A Third Type of Resistance to Cydia pomonella Granulovirus in Codling Moths Shows a Mixed Z-Linked and Autosomal Inheritance Pattern

Abstract

Different isolates of Cydia pomonella granulovirus (CpGV) are used worldwide to control codling moth larvae () in pome fruit production. Two types of dominantly inherited field resistance of to CpGV have been recently identified: Z-chromosomal type I resistance and autosomal type II resistance. In the present study, a CpGV-resistant field population (termed SA-GO) from northeastern Germany was investigated. SA-GO individuals showed cross-resistance to CpGV isolates of genome group A (CpGV-M) and genome group E (CpGV-S), whereas genome group B (CpGV-E2) was still infective. Crossing experiments between individuals of SA-GO and the susceptible strain CpS indicated the presence of a dominant autosomal inheritance factor. By single-pair inbreeding of SA-GO individuals for two generations, the genetically more homogenous strain CpRGO was generated. Resistance testing of CpRGO neonates with different CpGV isolates revealed that isolate CpGV-E2 and isolates CpGV-I07 and -I12 were resistance breaking. When progeny of hybrid crosses and backcrosses between individuals of resistant strain CpRGO and susceptible strain CpS were infected with CpGV-M and CpGV-S, resistance to CpGV-S appeared to be autosomal and dominant for larval survivorship but recessive when success of pupation of the hybrids was considered. Inheritance of resistance to CpGV-M, however, is proposed to be both autosomal and Z linked, since Z linkage of resistance was needed for pupation. Hence, we propose a further type III resistance to CpGV in, which differs from type I and type II resistance in its mode of inheritance and response to CpGV isolates from different genome groups. The baculovirus Cydia pomonella granulovirus (CpGV) is registered and applied as a biocontrol agent in nearly all pome fruit-growing countries worldwide to control codling moth caterpillars in an environmentally friendly manner. It is therefore the most widely used commercial baculovirus biocontrol agent. Since 2005, field resistance of codling moth to CpGV products has been observed in more than 40 field plantations in Europe, threatening organic and integrated apple production. Knowledge of the inheritance and mechanism(s) of resistance is indispensable for the understanding of host response to baculovirus infection on the population level and the coevolutionary arms race between virus and host, as well as for the development of appropriate resistance management strategies. Here, we report a codling moth field population with a new type of resistance, which appears to follow a highly complex inheritance in regard to different CpGV isolates.

Pesticidal natural products – status and future potential

“…Therefore, in more than 50 years of commercial use, incidences of resistance are rare. Examples include resistance by the diamondback moth after repeated frequent uses of sprayable Bacillus thuringiensis and repeated frequent uses of codling moth granulosis virus in organic apple production in Europe …”

Pest Management Challenges and Control Practices in Codling Moth: A Review

“…The recent research by Sauer et al [46] described autosomal and dominant inheritance of this resistance and demonstrated cross-resistance to different CpGV genome groups. The same authors report a CM field population with a new type of resistance, which appears to follow a highly complex inheritance in regards to different CpGV isolates [47]. In the European Union (EU) there are no strategic integrated pest management (IPM) programs that solve the current confusion surrounding CM control and resistance.…”

Cryptophlebia peltastica Nucleopolyhedrovirus Is Highly Infectious to Codling Moth Larvae and Cells

“…Larvae of CpR5M exhibited resistance to CpGV-M and also to CpGV-S, CpGV-I12, and CpGV-I07. More recently, a third type of resistance, type III resistance, was postulated for the laboratory strain CpRGO, a homogenous inbred strain of a resistant field population in East Germany (19). CpRGO is characterized by cross-resistance to CpGV-M and CpGV-S (19).…”

“…More recently, a third type of resistance, type III resistance, was postulated for the laboratory strain CpRGO, a homogenous inbred strain of a resistant field population in East Germany (19). CpRGO is characterized by cross-resistance to CpGV-M and CpGV-S (19). So far, the only known commercially applied isolate that can overcome all three types of resistance is CpGV-E2 (13,19).…”

“…CpRGO is characterized by cross-resistance to CpGV-M and CpGV-S (19). So far, the only known commercially applied isolate that can overcome all three types of resistance is CpGV-E2 (13,19).…”