. In the present study, we investigated the effect of ambient illumination intensity on the activity of ant species and their community composition under herbaceous and woody plants in 24 localities from Kyiv and Kyiv region, Ukraine. Our results showed that the ambient illumination properties of the habitat type affect the presence of ant species and the activity of their workers. In open habitats, the maximum ambient illumination had a negative effect, whereas in closed, woody habitats the maximum ambient illumination and tree circumference generally had a positive effect on the number of non-dendrobiotic ant individuals found on individual plants. The dendrobiotic species were less affected by the maximum illumination intensity. Although, in closed habitats, the effect of the previous variables and their interaction had species-specific aspects. Based on the former, we can tell that more structured forest habitats can provide broader illumination intensity ranges, allowing more ant species to coexist. However, similar illumination intensity ranges can lead to overlaps in the activity of ant species under the same illumination conditions, especially in open habitats. The outcomes of these interactions are highly influenced by larger trees that besides lowering illumination intensities, can enhance ant worker activity and promote species coexistence

The role of nature reserves in preserving saproxylic biodiversity: using longhorn beetles (Coleoptera: Cerambycidae) as bioindicators

The potential of forest nature reserves as refuges for biodiversity seems to be overlooked probably due to their small size. These, however, may constitute important safe havens for saproxylic organisms since forest reserves are relatively numerous in Europe. Saproxylic beetles are among the key groups for the assessment of biodiversity in forest habitats and longhorn beetles may play an important role in bioindication as they are ecologically associated with various micro-habitats and considered a very heterogeneous family of insects. To study the role of forest reserves as important habitats for saproxylic beetles, we compared cerambycid assemblages in corresponding pairs of sites (nature reserves and managed stands) in a forest region under high anthropogenic pressure (Upper Silesia, Poland, Central Europe). Moreover, we also intended to assess the role played by these beetles as bioindicators in the different forest types from this area. According to the obtained diversity index values, the most valuable stands are located in nature reserves, whilst sites with the lowest value included managed forests together with two homogeneous and relatively recently established nature reserves. Our analyses demonstrated a positive correlation between deadwood volume and biodiversity, for both species richness and abundance. Our results indicate that the decisive factor is the type of a given habitat, whose characteristics can be mainly influenced/determined by forest management. The potential role of longhorn beetles as bioindicators is highlighted and the effectiveness of using traps in this family, as well as general issues regarding the use of non-selective lethal traps in the study of single invertebrate groups in protected areas are discussed

Comparison of foraging tool use in two species of myrmicine ants (Hymenoptera: Formicidae)

Many ant species are known to exhibit foraging tool use, during which ants place various debris items (e.g., pieces of soil, leaves, pine needles, etc.) into liquid food, and then they carry the food-soaked tools back to the nest. In the present study, we compared the tool-using behavior in captive colonies of two closely related myrmicine ants with different feeding preferences: Aphaenogaster subterranea, an omnivorous species, and Messor structor, a mainly granivorous seed-harvester species. We supplied foraging ants with honey-water baits and six types of objects they could use as tools: sand grains, small soil grains, large soil grains, pine needles, leaves, and sponges. We found that the workers of A. subterranea both dropped more tools into honey-water baits and retrieved more of these tools than the workers of M. structor. While A. subterranea preferred smaller tools over larger ones, tool preferences for M. structor did not differ significantly from random. In addition, tool dropping was significantly faster in A. subterranea, and both the dropping and retrieving of tools began significantly earlier than in M. structor. For Aphaenogaster species that regularly utilize and compete for liquid food sources, the ability to efficiently transport liquid food via tools may be more important than it is for seed-harvester ants. Dropping tools into liquids, however, may still be useful for seed-harvester species as a means to supplement diet with liquid food during periods of seed shortage and also to serve as a means of getting rid of unwanted liquids close to the nest

Pollen as alternative source for submissive species in suboptimal circumstances

Insects are known to be the most important pollinators. However, ants are usually considered to be poor pollinators due to their negative effect on flowers and pollen survival. Plants apply various strategies to repell ants from flowers. Consequently pollen consumption is very rarely observed in ants, and, though they are omnivourus, ants are not commonly considered as pollenivores. In suboptimal circumstances, though, species might turn to sources rarely used before. Such suboptimal conditions may arise under strong competitive pressure, as the presence of a supercolonial territorial ant species. We studied the food preferences and competitive strategies of ants within a Formica polyctena supercolony in Central Polish woodland by offering them mixed pollen, and then tuna as animal protein source on the next day. F. polyctena was not interested in pollen baits almost at all, however, Myrmica spp. exploited them most heavily where next day F. polyctena was the most abundant on baits. In the case of the tuna baits there was a negative relationship between the abundance of F. polyctena and Myrmica spp. as predicted by the territorial behaviour of the first species. The results come to support the fact the pollen itself can be used as food source by ants mostly in suboptimal conditions, where food availability is hindered e.g. by superior competitors

Tool selection during foraging in two species of funnel ants

This work was supported by European Commission (FP7-MC-ERG-2009-256524 to PdE).Tool use by non-human animals has received much research attention in the last couple of decades. Nonetheless, research has focused mostly on vertebrates, particularly primates and corvids, even though tool use has also been documented in insects. One of the best documented examples involves ants using debris (e.g., sand grains, mud, leaf fragments) to collect and transport liquid food to their nest. However, little is known about the factors that determine the selection of materials to be used as tool. We investigated tool selection in two species of Aphaenogaster ants by giving them the choice between different kinds of potential tools (natural and artificial objects). Ant workers showed a clear preference for certain materials to be used as tool objects. Tool selection was also shaped by familiarity with the material as ants developed a preference for artificial tools with a good soaking capacity that cannot be found in their natural environment. Our results indicate that ants of this genus evolved unique foraging strategies and show plasticity in their behaviour.PostprintPeer reviewe