Behavioral strategies underlying pheromone-modulated flight in moths: lessons from simulation studies

Several mechanisms have been proposed to underlie the characteristic `zigzag' tracks produced by moths flying up an odor plume. To test which, if any, of these are capable of reproducing the animals' behavior, we constructed behavioral-level simulations. The simulations are as tightly constrained as possible by the known biology, and incorporate realistic physical effects such as air turbulence, and delays due to sensory transduction and axonal condition, to mimic the dynamics of sensory information encountered by real moths. Formulated as schemas, the models all share a common set of sensory and motor systems, but differ in the interposed control systems. We analyzed the behavior of the models with the same methods we use for real moths. Even the simplest of the models was capable of successful orientation some of the time, and of producing flight tracks similar to those of moths. Individuals which succeeded in tracking the odor plume produced average behavior not significantly different from that of real moths. As a population, however, none of the models was as successful as the moths. The best of the models had a success rate in tracking the plume of about 30%, compared to the average of 70% seen in the insects. Accepted: 25 March 1998     

Competing species model with behavioral adaptation

This paper studies the properties of a modified Lotka-Volterra model for two competing species, in which the coefficients of the interaction terms are time-dependent averages of the level of interaction over the entire past. For this model, it is shown that (1) competitive exclusion does not occur, (2) there are two possible stable equilibrium points, and (3) in a certain region of parameter space numerical simulations suggest the existence of interesting oscillatory solutions.     

Cost effectiveness in captive management

The purpose of this paper is to encourage recognition that economic constraints are of paramount importance to all management decisions. An early acceptance of this fact minimizes the disastrous effects of those constraints. Each decision considered, whether research, conservation, education, or management, must be approached with cost effectiveness as a primary component of its developmental phases.     

Sample Optimization for Five Plant-Parasitic Nematodes in an Alfalfa Field

A data base representing nematode counts and soil weight from 1,936 individual soil cores taken from a 7-ha alfalfa field was used to investigate sample optimization for five plant-parasitic nematodes: Meloidogyne arenaria, Pratylenchus minyus, Merlinius brevidens, Helicotylenchus digonicus, and Paratrichodorus minor. Sample plans were evaluated by the accuracy and reliability of their estimation of the population and by the cost of collecting, processing, and counting the samples. Interactive FORTRAN programs were constructed to simulate four collecting patterns: random; division of the field into square sub-units (cells); and division of the field into rectangular sub-traits (strips) running in two directions. Depending on the pattern, sample numbers varied from 1 to 25 with each sample representing from 1 to 50 cores. Each pattern, sample, and core combination was replicated 50 times. Strip stratification north/south was the most optimal sampling pattern in this field because it isolated a streak of fine-textured soil. The mathematical optimmn was not found because of data range limitations. When practical economic time constraints (5 hr to collect, process, and count nematode samples) are placed on the optimization process, all species estimates deviate no more than 25 % from the true mean. If accuracy constraints are placed on the process (no more than 15% deviation from true field mean), all species except Merlinius required less than 5 hr to complete the sample process.     

First report of computational protein–ligand docking to evaluate susceptibility to HIV integrase inhibitors in HIV-infected Iranian patients

BackgroundIran has recently included integrase (INT) inhibitors (INTIs) in the first‐line treatment regimen in human immunodeficiency virus (HIV)-infected patients. However, there is no bioinformatics data to elaborate the impact of resistance-associated mutations (RAMs) and naturally occurring polymorphisms (NOPs) on INTIs treatment outcome in Iranian patients.MethodIn this cross-sectional survey, 850 HIV-1-infected patients enrolled; of them, 78 samples had successful sequencing results for INT gene. Several analyses were performed including docking screening, genotypic resistance, secondary/tertiary structures, post-translational modification (PTM), immune epitopes, etc.ResultThe average docking energy (E value) of different samples with elvitegravir (EVG) and raltegravir (RAL) was more than other INTIs. Phylogenetic tree analysis and Stanford HIV Subtyping program revealed HIV-1 CRF35-AD was the predominant subtype (94.9%) in our cases; in any event, online subtyping tools confirmed A1 as the most frequent subtype. For the first time, CRF-01B and BF were identified as new subtypes in Iran. Decreased CD4 count was associated with several factors: poor or unstable adherence, naïve treatment, and drug user status.ConclusionAs the first bioinformatic report on HIV-integrase from Iran, this study indicates that EVG and RAL are the optimal INTIs in first-line antiretroviral therapy (ART) in Iranian patients. Some conserved motifs and specific amino acids in INT-protein binding sites have characterized that mutation(s) in them may disrupt INT-drugs interaction and cause a significant loss in susceptibility to INTIs. Good adherence, treatment of naïve patients, and monitoring injection drug users are fundamental factors to control HIV infection in Iran effectively.     

Magnetic and other non-visual orientation mechanisms in some cave and surface urodeles

Animals adapted to light-deprived habitats might have improved non-visual sensory systems. Specimens of several cave-dwelling species of urodeles spontaneously and persistently align to natural or artificially-modified permanent magnetic fields. Video observations under dim infrared illumination revealed an obvious individual preference for one particular magnetic direction in every animal tested. Therefore, animals changed alignments predictably when the horizontal magnetic field vector (compass direction) was artificially reversed or deviated. When the vertical vector was compensated, individuals aligned axially. With the vertical vector reversed (inclination upward), either axial alignment was still typical, or the individuals behaved as with the horizontal vector reversed. However, reactions as to the natural field occurred as well. The findings suggest a receptor mechanism that needs both horizontal and vertical magnetic cues, but it is still an open question how and where the physical and physiological mechanisms of magnetic transduction and reception are realized. The visual system is likely not necessary because Proteus is ontogenetically deprived of eyesight, and the other species were blindfolded due to the faint infrared illumination. The results therefore tend to favor those putative receptor mechanisms, assumed to work by means of magnetite nano-elements. In sum, the ability to align within the geomagnetic field may be considered a prerequisite for magnetic orientation and is, among other sensory improvements, judged to be highly relevant as an important sensorial and ecological adaptation to light-deprived habitats.     

Natural Resource Management: Historical Lessons from Indonesia

This paper uses a variety of historical evidence from Indonesia to explore the conditions for sustainable management of natural resources. In the agricultural sphere, history gives reason for optimism regarding the ability of individuals to conserve and improve soil resources on an uncoordinated, anarchic basis under systems of intensive smallholder farming and agroforestry. It also suggests that this ability may be enhanced, rather than eroded, both by population growth and by the commercialization of agriculture. When it comes to the management of forests and fisheries and the conservation of nature, by contrast, there is less reason for optimism. If sustainable solutions are to be found in these spheres, the historical evidence suggests that they will involve political hierarchy, and will depend on the honouring of a social contract in which the state serves the public interest while retaining the powers of coercion which it needs in order to do just that.     

Ecological engineering: First steps towards economic analysis

Ecosystems fulfill a large number of ecological and economic functions. Increasing economic activity and population pressure are threatening the quality of ecosystems, and strengthen the need for ecological engineering. In this article some of the economic aspects of ecological engineering are discussed. In particular, the various methods to establish the economic costs and benefits of ecological engineering. For benefit estimation various methods are developed, including the contingent valuation method, the hedonic pricing method, the travel cost method and the shadow project method. The economic background, and the applicability and appropriateness of these methods are discussed. Next, the results of several studies on wetland valuation are shortly presented. It is concluded that the full socio-economic assessment of ecological engineering is still to be developed, and that further cooperation between ecologists and economists is required to make progress in this field that is rapidly gaining importance in policy making, both at the European and the global level.     

Context dependence of personalities: risk-taking behavior in a social and a nonsocial situation

Individuals of many species differ consistently in their behavioralreaction to mild novel challenges. Suites of these behaviorsare referred to as behavioral syndromes or personalities. Personalitytraits are often phenotypically and genetically correlated.Therefore, animal personalities are generally considered asbroad characteristics, with one underlying genetical and physiologicalmechanism that is expressed across situations and contexts.Because there are carryover effects between situations, animalsare not entirely flexible in their behavior in each situation.This may cause behaviors to seem nonadaptive in isolated situations.To test whether individuals with different personalities couldreact differently to changes in their environment, we studiedcontext dependence of personalities in the great tit (Parusmajor). We tested birds categorized as either fast or slow explorersfor their latency to come back to a feeding table after a mildstartle (risk-taking behavior) in a nonsocial followed by asocial context. We found that the relation between exploratorybehavior and risk-taking behavior depended on the social context.Females in general returned later in the social test, whilemale reaction to the presence of a conspecific was dependenton their behavioral type. Slow males thereby reacted to thebehavior of the companion and fast males did not. These resultsshow that although personalities have a rigid structure therelation between personality traits is context dependent. Theseresults are discussed in the perspective of the adaptive significanceand maintenance of personalities.