A new population of the biocontrol agent Aphalara itadori performs best on the hybrid host Reynoutria x bohemica

Camargo, Ana M; Kurose, Daisuke; Post, Michel J.C.; Lommen, S.T.E.

doi:10.1016/j.biocontrol.2022.105007

Cited by 9 publications

(23 citation statements)

References 26 publications

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“…When presented with a choice between three knotweed species, both the parental and hybrid A. itadori populations accepted all three species for oviposition (Figure 2). This indiscriminate egg-laying behavior was also observed in a recently collected distinct population (Murakami) of A. itadori in paired-choice tests (Camargo et al, 2022).…”

Section: Discussionsupporting

confidence: 77%

Could hybridization increase the establishment success of the biological control agent Aphalara itadori (Hemiptera: Aphalaridae) against invasive knotweeds?

Yoshimoto,

Szűcs

2024

Ecology and Evolution

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Intraspecific hybridization between distinct populations could increase the fitness and adaptive potential of biological control agents that often have low genetic diversity and can be inbred due to long‐term laboratory rearing often at small population sizes. Hybridization can also alter host preference and performance when the parental insect populations are adapted to different host plants. We investigated the effects of hybridization between two populations (Northern and Southern) of the psyllid, Aphalara itadori, that have different fitness on three invasive knotweed species (Japanese, giant, and Bohemian). Fecundity, host choice, and developmental success of second‐generation reciprocal hybrids and the parental psyllid populations were compared on the three knotweed species in multiple‐choice tests. Hybridization did not increase fecundity. All three knotweed species were accepted for oviposition without preference by the Southern and the two hybrid psyllid populations. The northern psyllid population laid the most eggs on Bohemian knotweeds but those were maladaptive choices since almost all eggs failed to develop. The developmental success of the parental psyllid populations was highest on the knotweed species they were originally collected from, on Japanese knotweed of the Southern psyllids and giant knotweed of the Northern psyllids. Hybrids had intermediate or higher survival on given knotweed hosts compared to their parents. These results can inform release tactics of A. itadori in different regions especially where there appear to be climatic and/or host mismatches such as in Michigan. In southern Michigan, based on climate the Northern psyllid population should be released. However, the most common knotweed species in the region are Bohemian and Japanese knotweeds that do not support the development of the Northern psyllids. In this case, hybrids that may carry cold adaptations of the Northern psyllids but have better developmental success on the prevailing knotweed species may be considered for release to increase establishment success.

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Section: Discussionsupporting

confidence: 77%

Could hybridization increase the establishment success of the biological control agent Aphalara itadori (Hemiptera: Aphalaridae) against invasive knotweeds?

Yoshimoto,

Szűcs

2024

Ecology and Evolution

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“…Additionally, the creation of false galls may improve our ability to monitor for the presence of A. itadori nymphs in large knotweed stands. Camargo et al (2022) recently reported on the strong preference and improved performance of the Murakami line of A. itadori on R. × bohemica. Our study offers additional support for the use of Murakami A. itadori as a biocontrol agent of R. × bohemica.…”

Section: Discussionmentioning

confidence: 99%

“…data). The psyllids that were collected from central Japan (Murakami prefecture) have been found to consistently produce leaf-roll galls in R. × bohemica (Camargo et al, 2022). These galls have the potential to alleviate all of the mortality factors that have hampered the success of previous lines on A. itadori.…”

mentioning

confidence: 99%

Leaf‐roll gall formation in Reynoutria × bohemica and its implications for biological control with Aphalara itadori

Jones,

Kurose,

Shaw

et al. 2023

Entomologia Exp Applicata

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The psyllid Aphalara itadori Shinji (Hemiptera: Psyllidae) is a biocontrol agent against invasive knotweed species (Polygonaceae) in Europe and North America. Despite an extensive release program, successful establishment of the agent has never been confirmed. The slow establishment of A. itadori in its introduced range appears to be predominantly the result of nymphal mortality, either through desiccation, predation, or the adaptation of captive populations to low‐stress environments. In 2016, CABI UK collected a new line of psyllids from Murakami, Niigata Prefecture, in Japan, where it was observed causing severe leaf‐roll galling on one of the many varieties of native knotweeds. The induction of leaf‐roll galls by Murakami psyllids on invasive Bohemian knotweed, Reynoutria × bohemica, has the potential to alleviate some or all of the observed nymphal mortality factors. We conducted a series of growth chamber experiments to explore the psyllid behaviors that initiate leaf‐roll galls, and the ways in which the galls might benefit the psyllids and inhibit invasive knotweed. Reynoutria × bohemica exposed to A. itadori for 4 weeks suffered reduced stem elongation and leaf area compared to control plants. Artificial leaf‐roll galls were consistently utilized by developing A. itadori nymphs, and contributed to their survival. Leaf‐roll galling in R. × bohemica was predominantly initiated by early instar nymphs of A. itadori, and only occurred when leaves were attacked at a very early stage in their development. Our results can inform the knotweed biocontrol program in several key ways. Releases of A. itadori should be timed so that developing nymphs have access to newly emerging leaves. Monitoring efforts at release sites should focus on the growing tips of R. × bohemica, where the highly mobile nymphs appear to migrate. Finally, our results provide motivation to seek additional lines of A. itadori that may affect other invasive knotweed species in similar ways.

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“…Disappointing results led to the search for and subsequent release of a better climatically matched new strain on the hybrid knotweed R . × bohemica which causes more visible damage in the field in the UK and the Netherlands (Camargo et al, 2022) but whose long‐term impact is as yet unknown. Second, the floating fern, Azolla filiculoides , has been successfully biologically controlled in parts of Europe by an accidentally introduced weevil Stenopelmus rufinasus (Coleoptera: Curculionidae) from South America even though this IAP is not on the EU list due to its relatively limited area of impact.…”

Section: Discussionmentioning

confidence: 99%

“…We applied Kmeans clustering to group the 40 species based on their scores obtained for the three score classes. To evaluate the number of clusters best separating the species, we used the function NbClust from the NbClust R Package version 3.0(Charrad et al, 2014), which evaluates the number of clusters based on 30 different indices. The optimal number of clusters was chosen according to the majority rule.…”

mentioning

confidence: 99%

Prioritising environmental invasive weeds of European concern for classical biological control: A reanalysis

Lesieur¹,

Sforza²,

Sheppard³

et al. 2023

Weed Research

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Invasive alien plant species (IAPs) are causing significant negative impacts on agricultural production, threatened native species and ecosystems, the services they provide and public health thereby affecting European biodiversity and its economy. IAPs invade all types of natural and managed habitat and their impacts, through increased numbers and area invaded, are growing exponentially. Current control options in Europe are largely limited to manual and chemical control, which is high cost, shortterm in effectiveness and with regards to chemical control declining in public acceptability. Globally, classical biological control (CBC) is widely and successfully used to manage many IAPs. CBC aims to redress the ecological imbalance caused by the IAPs, generally being released without their natural enemies. The steps are to select, risk assess potential specific natural enemy biocontrol agents of the IAP (from the IAP's native range) and follow regulatory approval prior to releasing them to ecologically suppress their abundance. CBC is not widely used in Europe. Only five active programmes exist. In this paper, we apply an existing framework to develop a ranked list of environmental IAPs named in the EU Regulation on Invasive Species for biocontrol. We used a scoring system based on existing knowledge on the IAPs impacts, the amount of effort needed to deliver a CBC programme targeting them and the feasibility and likelihood of success of such programmes. We identify 16 IAPs in Europe for which CBC has relatively high potential and discuss existing knowledge that can underpin any future investments in such activities against each of these IAPs. The top three species being Pontederia crassipes, Pistia startiotes and Acacia saligna. This research should support decision-making on the instigation of future CBC programmes against environmental IAPs in Europe. We set this analysis in the context of other operational and regulatory constraints on developing CBC programmes against environmental IAPs in Europe.

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A new population of the biocontrol agent Aphalara itadori performs best on the hybrid host Reynoutria x bohemica

Cited by 9 publications

References 26 publications

Could hybridization increase the establishment success of the biological control agent Aphalara itadori (Hemiptera: Aphalaridae) against invasive knotweeds?

Could hybridization increase the establishment success of the biological control agent Aphalara itadori (Hemiptera: Aphalaridae) against invasive knotweeds?

Leaf‐roll gall formation in Reynoutria × bohemica and its implications for biological control with Aphalara itadori

Prioritising environmental invasive weeds of European concern for classical biological control: A reanalysis

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