Technological Advances to Address Current Issues in Entomology: 2020 Student Debates

The 2020 Student Debates of the Entomological Society of America (ESA) were live-streamed during the Virtual Annual Meeting to debate current, prominent entomological issues of interest to members. The Student Debates Subcommittee of the National ESA Student Affairs Committee coordinated the student efforts throughout the year and hosted the live event. This year, four unbiased introductory speakers provided background for each debate topic while four multi-university teams were each assigned a debate topic under the theme ‘Technological Advances to Address Current Issues in Entomology’. The two debate topics selected were as follows: 1) What is the best taxonomic approach to identify and classify insects? and 2) What is the best current technology to address the locust swarms worldwide? Unbiased introduction speakers and debate teams began preparing approximately six months before the live event. During the live event, teams shared their critical thinking and practiced communication skills by defending their positions on either taxonomical identification and classification of insects or managing the damaging outbreaks of locusts in crops.     

Secondary Metabolites from the Marine Sponges of the Genus Petrosia: A Literature Review of 43 Years of Research

Sponges are prolific sources of various natural products that have provided the chemical scaffolds for new drugs. The sponges of the genus Petrosia inhabit various regions and contain a variety of biologically active natural products such as polyacetylenes, sterols, meroterpenoids, and alkaloids. This review aims to provide a comprehensive summary of the chemical structures and biological activities of Petrosia metabolites covering a period of more than four decades (between 1978 and 2020). It is also described in this review that the major groups of metabolites from members of the genus Petrosia differed with latitude. The polyacetylenes were identified to be the most predominant metabolites in Petrosia sponges in temperate regions, while tropical Petrosia species were sources of a greater variety of metabolites, such as meroterpenoids, sterols, polyacetylenes, and alkaloids.     

Influence of phosphate sorption on dispersion of a Ferralsol

Abstract

Soil dispersion induces soil erosion and colloidal leaching. Nutrients are lost at the same time and this causes water contamination. Phosphate is an essential element for living organisms. Because phosphate influences soil dispersion and it is an important limited resource, this influence must be evaluated well in order to diminish negative effects on soil structure. In this paper, we firstly evaluated the influence of phosphate sorption on soil dispersion by calculating repulsive potential energy between soil particles. Ferralsol, which is a typical soil in rainy tropical regions, was used as the material. The dispersion-flocculation phenomena were investigated with absorbance of soil suspension under different pH, phosphate adsorption and electrolyte concentration in an Na-NO₃-PO₄ system. The repulsive potential energy was calculated based on the diffuse double layer theory and the measured zeta potential. We indicated that the measured absorbance increased with the increase of the repulsive potential energy. The repulsive potential energy increased with increasing phosphate sorption up to about 5 to 20 mmol kg^?1 at all pH, and it induced the soil dispersion, because phosphate sorption increased the negative charge of the soil. After its peak, it decreased with increasing phosphate sorption because the electrolyte concentration increased and the electrolyte screened the electric field near the soil surface. The repulsive potential energy also increased with increasing pH because of the increase of the negative charge of the soil. Even at low pH, after a certain amount of phosphate sorption, the soil dispersed due to the increase of repulsive potential energy, although the soil flocculated before phosphate application. Because the soil dispersion causes soil and phosphorus loss, the influence of soil pH and phosphate sorption on the soil dispersion should be considered for good soil management.     

Filtrating forms of soil bacteria

Filtrating (ultramicroscopic) forms (FF) of bacteria were studied in a soddy-podzolic soil and the root zone of alfalfa plants as part of populations of the most widespread physiological groups of soil bacteria. FF were obtained by filtering soil solutions through membrane filters with a pore diameter of 0.22 μm. It was established that the greater part of the bacteria in the soil and in the root zone of the plants has an ultramicroscopic size: the average diameter of the cells is 0.3 μm, and their length is 0.6 μm, which is significantly less than the cell size of banal bacteria. The number of FF varies within a wide range depending on the physicochemical conditions of the habitat. The FF number’s dynamics in the soil is of a seasonal nature; i.e., the number of bacteria found increases in the summer and fall and decreases in the winter-spring period. In the rhizosphere of the alfalfa, over the vegetation period, the number of FF and their fraction in the total mass of the bacteria increase. A reverse tendency is observed in the rhizoplane. The morphological particularities (identified by an electron microscopy) and the nature of the FF indicate their physiological activity.     

Microwave heat dyeing of polyester fabric

The effect of padding solution on the microwave heat dyeing of polyester fabric was studied extensively. Polyester fabrics were impregnated in aqueous urea solution and aqueous sodium chloride solution for 10 min and then dyed for 7 min by microwave apparatus (2 450 MHz, 700 W) under optimum conditions which provide good exhaustion. Aqueous solutions of urea and sodium chloride showed more effective than water as a padding solution for microwave heat dyeing. The type of solvent added in padding media and its concentration significantly affects the K/S values of dyed polyester fabric. Added solvents such as n-hexane, acetone, and dimethyl formamide were also more effective than 100% water as padding media for the microwave heat dyeing. It is supposed that the effect of used solvents on dyeing property of polyester fabrics depends on the solubility parameter difference between solvent and polyester fabric.     

Relationships between ground cover,intercepted solar radiation,leaf area index and infrared reflectance of potato crops

Summary In field trials with potato several methods determining the proportion of intercepted solar radiation by the crop were compared. Non-destructive measurement of the proportion of ground cover with the aid of a grid correlated well with the proportion of intercepted photosynthetically active radiation as measured with a tube solarimeter and with the leaf area index. Measurement of the infrared reflectance of the crop proved to be an efficient and objective method to show differences between treatments. Moreover, it showed a good correlation with ground cover and radiation interception until full closure of the canopy. Percentage ground cover is useful for assessing intercepted solar radiation and leads to fewer errors in calculation of efficiency of conversion into dry matter than the other methods.     

Potato (Solanum spp.) production using apical cuttings and tuberlets under three contrasting environments of Vietnam

Potato production from rooted apical cuttings or from small tubers (l–20g) produced in high density beds has great potential in Asia. This is particularly important in non-traditional warmer environments. This research was conducted to assess the feasibility of producing many small tubers in high density beds. A second objective compared tubers from beds with transplanted rooted cuttings and traditional seed tubers for growth and yield in the field. Tuberlet production in beds exceeded 2000/m² with a density of 1000 plants/m² under optimal growing conditions while under high temperatures only about 1.25 tuberlets/plant were produced. In field experiments, transplanted cuttings yielded 20 t/ha in the mid and high elevation areas, only slightly less than tuberlets of 5–10g while at the hot site, yields were generally only 8 to 10 t/ha for both materials. Larger healthy seed tubers produced significantly higher yields at the low and high elevation sites. Tuberlets of 1–5g were also able to give yields of 20 t/ha in the mid-elevation site. These results indicate that cuttings and small tuberlets are two ways of growing potatoes which need to be further evaluated for socioeconomic assessment by farmers.     

Soil organic carbon stocks in Flemish grasslands: how accurate are they?

Articles 3·3 and 3·4 of the Kyoto protocol provide Annex I countries the possibility to reduce greenhouse gas emissions through the sequestration of carbon (C) in their terrestrial ecosystems. For such accounting, the 1990 flux is needed and, therefore, a correct knowledge of the baseline (1990) C stocks is necessary. In addition, a correct methodology should be used to investigate the capacity of ecosystems to sequester C through changes in land use or management by the end of the first commitment period (2008–2012). At national and regional scales, formulation of baseline C stocks in terrestrial ecosystems is difficult and uncertain. Differences in method of analysis, sampling depth of soil, lack of sufficient C data and the necessity to extrapolate C data to total soil organic C stocks, provide problems when comparing databases with each other. In this study, three extrapolation models were compared with the classical layer‐based method to determine the model with the best fit. The model with the best predictions, in relation to the classical layer‐based model, uses recent soil C profiles for estimating the parameter k, which represents the decrease in the proportion of soil organic C with depth, and for extrapolating the C data available for 1990 and 2000 to a depth of 1 m. The other two models gave large underestimates.     

Soil temperature and moisture control in relation to screeningSolanum spp. for resistance to the potato cyst nematode (Globodera spp.) in greenhouses

Summary Recent improvements in screeningSolanum populations for resistance to the potato cyst nematode are described. Soil temperature control within the required optimum range is obtained in greenhouse by cooling the bench. The use of a cotton blanket (capillary matting) on the bench under the pots reduced the frequency of watering to once or twice a week. The system is reliable, and provides a large capacity/low cost facility for large-scale resistance screening.

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Zusammenfassung Es werden neuartige Verbesserungen zur Auslese vonSolanum-Hybriden auf Resistenz gegen Kartoffel-Zystennematoden beschrieben. Bei diesem Pathosystem ist das mass für die Resistenz quantitativ; ein Klon ist resistent, wenn die Vermehrungsrate des Nematoden an seinem Wurzelsystem 0,20 oder weniger ist (Kort et al., 1977). Verschiedene Faktoren beeinflussen die Vermehrung der Nematoden, von denen Bodentemperatur und Feuchtigkeit für die Zuverl?ssigkeit der Ergebnisse bei der Auslese oft entscheidend sind (Wallace, 1963; Clarce & Perry, 1977; Ferris, 1957; Trudgill, 1970). Um die Bodentemperatur innerhalb des Bereiches von 16 bis 23°C zu halten, wurde ein Kühlsystem errichtet, in dem gekühltes Wasser durch eine Hohlstruktur auf einem Gew?chshaustisch zirkulierte. Der Tisch war mit schwarzer Poly?thylenfolie wasserdicht gemacht worden, Kan?le entstanden durch Verwendung gewellter Polyesterplatten, die auf der Poly?thylenfolie auflagen und mit Kies bedeckt waren, um eine horizontale und flache Oberfl?che herzustellen. Auf dem Kies lag eine Poly?thylenmatte mit Kapillarbelag, auf diese wurden die Gef?sse mit verschiedenen Bodentypen gestellt. De Pflanzen in den Gef?ssen wurden ein- oder zweimal in der Woche gegossen. Der Effekt der Kühlung wird in Abbildung 1 gezeigt. Ein derartiges System scheint die Einhaltung der Bodentemperatur innerhalb des Optimalbereiches sogar unter ziemlich extremen Bedingungen in unseren Gew?chsh?usern gew?hrleisten. Wird die Frequenz des Giessens zur Erh?hung der Effizienz von einmal t?glich auf einoder zweimal w?chentlich reduziert, so wird es schwieriger, die Bodenfeuchtigkeit im optimalen Bereich zu halten. Wurde jedoch Erde mit hohem Gehalt an organischer Substanz verwendet, ergaben sich bei der Kombination mit kapillarischer Wasserführung keine Schwierigkeiten. Lehmiger Sand mit einer pF-Charakteristik nach Abb. 2 war ebenfalls verwendbar, mit einem Bodenwasser-Potential nahe dem Optimum von pF 2,3–2.4. Andere Bodentypen waren für diesen Zweck weniger gut geeignet (Tabelle 1). Die durchschnittliche Nematodenvermehrung war auf diesen Bodentypen meist geringer, und die Variationskoeffizienten stiegen an. Der Arbeitsaufwand für den Wurzelballentest reduzierte sich von zwei Minuten auf insgesamt eine Minute.

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Résumé Des améliorations récentes dans la recherche d'hybrides deSolanum pour leur résistance au nématode à kyste de la pomme de terre sont décrites. Dans ce système pathologique, la mesure de résistance est quantitative; un clone est résistant quand la multiplication du nématode sur le système racinaire est de 0,20 ou moins (Kort et al., 1977). De nombreux facteurs modifient la multiplication du nématode parmi lesquels la température et l'humidité du sol sont décisives pour une bonne fiabilité des résultats de recherche (Wallace, 1963; Clarke & Perry, 1977; Ferris, 1957; Trudgill, 1970). Pour contr?ler la température du sol à l'intérieur d'un intervalle 16–23°C, un système de refroidissement a été mis en place dans lequel de l'eau fra?che circulait à travers une structure évidée construite sur les tablettes d'une serre. La tablette a été rendue étanche par du polythène noir et des canaux ont été effectués avec des feuilles de polyester ondulées sur le polythène et recouverts de graviers afin d'obtenir une surface horizontale et plate. Un film de polythène avec un paillage capillaire a été étendu sur ce gravier et des pots de différents types de sol ont été déposés sur le paillage. Les plantes en pots ont été arrosées une à deux fois par semaine. L'effet de refroidissement sur la température du sol est indiqué dans la figure I. Un tel système permet de contr?ler la température du sol dans une échelle optimale même sous des conditions extrêmes dans notre serre. Quand la fréquence de l'arrosage est réduite de une fois par jour à une à deux fois par semaine pour augmenter l'efficacité, il devient plus difficile de contr?ler l'humidité dans une échelle optimale, mais lorsque une terre mise en pot contenant beaucoup de matière organique est utilisé avec un paillage capillaire, aucune difficulté n'apparait. Un sable argileux, avec un pF caractéristique comme il est indiqué dans la figure 2 peut être aussi utilisé avec un potentiel hydrique près de l'optimum de pF 2,3 à 2,4. D'autres types de sol étaient moins adaptés pour ce but (tableau 1). La multiplication moyenne de nématodes était généralement plus basse avec ces types de sol et les coefficients de variation augmentaient. Le temps nécessaire pour le test ‘Rootball’ étant réduit à un total de 1 minute par plante seulement, au lieu de 2 minutes, lorsque les pots étaient enterrés dans de la tourbe et arrosés une fois par jour.