Lessons learned: rearing the crown-boring weevil, Ceutorhynchus scrobicollis (Coleoptera: Curculionidae), in containment for biological control of garlic mustard (Alliaria petiolata)

In this paper, we describe lessons learned and protocols developed after a decade of rearing Ceutorhynchus scrobicollis Nerenscheimer and Wagner in a Biosafety Level 2 containment facility. We have developed these protocols in anticipation of approval to release C. scrobicollis in North America for the biocontrol of garlic mustard. The rearing protocol tried to minimize the potential of attack by the adult parasitoid, Perilitus conseutor, which may be present in field collected C. scrobicollis from Europe to prevent inadvertent introduction of parasitoids into North America. All C. scrobicollis used for our quarantine rearing were field collected near Berlin, Germany. We have successfully reared C. scrobicollis on caged garlic mustard plants in a growth chamber by alternating temperatures and photoperiods to simulate those in its native range. In Germany, C. scrobicollis produces one generation per year and F1 adults emerge in late May. In containment, a new generation of adults emerged an average of 108 days after adults were placed on plants. We found the optimal time spent to collect F1 adults was four weeks after the appearance of the first F1 adult, with 95% of potential adults collected. Simulating a three-month summer aestivation period, followed by a week of fall, and three weeks of winter conditions resulted in optimum levels of oviposition in F1 females. Larvae first hatched 8- to-10 days after adults were placed on plants at 15/14 C day/night temperatures with a 9.5 hour photoperiod. We therefore recommend that C. scrobicollis adults are removed from garlic mustard rosettes after 8 days. This will maximize the period of female oviposition while minimizing the time when larvae are available for attack from P. conseutor

Lessons learned: rearing the crown-boring weevil, Ceutorhynchus scrobicollis (Coleoptera: Curculionidae), in containment for biological control of garlic mustard (Alliaria petiolata)

In this paper, we describe lessons learned and protocols developed after a decade of rearing Ceutorhynchus scrobicollis Nerenscheimer and Wagner in a Biosafety Level 2 containment facility. We have developed these protocols in anticipation of approval to release C. scrobicollis in North America for the biocontrol of garlic mustard. The rearing protocol tried to minimize the potential of attack by the adult parasitoid, Perilitus conseutor, which may be present in field collected C. scrobicollis from Europe to prevent inadvertent introduction of parasitoids into North America. All C. scrobicollis used for our quarantine rearing were field collected near Berlin, Germany. We have successfully reared C. scrobicollis on caged garlic mustard plants in a growth chamber by alternating temperatures and photoperiods to simulate those in its native range. In Germany, C. scrobicollis produces one generation per year and F1 adults emerge in late May. In containment, a new generation of adults emerged an average of 108 days after adults were placed on plants. We found the optimal time spent to collect F1 adults was four weeks after the appearance of the first F1 adult, with 95% of potential adults collected. Simulating a three-month summer aestivation period, followed by a week of fall, and three weeks of winter conditions resulted in optimum levels of oviposition in F1 females. Larvae first hatched 8- to-10 days after adults were placed on plants at 15/14 C day/night temperatures with a 9.5 hour photoperiod. We therefore recommend that C. scrobicollis adults are removed from garlic mustard rosettes after 8 days. This will maximize the period of female oviposition while minimizing the time when larvae are available for attack from P. conseutor

Assessment of the microcyclic rust Puccinia lantanae as a classical biological control agent of the pantropical weed Lantana camara

Lantana camara is a flowering shrub of the family Verbenaceae, native to the Americas which has become a major invasive weed in the Palaeotropics; affecting both natural and agricultural ecosystems. It has been the focus of classical biological control for over a century but has proven to be a problematic target because of its high genetic diversity. Here, we report on an aggressive pathotype of the microcyclic rust Puccinia lantanae collected in the Amazonian rainforest, which – based on greenhouse screening – is damaging to a wide range of biotypes of the L. camara complex. Host-range testing within the Verbenaceae and related plant families, involving leaf clearing and staining, showed the pathotype to be highly specific to L. camara sensu lato but with detectable symptoms in several other verbenaceous species. These results, together with a taxonomic re-appraisal of Puccinia lantanae, are discussed in relation to the potential of the rust as a classical biological control agent of L. camara. We conclude that this pathotype of P. lantanae is a valuable addition to the biological control armoury and posit that it should be especially successful in humid forest situations

Efficacy and host specificity compared between two populations of the psyllid Aphalara itadori, candidates for biological control of invasive knotweeds in North America

Invasive knotweeds are large perennial herbs in the Polygonaceae in the genus Fallopia that are native to Asia and invasive in North America. They include Fallopia japonica (Japanese knotweed), F. sachalinensis (giant knotweed), and a hybrid species F. x bohemica (Bohemian knotweed). Widespread throughout the continent and difficult to control by mechanical or chemical methods, these plants are good targets for classical biological control. We examined the suitability of two populations of the psyllid Aphalara itadori from Japan as biological control agents by comparing their impact on the target weeds and assessing their fundamental host ranges. Both populations were capable of halting knotweed plant growth and reducing both above and below ground biomass by more than 50% in just 50 days. Moreover, the psyllids caused mortality of several of the plants during this period. The two populations differed markedly in their reproductive potential on the different knotweed species. The Kyushu psyllid performed best on F. japonica and F. bohemica and the Hokkaido psyllid performed best on F. sachalinensis. Both were found to be specialized to knotweeds, with only very low occurrence of development on a small number of related non-target plant species. For the few non-target plant species that supported development, choice tests and multi-generational tests were used to further evaluate the likelihood of non-target host use. We conclude that A. itadori would be both effective and low risk as a biological control agent for invasive knotweeds and that both the Kyushu and Hokkaido populations may be needed to effectively control the entire knotweed species complex.This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/Keywords: Fallopia japonica, Fallopia sachalinensis, North America, Host specificity, Aphalara itadori, Knotweed biological contro

Assessment of the microcyclic rust Puccinia lantanae as a classical biological control agent of the pantropical weed Lantana camara

Lantana camara is a flowering shrub of the family Verbenaceae, native to the Americas which has become a major invasive weed in the Palaeotropics; affecting both natural and agricultural ecosystems. It has been the focus of classical biological control for over a century but has proven to be a problematic target because of its high genetic diversity. Here, we report on an aggressive pathotype of the microcyclic rust Puccinia lantanae collected in the Amazonian rainforest, which – based on greenhouse screening – is damaging to a wide range of biotypes of the L. camara complex. Host-range testing within the Verbenaceae and related plant families, involving leaf clearing and staining, showed the pathotype to be highly specific to L. camara sensu lato but with detectable symptoms in several other verbenaceous species. These results, together with a taxonomic re-appraisal of Puccinia lantanae, are discussed in relation to the potential of the rust as a classical biological control agent of L. camara. We conclude that this pathotype of P. lantanae is a valuable addition to the biological control armoury and posit that it should be especially successful in humid forest situations