Biological Fitness Costs in Emamectin Benzoate-Resistant Strains of Dysdercus Koenigii

Entomologia Generalis, Vol. 41 (2021), Issue 3, 267–278 Article Published online 29 April 2021

Biological fitness costs in emamectin benzoate-resistant strains of Dysdercus koenigii

Rabia Saeed1, Naeem Abbas2,*, and Abdulwahab M. Hafez2,*

1 Entomology Section, Central Cotton Research Institute, Multan 60000, Pakistan 2 Pesticides and Environmental Toxicology Laboratory, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia * Corresponding authors: [email protected], [email protected]

With 5 figures and 3 tables

Abstract: Dysdercus koenigii is an economically important cotton-staining pest in Asia. The population of D. koenigii in Pakistan showed resistance to emamectin benzoate, a semi-synthetic pesticide used for the control of several pests. To investigate the biological fitness cost of emamectin benzoate resistance in D. koenigii, the biological traits of emamectin benzoate-resistant (EMB-RR), -susceptible (EMB-SS), hybrid (RS1, EMB-RR♂ × EMB-SS♀), and hybrid (RS2, EMB-RR♀ × EMB-SS♂) D. koenigii strains were compared using the established life table based on age, stage, and two sex patterns. Compared with the EMB-SS strain, the relative fitness of the EMB-RR, RS1, and RS2 D. koenigii strains were 0.538, 0.545, and 0.424, respectively, with substantial decreases in the net reproductive rate, fecundity, age-stage reproductive value and life expectancy, gross reproduction rate, and generation time. The development durations of nymphs, male total longevity, female total longevity, and total preoviposition period were significantly shorter, whereas female’s preoviposition period was prolonged in the EMB-RR, RS1, and RS2 D. koenigii strains. No significant difference was observed in reproductive female ratio, female ratio, and intrinsic and finite rates of increase among the strains. The findings of current study suggest that emamectin benzoate resistance may lead to dominant fitness costs in D. koenigii. Also they provided valuable data for facilitating the rational strategies for controlling D. koenigii.

Keywords: pyrrhocoridae, red cotton bug, insecticide resistance, life table

1 Introduction to D. koenigii (Shah 2014). Insecticide application is a pri- mary management practice for controlling cotton pests, so The cotton stainer bug, Dysdercus koenigii (Fabricius) yield losses. Currently, different new chemical insecticides (Hemiptera: Pyrrhocoridae) is an economically important are being used to suppress the population of this cotton pest. cotton pest in many countries (Sahayaraj & Merin Fernandez However, selection of resistant pest populations against new 2017; Saeed & Abbas 2020). Dysdercus D. koenigii has chemical insecticides is an increasing and alarming problem several hosts, including okra (Abelmoschus esculentus (L.) for cotton producers (Jan et al. 2015; Saddiq et al. 2015; (Malvales: Malvaceae)); yellow corn (Zea mays L. (Poales: Ullah et al. 2016; Saeed et al. 2017; 2018; 2020; Abbas et al. Poaceae)); ground nut (Arachis hypogaea L. (Fabales: 2018; Saeed & Abbas 2020). Fabaceae)); eggplant (Solanum melongena L. (Solanales: Emamectin benzoate is a semi-synthetic pesticide that Solanaceae)); hollyhock (Alcea rosea L. (Malvales: has a glutamate-gated chloride-channel allosteric modula- Malvaceae)), and simal (Salmalia malabarica Schott & tor mode of action that disrupts the nervous and muscular Endl. (Malvales: Bombacaceae)) (Jamal 2014; Naqqash systems of target pests (IRAC 2020). This semi-synthetic et al. 2014). D. koenigii nymphs, as well as adults, suck the pesticide is important due to its effectiveness against a broad sap of seeds by injecting their proboscis inside fresh cotton spectrum of pests, including D. koenigii, and its good safety bolls. They deteriorate seed and lint quality directly by stain- profile against natural enemies and pollinators in com- ing inside the boll and indirectly by transmitting the fungus, parison to conventional insecticides (Mansoor et al. 2013; Nematospora gossypii Ashby & Nowell, which develops Karthikeyan & Ayysamy 2017). However, possible risks inside the cotton bolls (Shah 2014; Saeed et al. 2020). About of control failures due to resistance, sub-lethal effects on 2 million dollars economic losses per season are attributed non-target organisms, and outbreaks of secondary pests are