An Unbalanced Nested Error Component Model for Estimating Pest Damage Functions and the Value of Rootworm Bt Corn

We apply Antweiler’s (2001) double-nested unbalanced panel data model to estimate a western corn rootworm damage function using data from field trials in Illinois and Nebraska. Results imply that expected yield losses for a one unit difference in the node injury scale are 16.4%. Estimated random year and state effects are statistically significant, as is the estimated random experimental effect. The experimental effect is relatively large indicating the tremendous variability in yield losses at the small scale for plots with the same node injury scale measure of root damage. Using the estimated pest damage function to assess the value of Bt corn for farmers in Nebraska and Illinois, we find that, with a mean yield of 200 bu/ac, a yield CV of 25%, a corn price of $3.50/bu, and a Bt corn technology fee of$16/ac, the value of Bt corn for farmers is $173.35/ac and$156.14/ac under very high and high pest pressure respectively.Crop Production/Industries,

Solving the Problem of Sustainable Use of Bt Crops

Transgenic plants producing insecticidal protein derived from Bacillus thuringiensis (Bt) have been widely adopted since their commercial introduction in 1996. The widespread adoption of such plants has reduced use of conventional insecticides while attaining yield gains, thus providing economic, environmental and human health benefits. However, the benefits from Bt crops will be reduced or even eliminated if pests develop resistance to these toxins so that Bt crops are less or no longer effective. Although field resistance to Bt crops has not yet been found in the continental U.S., resistance to Bt sprays has been found in diamondback moth and greenhouse populations of cabbage looper. Hence, considerable attention has been devoted to developing management programs to prevent, delay or even reverse the spread of resistance. The existing literature on the economic management of pest resistance has generally assumed that pest susceptibility (the converse of pest resistance) is nonrenewable, which means resistance can only increase once it has happened. With the assumption of irreversible resistance, the optimal policy is not to exhaust susceptibility before the new technology, if any, becomes available. Following this logic, the U.S. Environmental Protection Agency (EPA) currently requires Bt crop growers to also plant non-Bt (conventional) crops on a minimum percentage of their total Bt crop acreage as a refuge for susceptible (Bt toxin sensitive) pests. Refuge allows susceptible pests to survive and mate with resistant adults surviving on Bt crops and so delays the development of resistance in the pest population. The cost of this resistance control method includes yield loss of conventional crops relative to Bt crops and sometimes conventional pesticide use. Instead of assuming susceptibility is nonrenewable, some have proposed an alternative source of susceptibility — mass-rearing and releasing harmless susceptible (toxin-sensitive) pests into the environment (Alphey et al. 2007). With this resistance control method in hand, pest susceptibility is now renewable and resistance could be reversed. Based on this method, it is plausible to predict that the optimal resistance management policy should take a cycling pattern, i.e., not planting refuge and allowing resistance to increase until a critical threshold is reached. Once resistance exceeds this threshold, it becomes economical to release susceptible pests to reverse the development of resistance. After resistance is reduced to a desired level, again no refuge needs to be planted and no alternative resistance management actions need to be used until the resistance reaches the threshold again. The cycling feature of the optimal path is due to the reversibility of resistance under this scenario. Also, there is no need to continuously use a resistance control method (as in the case of current refuge policy), since the desired level of resistance can be achieved, at a cost, when needed. However, the crucial consideration is that it is less costly to manage resistance when it is low rather than high. The task of dynamic programming is to find the optimal path where the marginal benefit of resistance control can just cover the marginal cost of resistance. We notice the cycling pattern of this resistance management model and introduce a real options approach originally used in financial analysis. We propose to view pest susceptibility as an investment and the possibility to release susceptible pests as a real option, which can be exercised to improve the expected value of this investment. We formulate the social planner’s decision of releasing susceptible pests as an optimal sequential stopping problem and solve it using stochastic dynamic programming. We first consider releasing pests with a constant ratio for released to natural pests, but then extend the model to allow for selection of a time-varying ratio. The cost of this resistance control technology includes only the cost of monitoring resistance and rearing and releasing susceptible pests. The cycling pattern of this resistance management method is attractive since cost tends to be lower than continuous refuge-based resistance management, as costs are targeted to areas and times when it is needed, rather than being annually implemented across all acres planted to Bt crops. We compare three resistance management programs: refuge only, releasing susceptible pests only, and using both refuge and released pests. The dynamic optimizations are solved numerically using parameters for Bt corn and western corn rootworm. Consistent with previous economic analyses, our dynamic refuge study finds that more refuge should be planted early in commercialization to prevent the rapid development of resistance and that refuge should be planted continuously so that the evolution of resistance is always under control. Once refuge is no longer planted, resistance develops rapidly. For the dynamic releasing of susceptible pests, there is a steady state (economic threshold) of the level of resistance. Whenever the threshold is crossed, resistance control is triggered. The optimal path of the pest population peaks whenever the resistance control (releasing susceptible pests) is exercised. Intuition might consider the pest population peaks as a failure of optimization, however, taking into account that those pests are harmless as long as Bt toxins stay effective, these “bumps” in pest population are fairly acceptable. Our analysis compare these three resistance management programs and find that the optimal resistance control strategy depends on many factors such as yield loss on refuge, the cost of monitoring resistance and rearing and releasing pests, as well as the natural growth rate of pests and the discount rate. We see high potential for generating discussion as the EPA and researchers have been examining changes in refuge requirements for Bt corn, including the recent approval use of mixed seed; however, mitigation once resistance has developed has received little attention. Although we discuss resistance control mostly in the scenario of agricultural pests, the same or similar methodology can also be used in a much broader context in public health economics such as antibiotic resistance or using genetically engineered mosquitoes to fight malaria.resistance, bio-tech, sustainable, Agricultural and Food Policy, Crop Production/Industries, Environmental Economics and Policy,

PM-VIS+: High-Performance Video Instance Segmentation without Video Annotation

Video instance segmentation requires detecting, segmenting, and tracking objects in videos, typically relying on costly video annotations. This paper introduces a method that eliminates video annotations by utilizing image datasets. The PM-VIS algorithm is adapted to handle both bounding box and instance-level pixel annotations dynamically. We introduce ImageNet-bbox to supplement missing categories in video datasets and propose the PM-VIS+ algorithm to adjust supervision based on annotation types. To enhance accuracy, we use pseudo masks and semi-supervised optimization techniques on unannotated video data. This method achieves high video instance segmentation performance without manual video annotations, offering a cost-effective solution and new perspectives for video instance segmentation applications. The code will be available in https://github.com/ldknight/PM-VIS-plusComment: MIPR 202

Analysis of 28S rRNA and COⅠ Gene Sequence of Nine Necrophagous Calliphorid Flies from Luoyang#br#

Objective To assess the feasibility of using 28S ribosomal RNA （28S rRNA） and mitochondrial cytochrome c oxidase subunit Ⅰ （COⅠ） gene sequences of nine necrophagous Calliphorid flies for the identification of common necrophagous Calliphorid flies, and to provide technical support for postmortem interval （PMI） estimation. Methods Twenty-three Calliphorid flies were collected and identified morphologically, and DNA were extracted from legs. The gene fragments of 28S rRNA and COⅠ were amplified and sequenced, then the sequence alignment was performed with BLAST. The composition of obtained sequences was analyzed and evolutionary divergence rate between species and intraspecies were established. The phylogeny tree was constructed with Neighbor-Joining method. Results The 23 necrophagous Calliphorid flies were identified to 9 species of 5 genera. The 715 bp from 28S rRNA and 637 bp from COⅠ gene were obtained and the online BLAST result showed more than 99% of similarity. The phylogeny tree showed that the necrophagous flies could cluster well into 9 groups, which was consistent with morphological identification results. The intraspecific difference in 28S rRNA was 0 and the interspecific difference was 0.001-0.033. The intraspecific difference in COⅠ was 0-0.008 and the interspecific difference was 0.006-0.101. Conclusion Combined use of 28S rRNA and COⅠ gene sequence fragments can effectively identify the nine Calliphorid flies in this study. However, for closely related blowfly species, more genetic markers should be explored and used in combination in future

Relationship between Electrical Conductivity and Chemical Content of Rat Skeletal Muscle Impregnating Solution and Postmortem Interval

Objective To study the mechanism of change of the electrical conductivity （EC） of rat skeletal muscle impregnating solution that occurs with the change of postmortem interval （PMI）. Methods Healthy Sprague-Dawley rats were killed and kept at about 25 ℃. Skeletal muscles were extracted at different PMI——immediate （0 d）, 1 d, 2 d, 3 d, 4 d, 5 d, 6 d, and 7 d, then mixed with deionized water to make impregnating solution with a mass concentration of 0.1 g/mL. The solution’s EC and nine common chemicals in it, such as potassium ion, calcium ion, and chloride ion, were determined. Results EC increased gradually with the extending of PMI （P=0.024） during the 7 days after the rats’ death. The content of uric acid （P=0.032）, urea nitrogen （P=0.013） and phosphorus （P=0.022） also increased during the extension. However, the content of magnesium ions decreased with extending of PMI （P=0.047）. The correlation between potassium ion, sodium ion, chlorine ion, calcium ion, creatinine and PMI were weak （P>0.05）. Conclusion The molecular basis of skeletal muscle EC change in rats after their death is the changes of uric acid, urea nitrogen, inorganic phosphorus and other chemical components. Furthermore, combine use of various indicators can improve the accuracy of the EC method to infer PMI

Relationship between Early Postmortem Interval and Electrical Conductivity of Rat Liver, Spleen and Kidney after Death in Rats

Objective To determine the electrical conductivity （EC） of the liver, spleen and kidney of rats at different postmortem intervals （PMIs） within 24 hours for investigating the relationship between EC of different organs and early PMI. Methods Totally 45 SD rats were sacrificed by cervical dislocation and kept at a constant temperature of 25 ℃. Tissues were taken from the liver, spleen, and kidney of rats at 0, 3, 6, 9, 12, 15, 18, 21 and 24 h. Impregnating solution with a mass concentration 0.1 g/mL was prepared using deionized water. The EC value of impregnating solution with different organs was separately determined. The regression equations of EC and PMI for different organs were established, respectively. The relationship between EC of different organs and early PMI was analysed in deceased rats. Results The relationship between PMI and EC of the liver and spleen was well fitted with the linear equation. The liver showed the best fitting degree followed by the spleen, while the EC of the kidney showed no significant changes within 24 h. There was a good linear relationship between early PMI and the EC of the liver and spleen. Conclusion A good linear relationship between early PMI and the EC of the liver and spleen can be found in rats after death, which can be used for the early PMI estimation

From Waterloo to the Great Wall: A retrospective, multicenter study on the clinical practice and cultural attitudes in the management of premature ejaculation, in China

Premature ejaculation (PE), despite its wide prevalence, is largely underdiagnosed and undertreated. Being a multifactorial dysfunction with strong cultural characteristics, PE requires skillful attitudes in the psychosexological support, necessary to manage the patient's and the couple's expectations, as well as in the medical treatment. Dapoxetine is a short-acting selective serotonin reuptake inhibitor approved for use in lifelong and acquired PE in a number of countries. Opinions, not always generated by the evidence-based medicine, impacted the attitudes of Western andrologists, as a nocebo effect which produced a drug's Waterloo, characterized by low prescription rates much more built on the patients' and doctors' expectations than on costs, side effects, and efficacy.In the present study, we retrospectively reviewed real-life data from eight Andrology and Sexual Medicine Public Centers in China to assess the prevalence of PE among attending patients, its association with erectile dysfunction, its subtype, and the proposed treatments. In 2019, among 156,486 patients coming to the centers, 32,667 visits having PE as the chief complaint were performed (20.9%). Almost all patients received treatment prescriptions (32,641 patients, 99.92%); 23,273 patients came back for a follow-up visit in the subsequent 12 months (71.2% of those who initially received treatment). Dapoxetine, either alone or in combination with another therapy, was the most prevalent treatment, prescribed to 22,767 patients (69.7% of treated patients), followed by traditional Chinese medicine (TCM) (39.4%). At follow-up, 8174 patients were unsatisfied with treatment, and a new treatment was proposed (35.12%). Dapoxetine was the best treatment, with an overall 27.1% switching rate when used either alone or in combination: Although the switching rate for Dapoxetine alone was 44.2%, the association of the same drug with psychotherapy resulted in much lower rates (19.5%) and reached a minimum of 12% when also combined with TCM demonstrating how cultural aspects and medical attitudes may dramatically impact on the therapy of a multifaceted, complex, and culture-grounded sexual symptom such as PE.In conclusion, taking switching rates as surrogate markers of treatment failure, this real-life study-the largest in the field-shows that in a more patient-oriented (as in Chinese medical culture), and less symptom-oriented (as in Western medical attitudes), Dapoxetine is a successful treatment for PE patients, with higher reliability when used alone or as part of combined and integrated therapies

Solving the Problem of Sustainable Use of Bt Crops

Transgenic plants producing insecticidal protein derived from Bacillus thuringiensis (Bt) have been widely adopted since their commercial introduction in 1996. The widespread adoption of such plants has reduced use of conventional insecticides while attaining yield gains, thus providing economic, environmental and human health benefits. However, the benefits from Bt crops will be reduced or even eliminated if pests develop resistance to these toxins so that Bt crops are less or no longer effective. Although field resistance to Bt crops has not yet been found in the continental U.S., resistance to Bt sprays has been found in diamondback moth and greenhouse populations of cabbage looper. Hence, considerable attention has been devoted to developing management programs to prevent, delay or even reverse the spread of resistance. The existing literature on the economic management of pest resistance has generally assumed that pest susceptibility (the converse of pest resistance) is nonrenewable, which means resistance can only increase once it has happened. With the assumption of irreversible resistance, the optimal policy is not to exhaust susceptibility before the new technology, if any, becomes available. Following this logic, the U.S. Environmental Protection Agency (EPA) currently requires Bt crop growers to also plant non-Bt (conventional) crops on a minimum percentage of their total Bt crop acreage as a refuge for susceptible (Bt toxin sensitive) pests. Refuge allows susceptible pests to survive and mate with resistant adults surviving on Bt crops and so delays the development of resistance in the pest population. The cost of this resistance control method includes yield loss of conventional crops relative to Bt crops and sometimes conventional pesticide use. Instead of assuming susceptibility is nonrenewable, some have proposed an alternative source of susceptibility — mass-rearing and releasing harmless susceptible (toxin-sensitive) pests into the environment (Alphey et al. 2007). With this resistance control method in hand, pest susceptibility is now renewable and resistance could be reversed. Based on this method, it is plausible to predict that the optimal resistance management policy should take a cycling pattern, i.e., not planting refuge and allowing resistance to increase until a critical threshold is reached. Once resistance exceeds this threshold, it becomes economical to release susceptible pests to reverse the development of resistance. After resistance is reduced to a desired level, again no refuge needs to be planted and no alternative resistance management actions need to be used until the resistance reaches the threshold again. The cycling feature of the optimal path is due to the reversibility of resistance under this scenario. Also, there is no need to continuously use a resistance control method (as in the case of current refuge policy), since the desired level of resistance can be achieved, at a cost, when needed. However, the crucial consideration is that it is less costly to manage resistance when it is low rather than high. The task of dynamic programming is to find the optimal path where the marginal benefit of resistance control can just cover the marginal cost of resistance. We notice the cycling pattern of this resistance management model and introduce a real options approach originally used in financial analysis. We propose to view pest susceptibility as an investment and the possibility to release susceptible pests as a real option, which can be exercised to improve the expected value of this investment. We formulate the social planner’s decision of releasing susceptible pests as an optimal sequential stopping problem and solve it using stochastic dynamic programming. We first consider releasing pests with a constant ratio for released to natural pests, but then extend the model to allow for selection of a time-varying ratio. The cost of this resistance control technology includes only the cost of monitoring resistance and rearing and releasing susceptible pests. The cycling pattern of this resistance management method is attractive since cost tends to be lower than continuous refuge-based resistance management, as costs are targeted to areas and times when it is needed, rather than being annually implemented across all acres planted to Bt crops. We compare three resistance management programs: refuge only, releasing susceptible pests only, and using both refuge and released pests. The dynamic optimizations are solved numerically using parameters for Bt corn and western corn rootworm. Consistent with previous economic analyses, our dynamic refuge study finds that more refuge should be planted early in commercialization to prevent the rapid development of resistance and that refuge should be planted continuously so that the evolution of resistance is always under control. Once refuge is no longer planted, resistance develops rapidly. For the dynamic releasing of susceptible pests, there is a steady state (economic threshold) of the level of resistance. Whenever the threshold is crossed, resistance control is triggered. The optimal path of the pest population peaks whenever the resistance control (releasing susceptible pests) is exercised. Intuition might consider the pest population peaks as a failure of optimization, however, taking into account that those pests are harmless as long as Bt toxins stay effective, these “bumps” in pest population are fairly acceptable. Our analysis compare these three resistance management programs and find that the optimal resistance control strategy depends on many factors such as yield loss on refuge, the cost of monitoring resistance and rearing and releasing pests, as well as the natural growth rate of pests and the discount rate. We see high potential for generating discussion as the EPA and researchers have been examining changes in refuge requirements for Bt corn, including the recent approval use of mixed seed; however, mitigation once resistance has developed has received little attention. Although we discuss resistance control mostly in the scenario of agricultural pests, the same or similar methodology can also be used in a much broader context in public health economics such as antibiotic resistance or using genetically engineered mosquitoes to fight malaria

Can Conventional Crop Producers Also Benefit From Bt Technology?

Transgenic plants producing insecticidal protein derived from Bacillus thuringiensis (Bt) have been widely adopted since their commercial introduction in 1996. In 2009, 25 countries planted 134 million ha of transgenic crops. The widespread adoption of such plants has reduced use of conventional insecticides while attaining yield gains, thus providing economic, environmental and human health benefits. Because of Bt crops’ high pest control efficacy, there is concern that pests will develop resistance to Bt toxins so that Bt crops are less or no longer effective. To delay the evolution of resistance, the U.S. Environmental Protection Agency (EPA) currently requires Bt crop growers to also plant non-Bt (conventional) crops on a minimum percentage of their total Bt crop acreage as a refuge for susceptible (Bt toxin sensitive) pests. Refuge allows susceptible pests to survive and mate with resistant adults surviving on Bt crops and so slows the development of resistance in the pest population. The existing literature on the welfare analysis of Bt crops generally does not consider the fact that planting Bt crops not only increases the yields of Bt crops themselves but can also increase the yields of non-Bt (conventional/refuge) crops by reducing pests pressure. For example, based on annual population surveys of European corn borer (the most widespread insect pest throughout the U.S. Corn Belt) from the initial invasion of the pest into the Midwestern United States in the 1940s through the commercial adoption of Bt corn during the period 1996 to 2009, Hutchison et al. (2010) showed that ECB populations have declined relative to the pre-Bt era since commercialization of Bt corn, particularly since 2002. The existing literature typically claims that Bt crop producers are possibly winners if the yield increasing effect of the Bt crop beats the price reducing effect. However, conventional crop producers are sure to lose since the price reducing effect — the only effect comes to play for them — reduces their economic surplus. This outcome makes producers skeptical of the benefits for allowing pests to survive in non-Bt crop refuge and is at the root of the refuge compliance problem. Take Bt corn for example. Based on USDA data, Jaffe (2009) estimates that farmer compliance over all three categories of Bt corn, ECB (European corn borer), CRW(corn rootworm), and stacked hybrids, averaged 73% for distance and 74% for size. In other words, one out of four producers did not comply with the Bt corn refuge requirements. Failure to incorporate the positive externality of Bt crops on conventional crops in existing literature results in underestimation of consumer surplus and overestimation of Bt crops growers’ producer surplus. We model the positive externality of Bt crops on conventional crops as a kind of “technology spillover”. Therefore, planting Bt crops will shift the supply curve to the right, not only for Bt crops growers, but also for conventional crop growers, although the magnitudes should differ. Following Alston et al. (1995), we describe a framework to analyze distribution of gains from planting Bt crops in a large open economy context incorporating the technology spillover from Bt crops to conventional crops. We assume that the U.S. is a large open economy that exports crops to the rest of world. Rather than assuming specific functional forms for the supply and demand curves, we instead use a logarithmic differential approximation to solve the model. According to Alston and Wohlgenant (1990), the logarithmic differential (linear elasticity) approximation is good for small changes with constant elasticity supply and demand and is exact with linear supply and demand. We conclude that all world consumers always win due to the introduction of Bt crops since the Bt toxin is effective at increasing yield and reducing production costs. Bt crop producers might win depending on which effect (the yield increasing effect or the price reducing effect) is dominant. Conventional crop producers are no longer doomed to lose, as they might also win if the yield increasing effect of the “technology spillover” due to fewer pests outweighs the price reducing effect. This finding provides more evidence that Bt crop producers have incentives to comply with refuge policy. In the United States, corn has been the most abundant transgenic crop planted to resist insect pests and the most widespread insect pest throughout the U.S. Corn Belt has been the European corn borer which before the advent of Bt corn cost growers about $1 billion annually in losses and control costs. We apply the above model to analyze the distribution of gains from planting ECB Bt corn. The estimated of shift of conventional corn’s supply curve induced by planting ECB Bt corn is crucial to the economic surplus calculation. We combine information from farmer survey and USDA data to refine our estimates. We find that for year 2009, ignoring the positive externality of ECB Bt corn on conventional corn results in underestimation of world consumer surplus by 15.64% and overestimation of Bt corns growers’ producer surplus by 8.43%. The magnitude of these results indicates the importance of including the technology spillover from Bt crops to conventional crops when estimating the welfare effect of Bt crops. In addition, we find that conventional crop producers can also benefit when others use Bt technology. We see high potential for generating discussion as grower compliance with refuge policy for Bt crops continues to be a problem and has apparently gotten worse (Jaffe 2009). Our finding that both Bt and non-Bt acres can benefit from Bt crops will help encourage growers that the refuge/conventional crops that they plant can also benefit from Bt technology