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Animals frequently have to decide between alternative resources and in social insects these individual choices produce a colony-level decision. The choice of nest site is a particularly critical decision for a social insect colony to make, but the decision making process has still only been studied in a few species. In this study, we investigated nest selection by the Pharaoh’s ant, Monomorium pharaonis, a species renowned for its propensity to migrate and its use of multi-component trail pheromones to organise decision-making in other contexts. When presented with the choice of familiar and novel nests of equal quality in a Y set-up, colonies preferentially migrated towards the familiar nest, suggesting a form of colony-level ‘memory’ of potential nest sites. However, if the novel nest was superior to the familiar nest, then colonies began migrating initially to the familiar nest, but then redirected their migration to the superior quality novel nest. This may be an effective method of reducing colony exposure while searching for an optimum nest site. Branches that had previously led to a selected nest were attractive to ants in subsequent migrations, suggesting that trail pheromones mediate the decision making process. The adaptive, pheromone-based organisation of nest-site selection by Pharaoh’s ants matches their ephemeral environment and is likely to contribute to their success as a 'tramp' species.

The Pharaoh's ant (Monomorium pharaonis), a significant pest in many human environments, is phenomenally successful at locating and exploiting available food resources. Several pheromones are utilized in the self-organized foraging of this ant but most aspects of the overall system are poorly characterised. Agent-based modelling of ants as individual complex X-machines facilitates study of the mechanisms underlying the emergence of trails and aids understanding of the process. Conducting simultaneous modelling, and simulation, alongside empirical biological studies is shown to drive the research by formulating hypotheses that must be tested before the model can be verified and extended. Integration of newly characterised behavioural processes into the overall model will enable testing of general theories giving insight into division of labour within insect societies. This study aims to establish a new paradigm in computational modelling applicable to all types of multi-agent biological systems, from tissues to animal societies, as a powerful tool to accelerate basic research.

Many ants use pheromone trails to organize collective foraging. This study investigated the rate at which a well-established Pharaoh's ant, Monomorium pharaonis (L.), trail breaks down on two substrates (polycarbonate plastic, newspaper). Workers were allowed to feed on sucrose solution from a feeder 30 cm from the nest. Between the nest and the feeder, the trail had a Y-shaped bifurcation. Initially, while recruiting to and exploiting the feeder, workers could only deposit pheromone on the branch leading to the feeder. Once the trail was established (by approximately 60 ants per min for 20 min), the ants were not allowed to reinforce the trail and were given a choice between the marked and unmarked branches. The numbers of ants choosing each branch were counted for 30 min. Initially, most went to the side on which pheromone had been deposited (80% and 70% on the plastic and paper substrates, respectively). However, this decayed to 50% within 25 min for plastic and 8 min for paper. From these data, the half-life times of the pheromone are estimated as approximately 9 min and 3 min on plastic and paper, respectively. The results show that, for M. pharaonis, trail decay is rapid and is affected strongly by trail substrate.

Faranal (1), the trail-following pheromone of the worker of Pharaoh's ant (Monomorium pharaonis), was synthesized by the coupling reaction of the iododiene 3 with the chiral building block 8 as the key step. The geometrically pure iododiene 3 was prepared by the zirconocene-mediated carboalumination reaction of 2 followed by treatment with iodine.

The infestation of the Pharaoh’s ant, Monomorium pharaonis L. is widespread and, sometimes, very serious in homes, hospitals, restaurants, factories, etc. People are helpless because effective baited traps are not available locally, and little has been done locally to develop effective control strategies for these ants. The study aimed at developing an appropriate bait system from local materials for the control of the Pharaoh’s ant. Nine baits and three insecticides were evaluated in the laboratory and field situations. Groundnut cake, dry fish and granulated sugar were the most attractive baits. Rimon (a Benzoylphenyl urea), an insect growth regulator, was the most promising insecticide for incorporation into the bait system. It is, therefore, recommended that a bait system, containing groundnut cake, sugar and dry fish, mixed with 1% Rimon, be evaluated for Pharaoh’s ant control.

In an institutional setting in Brazil, the pharaoh’s ant, Monornorium phuruonis was found to be the dominant and most abundant ant present throughout the year. The only other regularly collected ant was the exotic Tupinomu melunoce hufum. However, M. phuruonis dominated bait station visitations, although locally concentrated, wit[ other species restricted to regions in which M. phuruonis was not found.

The immature development of pharaoh's ant, Monomorium pharaonis, workers was studied in a naturally collected Brazilian population. Three larval instars were confirmed by measuring maximal cephalic widths in cohorts of known age. Minimum egg to adult duration was 25 days, while the maximum duration was 54 days, both of which are larger than those reported for European populations. Larval instar development is cyclical at the colony level, suggesting reproductive bursts followed by lower reproductive activity of the queens. Zusammenfassung Larvenstadien und Entwicklung einer brasilianischen Population der Pharao-Ameise, Monomorium pharaonis (L.) (Hym., Formicidae) Die Entwicklung der Pharao-Ameise, Monomorium pharaonis, wurde anhand einer in Brasilien gesammelten Population untersucht. Mittels Messung der maximalen Kopfkapselbreiten wurden 3 Larvalstadien festgestellt. Die minimale Ei-Adulten-Entwicklungszeit wurde mit 25 Tagen ermittelt, wahrend die Maximaldauer 54 Tage betrug. Beide Werte sind groser als die von europaischen Populationen bekannten. Die Larvalentwicklung verlauft im Kolonie-Bereich zyklisch, woraus hervorgeht, das Phasen starkerer Produktionskraft der Koniginnen mit solchen geringerer Produktion abwechseln.

The results from simple choice test experiments with laboratory and field colonies of pharaoh's ants have revealed two behavioural traits that influence the way in which foraging worker ants respond to foods. Initially, worker ants from laboratory colonies showed a distinct preference for certain foods (e.g. honey and peanut butter). However, when given only these ‘preferred’ foods continuously for several weeks, workers showed a marked preference for other foods when offered a choice. This ‘satiation’ response occurred even though the initial diet was originally highly attractive to foraging workers. In addition, workers show a marked tendency to alternate between carbohydrate foods and protein foods. Thus, workers from colonies fed predominantly on proteins, subsequently showed a marked preference for carbohydrates, and vice versa. The ‘satiation’ and ‘alternation’ responses to foods ensure that colonies receive a diet that is both varied and balanced. In addition, these aspects of feeding behaviour have important consequences for the use of food-based baits in control measures against Monomorium pharaonis (L.).

(3 S 4 R )-(+)-Faranal and its antipode were synthesized. The former was comparable in bioactivity with that of the natural pheromone.

SUMMARY Four isomers of 3-butryl-methyloctahydroindolizine (monomorine 1), a major component of the trail pheromone of Monomorium pharaonis, was tested for attractant and trail-initiating activity, One isomer showed attractancy and, under colony condition, tow initiated trail-following bahaviour. Only the all-cis isomer (monomorine 1a) had both attractant and trail-initiating activity. The results indicated that these compounds may have only limited potential for use in control measures against this species.

(+)-Faranal 1a , the trail pheromone of Pharaoh's ant, and its congener, (+)-13-norfaranal 1b were synthetized from chiral building block 4 employing diastereoselective carbon-carbon bond formation. The application of crude pig liver esterase enzyme for the preparation of 4 is also discussed.

(+)-Faranal 1 , the trail pheromone of Pharaoh's ant, was synthesized in 10 % overall yield starting from an easily available chiral building block 2 and employing diastereoselective carbon—carbon bond formation.

Fertile queens of the antMonomorium pharaonis produce a chemical substance which is not present in worker ants or in young, alate (virgin) queens. The material has been identified as (E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene (neocembrene). This chemical is produced in the Dufour's gland of fertile queens and may serve as a queen-recognition pheromone.

Laboratory colonies of Monomorium pharaonis (L.) were given access only to food containing the juvenile hormone analogue isopropyl-11-methoxy-3, 7, 11-trimethyl-dodeca-2, 4-dienoate (Altosid). In contrast to control colonies all the brood died in 4–8 weeks and queens ceased to lay eggs at about this time. Comparison of ovaries dissected from treated and untreated queens showed the former to be atrophied and without developing oocytes. In treated colonies the worker caste became extinct between 9 and 20 weeks after treatment commenced but queens remained alive for more than 20 weeks. Treatments were lethal with exposure periods of one week only. Juvenile hormone analogues show real potential for the control of M. pharaonis.

1. 1. Foraging workers of Monomorium pharaonis orientated to scent marks on the ground. The scent marks were laid by other workers when they were returning to the nest after finding food. Such successful foragers orientated to the nest partly by scent marks and partly by another orientation, probably a visual one. 2. 2. When a successful forager arrived in the nest it activated a small group of workers. These recruits followed a trail of scent laid by the scout, fed and returned to the nest by the same trail, reinforcing it with new scent. In the nest they activated more recruits. 3. 3. Recruits were not informed by the scout of the nature of the food to which they were recruited, nor of its distance from the nest. There was ao evidence that recruits became habituated to a particular kind of bait after feeding on it for 1–2 hours. 4. 4. When recruits were running on a system with two branch trails, the branch which they took appeared to be decided by chance. The abandonment of a trail which no longer led to food was probably due to the fading of the scent in the absence of successful foragers to reinforce it. 5. 5. The vestiges of the foraging trails formed a system of 1–4 trunk routes leading from the nest. One of these routes formed the proximal part of every scout's return path; hence this part of the route was continually reinforced with new scent and was constant in position. All; scouts left the nest along a route so that the distribution of scouts was related to the distribution of finds of food in the past.

Summary o 1. Experiments were carried out with populations of a queen and about eight workers of Monomorium pharaonis (L.) kept at constant temperature in very artificial conditions. Foodsharing occurred between the members of the group; workers fed the queen and each other, very rarely the queen fed a worker. The behaviour associated with food-sharing is described. The activity of the ants was variable and sometimes none of them moved for a few minutes, this inertia was broken by spontaneous movements of one ant which disturbed its neighbours. 2. When a new source of food (rabbit liver) was added the behaviour of the population altered. Foragers, who appeared to find the food by undirected search, returned to the nest and entered in an “excited” way, which is described. This excited behaviour caused all but one or two of the workers in the nest cell to leave the cell and feed at the liver. After a variable time the workers returned to the nest cell. The queen, who rarely foraged, was not fed at once by the returned workers, and often she solicited food without success for 20 minutes. 3. The methods by which Monomorium pharaonis workers communicate with one another are discussed in relation to those of other social insects. The significance of washing in their behaviour is also discussed.

(+)-Faranal 1 , the trail pheromone of Pharaoh's ant, was synthesized in 10 % overall yield starting from an easily available chiral building block 2 and employing diastereoselective carbon—carbon bond formation.

An assessment of the incidence of Pharaoh's ant infestations in NHS hospitals in England was made by analysing the answers to a questionnaire completed by domestic services and other hospital staff trained to recognize this insect. About half of all hospitals in England were covered by the survey and over 10 per cent were reported as infested. When the hospitals were allocated to their Health Districts, nearly half of those covered by the survey contained at least one infested hospital. The incidence or distribution of these ants could not be related to climatic or demographic factors but London and its suburbs were particularly heavily infested.

The ability of ants to reacting to sublethal high temperatures with production of gynandromorphs is reported for the first time. The abnormal forms produced in the pharaoh's ant range from ergatandromorphs to classical halfsidegynanders.

Racemic (3S,4R/3R,4S)-faranal [(1a)+(1b)] has been synthesised by a convergent, stereospecific route which employed the addition of alkylcopper complexes to terminal acetylenes, to generate two trisubstituted double bonds, and a Diels–Alder reaction to establish the relative stereochemistry of the C-3, C-4 methyl groups. A diastereoisomeric mixture of faranals, enriched in the (3S,4S/3R,4R)-enantiomeric pair [(1c)+(1d)], has been synthesised by a somewhat shorter route via an intermediate diester, obtained from electrochemical dimerisation of ethyl crotonate.

Recemic (3R, 4S/3S, 4R)-faranal, has been synthesised by a convergent, stereospecific route from (1E, 5Z)-1-iodo-2, 6-dimethylocta-1,5-diene in good overall yield; this synthesis employed the addition of alkylcopper complexes to terminal acetylenes to generate the two trisubstituted double bonds, and a Diels–Alder reaction to establish the relative configuration of the C-3, C-4 methyl groups.

Pharaoh's ant2 (Monomorium pharaonis Linn) is the smallest, reddishbrown ant, the most frequent ant invader, and the most difficult ant to eradicate of all species of ants occurring in Kansas homes. Several local invasions have proved to be very difficult to eradicate. The question arose as to whether there had been suggested any good control methods for this species other than those being used against them. In order to have available the widely scattered information about the life history, habits and control of this ant, it was decided to prepare a summary of the important available published accounts. It is believed that this paper includes all information of importance which has been published to date on this ant. Little attempt has been made to quote the author first suggesting any point of life history or control.