Edward J. Bechinski

Occurrence, Degradation and Fate of Pesticides During Composting

This paper reviews the findings of research reported in the currently available literature regarding the occurrence and transformations of pesticides through the composting process and the use of compost. Part I summarizes the composting process, pesticides and mechanisms of pesticide degradation. Part II reviews research studies concerning the occurrence and fate of pesticides during composting. Investigations of pesticide residues in composting feedstocks and finished compost detected few of the target pesticides. The compounds that were found occurred at low concentrations. The majority of the compounds detected were insecticides in the organochlorine category, including chemicals that have been banned from use in the U.S. for many years. Generally, organophosphate and carbamate insecticides and most herbicides were rarely detected. Comparisons of pesticide concentrations before and after composting also showed organochlorine compounds to be most resistant to biodegradation during composting. With some...

Literature Review: Occurrence, Degradation and Fate of Pesticides During Composting: Part II: Occurrence and Fate of Pesticides in Compost and Composting Systems

This paper reviews the findings of research reported in the currently available literature regarding the occurrence and transformations of pesticides through the composting process and the use of compost. Part I summarizes the composting process, pesticides and mechanisms of pesticide degradation. Part II reviews research studies concerning the occurrence and fate of pesticides during composting. Investigations of pesticide residues in composting feedstocks and finished compost detected few of the target pesticides. The compounds that were found occurred at low concentrations. The majority of the compounds detected were insecticides in the organochlorine category, including chemicals that have been banned from use in the U.S. for many years. Generally, organophosphate and carbamate insecticides and most herbicides were rarely detected. Comparisons of pesticide concentrations before and after composting also showed organochlorine compounds to be most resistant to biodegradation during composting. With some exceptions, pesticides in other categories decomposed moderately well to very well. Studies that followed the mechanisms of degradation indicate that mineralization accounts for only a small portion of pesticide disappearance. Other prominent fates include partial degradation to secondary compounds, adsorption, humification, and volatilization. In general the research results suggest that the pattern of pesticide degradation during composting is similar to the degradatiion observed in soils. With a few important distinctions, composting can be considered a biologically active soil environment in which degradation is accelerated. However, as some studies noted, composting does not always speed the degradation of all pesticides. The nature of the pesticide, specific composting conditions and procedures, the microbial communities present, and the duration of composting affect the extent and the mechanisms of degradation.

Developmental and Phenological Modeling of Russian Wheat Aphid (Hemiptera: Aphididae)

Abstract We applied 14 insect development models, both deterministic and distributed, to describe Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae), development and phenology. The Russian wheat aphid developmental data were from a laboratory experiment of 25 combinatorial treatments of five temperatures and five spring barley, Hordeum vulgare L., plant growth stages. The developmental times of 1,800 individual Russian wheat aphids at various stages were recorded in the experiment. We first compared 11 deterministic development models and discussed some problems associated with the fitting of these models. Not all nonlinear models could be fitted to every Russian wheat aphid stage. The results show that Stinner’s model overall best fit Russian wheat aphid developmental rate data, as judged by mean square error (MSE) and successful convergence. However, we observed a seemingly inescapable dilemma: when one introduces more complex nonlinear models to increase the descriptive power of models (with the hope that model parameters have some biological meanings), the more difficult it is to successfully fit the model. Even if the model is fitted successfully, the values of the model parameters may well be beyond biologically meaningful ranges. Furthermore, we believe that a potentially more serious trap associated with complex nonlinear model is the extreme low tolerance of model parameters. Our results show that the extreme low tolerance associated with the parameter estimate may occur even if the MSE of model fitting is very small. The second part of our results presented same-shape distribution models for Russian wheat aphid development. Stinner’s model performed well and successfully fitted all 22 data sets, whereas the Weibull distribution and logistic model only succeeded in 17 and six of 22 data sets, respectively. Finally, Population Model Design System software was used to simulate Russian wheat aphid phenology based on the integration of deterministic nonlinear developmental rate models and same-shape distributions models.

An approach to the nonlinear dynamics of Russian wheat aphid population growth with the cusp catastrophe model

Many insect field populations, especially aphids, often exhibit irregular and even catastrophic fluctuations. The objective of the present study is to explore whether or not the population intrinsic rates of growth (rm) obtained under laboratory conditions can shed some light on the irregular changes of insect field populations. We propose to use the catastrophe theory, one of the earliest nonlinear dynamics theories, to answer the question. To collect the necessary data, we conducted a laboratory experiment to investigate population growth of the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in growth chambers. The experiment was designed as the factorial combinations of five temperatures and five host plant‐growth stages (25 treatments in total): 1800 newly born RWA nymphs arranged in the 25 treatments (each treatment with 72 repetitions) were observed for their development, reproduction and survival through their entire lifetimes. After obtaining the population intrinsic rates of growth (rm) from the experimental data under various environmental conditions, we built a cusp catastrophe model for RWA population growth by utilizing rm as the system state variable, and temperature and host plant‐growth stage as control variables. The cusp catastrophe model suggests that RWA population growth is intrinsically catastrophic, and dramatic jumps from one state to another might occur even if the temperature and plant‐growth stage change smoothly. Other basic behaviors of the cusp catastrophe model, such as catastrophic jumps, hystersis and divergence, are also expected in RWA populations. These results suggest that the answer to the previously proposed question should be “yes”.

Nutrient Management Practices Used in Potato Production In Idaho

Sound nutrient-management practices are an essential component of modern intensive potato (Solanum tuberosum) production systems. Economic and environmental issues are requiring Idaho potato producers to use management practices that are effective and efficient to remain competitive in the market. Identical potato production management surveys were conducted in 1997 and again in 2006–2007 to determine current nutrient management practices used by Idaho potato growers. This Dillman mail-based survey collected data that were used to determine current nutrient-management strategies and changes that have occurred over the past 10 years. In 2006–2007, more than 77% of growers used preplant soil tests for determining nitrogen (N) application needs. More than 96% of potato growers relied on petiole analysis of potato plant tissue for N management during the growing season. Changes have occurred in only 7 of 28 nutrient-management categories evaluated in the past 10 years, indicating maturity rather than evolution in nutrient management strategies for potatoes. Over the past 10 years, application rates of N have decreased, while potassium (K) rates have increased. There has been a decrease in the number of growers who plant legumes in crop rotation as a source of N. The use of nitrification inhibitors, precision fertilizer management, and application of manure to potato fields has increased in the past 10 years. The overall lack of changes in nutrient management in the past 10 years may indicate that nutrient-management strategies for potatoes in Idaho are mature and successful.

Derivation and Validation of a Binomial Sequential Decision Plan for Managing Pea Aphids (Hemiptera: Aphididae) as Direct Pests of Dry Pea (Fabales: Fabaceae) in the Pacific Northwest

ABSTRACT We developed a binomial sequential decision plan that classifies the economic status of nonviruliferous pea aphids, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), in commercial dry peas, Pisum sativum L. (Fabales: Fabaceae), in the Palouse region of northern Idaho and eastern Washington state. Relationships between mean pea aphid density per plant (x) and the proportion of aphid-infested plants (Pi) were determined by in situ visual counts of 100 plants on each of 27 seasonal dates during 2011 from early vegetative plant growth (stage V105) to late reproductive growth (stage R207) at two field sites near Moscow, ID. The best-fit Nachman model Pi = 1 - exp(-0.3616 x0.808) was used to restate the limits of noneconomic and economic infestations from one and three aphids per plant to 30 and 58% aphid-infested plants, respectively. Sequential decision plans were computed using the stop-line formulas of Waters for Walds Sequential Probability Ratio Test. Validation of the sequential decision plan by simulated sampling from the 2011 data as well as from six commercial fields sampled during 2012 showed that when observed field densities either exceeded the economic injury level or were less than one third the economic injury level, the plan correctly classified aphid economic status in >99% of the resampling trials. Practical implementation of the plan is discussed.