Invasive Pest Research Articles

Reproductive Biology of Trichopria anastrephae (Hymenoptera: Diapriidae), a Biological Control Agent of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae).

Hymenopteran parasitoids, like any other insect, employ strategies to ensure their reproduction. Understanding these strategies is important for ecological purposes, but also to improve mass rearing of biological control agents. Here, we describe mating strategies used by the pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae), a potential biocontrol agent, that has been considered for augmentative releases for management of the invasive pest species Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). We studied the emergence pattern of males and females of T. anastrephae and the effects of parental ae on offspring number and sex ratio. Polygamy was also studied and its effects on parasitism and offspring production were described. Adults from this species emerge in the first hours of photophase, and males emerge before females, demonstrating that T. anastrephae is a protandrous species. Parasitoid age when first mated influences the parasitism and sex ratio. Younger females result in a higher number of offspring (8.16 parasitoids/day), while older males result in a more female-biased sex ratio of offspring (64% females). Both males and females are polygamic, and the order in which a female is mated by the male affects parasitism, viability of parasitized pupae, and sex ratio of offspring, with the first female performing the highest parasitism and sex ratio (63.83 and 61% of females, respectively), but the lowest viability (92.92%). Females that are allowed to mate multiple times generate lower numbers of offspring (113.05 parasitoids) when compared to virgin or single-mated females (135.20 and 130.70 parasitoids, respectively), but the highest sex ratio (49% of females). Data present in this study and how it can be used to improve parasitoid rearing and field releases of T. anastrephae, in biological control programs for D. suzukii are discussed.

Effectiveness of chitosan nanohydrogel mediated encapsulation of EcR dsRNA against the whitefly, Bemisia tabaci Asia-I (Gennedius) (Hemiptera: Aleyordidae)

Bemisia tabaci is a global invasive pest causing substantial loss on several economically important crops and has developed a very high level of resistance to insecticides making current management practices ineffective. Thus, the novel pest management strategy like RNA interference (RNAi) has emerged as a potential molecular tool in the management of insect pests particularly B. tabaci. The present study investigated RNAi mediated silencing of the Ecdysone Receptor (EcR) gene in B. tabaci Asia-I using biodegradable Chitosan Nanoparticles (CNPs) hydrogel containing EcR dsRNA. The formation of nanohydrogel and dsRNA loading were characterized by gel retardation assay, scanning electron microscopy (SEM); transmission electron microscopy (TEM) and Fourier transform infrared microscopy (FTIR). The stability of CNPs/dsRNA was assessed by exposure to direct sunlight and UV light for different time periods. The CNPs/dsRNA exhibited increased stability over the untreated control and further confirmed by bioassay studies which yielded mortality over 80% and effectively down regulated the expression of the EcR gene as confirmed by qRT-PCR analysis. These investigations provide potential avenues for advancing innovative pest management strategies using biopolymer CNPs hydrogel, which can enhance the efficiency of dsRNA as a safe and targeted solution in the management of whiteflies.

The application of entomopathogenic nematode modified microbial communities within nesting mounds of the red imported fire ants, Solenopsis invicta

Entomopathogenic microorganisms (e.g., fungi, bacteria, nematodes) have been widely used in biological control of soil-dwelling pests, including the red imported fire ant (RIFA), Solenopsis invicta, a notorious invasive pest worldwide. The application of large amounts of entomopathogenic microorganisms to soil may affect the indigenous soil microbial communities. However, reports about the effect of entomopathogenic nematodes (EPN) on soil microbial communities are very few. In this study, the effects of EPN on RIFA populations and microbial communities in mounds were investigated. Our results showed that the application of the EPN Steinernema carpocapsae. All strain on mounds efficaciously suppressed RIFA worker populations, without forming significantly more satellite mounds compared with the control treatment. The application of EPN did not impact the bacterial and fungal diversity in soils derived from the RIFA mounds. However, it slightly altered the taxonomic make-up of the bacterial communities, but significantly altered the taxonomic composition of fungal communities at the phylum, family, and genus levels. The abundances of some beneficial bacteria and fungi, such as Streptomyces, decreased, while those of plant and animal pathogenic bacteria and fungi, dramatically increased, after EPN treatment. On the other hand, the abundances of some entomopathogenic fungi, such as Fusicolla, Clonostachys, and Mortierella, increased. Redundancy analysis or canonical correspondence analysis revealed a positive correlation between the efficacious EPN control and the presence of the insect-resistant bacteria, Sinomonas, as well as entomopathogenic fungi Fusicolla and Mortierella. This suggests that the interactions between EPN and entomopathogenic fungi may play a role in the biological control of RIFA. Our discoveries shed light on the interactions among EPN, RIFA, and soil microbial communities, and emphasize a possible mutualistic relationship between EPN and entomopathogenic fungi in the biological control of RIFA.

Trehalose-6-Phosphate Synthase Contributes to Rapid Cold Hardening in the Invasive Insect Lissorhoptrus oryzophilus (Coleoptera: Curculionidae) by Regulating Trehalose Metabolism.

Rapid cold hardening (RCH) is known to rapidly enhance the cold tolerance of insects. Trehalose has been demonstrated to be a cryoprotectant in Lissorhoptrus oryzophilus, an important invasive pest of rice in China. Trehalose synthesis mainly occurs through the Trehalose-6-phosphate synthase (TPS)/trehalose-6-phosphate phosphatase (TPP) pathway in insects. In this study, the TPS gene from L. oryzophilus (LoTPS) was cloned and characterized for the first time. Its expression and trehalose content changes elicited by RCH were investigated. Our results revealed that RCH not only increased the survival rate of adults but also upregulated the expression level of LoTPS and increased the trehalose content under low temperature. We hypothesized that upregulated LoTPS promoted trehalose synthesis and accumulation to protect adults from low-temperature damage. To further verify the function of the LoTPS gene, we employed RNA interference (RNAi) technology. Our findings showed that RCH efficiency disappeared and the survival rate did not increase when the adults were fed dsRNA of LoTPS. Additionally, inhibiting LoTPS expression resulted in no significant difference in trehalose content between the RCH and non-RCH treatments. Furthermore, the expression patterns of trehalose transporter (TRET) and trehalase (TRE) were also affected. Collectively, these results indicate the critical role of LoTPS in L. oryzophilus cold resistance after RCH induction. LoTPS can enhance survival ability by regulating trehalose metabolism. These findings contribute to further understanding the role of TPS in insect cold resistance and the invasiveness of L. oryzophilus. Moreover, RNAi of LoTPS opens up possibilities for novel control strategies against L. oryzophilus in the future.

Adaptive migratory orientation of an invasive pest on a new continent

Many species of insects undertake long-range, seasonally reversed migrations, displaying sophisticated orientation behaviors to optimize their migratory trajectories. However, when invasive insects arrive in new biogeographical regions, it is unclear if migrants retain (or how quickly they regain) ancestral migratory traits, such as seasonally preferred flight headings. Here we present behavioral evidence that an invasive migratory pest, the fall armyworm moth (Spodoptera frugiperda), a native of the Americas, exhibited locally adaptive migratory orientation less than three years after arriving on a new continent. Specimens collected from China showed flight orientations directed north-northwest in spring and southwest in autumn, and this would promote seasonal forward and return migrations in East Asia. We also show that the driver of the seasonal switch in orientation direction is photoperiod. Our results thus provide a clear example of an invasive insect that has rapidly exhibited adaptive migratory behaviors, either inherited or newly evolved, in a completely alien environment.

From Field Data to Practical Knowledge: Investigating the Bioecology of the Oak Lace Bug-An Invasive Insect Species in Europe.

Corythucha arcuata, commonly known as the oak lace bug (OLB), is an insect species originally native to North America that has become an invasive species of significant concern in Europe. This invasive pest has been observed in various European countries, raising concerns about its impact on forest ecosystems. In 2015, it was first documented in Romania, further highlighting the need for research on its bioecology and life cycle. This study investigated the bioecology of the OLB in the southern region of Romania, focusing on its life cycle, development, and population dynamics. The results indicated that the OLB has three generations per year and overwinters in the adult stage in sheltered locations. Temperature significantly influenced the timing of egg hatching, nymph appearance, and adult development, with variation observed between generations. Additionally, a life table analysis provided insights into the population dynamics of the OLB in its natural environment, revealing variation in egg laying trends across generations. This research contributes to a better understanding of the OLB's bioecology and provides essential data for forest managers developing science-based management strategies to mitigate its impact. By elucidating the life cycle and development patterns of the OLB in southern Romania, this study aids in the development of predictive models and life tables tailored to the region. These findings empower forest managers with the knowledge needed to make informed decisions for effective OLB management, ultimately preserving the health of forest ecosystems.

Heterosis effect for larval performance of fall armyworm interstrain hybrids.

Spodoptera frugiperda, also known as fall armyworm (FAW), is an invasive crop pest that can feed on a variety of host plants, posing a serious threat to food security. There are two sympatric strains of FAW that are morphologically identical but described with different food preferences: the "rice strain" (SfR) and the "corn strain" (SfC). A few genetic loci exist to identify these two strains. Mitochondrial and Z-chromosome-linked haplotypes are the most used, but the biggest part of the genome displays little polymorphism between strains that could explain their adaptation to different plants. We have previously observed consistent transcription differences between the strains in both laboratory and natural populations. Therefore, we wonder if there are effects from host-strain-associated loci, maternally or paternally inherited, on FAW performance that could explain the divergence between the two FAW strains. To test this hypothesis, we first produced two F1 hybrid generations (SfR ♀ × SfC ♂, SfC ♀ × SfR ♂). These reciprocal hybrids should be heterozygous for all chromosomes except for the maternally inherited mitochondrial and sexual W chromosomes. To evaluate whether plant preference is determined by these genetic loci, we cultivated the two hybrids and the two parental strains in triplicate on an artificial diet and recorded several phenotypic traits such as weight over time, survival rate, emerging rate, developmental time, and sex ratio. Then, the same performance experiment was carried out on corn plants. Surprisingly, on the artificial diet, the two hybrid genotypes were both more performant than the two parental strains in terms of survival rate, pupal emerging rate, and developmental time, whereas they were intermediate to the inbred parental strains in pupal weight. On the corn plant diet, both hybrid genotypes outperformed the two parental strains in larval weight. Although these asymmetrical results revealed that mitochondrial or sex-linked haplotypes alone cannot explain the performance differences, they suggested a heterosis effect in FAW. A reduction of the female number for the CR genotype and the decreased F1 offspring reproduction in both hybrids suggested the possibility of Haldane's rule, which might be explained by the dominance model.

Rugose spiralling whitefly, Aleurodicus rugioperculatus Martin infested host plant volatiles elicit a host locating behavior of aphelinid parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae)

Parasitoids find their hosts by using cues released by herbivores and their host plants. In crop fields, these semiochemicals could be used for insect pest control by attracting and retaining natural enemies. The hymenopteran aphelinidae endoparasitoid, Encarsia guadeloupae (E. guadeloupae), selectively parasitizes rugose spiralling whitefly (RSW), Aleurodicus rugioperculatus Martin, an invasive pest of coconut in India, thus offering an effective way to improve RSW control under natural field conditions. However, the chemical interactions that occur in between the RSW infected host plants and E. guadeloupae were unknown. Hence, using olfactometer assays and chemical analyses, we investigated the volatile organic compounds (VOCs) mediating attraction of the parasitoid to RSW infested host plants. To investigate the attraction of the E. guadeloupae towards the healthy and RSW infected leaves of coconut (Cocos nucifera L), banana (Musa paradisiaca L) and custard apple (Annona squmosa L), we employed a six-arm olfactometer. The E. guadeloupae preferred the volatile compounds from RSW-infested host plants rather than healthy plants. A higher percent response rate of E. guadeloupae was observed in RSW-infected banana (35.83 %), followed by healthy banana (24.33 %), RSW-infested custard apple (16.33 %), and RSW-infested coconut (9.00 %) leaf volatiles, respectively. The volatile compounds emitted from RSW-infested and healthy plants have been studied using GC–MS with thermal desorption (TD). The results revealed more than 20 volatile compounds belonging to seven chemical classes were identified and characterized from infested plants by RSW. Of these, α-Ocimene, α-Pinene, 3-Carene, trans-α-Ocimene, and (E)-hex-3-ene-2, 5-diol were emitted at higher levels than other compounds its proven through PCA and Heat map analysis. These five compounds elicited the greatest attraction of E. guadeloupae towards RSW damaged plants. The synthetic blend of the above volatiles could be used as attractants to enhance the population of E. guadeloupae to manage RSW under field conditions.

Infestation intensity by the invasive oak lace bug, Corythucha arcuata (Say) in mixed and pure oak stands

AbstractThere has been accumulating evidence for effects of tree species composition on herbivory with many examples of lower damage by specialist feeders in tree species rich forests. In a joint study in five Central and Southeastern European countries, we studied the effect of tree species richness on infestation intensity of the oak lace bug, Corythucha arcuata (Say) (Heteroptera, Tingidae), an invasive pest on oak trees that has spread rapidly across the Balkan Peninsula and Central Europe. Intensity of infestation by C. arcuata on oaks was assessed on three or four study plots with high (pure stands) and three or four plots with low percentage of oak (mixed stands) in each country. Ordinal regression analysis showed that intensity of infestation of trees by C. arcuata differed between countries; no significant effect of stand type (mixed or pure) on infestation levels was detected. When analysing the percentage of trees in the highest infestation class, stand type had a significant effect with more intensive infestation in pure stands. We conclude that mixed stands will not prevent severe infestation but may help mitigating the impact of established C. arcuata populations.

Characterization of genes encoding heat shock proteins reveals a differential response to temperature in two geographic populations of Liriomyza trifolii (Diptera: Agromyzidae)

Liriomyza trifolii is a significant, invasive pest that damages horticultural crops and vegetables. The distribution of L. trifolii is influenced by temperature, and prior research has demonstrated that variations in thermal adaptability differ among geographic populations of the insect. Heat shock proteins (Hsps) are involved in adaptation to temperatures; however, the underlying molecular mechanism for thermal adaption in different L. trifolii populations remains unclear. This study examines the temperature adaptability of two L. trifolii populations from Hainan (HN) and Jiangsu (JS) provinces. The results indicate that the HN population has a higher survival rate and a higher critical thermal maximum (CTmax) than the JS population under high temperature stress. Transcriptome data at 42 °C revealed that the JS population has more differentially expressed genes (DEGs) than the HN population, while the HN population has more upregulated DEGs. The two populations were similar in functional annotation of DEGs, and a large number of Hsps were upregulated. However, the HN population had larger numbers and higher expression levels of Hsps during heat stress as compared to the JS population. Additionally, the expression patterns of differentially expressed Hsps varied between the HN and JS populations in response to different elevated temperatures. Notably, the transcription levels of Hsp70s were higher in the HN population as compared to the JS population, while the expression level of genes encoding small heat shock proteins was higher in the JS population. These findings have significant scientific value in understanding the underlying mechanism of temperature adaption in L. trifolii and provide a fresh perspective on the distribution of this invasive pest.

Overexpression of ABCB transporter genes confer multiple insecticide tolerances in Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Bactrocera dorsalis is a notable invasive pest that has developed resistance to several commonly used insecticides in the field, such as avermectin, beta-cypermethrin and malathion. Investigating the mechanisms of insecticide resistance in this pest is of paramount importance for ensuring its effective control. The ATP-binding cassette transporter subfamily B (ABCB) genes, responsible for encoding transmembrane efflux transporters, represent a potential source of insecticide detoxification activity or transportation that remains largely unexplored in B. dorsalis. In this study, seven BdABCB genes were identified and comprehensive analyzed based on the latest genome and transcriptome dataset. Subsequently, we characterized the expression profiles of these genes across different development stages and tissues, as well as under different insecticide exposures. The results showed that the BdABCB genes were expressed at all stages in B. dorsalis, with BdABCB2 and BdABCB7 being highly expressed in the pupal stage, while BdABCB5 and BdABCB6 were highly expressed in the larval stage. Besides, the BdABCBs were highly expressed in the detoxification metabolic tissues. Among them, BdABCB5 and BdABCB6 were significantly overexpressed in the midgut and Malpighian tubules, respectively. Furthermore, with the exception of BdABCB6, the expression levels of the other six BdABCBs were significantly up-regulated following induction with avermectin, beta-cypermethrin and malathion. Six BdABCBs (BdABCB1–5 and BdABCB7) were knocked down by RNA interference, and the interference efficiencies were 46.58%, 39.50%, 45.60%, 33.74%, 66.37% and 63.83%, respectively. After injecting dsBdABCBs, the mortality of flies increased by 25.23% to 39.67% compared to the control upon exposure to the three insecticides. These results suggested that BdABCBs play crucial roles in the detoxification or tolerance of B. dorsalis to multiple insecticides.

Who eats the yellowmargined leaf beetle? Field observations and genetic surveillance to identify local predators of a novel invasive pest

The yellowmargined leaf beetle, Microtheca ochroloma Stahl (Coleoptera: Chrysomelidae), invaded the Southeastern United States and rapidly emerged as a leading pest of crucifer crops, yet little is known about which native predators might effectively provide biological control. The objective of this research is to identify potential predators of this understudied invader through field observation and genetic surveillance. Over two years, arthropods were surveyed on a variety of susceptible Brassica cultivars and a shortlist of commonly associated predators was developed. In a survey of turnip plants in year 1, lady beetles were positively predicted by densities of M. ochroloma, suggesting a numerical response to densities of the invasive pest. Surveys at a different site in year 2 revealed that big-eyed bugs were also positively predicted by M. ochroloma, while pink-spotted lady beetles negatively associated, suggesting a pattern of suppression. Ants (primarily the red imported fire ant) and spiders were commonly observed predators on plants in both years, but neither associated with densities of M. ochroloma. No predators were observed consuming M. ochroloma eggs. Molecular gut-content analysis using specially generated M. ochroloma primers confirmed the observed predatory links and suggested a density-dependent tracking response from pink-spotted lady beetles and ground beetles also have density-dependent tracking re Table 3. Our results may enable farmers to bolster these predator populations with fine-tuned habitat management tools and better suppress the spreading pest.

Potential side effects of the interaction between Phthorimaea absoluta parasitoids: the exotic Dolichogenidea gelechiidivoris and the native Bracon nigricans

The coexistence and efficiency in pest control of introduced and native parasitoids can be challenging. Continuous observations of the cohabitation of parasitoid species could confirm the persistence of the introduced parasitoid in the ecosystem under co-existence scenarios. This study provides an example of such a co-existence for biocontrol of the invasive pest, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae). Two parasitoids, the introduced endoparasitoid Dolichogenidea gelechiidivoris (Marsh) (Hymenoptera: Braconidae) and the native ectoparasitoid Bracon nigricans Szépligeti (Hymenoptera: Braconidae) were released in cages containing a tomato plant infested with P. absoluta. Parasitism and killing rate of P. absoluta by both parasitoid species, and the parasitoid and P. absoluta population were monitored weekly. The parasitoid species coexisted for seven weeks in the experimental units. Parasitism by D. gelechiidivoris was significantly affected by the presence of B. nigricans, with 73% and 22% parasitism in the absence and presence of B. nigricans, respectively. Parasitism by B. nigricans was not affected by its co-existence with D. gelechiidivoris. The number of D. gelechiidivoris adults increased eight-fold in five weeks in the absence of B. nigricans, while less than the initial number of adults were present in co-existence with B. nigricans. The P. absoluta infestation declined from the fifth week to 98% lesser than the control in all the treatments, either D. gelechiidivoris or B. nigricans as standalone treatments, as well as in combination. Since B. nigricans negatively affected D. gelechiidivoris population growth, releases of this introduced parasitoid should be considered with caution in areas where B. nigricans occurs.

Population dynamics and insecticide resistance in Tuta absoluta (Lepidoptera: Gelechiidae), an invasive pest on tomato in Kenya

Tuta absoluta feeds on solanaceous plants with preference on tomato. Management of the pest is mostly with chemical insecticides. This study identified insecticide resistant populations and predicted resistance to insecticides. Insecticide resistance development was modelled using system thinking, and system dynamics approaches. The model showed the pest resistance development is alarming with an exponential increase of the resistance strength mostly in recent years. Furthermore, we used seven insecticide-resistance gene markers to resolve the population structure and genetic differentiation of insecticide-resistant populations in Kenya. The genes for resistance (knockdown resistance (kdr) mutations, acetylcholinesterase (AChE) and voltage gated sodium channel (para)) were detected in all populations. Population structure analyses separated T. absoluta populations into three genetic clusters with resistant genes that are interconnected. A better insight on the population dynamics and the genetic structure T. absoluta resistant genes in Kenya will help estimate resistance strength and determine the most effective pest control strategies.

Dynamic changes in Wolbachia infection over a single generation of Drosophila suzukii, across a wide range of resource availability.

Wolbachia bacteria are maternally inherited symbionts that commonly infect terrestrial arthropods. Many Wolbachia reach high frequencies in their hosts by manipulating their reproduction, for example by causing reproductive incompatibilities between infected male and uninfected female hosts. However, not all strains manipulate reproduction, and a key unresolved question is how these non-manipulative Wolbachia persist in their hosts, often at intermediate to high frequencies. One such strain, wSuz, infects the invasive fruit pest Drosophila suzukii, spotted-wing drosophila. Here, we tested the hypothesis that wSuz infection provides a competitive benefit when resources are limited. Over the course of one season, we established population cages with varying amounts of food in a semi-field setting and seeded them with a 50:50 mixture of flies with and without Wolbachia. We predicted that Wolbachia-infected individuals should have higher survival and faster development than their uninfected counterparts when there was little available food. We found that while food availability strongly impacted fly fitness, there was no difference in development times or survival between Wolbachia-infected and uninfected flies. Interestingly, however, Wolbachia infection frequencies changed dramatically, with infections either increasing or decreasing by as much as 30% in a single generation, suggesting the possibility of unidentified factors shaping Wolbachia infection over the course of the season.

Relevance of molecular systematics in insect pest management

Relevance of molecular systematics in insect pest management

Exploring the association between social media and farmers' knowledge of a worldwide invasive agricultural pest, Spodoptera frugiperda (Lepidoptera: Noctuidae).

Public education has profound effects on the management effectiveness of invasive alien species by shaping stakeholders' knowledge systems. However, our understanding of the association between social media and farmers' knowledge is lacking for the majority of invasive agricultural pests. In this study, we used the fall armyworm (FAW), Spodoptera frugiperda, one of the most invasive insects globally, as a case to test the hypothesis that social media has a significant association with farmers' knowledge of FAW. To address this, we developed a theoretical framework, conducted extensive household questionnaires in the China-Myanmar-Laos border region (China), and used quantitative descriptions and binary logistic regressions in statistical analyses. Our results showed that (1) farmers frequently reported using 12 social media applications on smartphones (SMASs), and obtained FAW-relevant information from six of them, with high preferences for WeChat and TikTok, (2) farmers possessed a generally high level of knowledge of FAW which was significantly associated with their socio-demographic profiles, and (3) FAW-relevant information from SMASs was significantly associated with certain aspects of farmers' knowledge of FAW. We concluded that social media has a significant association with farmers' knowledge of FAW. We suggest that well-designed and -conducted educational programs based on the use of SMASs could help improve the management of FAW, and the Department of Agricultural Extension could play an important and necessary role. Our findings provide insights into this novel educational approach for the management of serious invasive agricultural pests. © 2023 Society of Chemical Industry.

Estimation of the potential geographical distribution of invasive peach fruit fly under climate change by integrated ecological niche models

Climate change and biological invasions of insect pests are interlinked global concerns that drive shifts in the distribution of invasive insects. The peach fruit fly, Bactrocera zonata Saunders, is one of the most economically important Tephritidae species that attack several host plants and causes serious damage in Asia and Africa. Currently, B. zonata is absent from many countries and regions but has a risk of invasion. Therefore, it is crucial to investigate the impact of climate change on the global potential distribution of B. zonata. In this study, we used MaxEnt and CLIMEX models to estimate the risk area for B. zonata under near current and future climate conditions. The MaxEnt and CLIMEX results showed that the south of North and Central America was suitable for B. zonata. The European countries were slightly suitable for B. zonata. In Asia, the highly suitable regions of B. zonata included Saudi Arabia, United Arab Emirates, Oman, Iran, Pakistan, India, Nepal, Bangladesh, Bhutan, Myanmar, Thailand, Vietnam, and Laos. Moreover, China, Philippines, Indonesia, and Japan showed highly climate suitability for B. zonata. The climate suitability of B. zonata was increasingly high in the projection under climate change. The result of the two models showed that the climatic suitability for B. zonata will increase under climate change in China. Taken together, these predictive results support the quarantine of B. zonata for high-risk countries and provide in-depth information on how climatic changes may affect its possible geographic range.

Insecticidal Activity of Selected Essential Oils against Drosophila suzukii (Diptera: Drosophilidae).

The spotted wing drosophila (SWD), Drosophila suzukii Matsumura (Diptera: Drosophilidae), is an invasive polyphagous pest of soft-skinned fruit that has started to threaten small fruit production in Europe since 2008. High reproductive capacity, short generation time, and difficulties in visualizing early damage contribute to its rapid spread. Currently, the control strategy against D. suzukii mostly relies on treatment with synthetic insecticides. Keeping in mind that this pest causes the greatest damage during the harvesting period, control using chemicals is not recommended due to the increased risk of high pesticide residue levels in the fruit. With the aim of reducing the use of insecticides, there is a need for developing an environmentally safer way of control. Alternative solutions could rely on the use of essential oils (EOs), which can be used in conventional and organic production systems. Four essential oils, geranium (Pelargonium graveolens), dill (Anethum graveolens), Scots pine (Pinus sylvestris), and bergamot (Citrus bergamia), were assessed for their insecticidal effects using four different tests (contact toxicity, fumigant-contact toxicity, repellent effect, and multiple-choice tests). The EOs applied were dissolved in acetone at three different concentrations. The most promising one was the geranium essential oil, which had the best effect in all conducted tests, even at the lowest applied concentration. Geranium oil caused very high mortality (95%), even at the lowest concentration applied, after 24 h in the fumigant-contact test, and it caused a mortality of over 85% in the contact test. It was also noticed that geranium demonstrated a deterrent effect by repelling females from laying eggs for four days after at the lowest applied concentration. Scots pine and dill EOs have moderate to strong effects in most tests. The mortality of 100% was achieved for the highest applied concentration in the fumigant-contact and contact tests. Bergamot EO did not have any significant insecticidal activity. Geranium, Scots pine, and dill have great potential to be used as an environmentally friendly way of controlling D. suzukii as they exhibit deterrent, repellent, and insecticidal effects.

Guidelines and framework to assess the feasibility of starting pre-emptive risk assessment of classical biological control agents

Non-native invasive arthropod species threaten biodiversity and food security worldwide, resulting in substantial economic, environmental, social and cultural costs. Classical biological control (CBC) is regarded as a cost-effective component of integrated pest management programmes to manage invasive arthropod pests sustainably. However, CBC programmes are traditionally conducted once a pest has established in a new environment, and invariably all research needed to achieve approval to release a biological control agent can take several years. During that time, adverse impacts of the pest accelerate. A pre-emptive biocontrol approach will provide the opportunity to develop CBC for invasive pests before they arrive in the country at risk of introduction and therefore enhance preparedness. A critical aspect of this approach is that risk assessment is carried out in advance of the arrival of the pest. Implementing pre-emptive biocontrol risk assessment means that natural enemies can be selected, screened in containment or abroad and potentially pre-approved prior to a pest establishing in the country at risk, thus improving CBC effectiveness. However, such an approach may not always be feasible. This contribution defines the fundamental prerequisites, principles, and objectives of pre-emptive biocontrol risk assessment. A set of guidelines and a decision framework were developed, which can be used to assess the feasibility of conducting a pre-emptive risk assessment for candidate biological control agents against high-risk arthropod pests.