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Determining the most likely source of an invasive pest species might help to improve their management by establishing efficient quarantine measures and heading the search of efficient biological control agents. Planococcus ficus is an invasive mealybug pest of vineyards in Argentina, California, Mexico, Peru and South Africa. This mealybug pest had a previously known geographic distribution spanning southern Europe, the Middle East, and parts of northern Africa. In North America, Pl. ficus was first discovered in the early 1990s and soon thereafter in Mexico. To determine the origin of invasive populations in North America, Pl. ficus from California and Mexico were compared with material throughout its presumptive native range in the Mediterranean region, as well as material collected from an older invasion in South Africa and recently invaded Argentina. From each sample location, genomic DNA was sequenced for the nuclear internal transcribed spacer one (ITS1) and the mitochondrial cytochrome c. oxidase one (CO1). Phylogenetic analyses of CO1, ITS1 and concatenated CO1 and ITS1 data-sets using Bayesian and neighbor-joining analysis support two major divisions: a European grouping (Europe, Tunisia, Turkey) and a Middle Eastern grouping (Israel and Egypt). The invasive populations in Argentina and South Africa align with the European group and the invasive populations in North America align with the Middle Eastern group, with one Israel sample aligning closely with the North American clade, suggesting that Israel was the origin of those populations.

The egg parasitoid Gryon aetherium Talamas (Hymenoptera: Scelionidae) is a promising candidate for biocontrol of Bagrada hilaris Burmeister (Hemiptera: Pentatomidae) in the Southwestern USA. Bagrada hilaris is a worldwide invasive pest of crops in the family Brassicaceae. The present study aims to evaluate the parasitoid's host range in a European context. These tests complement studies underway in California and provide risk information for a potential release of G. aetherium in southern continental Europe where B. hilaris is likely to spread in the future. Of the 11 nontarget species tested, four pentatomids were in the physiological host range of G. aetherium: Carpocoris mediterraneus, Dolycoris baccarum, Graphosoma italicum and Ancyrosoma leucogrammes. Parasitism rates on these four species were lower in choice than in no-choice conditions. Surprisingly, the three Eurydema spp. that belong to the same tribe as B. hilaris (Strachiini) and feed on plants in the family Brassicaceae were not parasitized. No parasitism was observed on the cosmopolitan invasive pentatomids Nezara viridula and Halyomorpha halys, nor on the rhopalid Liorhyssus hyalinus. Parasitoids that developed from non-target species were larger than ones developing on B. hilaris and took more time to complete development. [ABSTRACT FROM AUTHOR]

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, short‐term 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. [ABSTRACT FROM AUTHOR]

Simple Summary: The greatest challenge for modern agriculture is the management of the damage caused by insect pests, in alternative to chemical insecticides, which are the most widely used tools for controlling these pest species. Among the sustainable alternatives to chemical insecticides, the Sterile Insect Technique (SIT) can help to control the target population through the release of adults that have been rendered sterile via irradiation in the field. In order to evaluate the applicability of this technique, a great deal of knowledge about the biology of the target species is required. In this study, we investigated the mechanism of sperm competition in a polyandrous stink bug species, Bagrada hilaris. In view of the possible application of the SIT, it is important that irradiated males have the same potential to compete with wild non-irradiated ones, even at the post-copulation stage. The results obtained showed a mechanism of sperm mixing. The stink bug, Bagrada hilaris, is a pest of mainly Brassicaceae crops. It is native to Africa and Asia and was recently reported as invasive in the southwestern part of the USA and in South America. There are no mitigation programs in place that do not involve pesticides. Therefore, much attention has recently been paid to the study of this species in order to identify sustainable and effective control strategies, such as the Sterile Insect Technique (SIT). In order to evaluate the suitability of the SIT on this pest, the mechanism of post-copulatory sperm competition was investigated. This is a polyandrous species, and it is thus important to understand whether irradiated males are able to compete with wild, e.g., non-irradiated, males for sperm competition after matings. Sperm competition was studied by sequentially mating a healthy virgin female first with a non-irradiated male, and then with a γ-irradiated (Co-60) one, and again in the opposite order. Males were irradiated at three different doses: 60, 80, and 100 Gy. The fecundity and fertility of the females, in the two orders of mating, were scored in order to perform an initial assessment of the success of sperm competition with a P2 index. Sperm from the non-irradiated male were utilized at the lowest irradiation doses (60 and 80 Gy), whereas the irradiated sperm were preferentially utilized at the highest dose (100 Gy). Bagrada hilaris exhibited high variability in P2 indexes, indicating a sperm-mixing mechanism. [ABSTRACT FROM AUTHOR]

These parasitoid species have been detected in Pakistan using sentinel eggs, an extremely valid biocontrol tactic based on exposing a consistent number of eggs of the target pest species for an amount of time suitable to obtain the egg parasitoid oviposition [[17]]. The overall effect of dose and cross types on the number of eclosed eggs, the number of oviposited eggs, and the proportion of eggs hatched per female are reported. [Extracted from the article]

The phytophagous stinkbug pest Bagrada hilaris (Hemiptera: Pentatomidae) (= bagrada) buries single eggs in the ground, an exception among pentatomids. To investigate potential biological control strategies to mitigate the pest’s damages, an evaluation of the egg parasitoid Gryon gonikopalense (Hymenoptera: Scelionidae) as a biocontrol agent is ongoing. Its ability to detect and parasitize buried bagrada eggs could be a key factor in the short and long-term regulation of bagrada populations in the U.S. However, this foraging ability would be relevant only if bagrada mainly oviposits in the soil and if G. gonikopalense mainly parasitizes buried eggs, which is currently unknown. We assessed the oviposition pattern of bagrada in presence of three host plants (broccoli, white mustard and white rocket) and at three density levels (one, five or fifteen copulae). The prevalent oviposition site of bagrada was in the soil (92% of eggs) with no effect from the host plant neither the bagrada density. Eggs oviposited on mustard were mainly present on the top third, but no distribution pattern was observed on broccoli and white rocket. Gryon gonikopalense preferred parasitizing buried eggs (87% of total parasitism). It was also able to parasitize non-buried eggs whatever their location. Artificially increasing the number of non-buried eggs in the experimental design only resulted in a slight reduction in the parasitism of buried eggs (70%). As a result, this study highlights the relevance of using G. gonikopalense against bagrada as its specific foraging behaviour responds well to the main oviposition behaviour of its host. [ABSTRACT FROM AUTHOR]

Invasive stink bugs (Hemiptera: Pentatomidae) are responsible for high economic losses to agriculture on a global scale. The most important species, dating from recent to old invasions, include Bagrada hilaris (Burmeister), Halyomorpha halys (Stål), Piezodorus guildinii (Westwood), Nezara viridula (L.), and Murgantia histrionica (Hahn). Bagrada hilaris, H. halys, and N. viridula are now almost globally distributed. Biological control of these pests faces a complex set of challenges that must be addressed to maintain pest populations below the economic injury level. Several case studies of classical and conservation biological control of invasive stink bugs are reported here. The most common parasitoids in their geographical area of origin are egg parasitoids (Hymenoptera: Scelionidae, Encyrtidae, and Eupelmidae). Additionally, native parasitoids of adult stink bugs (Diptera: Tachinidae) have in some cases adapted to the novel hosts in the invaded area and native predators are known to prey on the various instars. Improving the efficacy of biocontrol agents is possible through conservation biological control techniques and exploitation of their chemical ecology. Moreover, integration of biological control with other techniques, such as behavioural manipulation of adult stink bugs and plant resistance, may be a sustainable pest control method within organic farming and integrated pest management programs. However, additional field studies are needed to verify the efficacy of these novel methods and transfer them from research to application. [ABSTRACT FROM AUTHOR]

In weed biocontrol, there is a need for pre-release efficacy assessments for potential agents. Genista monspessulana ((L.) L. A. S. Johnson (Fabaceae), French broom) is an invasive perennial shrub in the western U.S. The galling weevil Lepidapion argentatum Gerstaecker is a potential biocontrol agent. The impact of increasing weevil density on galling damage, plant height, width, leaf damage, and relative growth rate (RGR) was assessed in greenhouse experiments on two to three-month-old seedlings infested with either one or three weevils. Infestation by three female weevils caused 48% more galls producing 27% more larvae than did infestation with one female while causing only 1% leaf damage and no difference in total leaf area. Infestation with multiple weevils caused a 55% and 29% decrease in plant height and canopy width respectively, while single-weevil infestation decreased height by 32% and width to the same degree as for multiple weevils. The RGR of seedlings infested with three weevils was three times slower than the controls, while growth was reduced 2-fold by single-weevil infestation. Reductions in plant size and growth rate induced by weevil galling could reduce plant competitive survival to reproduction and also plant population dispersal as seedlings. Our results suggest that L. argentatum has the potential to cause impact to French broom seedlings if released in the invasive range. [ABSTRACT FROM AUTHOR]

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A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no action (ongoing impacts from invasive weeds). [ABSTRACT FROM AUTHOR]

A simple molecular tool was developed and tested to identify seven mealybug species found in North American vineyards: Pseudococcus maritimus Ehrhorn, Pseudococcus viburni (Signoret), Pseudococcus longispinus (Targioni-Tozzeti), Pseudococcus calceolariae (Maskell), Planococcus ficus (Signoret), Planococcus citri (Risso), and Ferrisia gilli Gullan. The developed multiplex PCR is based on the mitochondrial cytochrome c oxidase subunit one gene. In tests, this single-step multiplex PCR correctly identified 95 of 95 mealybug samples, representing all seven species and collected from diverse geographic regions. To test the sensitivity, single specimen samples with different Pl. ficus developmental stages (egg to adult female and adult male) were processed PCR and the resulting output provided consistent positive identification. To test the utility of this protocol for adult males caught in sex baited pheromone traps, Pl. ficus adult males were placed in pheromone traps, aged at a constant temperature of 26 ± 2°C, and processed with the multiplex each day thereafter for 8 d. Results showed consistent positive identification for up to 6 d (range, 6-8 d). Results are discussed with respect to the usefulness of this molecular tool for the identification of mealybugs in pest management programs and biosecurity of invasive mealybugs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Host stockpiling for parasitoid production is a challenge in a biocontrol program. • G. gonikopalense rearing can be optimized with bagrada egg storage for biocontrol programs. • Parasitism was seven and nine times higher with eggs stored at 5 °C than at 13 and −20 °C respectively. • Egg storage temperature influenced the progeny's emergence rate but not longevity or body length. • Host deprivation allowed parasitism after 60 days but fecundity was reduced by 84%. The cold storage of host eggs has been utilized in the production of egg parasitoids used in biological control programs. However, similar stockpiling methods can lead to various responses depending on the parasitoid species considered. Hence, standardization of storage methods is difficult. The egg parasitoid Gryon gonikopalense Sharma, is currently being evaluated as a biocontrol agent of Bagrada hilaris (Burmeister), an invasive pest on Brassicaceae crops in the Americas. In this study, we investigated cold storage methods and the effect of host deprivation on G. gonikopalense in order to optimize its rearing process. Laboratory tests were conducted with bagrada bug eggs stored under three temperature treatments (-20 °C, 5 °C, 13 °C) and six durations (one week to three months). In addition, we assessed the effect of host deprivation on parasitoid fecundity and progeny development. Bagrada bug eggs stored at 5 °C up to one month allowed three and nine times more parasitism than eggs stored at 13 and -20 °C respectively. Progeny emergence rate was also the best with eggs stored at 5 °C (94.1%) while eggs stored at 13 and -20 °C led to 77.7 and 89.2 % of emergence respectively. However, the different storage treatments led to similar longevities and body lengths for male and female progeny. In addition, G. gonikopalense did parasitize bagrada eggs after 60 days of host deprivation, but fecundity was reduced by 84%. The results can be used to optimize bagrada bug egg production for use in laboratory and / or field experiments and improve G. gonikopalense rearing and production. [ABSTRACT FROM AUTHOR]

Simple Summary: French broom is a leguminous shrub that is an internationally significant invasive alien weed in California and nearby US states that competes with native vegetation and increases the risk of wildfires. French broom originates from the Mediterranean region and is the target for classical biological control. Exploration for prospective biological control agents in the native region of Western Europe resulted in the collection of the weevil Lepidapion argentatum. We conducted preliminary field studies showing that this weevil can impact seed production in the native habitat. We also measured the specificity of this candidate biocontrol agent in laboratory conditions on 36 plant species growing in California and Australia. Our data showed that, in no-choice tests, seven species were directly negatively impacted by gall formation induced on plant stems by the weevil, but at different levels, including two lupine species commonly distributed in California. Further experiments are needed to ascertain the safety of this candidate biocontrol agent prior to release. French broom (Genista monspessulana) (Fabaceae) is a perennial species native to the Mediterranean basin. Introduced in the 19th century as an ornamental plant, it is currently invasive in California and Australia. The current research is focused on biocontrol with the use of the phytophagous weevil Lepidapion argentatum (Brentidae). Its capacity to develop both in the stem galls and pods of French broom makes it a promising candidate. The impact on the reproduction of French broom was studied in Southern France and revealed that it could effectively reduce the number of viable seeds by 18.8%, but also increased the number of aborted seeds by 10% within the attacked pods. To evaluate the specificity of L. argentatum, choice and no-choice tests were performed in 2012 and 2015 on a total of 36 non-target closely related species. Results revealed the presence of galls and larvae in the stems of seven species, including two endemic Californian lupines; i.e., Lupinus arboreus blue and Lupinus chamissonis. In the future, new tests will be conducted to determine if L. argentatum is able to complete its entire development lifecycle on the non-target species where galls have previously been observed. [ABSTRACT FROM AUTHOR]

Simple Summary: Tree of heaven is a tree native from Asia, considered a serious weed where ever it occurs outside of its native range. Among the herbivores which attack it is a tiny mite, Aculus mosoniensis, which causes serious malformations of the growing tips. In order to determine whether this species is safe to use as a biological control agent in Europe, where the mite has already been recorded, and elsewhere within the invasive range of tree of heaven, host range testing is required. After testing several tree species related to tree of heaven, it was found that this mite was unable to reproduce on any other species except tree of heaven, and importantly there was no damage or sign of feeding on any of the test species. Thus we conclude that this is a safe biological control agent and will help to control this highly invasive tree. Tree of heaven (Ailanthus altissima) is a fast-growing deciduous tree native to China, considered a serious invasive species worldwide, with several socio-economic and ecological impacts attributed to it. Chemical and mechanical methods have limited efficacy in its management, and biological controls may offer a suitable and sustainable option. Aculus mosoniensis (Ripka) is an eriophyid mite that has been recorded to attack tree of heaven in 13 European countries. This study aims to explore the host range of this mite by exposing 13 plant species, selected either for their phylogenetic and ecological similarity to the target weed or their economic importance. Shortly after inoculation with the mite, we recorded a quick decrease in mite number on all nontarget species and no sign of mite reproduction. Whereas, after just one month, the population of mites on tree of heaven numbered in the thousands, irrespective of the starting population, and included both adults and juveniles. Significantly, we observed evidence of damage due to the mite only on target plants. Due to the specificity, strong impact on the target, and the ability to increase its population to high levels in a relatively short amount of time, we find A. mosoniensis to be a very promising candidate for the biological control of tree of heaven. [ABSTRACT FROM AUTHOR]

Centaurea stoebe (subspecies C. s. stoebe and C. s. micranthos[S. G. Gmelin ex Gugler) Hayek] and Centaurea diffusa are Eurasian plant species that have invaded much of North America. We isolated seven microsatellite loci from C. stoebe and two loci from C. diffusa. All loci described here amplify in both species and have between six and 25 alleles each. These markers will be useful in examining population structure and addressing questions regarding these invasions. [ABSTRACT FROM AUTHOR]

Abstract: Two closely related teasels (Dipsacales: Dipsacaceae, Dipsacus spp.) of European origin have become invasive weeds in the United States. Common teasel (Dipsacus fullonum L.) and cutleaf teasel (Dipsacus laciniatus L.) have likely been in North America for more than two centuries, having been introduced along with cultivated teasel [D. sativus (L.) Honckney], an obsolete crop plant. There are few records of American insects or pathogens attacking Dipsacus spp. Invasive teasels have recently begun to spread rapidly throughout much of their current range, for reasons that are not yet known. Common and/or cut-leaf teasel have been listed as noxious in five US states and as invasive in 12 other states and four national parks. Because the family Dipsacaceae is an exclusively Old World family, classical biological control is an important component of the overall management strategy of this weed in the US. Field surveys for natural enemies of D. fullonum and D. laciniatus in their native ranges and literature reviews of natural enemies of plants in the family Dipsacaceae have yielded 102 species of insects in six orders, as well as 27 fungi from 10 orders, three mites, one nematode, and two viruses. Due to the biennial nature of these weeds, a strategy to assign highest priority to biological control candidates attacking first-year (rosette) plants has been established. Candidates selected for further study based on this strategy include Chromatomyia ramosa (Hendel) (Diptera: Agromyzidae), Longitarsus strigicollis Wollaston (Coleoptera: Chrysomelidae), Epitrimerus knautiae Liro (Acarina: Eriophyiidae), Euphydryas desfontainii (Godart) (Lepidoptera: Nymphalidae), Erysiphe knautiae Duby (Erysiphales: Erysiphaceae), and Sphaerotheca dipsacearum (Tul. and C. Tul.) (Erysiphales: Erysiphaceae). [Copyright &y& Elsevier]

Abstract: The use of molecular techniques is rapidly growing as the tools have become more diverse and powerful, more widely available, and easier to implement. Molecular analyses are able to elucidate information about target weeds that is critical to improving control success, such as taxonomic clarification, evidence of hybridization and cryptic species, better development of test plant lists, population structure and origin of invasions. Similarly, molecular approaches can improve our knowledge of biological control agents, providing taxonomic clarity, identification of immature arthropods and fungal pathogens, and description of genetic variability in agents. Molecular tools also allow easier identification of host associations and provide a tool for post-release evaluation and tracking of agents. This review provides an overview of how to use molecular approaches in biological control of weeds, with the aim of assisting the adoption and facilitating fruitful collaboration between scientists studying the biology and ecology of agents and their targets and those with skills using molecular approaches. We describe the current molecular techniques relevant to classical biological control of weeds, instruct how to collect field materials for molecular analyses, and give recent examples of the use of molecular methods in biological control of weeds, with comments on the most appropriate methods for analysis of molecular data. [Copyright &y& Elsevier]