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The genus Chelonus s. str. (Chelonus) Panzer (Hymenoptera: Braconidae: Cheloninae) is reviewed with particular focus on species associated with fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Additionally, information on the biology and various mass-rearing techniques of the enumerated species are furnished, underlining their significance in biological control and integrated pest management strategies. [ABSTRACT FROM AUTHOR]

In the Philippines, the Fall Armyworm (FAW) was initially documented infesting corn in June 2019 and rice in May 2021. Relying on commercially available insecticides as the primary, if not exclusive, management strategy raises concerns about potential issues arising from FAW developing resistance to these chemicals, and the associated risks these insecticides pose to non-target organisms and the environment. To address these challenges, it is imperative to explore potential naturally occurring indigenous biological control agents and entomopathogens of the FAW. Regular field samplings and monitoring of FAW and its natural enemies were systematically conducted in selected municipalities of Central and Northern Luzon, as well as the Cagayan Valley regions of the Philippines. FAW larvae suspected of parasitization were collected from the field and subsequently reared in the laboratory for parasitoid emergence and other natural enemies. The parasitoids that emerged were sent to the Centre for Agriculture and Biosciences International United Kingdom (CABI UK) Diagnostic and Advisory Service for identification. Two hymenopteran parasitoids, Brachymeria lasus Walker (Family: Chalcididae) and Copidosoma floridanum (Ashmead) (Family: Encyrtidae), were identified from the lab-reared FAW larval samples. These two FAW parasitoids are new records in the Philippines and elsewhere. [ABSTRACT FROM AUTHOR]

J Thomas Sanderson, Associate Professor, Institut National de la Recherche Scientifique-Institute Armand-Frappier, Université du Québec, Montréal, QC, H9R IG6, Canada tells of the importance of the aromatase enzyme, pesticide interactions with the enzyme and the possibility of endocrine disruption effects. © 2006. Research Information Ltd. All rights reserved.

The occurrence of the invasive apple snail Pomacea canaliculata in Indonesia was first reported in 1984. The species was introduced as an ornamental aquarium pet. Since then, people have begun to culture the snail in ponds usually adjacent to rice fields. When it was realized that the species multiplied rapidly and was a serious pest, this invasive apple snail had already spread widely. There are many cultural methods of controlling and preventing its distribution, but none are effective in keeping them at non-damaging levels. We mapped the distribution of P. canaliculata in Indonesia from the MZB’s collections as well as literature references and found that the snail invaded almost all large islands, such as Sumatra, Java, Kalimantan, Sulawesi, Maluku, and West Papua. We also studied the impact of P. canaliculata on the native apple snails P. ampullacea, P. scutata, and P. virescens in Lake Rawa Pening (a popular tourism destination) as a case study. The results showed that two species of Pila already disappeared from Lake Rawa Pening. Only P. scutata occurs still in the region and was found alive usually in shallow water and rice fields surrounding the lake. To resolve the problem we recommend that cleaning the lake periodically from the invasive aquatic weed Eichhornia crassipes (known to locals as “eceng gondok”) by a private company and harvesting the weeds for the local small craft industry by the local fishermen could be an alternative measure to reduce the population of the P. canaliculata, as well as collecting P. canaliculata for local food or for feeding ducks. Rearranging the number of fish-pens “karamba” and their location in the lake could be seen as an alternative way also for reducing the population of P. canaliculata, since the snails lay their egg masses on the bamboo stakes of “karamba.” Such rearrangement could make the landscape more attractive for tourism.

Self-consistent evaluations of the transmembrane potential (TMP) and possible membrane electroporation in spheroidal cells arising from an ultrashort, high-intensity pulse are reported. The present study couples the Laplace equation with Smoluchowski theory of pore formation, and uses double-shell models. It is shown that the response of prolate spheroids is faster than that of the sphere, with the outer membrane reaching its steady-state value in about 2 [micro]s. The simulation result also shows that the TMP across an inner organelle could exceed the value across the plasma membrane at least over the first 0.4 [micro]s or so, indicating a possibility of intracellular, electromanipulation of cells. The TMP induced by pulsed external voltages is predicted to be higher in oblate spheroids in comparison to both spherical and prolate spheroidal cells. This occurs due to flattening of the surface area. Index Terms--Bioelectric simulation, cellular electroporation, spheroidal cells, transmembrane voltage, ultrashort pulse.

This paper presents a simulation study of cell membrane electroporation in clusters by high-intensity voltage pulses. The focus is on assessing effects associated with: 1) the variability in shape and randomness of the cells within clusters; 2) the density of clusters; 3) the effects in heterogeneous tissues; 4) the role of pulse width on fractional electroporation for given electrical characteristics; and 5) conductivity and cell shape influences on the electric strength versus pulse duration behavior. Quantitative results are obtained based on two-dimensional, time-dependent, random Voronoi network analyses. The calculations predict that it is harder to electroporate cells in a cluster due to the random orientation of cell boundaries with regard to the applied field. Also, with increasing cellular distortions and shape irregularity, the poration is predicted to require higher voltage amplitudes or longer pulse durations to cause the same effects. Intracellular conductivity was shown to be a primary parameter influencing cell membrane poration, with membrane permittivity having a secondary effect. This has implications for tissue selectivity, especially for ultrashort duration pulsing. Finally, strength-duration (S-D) curves have been obtained, and shown to depend on the relative disorder and randomness within clusters. Index Terms--Cell clusters, electroporation, nanosecond electric pulse, shape and size effects, strength-duration (S-D) curve.

An improved model of our previous work is presented to compute spatial electric potentials in whole body biomodels. This is a distributed modeling scheme that employs symmetric factorization to decrease the memory requirement, reduce run-time overhead, and facilitate analyses of significantly larger biomodels. Such improved full-body modeling will help in the study of bioresponses to electrical stimuli in a more accurate, realistic, and comprehensive manner. For example, the voltages at various sites and tissue locations could be evaluated to probe the role of nanosecond high-intensity pulsed electric fields in blocking neural action potential propagation. Here, it is shown in rat and monkey biomodels that tissue and/or cell functionality at the spinal and thoracic regions is most likely to be affected in keeping with some recent experiments. Index Terms--Bioelectrics, Cholesky factorization, full-body modeling, parallel computation, simulation.

This paper describes the development of a simple model of a human B cell in suspension to predict the coupling frequency of a time varying external electric field to the nucleoplasm while minimizing any significant effects on the plasma membrane and nuclear envelope. The approach is based on the measured parameters for two-shelled model in the literature. The two-shelled model solves the Laplace's equation and assumes continuity of complex current and potential at each interface. The model is first solved using the symbolic feature in MATLAB. Using the complex current continuity boundary condition, we determine a simplified series equivalent circuit that is applicable to a specific frequency range, where most of the absorbed power in the cell occurs in the nucleoplasm. A smaller portion of the absorbed power occurs in the cytoplasm. The modeling also provides predictions of the operating frequency range for maximally selective energy targeting at the nucleoplasm. Index Terms--Biological cell modeling, cell nucleoplasm frequency absorption, two-shell cell equivalent circuit, two-shell intraeellular coupling.

Nanosecond electrical pulses have been successfully used to treat melanoma tumors by using needle arrays as pulse delivery systems. Reducing the pulse duration of intense electric field pulses from nanoseconds into the subnanosecond range will allow us to use wideband antennas to deliver the electromagnetic fields into tissue with a spatial resolution in the centimeter range. To explore the biological effect of intense subnanosecond pulses, we have developed a generator that provides voltage pulses of 160 kV amplitude, 200 ps rise time, and 800 ps pulse width. The pulses are delivered to a cylindrical Teflon chamber with polished flat electrodes at either end. The distance between the electrodes is variable and allows us to generate electric fields of up to 1 MV/cm in cell suspensions. The pulses have been applied to B16 (murine melanoma) cells, and the plasma membrane integrity was studied by means of trypan blue exclusion. For pulse amplitudes of 550 kV/cm, approximately 50% of the cells took up trypan blue right after pulsing, whereas only 20% were taking it up after 1 h. This indicates that the plasma membrane in a majority of the ceils affected by the pulses recovers with a time constant of about 1 h. The cells that show trypan blue uptake after this time suffer cell death through apoptosis. Evaluation of the experimental results and molecular dynamics modeling results indicate that with a pulse duration of 800 ps, membrane charging and nanopore formation are the dominant bioelectric effects on B16 cells. This information has been used in a continuum model to estimate the increase in membrane permeability and, consequently, the increase in pore size caused by repetitive pulsing. Index Terms--Apoptosis, biological cells, cell membranes, nanopores, picosecond pulses, pulse power, wideband antenna.

A theoretical study of possible neuromuscular incapacitation based on the application of high-intensity, ultrashort electric pulses is presented. The analysis is applied to a rat, but the approach is general and can be extended to any whole-animal and applies for any arbitrary pulse waveform. It is hypothesized that repeatable and reversible action potential blocks in nerves can be attained based on the electroporation mechanism. Our numerical studies are based on the Hodgkin-Huxley distributed circuit representation of nerves, and incorporate a nodal analysis for the time-dependent and volumetric perturbing potentials and internal electric fields in whole animals. The predictions are compared to actual 600-ns experimental reports on rats and shown to be in very good agreement. Effective strength-duration plots for neuromuscular incapacitation are also generated. Index Terms--Action potential (AP) block, electroporation, high-voltage pulse, myelinated nerve simulation, rat-model.