How to coexist with fire ants: The roles of behaviour and cuticular compounds

tBecause territoriality is energetically costly, territorial animals frequently respond less aggressively toneighbours than to strangers, a reaction known as the “dear enemy phenomenon” (DEP). The contrary,the “nasty neighbour effect” (NNE), occurs mainly for group-living species defending resource-basedterritories. We studied the relationships between supercolonies of the pest fire ant Solenopsis saevissimaand eight ant species able to live in the vicinity of its nests plus Eciton burchellii, an army ant predatorof other ants. The workers from all of the eight ant species behaved submissively when confrontedwith S. saevissima (dominant) individuals, whereas the contrary was never true. Yet, S. saevissima weresubmissive towards E. burchellii workers. Both DEP and NNE were observed for the eight ant species, withsubmissive behaviours less frequent in the case of DEP. To distinguish what is due to chemical cues fromwhat can be attributed to behaviour, we extracted cuticular compounds from all of the nine ant speciescompared and transferred them onto a number of S. saevissima workers that were then confronted withuntreated conspecifics. The cuticular compounds from three species, particularly E. burchellii, triggeredgreater aggressiveness by S. saevissima workers, while those from the other species did not

Dinomyrmex gigas (Latreille, 1802): a potential icon for Taman Negara Johor Endau Rompin

Dinomyrmex gigas (Latreille, 1802) is one of the largest ants in the world and the largest in Southeast Asia. It is also more commonly known as the giant forest ant. This large charismatic ant can be found in the forests of Southeast Asia, however it is not often sighted by the public due to its predominant nocturnal nature. Despite being considerably well studied compared to its smaller counterparts, most people know little about the giant forest ant beyond its large size. Most studies on this species focus on the populations found in Malaysia and Brunei characterizing many aspects of the natural history and biology of this species including its foraging behaviour, diet, territoriality, reproduction and colony structure. While much is known about the biology of this species, fragmented forest habitats may have an impact on the viability and behaviour of this majestic giant ant of the forest. This study involved insects’ viability observation and sampling of ant specimens. The results of observations showed that D. gigas is viable in Endau Rompin Johor National Park (TNJER). Then, various ecological aspects of D. gigas was investigated through field studies and secondary information. Due to its size and uniqueness this species has a potential to be developed into a nature tourism product for Malaysia. The present study elaborated to further discover its daily activity, nesting and defence behaviour which could be useful in developing it into a nature tourism product. As the species is also limited in distribution to undisturbed forest, the issue of its survival is discussed with relation to conservation of the tropical rainforest

Controlling invasive ant species: a theoretical strategy for efficient monitoring in the early stage of invasion

Invasion by the red imported fire ant, Solenopsis invicta Buren, has destructive effects on native biodiversity, agriculture, and public health. This ant's aggressive foraging behaviour and high reproductive capability have enabled its establishment of wild populations in most regions into which it has been imported. An important aspect of eradication is thorough nest monitoring and destruction during early invasion to prevent range expansion. The question is: How intense must monitoring be on temporal and spatial scales to eradicate the fire ant? Assuming that the ant was introduced into a region and that monitoring was conducted immediately after nest detection in an effort to detect all other potentially established nests, we developed a mathematical model to investigate detection rates. Setting the monitoring limit to three years, the detection rate was maximized when monitoring was conducted shifting bait trap locations and setting them at intervals of 30 m for each monitoring. Monitoring should be conducted in a radius of at least 4 km around the source nest, or wider --depending on how late a nest is found. For ease of application, we also derived equations for finding the minimum bait interval required in an arbitrary ant species for thorough monitoring.Comment: Revised the manuscrip

Anti-pheromone as a tool for better exploration of search space

Many animals use chemical substances known as pheromones to induce behavioural changes in other members of the same species. The use of pheromones by ants in particular has lead to the development of a number of computational analogues of ant colony behaviour including Ant Colony Optimisation. Although many animals use a range of pheromones in their communication, ant algorithms have typically focused on the use of just one, a substance that encourages succeeding generations of (artificial) ants to follow the same path as previous generations. Ant algorithms for multi-objective optimisation and those employing multiple colonies have made use of more than one pheromone, but the interactions between these different pheromones are largely simple extensions of single criterion, single colony ant algorithms. This paper investigates an alternative form of interaction between normal pheromone and anti-pheromone. Three variations of Ant Colony System that apply the anti-pheromone concept in different ways are described and tested against benchmark travelling salesman problems. The results indicate that the use of anti-pheromone can lead to improved performance. However, if anti-pheromone is allowed too great an influence on ants' decisions, poorer performance may result

H-ACO: A Heterogeneous Ant Colony Optimisation approach with Application to the Travelling Salesman Problem

This is the author accepted manuscript. The final version is available from the publisher via the link in this record.Ant Colony Optimization (ACO) is a field of study that mimics the behaviour of ants to solve computationally hard problems. The majority of research in ACO focuses on homogeneous artificial ants although animal behaviour research suggests that heterogeneity of behaviour improves the overall efficiency of ant colonies. Therefore, this paper introduces and analyses the effects of heterogeneity of behavioural traits in ACO to solve hard optimisation problems. The developed approach implements different behaviour by introducing unique biases towards the pheromone trail and local heuristic (the next hop distance) for each ant. The well-known Ant System (AS) and Max-Min Ant System (MMAS) are used as the base algorithms to implement heterogeneity and experiments show that this method improves the performance when tested using several Travelling Salesman Problem (TSP) instances particularly for larger instances. The diversity preservation introduced by this algorithm helps balance exploration-exploitation, increases robustness with respect to parameter settings and reduces the number of algorithm parameters that need to be set.We would like to thank the Faculty of Electronics and Computer Engineering (FKEKK), Technical University of Malaysia Malacca (UTeM) and the Ministry of Higher Education (MoHE) Malaysia for the financial support under the SLAB/SlAI program