Comparative analysis of pesticide effects on natural enemies in western orchards: A synthesis of laboratory bioassay data

Abstract

Pesticides are commonly used for pest management in apple, pear and walnut orchards in the western U.S. and may disrupt biological control of secondary pests in these crops. A comparative analysis was made of results obtained from a series of laboratory bioassays of acute mortality and life table response experiments to estimate lethal and sublethal effects of eight pesticides on seven natural enemy species through use of stage-structured population models. Even though a number of the pesticides tested were reduced-risk products, all of them with the exception of copper plus mancozeb and chlorantraniliprole, caused more than 80% acute mortality of at least one life stage of at least one of the natural enemy species at a full field-rate concentration and could thus be considered moderately harmful according to the International Organization for Biological Control classification for laboratory bioassays. Important sublethal effects included reductions in daily fecundity and egg fertility. From integration of the lethal and sublethal effects in matrix models, the mean of the estimated intrinsic rates of increase for natural enemy species was negative for exposure to cyantraniliprole, lambda-cyhalothrin and spinetoram, but positive and not significantly different from the control for exposure to chlorantraniliprole, copper plus mancozeb, novaluron, and sulfur. For comparisons among pesticides, there appears to be considerable variation in response among natural enemy species that can only be represented effectively from a full life table response experiment and a population-level endpoint, whereas among natural enemy species, their population-level response to the range of pesticides tested could frequently be represented by acute adult mortality alone.

Invertebrate biodiversity in apple orchards: agrichemical sprays as explanatory variables for inter‐orchard community differences

“…Nitrogen fertilizers are known to affect herbivorous insects, particularly phloem sap‐sucking species, via changes in plant quality (Butler et al ., ) and the same may hold true for leaf‐feeding detritivores. Sulphur (applied as a fungicide) can have direct impacts on invertebrates (Amarasekare et al ., ; Mills et al ., ) and on microbes that support decomposition of leaf material by invertebrates (Zubrod et al ., ). As with the apple orchards in the present study, Todd et al .…”

Integrated management of tortricid pests of tree fruit

“…Border sprays can be used to supplement programmes on uphill slopes and borders with proximity to extraorchard populations (Trimble and Vickers 2000). The selectivity of insecticides against the natural enemies of tortricids, as well as their impact on key natural enemies of secondary pests, has allowed development of programme strategies that optimize the role of biological control during the season (Valentine et al 1996;Beers et al 2005;Biondi et al 2012;Mills et al 2016).…”

“…From a positive perspective these ecological and societal pressures also created new opportunities for the development of more selective pesticides that can increase the role of biological control (Jones et al 2009a;Mills et al 2016;Beers et al 2016a,b), sprayer technologies (Fox et al 2008), orchard architecture (Simon et al 2006(Simon et al , 2007Dorigoni 2016), monitoring tools and implementation of action thresholds to avoid unnecessary perturbations to the ecosystem (Knight and Light 2005a,b;, partial replacement of pesticides with sex pheromone-based mating disruption (Miller and Gut 2015;Ioriatti and Lucchi 2016) and the rapid dissemination of expert knowledge of how to best implement IPM via sophisticated computeraided decision frameworks (Jones et al 2009b;Damos 2015). This chapter summarizes the recent literature associated with several applied aspects of tortricid management.…”

From planning to execution to the future: An overview of a concerted effort to enhance biological control in apple, pear, and walnut orchards in the western U.S.

“…Consequently, there are five papers in this issue that address different aspects of pesticide effects on natural enemy populations in both laboratory and field settings Beers et al, 2016a;Beers et al, 2016b;Mills et al, 2016a;Shearer et al, 2016). These papers show that, in general, laboratory bioassays based on life table response experiments and the use of a demographic approach to evaluation of the combined lethal and sub-lethal effects of pesticides on natural enemies provided an effective way to estimate the potential for disruption of natural enemy populations .…”