RESUMO
Adventive populations of Trissolcus japonicus (Ashmead), an egg parasitoid of the invasive agricultural pest, brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), have been detected in the United States since 2014. Given its importance as an H. halys biocontrol agent, efforts to redistribute T. japonicus began within some US states. Our surveillance for T. japonicus in northwestern Virginia in 2016-2017 yielded annual detections only in 1 county. Thus, to promote its broader establishment, releases of H. halys egg masses parasitized by T. japonicus from Virginia occurred in 2018 (2 releases) and 2020 (1 release) at 9 sites throughout Virginia's tree fruit production regions. Monitoring of T. japonicus and H. halys, using yellow sticky cards deployed in H. halys host trees and pheromone-baited sticky traps, respectively, was conducted from 2018 to 2022. Annual captures of H. halys adults and nymphs appeared to reflect adequate populations to support T. japonicus establishment across most or all sites. Prerelease monitoring yielded a single T. japonicus at 1 site. By 2022, T. japonicus was detected at or near 7 of the remaining 8 release sites, with first detections varying between 1 and 2 yr from the releases in 2018 and 2020. Captures at most sites were very low, but establishment at several locations was indicated by detections in 2-4 seasons. In 2022, T. japonicus surveillance at 11 additional sites in northwestern Virginia yielded detections at all locations, including those at which it had not been detected in 2016-2017, providing evidence for its range expansion.
Assuntos
Heterópteros , Himenópteros , Animais , Virginia , Estações do Ano , ÁrvoresRESUMO
Single photon emission computed tomography (SPECT) myocardial perfusion imaging remains a critical tool in the diagnosis of coronary artery disease. However, after more than three decades of use, photon detection efficiency remains poor and unchanged. This is due to the continued reliance on parallel-hole collimators first introduced in 1964. These collimators possess poor geometric efficiency. Here we present the performance evaluation results of a newly designed multipinhole collimator with 20 pinhole apertures (PH20) for commercial SPECT systems. Computer simulations and numerical observer studies were used to assess the noise, bias and diagnostic imaging performance of a PH20 collimator in comparison with those of a low energy high resolution (LEHR) parallel-hole collimator. Ray-driven projector/backprojector pairs were used to model SPECT imaging acquisitions, including simulation of noiseless projection data and performing MLEM/OSEM image reconstructions. Poisson noise was added to noiseless projections for realistic projection data. Noise and bias performance were investigated for five mathematical cardiac and torso (MCAT) phantom anatomies imaged at two gantry orbit positions (19.5 and 25.0 cm). PH20 and LEHR images were reconstructed with 300 MLEM iterations and 30 OSEM iterations (ten subsets), respectively. Diagnostic imaging performance was assessed by a receiver operating characteristic (ROC) analysis performed on a single MCAT phantom; however, in this case PH20 images were reconstructed with 75 pixel-based OSEM iterations (four subsets). Four PH20 projection views from two positions of a dual-head camera acquisition and 60 LEHR projections were simulated for all studies. At uniformly-imposed resolution of 12.5 mm, significant improvements in SNR and diagnostic sensitivity (represented by the area under the ROC curve, or AUC) were realized when PH20 collimators are substituted for LEHR parallel-hole collimators. SNR improves by factors of 1.94-2.34 for the five patient anatomies and two orbital positions studied. For the ROC analysis the PH20 AUC is larger than the LEHR AUC with a p-value of 0.0067. Bias performance, however, decreases with the use of PH20 collimators. Systematic analyses showed PH20 collimators present improved diagnostic imaging performance over LEHR collimators, requiring only collimator exchange on existing SPECT cameras for their use.