Comparison of Foraging Ability Between Solenopsis invicta and Tapinoma melanocephalum (Hymenoptera: Formicidae)

In this study, we investigated the foraging ability of the invasive ant Solenopsis invicta and native ant Tapinoma melanocephalum (Hymenoptera: Formicidae) by measuring their searching and recruitment time for 5 types of food (sausage, sausage & honey, honey, mealworm and peanut oil) in infested wasteland and litchi orchards in south China. The searching time was determined by measuring the time required for the first ant to find the food. The recruitment time was determined by measuring the time to recruit 10 ants to the food which was placed on petri dish 30 cm away from nest entrances. 30 colonies each of T. melanocephalum and S. invicta were tested. In the infested wasteland, the searching time of S. invicta for sausage & honey, sausage, mealworm and honey and the recruitment time of S. invicta for sausage & honey, mealworm and honey were significantly longer than those of T. melanocephalum, but the searching time of these two species of ants for peanut oil was not significantly different. In the infested litchi orchard, the recruitment time of S. invicta for sausage was significantly longer than that of T. melanocephalum, while the recruitment time for the other four types of food was not significantly different between the two species of ants. The searching time for all the five types of food was not significantly different between the two species of ants in the infested litchi orchard

The Effects of Temperature on the Foraging Activity of Red Imported Fire Ant Workers (Hymenoptera: Formicidae) in South China

In this study, we investigated the effects of temperature of the ambient air, ground surface, and the soil at 5-cm deep on the foraging activity of the workers of red imported fire ant, Solenopsis invicta Buren, in South China with the method of bait traps. Significant correlations were observed between the temperature and the foraging activity of fire ants. Specifically, when the ambient temperature was above 20 °C, the fire ants foraged actively, and the activity reached a maximum when the ambient temperature was between 25 to 33 °C. But the foraging activity decreased as the ambient temperature rose higher than 34 °C. Moreover, fire ants were found to forage at maximal rates with the soil surface temperature between 27 to 40 °C. The ants started foraging when the soil temperature at 5-cm deep was between 16 to 48 °C, while 28~37 °C was the optimal temperature for the foraging activity. The extreme temperature thresholds for foraging of the ambient air, soil-surface, and soil at 5-cm deep were 11 °C/44 °C, 10 °C/57 °C, and 12 °C/48 °C respectively.

Impact of Rainfall on the Nesting Activity of Solenopsis invcta in South China

Through field observations we found that workers of Solenopsis invcta would make prompt repair to the nest after the rainfall as the exits were often blocked with soils in the rain. Therefore, after each rain, the mounds were significantly higher but no significant change was found in diameter. The growth of the mound volume has a very close relationship with the rainfall and its duration. The longer the rain lasted, the greater the rainfall was, the greater the nest volume grew. The results showed that the volume of mounds was not changing constantly during the year, and it was quite different in different seasons. In November each year, the fire ants grew less active as the temperature decreased, and in the following December to February, the number of fire ant nests remained at a very low level. When April began, many new nests appeared as the temperatures rose and the rainfall increased. From May to July, it rained, and some extinct and new mounds appeared at the same time. The total number of active mounds increased significantly. Between August and October, when the temperature was relatively stable with not much rain, the mound number was maintained at a stable level

Types of Antennal Sensilla of Three Pseudacteon Species (Diptera: Phoridae) Females That Parasitize Red Imported Fire Ants (Solenopsis invicta) ( Hymenoptera: Formicidae)

While antenna is the main organ for insect to accept the external chemical signals, the antennal sensilla that are diverse in structure and function form the insect receptors in chemical communication. Since a variety of Pseudacteon species are important natural enemies of the red imported fire ant, Solenopsis invicta Buren (. invicta), to elucidate the types of Pseudacteon sensilla will promote the study and understanding of the selection behavior of Pseudacteon in parasitizing . invicta. This study has used scanning electron microscope (SEM) to observe and investigate the female’s antennal sensilla of three Pseudacteon species, the Pseudacteon (P.) litoralis, P. obtusus, and P. tricuspis, and demonstrated that there are four types of sensilla, the trichoid, basiconic, coeloconic, and chaetic sensilla, on their antennal flagellum. Among them, the former three are common in all three species, with trichoid sensillum as mostly abundant, while the chaetic sensillum exists only in the antennae of P. obtusus. The trichoid sensilla exhibit significant interspecies variations and are further classified into two subtypes based on the presence or absence of protrusions, the surface of which contains different shades of groove-like or irregular punctate structures. The basiconic sensilla resemble short spines with densely porous structures on the surface and are in the length of 7.3-9.8 μm and the width of 1.3-1.6 μm, upright or slightly bent. The coeloconic sensilla are irregularly formed in the middle and base of the flagellum, without surface pores; each coeloconic sensillum has eight finger-like folds in unequal lengths, while the end of the fold resembles a blunt cone. The chaetic sensilla enlarge at the base, possess multiple fold-like structures and fine-tipped ends, and are approximately 5 μm in length

Constructing Balance from Imbalance for Long-tailed Image Recognition

Long-tailed image recognition presents massive challenges to deep learning systems since the imbalance between majority (head) classes and minority (tail) classes severely skews the data-driven deep neural networks. Previous methods tackle with data imbalance from the viewpoints of data distribution, feature space, and model design, etc.In this work, instead of directly learning a recognition model, we suggest confronting the bottleneck of head-to-tail bias before classifier learning, from the previously omitted perspective of balancing label space. To alleviate the head-to-tail bias, we propose a concise paradigm by progressively adjusting label space and dividing the head classes and tail classes, dynamically constructing balance from imbalance to facilitate the classification. With flexible data filtering and label space mapping, we can easily embed our approach to most classification models, especially the decoupled training methods. Besides, we find the separability of head-tail classes varies among different features with different inductive biases. Hence, our proposed model also provides a feature evaluation method and paves the way for long-tailed feature learning. Extensive experiments show that our method can boost the performance of state-of-the-arts of different types on widely-used benchmarks. Code is available at https://github.com/silicx/DLSA.Comment: Accepted to ECCV 202

Studies on Rheological Behaviors of Bismaleimide Resin System for Resin Transfer Molding

AbstractThe rheological behavior of bismaleimide resin for resin transfer molding(RTM) was studied with DSC analysis and viscosity experiments. A rheological model based on the dual-Arrhenius equation was established and used to simulate the rheological behavior of the resin. The model predictions determined from the dual-Arrhenius equation were in good agreement with experimental data. The processing window of the resin system can be well determined based on the developed model. The rheological model is important for processing simulation and quality control of RTM processing for high performance composites

Bis(1,10-phenanthroline-κ2 N,N′)[2-(4-sulfonato­anilino)acetato-κO]copper(II) dihydrate

In the title compound, [Cu(C8H7NO5S)(C12H8N2)2]·2H2O, the CuII ion is coordinated by four N atoms from two 1,10-phenanthroline (phen) ligands and one O atom from a 2-(4-sulfonato­anilino)acetate (spia) ligand in a distorted square-pyramidal geometry. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds, as well as π–π inter­actions between phen ligands and between phen and spia ligands [centroid–centroid distances = 3.663 (3), 3.768 (3) and 3.565 (3) Å], result in a three-dimensional supra­molecular structure