David Mota-Sanchez

Colorado potato beetle resistance to insecticides

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is widely regarded as the most important insect defoliator of potatoes. Its current range covers about 16 million km2 in North America, Europe, and Asia and continues to expand. This insect has a complicated and diverse life history, which is well-suited to agricultural environments, and makes it a complex and challenging pest to control. Dispersal, closely connected with diapause, feeding, and reproduction, allow the Colorado potato beetle to employ “bet-hedging” reproductive strategies, distributing its offspring in both space (within and between fields) and time (within and between years). The Colorado potato beetle played a large role in creating the modern pesticide industry, with hundreds of chemicals tested against it. High selection pressure, together with natural propensity to adapt to toxic substances, eventually resulted in a large number of insecticide-resistant Colorado potato beetle populations. Since the middle of the last century, the beetle has developed resistance to 52 different compounds belonging to all major insecticide classes. Resistance levels vary greatly among different populations and between beetle life stages, but in some cases can be very high (up to 2,000-fold). Known mechanisms of Colorado potato beetle resistance to insecticides include enhanced metabolism involving esterases, carboxylesterases and monooxygenases, and target site insensitivity, as well as reduced insecticide penetration and increased excretion. There is also some evidence of behavioral resistance. Resistance mechanisms are sometimes highly diverse even within a relatively narrow geographical area. Resistance is usually inherited as an incompletely dominant or incompletely recessive trait, with one or several genes involved in its determination. Because of pleiotropic effects of resistant alleles, insecticide-resistant beetles often have reduced relative fitness in the absence of insecticides. Rotating different classes of insecticides and reducing insecticidal pressure on pest populations by provision of temporal and spatial refuges from exposure to toxins have been proposed to delay evolution of resistance. However, insecticide resistance in this insect will likely remain a major challenge to the pest control practitioners. Still limited understanding of beetle biology, its flexible life history, and grower reluctance to adopt some of the resistance management techniques create impediments to successful resistance management. Overcoming these obstacles is not an easy task, but it will be crucial for sustainable potato production.ResumenEl escarabajo de Colorado de la papa [(Leptinotarsa decemlineata (Say)] es considerado el insecto defoliador más importante de la papa. Su acción cubre una área de 16 millones de km2 en Norteamérica, Europa y Asia y continúa expandiéndose. Este insecto tiene un ciclo de vida complicado y diverso, el cual esta bien adecuado a entornos agrícolas y lo hace una plaga difícil de controlar. Su dispersión, íntimamente conectada con su quiescencia, hábitos de alimentación y reproducción permite al escarabajo de Colorado de la papa emplear estrategias de reproducción de “riesgo calculado”distribuyendo su descendencia en espacio (dentro del campo y entre campos) y tiempo (dentro y entre años). El escarabajo de Colorado de la papa jugó un rol muy amplio en la creación de la industria moderna de pesticidas, con cientos de químicos evaluados para su control. La alta presión de selección, junto a la propensión natural para adaptarse a las sustancias tóxicas, resultó en un gran número de poblaciones resistentes a los insecticidas. Desde mediados del siglo pasado, el escarabajo ha desarrollado resistencia a 52 diferentes compuestos pertenecientes a todas las clases importantes de insecticidas. Los niveles de resistencia varían mucho entre las diferentes poblaciones y estadíos en el ciclo de vida, pero en algunos casos pueden variar mucho más (hasta 2,000 veces). Los mecanismos conocidos de resistencia de este escarabajo a los insecticidas incluyen un elevado metabolismo de las esterasas, carboxilesterasas y monooxigenasas e insensibilidad al sitio objetivo, lo mismo que una penetración del insecticida reducida y excreción incrementada. También hay evidencia de resistencia por comportamiento. Los mecanismos de resistencia son a veces altamente variados, aun dentro de una reducida área geográfica. La resistencia es a menudo heredada como un carácter incompletamente dominante o incompletamente recesivo, con uno o varios genes involucrados en su determinación. Debido a los efectos pleiotrópicos de alelos resistentes, los escarabajos resistentes tienen una aptitud relativa reducida en ausencia de insecticidas. La rotación de diferentes clases de insecticidas y la reducción de la presión insecticida sobre las poblaciones de insectos por provisión de refugios temporales y espaciales contra la exposición de toxinas han sido propuestas para demorar la evolución de la resistencia. Sin embargo, la resistencia a insecticidas de este insecto permanecerá siendo un desafío para los practicantes de control de plagas. Todavía hay un limitado conocimiento sobre la biología del escarabajo, su ciclo de vida flexible y la renuencia del productor para adoptar algunas de las técnicas de manejo de la resistencia impiden el manejo exitoso de la resistencia. El vencer estos obstáculos no es tarea fácil, pero será importante para una producción sostenible de papa.

Global pesticide resistance in arthropods.

Global pesticide resistance in arthropods , Global pesticide resistance in arthropods , کتابخانه دیجیتال جندی شاپور اهواز

Defining Terms for Proactive Management of Resistance to Bt Crops and Pesticides

ABSTRACT Evolution of pest resistance to pesticides is an urgent global problem with resistance recorded in at least 954 species of pests, including 546 arthropods, 218 weeds, and 190 plant pathogens. To facilitate understanding and management of resistance, we provide definitions of 50 key terms related to resistance. We confirm the broad, long-standing definition of resistance, which is a genetically based decrease in susceptibility to a pesticide, and the definition of “field-evolved resistance,” which is a genetically based decrease in susceptibility to a pesticide in a population caused by exposure to the pesticide in the field. The impact of field-evolved resistance on pest control can vary from none to severe. We define “practical resistance” as field-evolved resistance that reduces pesticide efficacy and has practical consequences for pest control. Recognizing that resistance is not “all or none” and that intermediate levels of resistance can have a continuum of effects on pest control, we describe five categories of field-evolved resistance and use them to classify 13 cases of field-evolved resistance to five Bacillus thuringiensis (Bt) toxins in transgenic corn and cotton based on monitoring data from five continents for nine major pest species. We urge researchers to publish and analyze their resistance monitoring data in conjunction with data on management practices to accelerate progress in determining which actions will be most useful in response to specific data on the magnitude, distribution, and impact of resistance.

Integrated pest management in the global arena.

Integrated pest management in the global arena , Integrated pest management in the global arena , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Resistance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), larvae in Michigan to insecticides with different modes of action and the impact on field residual activity.

BACKGROUND The codling moth is one of the principal pests of apple in the world. Resistance monitoring is crucial to the effective management of resistance in codling moth. Three populations of codling moth in neonate larvae were evaluated for resistance to seven insecticides via diet bioassays, and compared with a susceptible population. In addition, apple plots were treated with labeled field rate doses of four insecticides. Treated fruit were exposed to neonate larvae of two populations from commercial orchards. RESULTS Two populations of codling moth expressed two- and fivefold resistance to azinphos-methyl, seven- and eightfold resistance to phosmet, six- and tenfold resistance to lambda-cyhalothrin, 14- and 16-fold resistance to methoxyfenozide and sixfold resistance to indoxacarb, but no resistance to acetamiprid and spinosad. The impact of the resistance to azinphos-methyl, measured as fruit damage, increased as the insecticide residues aged in the field. In contrast, fruit damage in methoxyfenozide- and lambda-cyhalothrin-treated fruit was observed earlier for resistant codling moth. No differences in efficacy were found for acetamiprid. CONCLUSIONS Broad-spectrum insecticide resistance was detected for codling moth. Resistance to azinphos-methyl, lambda-cyhalothrin and methoxyfenozide was associated with reduced residual activity in the field. Broad-spectrum resistance presents serious problems for management of the codling moth in Michigan.

Variation in Fitness among Geographically Isolated Colorado Potato Beetle (Coleoptera: Chrysomelidae) Populations

ABSTRACT Colorado potato beetle, Leptinotarsa decemlineata (Say), is a major pest of potatoes in North America, Europe, and parts of Asia. It adapts quickly to adverse environments, thereby limiting the longevity of control strategies. Better understanding of variability among geographically isolated populations of this insect might create an opportunity to customize control techniques for local conditions. We investigated insecticide resistance, heat tolerance, and growth potential in six beetle populations collected from different locations in the United States. Significant differences were detected in insecticide resistance, egg mass size, and egg hatchability among the tested populations. Large egg mass size appeared to be offset by lower egg hatchability. We also observed a female-biased sex ratio at least in one of the strains. Population growth rates were different among the strains, but this parameter was not correlated to insecticide resistance. This suggests that using allopatric populations in comparative studies of insecticide resistance might result in confusing effects of geographic isolation with the effects of selection toward resistance.

Penetrative and Dislodgeable Residue Characteristics of 14C-Insecticides in Apple Fruit

Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.

Geographic Variation in Cannibalism in Colorado Potato Beetle (Coleoptera: Chrysomelidae) Populations

ABSTRACT Cannibalism can have a large effect on population growth and survival in stressful environments, possibly including those created by insecticide use. In this study, we collected Colorado potato beetles from three isolated areas in the northeastern United States known for high levels of resistance to neonicotinoids. We measured resistance to imidacloprid in each of those populations, a laboratory susceptible population, and in hybrids between the three field populations and the laboratory susceptible population. We fed neonates eggs from resistant dams fed either imidaclopridtreated or untreated foliage to determine whether cannibals are exposed to toxins sequestered in eggs. We measured egg cannibalism by hatchlings within the clutch in each population and hybrids, and examined how fecundity and several variables associated with egg development varied among populations and with cannibalism, to see which traits might enhance or reduce cannibalism. Cannibalism varied significantly among populations, accounting for most of the variation in hatching success. Variability in egg development time and hatch rate in the absence of cannibalism in some populations affected rates of cannibalism. Resistance varied significantly among the field populations but was not related to cannibalism. Neonates fed eggs from dams on treated foliage showed signs of intoxication or death. Cannibalism appears to be part of a varying life history strategy in this species, with some populations laying larger and more cannibalistic clutches and the New York population laying smaller clutches with higher hatching success owing to reduced cannibalism.

Baseline susceptibility of spotted wing Drosophila (Drosophila suzukii) to four key insecticide classes

BACKGROUND The invasive drosophilid pest, Drosophila suzukii Matsumura, is affecting berry production in most fruit-producing regions of the world. Chemical control is the dominant management approach, creating concern for insecticide resistance in this pest. We compared the insecticide susceptibility of D. suzukii populations collected from conventional, organic or insecticide-free blueberry sites. RESULTS The sensitivity of D. suzukii to malathion and spinetoram declined slightly across the 3 years of monitoring, whereas it was more consistent for methomyl and zeta-cypermethrin. The sensitivity of D. suzukii to all four insecticides (LC50 and LC90 values) did not differ significantly among the blueberry fields using different management practices. CONCLUSIONS The baseline sensitivity of D. suzukii has been characterized, allowing future comparisons if field failures of chemical control are reported. The concentration achieving high control indicates that effective levels of control can still be achieved with field rates of these four insecticides. However, declining susceptibility of some populations of D. suzukii to some key insecticides highlights the need for resistance monitoring.

Prediction of multiple-trait and multiple-environment genomic data using recommender systems

In genomic-enabled prediction, the task of improving the accuracy of the prediction of lines in environments is difficult because the available information is generally sparse and usually has low correlations between traits. In current genomic selection, although researchers have a large amount of information and appropriate statistical models to process it, there is still limited computing efficiency to do so. Although some statistical models are usually mathematically elegant, many of them are also computationally inefficient, and they are impractical for many traits, lines, environments, and years because they need to sample from huge normal multivariate distributions. For these reasons, this study explores two recommender systems: item-based collaborative filtering (IBCF) and the matrix factorization algorithm (MF) in the context of multiple traits and multiple environments. The IBCF and MF methods were compared with two conventional methods on simulated and real data. Results of the simulated and real data sets show that the IBCF technique was slightly better in terms of prediction accuracy than the two conventional methods and the MF method when the correlation was moderately high. The IBCF technique is very attractive because it produces good predictions when there is high correlation between items (environment–trait combinations) and its implementation is computationally feasible, which can be useful for plant breeders who deal with very large data sets.