Short-range homing in camels: displacement experiments

Camels (Camelus dromedarius) are known to have good navigational abilities and can find their home after displacement to far places; however, there are no studies available on the navigational strategies employed by the camels in homing behavior. Thus, the aim of this study was to investigate the strategies by displacing female camels equipped with GPS trackers 6 km away from home to totally unfamiliar locations. The experiments comprised displacing nursing or non-nursing female camels 6 km from their living pens to an unfamiliar release site. Some camels were taken to the release site on foot, others were hauled on a truck, both during daytime and night-time. Displacements were either straight to the release points, or they consisted in convoluted paths. As a result, the camels were able to return home efficiently and rather directly after straight outward journeys but failed to do so after having performed convoluted trips to the release point. Moreover, impairing olfactory, visual, and auditory inputs by using mouth/nose muzzles eye covers and headphones did not affect homing ability. Based on these experiments the most likely hypothesis is that during their small-scale round trips the camels relied on path integration, and that this strategy is disrupted when the camels were subjected to disorientation procedures before release.

Behavioral response of insecticide-resistant mosquitoes against spatial repellent: A modified self-propelled particle model simulation

Rapidly increasing pyrethroid insecticide resistance and changes in vector biting and resting behavior pose serious challenges in malaria control. Mosquito repellents, especially spatial repellents, have received much attention from industry. We attempted to simulate interactions between mosquitoes and repellents using a machine learning method, the Self-Propelled Particle (SPP) model, which we modified to include attractiveness/repellency effects. We simulated a random walk scenario and scenarios with insecticide susceptible/resistant mosquitoes against repellent alone and against repellent plus attractant (to mimic a human host). Simulation results indicated that without attractant/repellent, mosquitoes would fly anywhere in the cage at random. With attractant, all mosquitoes were attracted to the source of the odor by the end. With repellent, all insecticide-susceptible mosquitoes eventually moved to the corner of the cage farthest from the repellent release point, whereas, a high proportion of highly resistant mosquitoes might reach the attractant release point (the human) earlier in the simulation. At fixed concentration, a high proportion of mosquitoes could be able to reach the host when the relative repellency efficacy (compare to attractant efficacy) was <1, whereas, no mosquitoes reached the host when the relative repellency efficacy was > 1. This result implies that repellent may not be sufficient against highly physiologically insecticide resistant mosquitoes, since very high concentrations of repellent are neither practically feasible nor cost-effective.

Individual Effective Dose and Nuclear Emergency Planning for Muntok NPP Area using TMI-2 Source Term

Probabilistic dose analysis from a postulated nuclear accident is performed for the Muntok area in the western Bangka region. Three-Mile Island unit 2PWR-type Nuclear Power Plant (TMI-2) source-term is compiled and used as accident data. The accident is also known as the Small-break Loss of Coolant Accident (SB-LOCA) accident. The isotopes used in the simulation are Kr-88, I-131, Xe-133, and Cs-137. The release point is a 50 m stack. Lagrangian particle dispersion method (LPDM) is used along with a 3-dimensional mass-consistent wind-field. Surface-level time-integrated air concentration and spatial distribution of ground-level total dose were obtained for dry conditions. Meteorological data is taken from hourly records obtained from an on-site meteorological tower in Muntok area for the 2014-2015 period. Effluent is released at a uniform rate during a 6-hour period and the dose is integrated for 12 hours from the beginning of the release until most of the plume left the model boundaries. The regulatory limit for the general public of 1 mSv was detected in an area located 2.5 km from the release point. Radioactive plume is spread from the postulated plant location to uninhabited areas consisted of bushes and farming areas in the SE-SSE direction and to W-NW direction to the Bangka Sea.

Comparison of computational fluid dynamics-based simulations and visualized seed trajectories in different seed tubes

The objective of this study was to compare computational fluid dynamics (CFD)-based simulations and visualized seed trajectories in different seed tubes that can provide seed incorporation into the soil with enhanced seed spacing. The other objective was to determine the relation between the seed trajectories and peripheral speed of the vacuum disk. In order to meet the first objective, 2 different seeds (corn and cotton) and artificial spherical material (Ø10 mm) were tested under laboratory conditions. The seeds and artificial material were released by free fall into the semitransparent seed tubes (seed tubes A and B) from different release points, and their trajectories were recorded using a video camera. For the second objective, corn seeds were used and released from a vacuum-type metering unit equipped with a semitransparent seed tube (seed tube A) at 3 different peripheral speeds of the vacuum disk, as a function of 3 forward speeds of the seeder. For both objectives, the seed tubes were modeled and release of the seeds into the seed tubes was simulated and analyzed using ANSYS Fluent for CFD. The results obtained from the captured video and simulations were compared. As a result of the comparisons, it was found that the seed release point was an effective parameter on both the seed trajectory and seed spacing, since seed bouncing and skating in the seed tube, based on the release point, may occur. The results also showed that the lab tests and simulations were found to be very similar in terms of the seed trajectories and seed spacings. It is believed that this study, using CFD, will be an example and enable the development and design of new seed tubes in order to obtain better seed distribution uniformity.

Dispersion Pattern of Giant Cicada (Hemiptera: Cicadidae) in a Brazilian Coffee Plantation

The giant cicada Quesada gigas (Olivier, 1790) (Hemiptera: Cicadidae) is a major pest of coffee plants in Brazil. To ensure the rational management and ecological equilibrium, information about the behavior, dispersion, and reproduction of giant cicada is fundamental. The present work was conducted in an area of 97 ha planted with Coffea arabica L. to investigate adult dispersion as well as mating and oviposition behaviors of Q. gigas. A sound trap was placed at a ‘release point’ used for the attraction, marking, and release of adults in the area. The recapture of insects was performed with the same sound trap positioned at 20 points distributed at 100, 250, 400, and 1,000 m from the release point. The highest recapture rates of Q. gigas were observed at 100 m from the release point, and the lowest recapture rates were observed at 1,000 m. The presence of Eucalyptus plants in the area apparently influenced dispersion, as high recapture rates were observed at the sites close to Eucalyptus plants. One copulation of Q. gigas lasted 41.6 ± 0.43 min, and the period of a single oviposition bout was 30.0 ± 0.20 min. Quesada gigas adult longevity in the field was estimated to be 49 d. Both males and females were observed performing multiple matings.

Dispersal of Lycorma delicatula (Hemiptera: Fulgoridae) Nymphs Through Contiguous, Deciduous Forest

Spotted lanternfly (Lycorma delicatula) is a recently introduced pest in the United States, where it threatens the wine, timber, and ornamentals industries. Knowledge of the dispersal ability of L. delicatula is key to developing effective management strategies for this invasive pest. We conducted a mark, release, re-sight study, marking nymphs with fluorescent powders and observing dispersal distances from a central release point at three time points over 7 d following release. To examine how dispersal patterns changed over the course of nymphal development, we repeated this process for each of L. delicatula’s four instars. All releases were conducted in contiguous, deciduous forest, which is a widespread habitat type within L. delicatula’s invaded range and a habitat where this pest may have negative ecological and economic impacts. We found that nymphs displayed clear directionality in their movement following release, apparently preferring to move uphill on the modest 6° grade at our release site. Most nymphs remained near the release location, while some moved tens of meters. The maximum displacement we observed was 65 m from the release point, 10 d after release. Nymphs were re-sighted singly and in small groups on a variety of trees, shrubs, and understory vegetation. All four instars had similar dispersal distances over time, though third instar nymphs moved farthest on average, with estimated median displacement of 16.9 m 7 d after release. Further studies are needed to provide additional information on what factors influence spotted lanternfly dispersal.

PROCEDURE FOR EVALUATION OF THE APPLICATION’S EFFICIENCY OF THE PARACHUTE SYSTEMS FOR THE AIR DROPPING

The article proposes a procedure for evaluation of the application’s efficiency (AE) of parachute systems (PS) for the air dropping (AD). Based on the analogy with the index of combat effectiveness of armament and military equipment, the AE of PS can be evaluated by using the typical mission performance probability of AD - personnel or cargo positioning to site, while maintaining their combat capability to accomplish a mission of the parachute assault force. In this formulation, the process of accomplishing the typical mission of AD consists of the following stages: delivery of cargo to the airborne objective area, the exit of the aircraft to the computed air release point, the actual air dropping. Further analysis showed that the most influential factors affecting successful accomplishment of the typical mission of AD by the stages are: the reliability of the aircraft, the ability to overcome the enemy air defense without consequences for the accomplishment of AD, the property retention of PS while in flight considering flying conditions of the aircraft to the area of ​​the AD, problem solving of determining of the computed air release point under the actual conditions, the accuracy of the aircraft's exit to the computed air release point, the reliability of the PS, the covertness of the AD, the accuracy of cargo’s landing to the size-defined site, speed of the cargo’s landing. For each of the factors, the calculating formulas were defined in the article in the form of the probability of a positive influence on the successful accomplishment of the mission of the AD. The product of all these probabilities is evaluation of the AE of PS. For example, the calculations of the AE of PS DPS and Status-CH types in equal conditions of AD and Status-CH by using various tactical techniques of AD were made. The results of the calculations are completely consistent with the logical considerations and practice of the PS application, which testifies to the adequacy of the proposed procedure and the feasibility of its application.

Behavioral response of insecticide-resistant mosquitoes against spatial repellent: a modified self-propelled particle model simulation

Rapidly increasing pyrethroid insecticide resistance and changes in vector biting and resting behavior pose serious challenges in malaria control. Mosquito repellents, especially spatial repellents, have received much attention from industry. Many of these repellents contain the same or similar chemicals as those used in insecticides. Does resistance to insecticides affect the efficacy of spatial repellents? We attempted to simulate interactions between mosquitoes and repellents using a machine learning method, the self-propelled particle (SPP) model, which we modified to include attractiveness/repellency effects. We simulated a random walk scenario and scenarios with insecticide susceptible/resistant mosquitoes against repellent alone and against repellent plus attractant (to mimic a human host). We assumed attractant odors and repellent chemicals diffused randomly and omnidirectionally, and that mosquitoes were confined in a cubic cage. We modified the velocity and direction components of SPP using attraction/repulsion rates and concentrations. Simulation results indicated that without attractant/repellent, mosquitoes would fly anywhere in the cage at random. With attractant, mosquitoes might or might not fly toward the source (i.e., the human), depending on the simulation time (and thus the attractant concentration distribution). Eventually, however, all mosquitoes were attracted to the source of the odor. With repellent, results depended on the amount of chemical used and the level of mosquito insecticide resistance. All insecticide-susceptible mosquitoes eventually moved to the corner of the cage farthest from the repellent release point. Surprisingly, a high proportion of highly resistant mosquitoes might reach the attractant release point (the human) earlier in the simulation when repellent was present compare to no repellent was present. At fixed concentration, a high proportion of mosquitoes could be able to reach the host when the relative repellency efficacy (compare to attractant efficacy) was <1, whereas, no mosquitoes reached the host when the relative repellency efficacy was > 1. This result implies that repellent may not be sufficient against highly physiologically insecticide resistant mosquitoes, since very high concentrations of repellent are neither practically feasible nor cost-effective.