Effect of humidity and temperature on the performance of three strains of Aphalara itadori, a biocontrol agent for Japanese Knotweed

Fung, Chanida; González‐Moreno, Pablo; Pratt, Corin F.; Oliver, Tom H.; Bourchier, Robert S.; González‐Suárez, Manuela

doi:10.1016/j.biocontrol.2020.104269

Cited by 11 publications

(10 citation statements)

References 37 publications

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“…× bohemica plants over the course of the experiment did not differ between psyllid and control treatments; however, average leaf length was significantly greater in the absence of A. itadori . These results corroborate those of Fung et al (2020) who observed reduced leaf growth in R. japonica plants exposed to Kyushu psyllids as well as hybrids of the Kyushu and Hokkaido strains. During our experiment, the presence of A. itadori did not reduce above‐ground biomass of R .…”

Section: Discussionsupporting

confidence: 92%

“…Artificial leaf‐roll galls contributed to increased survival of A. itadori nymphs compared to those on gall‐free control leaves. Aphalara itadori nymphs, as well as related psyllids, are susceptible to slower development and desiccation at low humidity (Hodkinson, 2009; Fung et al, 2020), and artificial leaf rolls likely aided the survival and development of nymphs by providing sheltered microhabitats with increased humidity and decreased air movement. Several previous studies have highlighted the ability of rolled leaves to ameliorate abiotic conditions experienced by their inhabitants (e.g., Henson, 1958; Hunter & Wilmer, 1989).…”

Section: Discussionmentioning

confidence: 99%

“…The slow establishment of A. itadori in its introduced range appears to be predominantly the result of nymphal mortality, either through desiccation (Hodkinson, 2009; Fung et al, 2020), predation, or the adaptation of captive populations to low stress environments (Jones et al, 2020). In addition to nymphal mortality, climatic mismatches may also have hindered the establishment of A. itadori in its introduced range (Grevstad et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…Despite large scale, repeated introductions of A. itadori using thousands of individuals locally, long-term establishment, population growth, and control of knotweeds has not been successful at any locations to date (Fung et al, 2020;Grevstad et al, 2018Grevstad et al, , 2022Jones et al, 2021). The lack of establishment may be due to multiple factors, including climate mismatch, predation, or low fitness of the agents because of long-term laboratory rearing (Andersen & Elkinton, 2022;Grevstad et al, 2022;Jones et al, 2020Jones et al, , 2021.…”

Section: Introductionmentioning

confidence: 99%

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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“…Herbicide causes the least damage to the surrounding environment, reduces the risk of accidental spread (Beerling, 1990;Hagen & Dunwiddie, 2008;Hagner et al, 2019) and costs considerably less than excavation. Biological control, despite some promising trials (e.g., Fung et al, 2020) is not currently an available option. Jones et al (2018) evaluated the use of phenologically-timed herbicide application for the control of R. japonica and highlighted that late season treatments with a glyphosate-based herbicide produce the best outcomes.…”

Section: Introductionmentioning

confidence: 99%

Regeneration and growth in crowns and rhizome fragments of Japanese knotweed (Reynoutria japonica) and desiccation as a potential control strategy

Lawson

Fennell

Smith

et al. 2021

PeerJ

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Reynoutria japonica (Japanese knotweed) is a problematic invasive plant found in many areas of Europe and North America. Notably, in the UK, the species can cause issues with mortgage acquisition. Control of R. japonica is complicated by its ability to regenerate from small fragments of plant material; however, there remains uncertainty about how much (in terms of mass) rhizome is required for successful regeneration. This study investigated the ability of crowns and rhizomes with different numbers of nodes to regenerate successfully from three sites in the north of England, UK. Two of the sites had been subject to herbicide treatment for two years prior to sampling and the third site had no history of herbicide treatment. No significant differences were observed in regenerated stem diameter, maximum height of stem and maximum growth increments among crowns. All traits measured from the planted crowns were significantly greater than those of the planted rhizome fragments and at least one node was necessary for successful regeneration of rhizomes. The smallest initial fragment weight to regenerate and survive the experiment was 0.5 g. Subjecting all plant material to desiccation for 38 days resulted in no regrowth (emergence or regeneration) after replanting. These findings suggest that desiccation could be a valuable management strategy for small to medium scale infestations common in urban settings.

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Effect of humidity and temperature on the performance of three strains of Aphalara itadori, a biocontrol agent for Japanese Knotweed

Abstract: Reading's research outputs onlineEffect of humidity and temperature on the performance of three strains of Aphalara itadori, a biocontrol agent for Japanese Knotweed Running title: Aphalara itadori as a biocontrol for Japanese Knotweed

Cited by 11 publications

References 37 publications

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

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

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

Regeneration and growth in crowns and rhizome fragments of Japanese knotweed (Reynoutria japonica) and desiccation as a potential control strategy

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