It is time to bridge the gap between exploring and exploiting: prospects for utilizing intraspecific genetic variation to optimize arthropods for augmentative pest control – a review

Self Cite

Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) is a predatory mite used to control whiteflies and thrips in protected crops. This biocontrol agent, originating from the Eastern Mediterranean region, has been mass-reared for commercial use since 2005 and is widely used in augmentative biocontrol programs. As a polyphagous predator, it has to cope with different biotic and abiotic factors. However, possible adaptation to mass rearing for production might be hindering its resilience and capacity for optimum performance in the field. In this study, we investigated the effect of long-term mass rearing on the genetic diversity of A. swirskii. We identified six microsatellite loci from wholegenome nanopore sequencing of A. swirskii and used these in a comparative analysis of the genetic diversity and differentiation in eight wild populations collected from Israel in 2017 and a commercially available population. Our results indicate that the commercial population is 2.59 less heterozygous than the wild A. swirskii. Furthermore, the commercial population has the highest genetic differentiation from all the natural populations, as indicated by higher pairwise F st values. Overall, we show that commercially reared A. swirskii have reduced genetic variation compared to their wild counterparts, which may reduce their performance when released to control pests in an integrated pest management (IPM) context.

Section: Discussionmentioning

confidence: 99%

Effect of mass rearing on the genetic diversity of the predatory mite Amblyseius swirskii

Paspati

Ferguson

Verhulst

et al. 2019

Self Cite

“…However, occasionally they must be used against certain pests, including key pests such as whiteflies [Bemisia tabaci (Gennadius)], major pests such as aphids, and secondary pests, such as true bugs [Nezara viridula (L.)], leafhoppers (Empoasca sp. Thus, this variation could be exploited to optimize the beneficial action of natural enemies (Bielza, 2016;Lommen et al, 2017). Usually these insecticide applications lead to the disruption of biological control.…”

Section: Discussionmentioning

confidence: 99%

Variation in susceptibility and selection for resistance to imidacloprid and thiamethoxam in Mediterranean populations of Orius laevigatus

Balanza

Mendoza

Bielza

2019

Imidacloprid and thiamethoxam are neonicotinoids that have been tested in several Orius species, including Orius laevigatus (Fieber) (Hemiptera: Anthocoridae), but not the variability in their effect among Orius populations of a single species. In this study, the variation in susceptibility to imidacloprid and thiamethoxam in 30 Mediterranean wild populations and four commercial populations of O. laevigatus was investigated in the laboratory using a standard dip bioassay method. Lethal concentration values (LC 50 ) and the mortality of adults at the maximum field rate (MFR) were calculated. The range of LC 50 of thiamethoxam was from 0.7 to 5.9 mg l À1 , an 8.4-fold variability, obtaining mortality at MFR (100 mg l À1 ) of >89.1% in all populations. The baseline obtained a value of 2.1 mg l À1 , which is very low compared to the MFR. For imidacloprid, the LC 50 varied from 7.7 to 94.7 mg l À1 (12.3-fold variability). Mortalities at the MFR (150 mg l À1 ) were 57.7-99.2%, that is, more variable than for thiamethoxam. The LC 50 value of the baseline was 48.7 mg l À1 , also low compared to the MFR. This variation was exploited to select two populations resistant to thiamethoxam and imidacloprid, respectively. Artificial selection for on average 40 cycles significantly increased the resistance to thiamethoxam (LC 50 = 149.1 mg l À1 ) and imidacloprid (LC 50 = 309.9 mg l À1 ). Mortalities at the MFR in the thiamethoxam-and imidacloprid-resistant populations were 44.5 and 36.9%, respectively. These results demonstrate that resistance can be enhanced in biocontrol agents by artificial selection under laboratory conditions, starting with populations showing no or very low tolerance. Our neonicotinoid-resistant populations might enhance the wider adoption of biological control by allowing punctual or hotspot applications of neonicotinoids to control several main and secondary pests.

“…Still, whereas the improvement in crops has been largely dependent upon selective breeding, this is not the case for the production of natural enemies. Nevertheless, recent years have witnessed a renewed interest in improving biocontrol agents via experimental evolution or artificial selection, judging from recent reviews (Arora & Shera, 2014;Venkatesan & Jalali, 2015;Routray et al, 2016;Lommen et al, 2017;Kruitwagen et al, 2018). One reason may be that selective breeding in agriculture has been done for thousands of years and thus is currently a fine-tuned methodology, whereas improvement of natural enemies for biological control is a recent strategy, still under development.…”

Section: The Use Of Experimental Evolution In Biological Controlmentioning

confidence: 99%

“…We do not focus on the genetics and genomics of biocontrol traits, as this has been the object of recent reviews (Routray et al, 2016;Lommen et al, 2017;Kruitwagen et al, 2018). First, we refer to the methodological underpinnings of experimental evolution and how they are (not) met in studies on biocontrol agents.…”

Section: The Use Of Experimental Evolution In Biological Controlmentioning

confidence: 99%

Does experimental evolution produce better biological control agents? A critical review of the evidence

Lirakis

Magalhães

2019

Biological control of crop pests is considered a good alternative or complement to the use of pesticides. However, legislation restricts the importation of natural enemies of pests. A potential way to circumvent this limitation is by using experimental evolution and/or artificial selection to improve native biological control agents. Here, we review studies that have used these methodologies and evaluate their success. Experimental evolution or artificial selection has been used on a wide range of traits, with most focusing on improving the performance of natural enemies in ecologically relevant environments, such as in the presence of pesticides or at different temperatures. Although most studies were poorly replicated, the selected traits generally improved following the selection process. However, correlated responses (often in the form of trade-offs) with other traits of interest were common. We suggest that the selection procedure can be improved by increasing replication and performing experimental evolution under more semi-natural environments, to ensure that the most useful traits are being selected.