Density thresholds and the incorporation of biocontrol into decision‐making to enhance the control of Cacopsylla pyri in pear (cv. Ercolini) orchards

Abstract

BACKGROUND Economic injury level (EIL) and economic threshold (ET) are customary tools for integrated pest management. Cacopsylla pyri L. is a major pest in pear orchards. The aim of this work was to establish EIL and ET for the optimization of the use of insecticides to control this psyllid, considering biocontrol and two spraying strategies (low‐toxicity versus broad spectrum chemicals). This research was conducted over 4 years in five commercial pear, cv. Ercolini, orchards in south‐eastern Spain. RESULTS Psyllids and ant populations were followed using periodic sampling, and the russet on fruits was quantified. The effect of spray intensity and ant exclusion on psyllid abundance and yield were also tested: both had a significant effect on the cumulative number of C. pyri (CNP), yield and fruit weight. Yield was found to be negatively correlated with CNP. The russet index (RI) increased in a sigmoidal fashion as a function of CNP, being significantly higher with than without ant exclusion. The commercial categorization of fruits was explained satisfactorily as a function of CNP and the cumulative number of ants (CNA). The quantitative EIL was established at a CNP of 427.2 for spraying with paraffinic oil and 425.7 for abamectin. As for the cosmetic EIL, when CNA was zero, this EIL was 24.2, at a CNP of 16.6 for spraying with paraffinic oil or abamectin. CONCLUSIONS The use of products of low toxicity, for the conservation of ants, is expected to increase ET and, thus, reduce the intensity of spraying. © 2021 Society of Chemical Industry.

Diversity, biology, and management of the pear psyllids: a global look

“…For summer generations leaf samples are taken (Burts and Retan 1973, Westigard et al 1979). Treatment thresholds for russet using spur and leaf samples are provided by Nottingham et al (2022b) for C. pyricola and Sanchez et al (2022) for C. pyri . Complications in sampling are caused primarily by seasonal changes in the spatial distribution of eggs and nymphs (Burts 1988, Stratopoulou and Kapatos 1992, Sanchez and Ortín-Angulo 2011).…”

“…This information in turn is helping to develop integrated pest management programs that control psyllids with minimal disruption of the natural enemy community (Beers et al 2016, Shearer et al 2016, Amarasekare and Shearer 2017, Nottingham et al 2022b). Comparisons of psyllid control programs across commercial orchards in both Europe and North America have shown that substituting selective insecticides and biological control for conventional insecticides leads to conservation of natural enemies and to psyllid control (DuPont and Strohm 2020, DuPont et al 2021, Sanchez et al 2022).…”

Psyllids in Natural Habitats as Alternative Resources for Key Natural Enemies of the Pear Psyllids (Hemiptera: Psylloidea)

“…This realization has prompted a slow shift into integrated programs in which selective insecticides, biological control, and cultural or horticultural practices are used as substitutes for high-toxicity psyllicides. A core tactic of these IPM approaches is to use practices that conserve natural enemies but which do not lead to economically damaging levels of psyllids [5][6][7][8][9]. Conservation practices include increased emphasis in monitoring of predators and parasitoids in orchards and in manipulating types, quantities, or timings of insecticides to minimize the effects of psyllicides on them [7][8][9].…”

Pear psylla and natural enemy thresholds for successful integrated pest management in pears

“…Few economic thresholds explicitly incorporate natural enemy predation ( Zhang and Swinton 2009 , Shakya et al 2010 , Zhang and Swinton 2012 , Sanchez et al 2022 ). In some cases, pest mortality has been incorporated using life tables ( Ostlie and Pedigo 1987 , Barrigossi et al 2003 ), predation or parasitism estimates ( Hamilton et al 2004 , Musser et al 2006 ), or inaction thresholds (Sterling 1984).…”