Susceptibility to Spirodiclofen in field populations of Tetranychus urticae (Acari: Tetranychidae) from strawberry plantations in Lima region, Peru

Juan Flores-Bernedo,Javier Vásquez-Castro

doi:10.21704/pja.v4i2.1546

Abstract

The use of inhibitors of lipids synthesis is among the available strategies for the control of Tetranychus urticae (Acari: Tetranychidae) in strawberry plantations. The study aimed to monitor the susceptibility to Spirodiclofen in field populations of T. urticae from strawberry plantations in Lima region, Peru. Adult T. urticae were collected from strawberry plantations in districts of Aucallama, Chancay, Huaral, and Santa Rosa de Quives in Lima region, Peru. A population collected from Acalypha wilkesiana in campus of the Universidad Nacional Agraria La Molina (UNALM), where chemical pesticide has never been applied, was used as a susceptible reference line. This reference line was subjected to toxicological bioassays to estimate the LC50 and LC95. Afterward, bioassays were conducted on the population using the LC50 and LC95 estimated for the susceptible reference line. The obtained data was subjected to one-way analysis of variance and mean comparison was done by Tukey test (α = 0.05). There were no significant differences between the four populations’ LC50 and LC95, with respect to the estimated susceptible reference line. This implies that the four studied populations of T. urticae are susceptible to Spirodiclofen, with no evident resistance problems. Therefore, Spirodiclofen is a useful tool for the control of T. urticae form strawberry plantations in the studied location. The factors that influenced the results are discussed in the present work.

Highlights

Peru registers 2,000 ha of strawberry (Fragaria x ananassa Duch.); of these registers, approximately 1,200 is located in the Lima region, where the valleys of Chancay, Huaral, and Huaura stand out, with more than 50% of the national production area (Olivera, 2012)
The formulation used for the bioassays was that of Spirosil® 250 SC (Spirodiclofen), which is registered for the control of T. urticae in strawberry (Fragaria x ananassa) (Servicio Nacional de Sanidad Agraria [SENASA], 2020)
This allowed other equidistant concentrations to be calculated in a logarithmic scale in order to carry out the bioassay to estimate LC50 and LC95

Summary

Introduction

Peru registers 2,000 ha of strawberry (Fragaria x ananassa Duch.); of these registers, approximately 1,200 is located in the Lima region, where the valleys of Chancay, Huaral, and Huaura stand out, with more than 50% of the national production area (Olivera, 2012). The chemical method is an important measure for controlling T. urticae; most strawberry producers employ this method as the only strategy to control this pest (Bernardi et al, 2013; López et al, 2014) This strategy becomes less efficient as a result of the ease in which this pest develops resistance to chemical acaricides. This is explained by the mite’s short life cycle, abundant progeny and arrhenotokous parthenogenesis, characteristics that favored the evolution of resistance, and reasons why this pest has become very difficult to control in many regions in the world (Bi et al, 2016; Van Leeuwen et al, 2010; Yalçin et al, 2018)

Methods

Results

Conclusion