Acrolepiopsis Assectella Research Articles

Complete mitochondrial genome of the hawthorn moth Scythropia crataegella Linnaeus, 1767 (Lepidoptera: Scythropiidae)

More extensive mitochondrial genome (mitogenome) sequence varieties are required to improve our understanding of Lepidoptera phylogeny and mitogenome evolution. However, only a limited mitogenome diversity is currently available in the lepidopteran superfamily Yponomeutoidea. This study reports the 15,350-bp complete mitogenome of the hawthorn moth Scythropia crataegella (Linnaeus, 1767), the first species in the family Scythropiidae in Yponomeutoidea. S. crataegella has the typical gene content and arrangement found in Lepidoptera. Having the A/T-biased genetic composition in whole mitogenome of S. crataegella (85.3%) A/T-only-containing codons, such as TTA, ATT, TTT, ATA, AAT, and TAT account for 53.21% of protein-coding genes. Including S. crataegella, all Yponomeutoidea species have a TTAGTAT conserved sequence motif at the trnS2 and ND1 junction, a mitochondrial transcription termination peptide binding site. Yponomeutoidea gene sequence divergences were highly variable, ranging from 8.47% (srRNA) to 19.95% (ND6), indicating a substantial substitution force difference among Yponomeutoidea mitochondrial genes. Phylogenetic analysis placed Scythropiidae, represented by S. crataegella, as a sister Glyphipterigidae group, represented by Acrolepiopsis assectella; however, this group’s nodal support was markedly low (bootstrap support = 30%). An extended taxon diversity is essential for further robust Yponomeutoidea phylogenetic inference. Adding a new Yponomeutoidea familial member benefits future mitogenome-based extensive phylogenetic study for this superfamily.

Butterfly Pests (Lepidoptera) Occurring on Vegetable Crops in Poland

Abstract There are over 2,240 butterfly species of Lepidoptera belonging to 17 families recorded in Poland. Of those, 63 phytophagous species have been noted in vegetable agrocenoses at a level of pest status. They constitute 18% of all harmful entomofauna found on vegetable crops. The species described in this paper are common on all vegetable crops growing in Poland, and all parts of plants. The most abundant pests found on aerial parts of crops include the silver Y moth (Autographa gamma), which causes damage to 20 species of vegetables, and species belonging to the genera Mamestra, Lacanobia and Anarta, which feed on more than 10 vegetable species. Of the polyphagous leaf roller moths (Tortricidae), the most numerous are the species belonging to the genus Cnephasia. Periodically, they pose a significant threat, among others for beetroot, pea, cucumber, and lettuce. The diamondback moth (Plutella xylostella) and the cabbage butterfly (Pieris rapae) are dominant butterfly pests on brassica vegetables. A component of harmful entomofauna on onion crops is leek moth (Acrolepiopsis assectella), a species permanently dominant on onion vegetables in Poland since 1930s. The species of the family Depressariidae cause the greatest damage on the generative organs of seed crops, mainly of dill, carrot and parsley. Underground parts of vegetable crops are damaged by cut-worms (Noctuidae), which belong to the group of soil-borne pests. Among more than 60 species belonging to this family, nine cause the greatest damage to vegetable crops. The turnip moth (Agrotis segetum), as a dominant species in recent years, accounted for about 80% of cutworms damaging vegetable crops, and prefers onion, leek, carrot, parsley, celery and corn. Although the European corn borer (Ostrinia nubilalis) is considered a polyphagous species, it forms the most abundant populations on maize out of all other crops.

Simulation-based evaluation of two insect trapping grids for delimitation surveys

In the United States of America, delimitation trapping surveys with square grids have been used for decades for exotic insects without rigorous evaluation. We used simulations to investigate the effectiveness of two representative designs: an 8-km grid for Acrolepiopsis assectella (leek moth) and a 14.5-km grid for Ceratitis capitata (Mediterranean fruit fly, “Medfly”). We investigated grid compositions and design factors, measuring performance as the mean probability of pest capture over all traps, p(capture), and designed improved grids for both species. For the standard designs, p(capture) was 0.86 for leek moth and 0.71 for Medfly, with the latter performing better due to greater lure and trap attractiveness. For both designs, 86 percent or more of mean p(capture) came from core area captures. Egress testing indicated that both grids were oversized. An improved grid for leek moths would use 177 traps in a 4.8-km diameter circle, which had mean p(capture) = 0.73 and reduced the cost by 80 percent. The best Medfly grid was a 4.8-km diameter circle with 232 traps, which gave mean p(capture) of 0.66 and reduced the cost by 86 percent. Simulation may be used to improve trapping survey plans, often saving significantly on costs while maintaining survey performance.

Determining the host range of Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae), a candidate biological control agent for diamondback moth Plutella xylostella linnaeus (Lepidoptera: Plutellidae) in Canada

Before a non-native agent is introduced for the classical biological control of a pest, its host specificity must be determined. We assessed the host specificity of Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae), a solitary pupal endoparasitoid being considered for biological control of the diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) in Canada. In black-box no-choice tests on nine non-target species, D. collaris successfully parasitized other species in the genus Plutella (the introduced Plutella porrectella Linnaeus and the native Plutella armoraciae Busck) as well as another introduced agricultural pest, the leek moth Acrolepiopsis assectella (Zeller) (Lepidoptera: Glyphipterigidae). This suggests that the fundamental host range of D. collaris includes other species in the Plutellidae, as well as Glyphipterigidae that are ecologically and morphologically similar to diamondback moth. Field tests in Switzerland comparing parasitism by D. collaris on sentinel diamondback moth pupae and leek moth pupae in both canola and leek fields revealed no parasitism of leek moth in leek fields, indicating that the ecological host range of D. collaris is in fact more restricted. Because of this, it would be premature to discount D. collaris as a potential biological control agent for diamondback moth in Canada.

Addition of nectar sources affects a parasitoid community without improving pest suppression

A life-table approach was used to test the effect of adding flowering buckwheat to leek plots on mortality and estimated population growth of the invasive leek moth, Acrolepiopsis assectella. This approach was used to estimate the benefits of nectar provisioning on multiple members of the leek moth’s parasitoid complex, and the impact of parasitism on the pest’s predicted population growth rate. Addition of buckwheat to leek plots shifted the relative abundance of different larval and pupal parasitoid species but did not increase or decrease parasitism levels or their population-level impact on the leek moth. The life-table analysis demonstrated that parasitoids reduced the estimated population growth rate of the leek moth by up to 72%, which far exceeds similar estimates from its native range. Parasitoids found to contribute to leek moth mortality were Itoplectis conquisitor, Conura albifrons and the biological control agent Diadromus pulchellus. In addition, Gambrus ultimus, Scambus calobatus, and Habrobracon sp. are reported here developing on A. assectella for the first time. This study reinforces the hypothesis that the addition of nectar resources to agricultural systems may not have straightforward positive effects and can favour some natural enemies over others, but may not have any overall impact on pest suppression.

Effects of floral resources on the efficacy of a primary parasitoid and a facultative hyperparasitoid

AbstractResources added to agroecosystems to enhance biological control are potentially available to multiple members of the resident insect community—not only the biological control agents for which the resources are intended. Many studies have examined the effects of sugar feeding on the efficacy of biological control agents. However, such information is lacking for other, interacting species such as facultative hyperparasitoids, which may contribute to pest suppression but can also interfere with introduced biological control agents. Under greenhouse conditions, we tested the direct effects of sugar and nectar provisioning on the longevity, host‐killing impact and offspring production of two pupal parasitoids associated with leek moth, Acrolepiopsis assectella: the introduced biological control agent, Diadromus pulchellus, and the native facultative hyperparasitoid, Conura albifrons. Adding sucrose, buckwheat or a combination of buckwheat and common vetch to a sugar‐deprived system (potted leek plants in cages) increased parasitoid longevity and resulted in higher leek moth parasitism and mortality compared to water or common vetch treatments. However, the two parasitoid species exhibited a distinct temporal response to the treatments, likely influenced by differences in their life histories. This study provides insight into how integrating conservation biological control techniques could affect the success of a classical biological control programme.

Development and Evaluation of Degree-Day Models for Acrolepiopsis assectella (Lepidoptera: Acrolepiidae) Based on Hosts and Flight Patterns.

The leek moth, Acrolepiopsis assectella (Zeller), was first discovered in Ottawa, Canada, during the 1993 growing season, representing the first known occurrence of this species in North America. Since then, it has become a significant concern in Allium vegetable production including garlic, leeks, and onions. Acrolepiopsis assectella was first detected in the contiguous United States during the 2009 growing season in northern New York. In this study, we evaluated the development of the US A. assectella population in the laboratory and commercial onion fields. Our results showed that this population required 443.9 degree-days to complete its life cycle on onions in the laboratory. The development of A. assectella on onion did not significantly differ from populations reared on garlic or leeks. Field studies revealed three distinct flight periods for overwintered, first- and second-generation adult males in northern New York. Life cycle duration in the field ranged from 4 to 8 wk. The degree-day prediction model evaluated in this study provided accurate estimates of the occurrence of the following generation. We conclude that this model can help growers to implement appropriate management strategies for different life stages in a timely manner and lessen damage by this new invasive pest.

Does parasitoid state affect host range expression?

The pre-release risk assessment of parasitoids for classical biological control generally involves non-target testing to define the agent’s host range. To ensure that no suitable host species are falsely rejected in these tests, it has been suggested that the physiological and informational state of parasitoids be manipulated to enhance their “motivation to oviposit”. However, the effects of such factors on host acceptance are not consistent across parasitoid species, making it laborious to identify the conditions necessary to maximise host acceptance. Our objective was to determine whether changes in parasitoid state could alter host acceptance behaviour sufficiently to affect host range expression. In addition, we tested the assumption that a state-dependent shift in motivation to oviposit on the target host will translate to a similar change in responsiveness to lower-ranked host species. Three-day-old and 10-day-old females of the candidate classical biological control agent, Diadromus pulchellus, were offered 12 non-target species of varying relatedness to the target pest, Acrolepiopsis assectella, in a series of no-choice and choice oviposition trials. Younger D. pulchellus females had previously demonstrated greater motivation to oviposit in the target pest and were, therefore, predicted to express a broader host range than older females. Parasitoid age had a minor effect on host range expression that was contrary to expectations. Older females more readily attacked one of the non-target species in no-choice tests and inflicted higher mortality in one of the choice tests. Ultimately however, young and old parasitoids still attacked the same four non-target species and their offspring emerged from the same three. There was an interaction between the effects of parasitoid condition and experimental design on responsiveness to low-ranked hosts: increasing non-target density in choice tests significantly altered attack rates by 10-day-old, but not by 3-day-old, parasitoids. The implications of these findings for host specificity testing depend largely on the specific aims of a host range assessment. Parasitoid state influenced the frequency of non-target attack but did not affect which non-target species were attacked.

Potential impact of the native hyperparasitoid Conura albifrons (Hymenoptera: Chalcididae) on the exotic biological control agent Diadromus pulchellus (Hymenoptera: Ichneumonidae)

The solitary pupal parasitoid Diadromus pulchellus was released in 2010 as a classical biological control agent against leek moth, Acrolepiopsis assectella, an important new pest of onion crops, Allium spp. in Eastern North America. Post-release monitoring using sentinel leek moth pupae revealed that the facultative hyperparasitoid Conura albifrons was attacking leek moth and potentially D. pulchellus as well. We used laboratory choice and no-choice tests to assess the potential impact of C. albifrons on leek moth and D. pulchellus. C. albifrons is capable of developing in newly formed leek moth pupae and leek moth pupae containing first instar D. pulchellus, as well as in fully developed D. pulchellus pupae. Survivorship of both leek moth and D. pulchellus exposed to C. albifrons was significantly lower than that of unexposed controls. In choice trials, prior host experience significantly influenced host choice by C. albifrons. These results suggest that C. albifrons could impact the establishment of D. pulchellus through both competition and intraguild predation, and that the impact has the potential to change as the relative frequency of the two hosts shifts in field populations.

Diadromus pulchellus in North America: field release against leek moth and new characters to distinguish it from Diadromus subtilicornis, a native diamondback moth parasitoid

We report successful overwintering of Diadromus pulchellus in North America (Ontario) following introduction of this species from Europe to control the leek moth, Acrolepiopsis assectella, a recently established alien species. Field rearing revealed that the native Diadromus subtilicornis emerged only from diamondback moth, Plutella xylostella, whereas D. pulchellus was reared almost exclusively from leek moth. The single D. pulchellus reared from diamondback moth was anticipated because host range studies found this species could develop on both leek moth and diamondback moth in the laboratory, although, it had not been previously reported from diamondback moth in the field in Europe. DNA barcoding of specimens of both Diadromus spp. confirmed their species status and novel morphological characters are presented to distinguish D. pulchellus from D. subtilicornis. In addition, DNA from specimens of D. subtilicornis from Europe clustered with DNA from specimens across Canada, confirming that it is a single Holarctic species. Finally, a new host association for D. subtilicornis is recorded from the dame's rocket moth: Pseudoplutella porrectella.

The effects of periodic warming on the survival and fecundity of Diadromus pulchellus during long-term storage

Biological control strategies capitalise on natural mechanisms such as predation and parasitism to reduce the need for chemical applications to control insect pests. In Canada, the parasitic wasp Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae) is being investigated for its use in the biological control of an invasive crop pest, the leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Large numbers of insects will be needed for releases to ensure that populations of D. pulchellus establish quickly and impact leek moth populations. Since the current culture is not producing the number of insects required for large-scale releases, the accumulation and storage of D. pulchellus might be a viable option to obtain ideal numbers. Currently, little is known about the optimal conditions for the long-term storage and release of D. pulchellus, which overwinter in nature as adults. Using insects from the active culture, the effect of intermittent, short-term warming on cold-stored adults was evaluated for survivorship and fecundity. In accordance with previous findings, females survived cold storage more readily than males. However, the warming regimes employed had no significant impacts on overall survivorship. Cold-stored females had reduced fecundity compared to females maintained in the culture, though no significant differences were noted between the treatments. In addition, the offspring sex-ratio for all treatments was male skewed. Thus, the warming procedures utilised provided no advantages over current techniques for the long-term storage of D. pulchellus intended for release.

Evaluation of Insecticide Chemistries Against the Leek Moth (Lepidoptera: Acrolepiidae), a New Pest in North America

Abstract The leek moth, Acrolepiopsis assectella (Zeller), is a newly introduced micro-lepidopteran pest in North America that attacks Allium crops, including onion, leek, and garlic. Eggs are laid on leaves and emerging larvae may cause extensive damage by mining leaves, feeding on leaf surfaces and feeding directly on bulbs. Little is known about existing natural enemies for this pest in North America, but classical biological control introductions are underway in Canada. However, other management options are needed because the threat to the onion production industry in New York State and the Great Lakes Region is imminent. Laboratory studies showed that lambda cyhalothrin (Warrior® II), spinetoram (Radiant® SC), methomyl (Lannate® LV), chlorantraniliprole (Coragen®), and spinosad (Entrust®) significantly increased larval mortality, compared to the control, at 2, 4, and 8 days after treatment, while Bacillus thuringiensis and azadirachtin insecticides did not. These results are explained in part by the ...

Manipulation of parasitoid state influences host exploitation by Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae)

In biological control programs, it should be possible to manipulate agents during host specificity trials so that they exhibit a lower host acceptance threshold. This would help to ensure that any non-target species that could be attacked in the field will also be attacked in the laboratory and flagged as potential hosts. The question is how to encourage agents to express the widest possible host range during trials. This study examined the effects of variation in parasitoid state (mating status, nutritional status, age, host experience) and the test environment (competition, arena size, presence of host-damaged leek leaves) on the degree of host exploitation by Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae). As a first step, this study looked for changes in oviposition by the parasitoid on its normal host, the leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Each of the seven factors was tested independently to assess its effect on the number of parasitoid offspring produced and host mortality. Previous host experience led to a marginal increase, while competition led to a per-capita decrease, in the degree of host exploitation. In contrast, mating status, arena size and the presence of host-damaged leek leaves had no measurable effects. Finally, parasitoid age and nutritional status had strong effects in the opposite direction to predictions, with younger and sugar-fed individuals exhibiting higher host exploitation than older and sugar-starved parasitoids, respectively. This study suggests that a sound understanding of species-specific reproductive biology and parasitoid–host interactions is likely required before oviposition-enhancing parasitoid states can confidently be identified.

Actual and potential distribution ofAcrolepiopsis assectella(Lepidoptera: Acrolepiidae), an invasive alien pest ofAlliumspp. in Canada

AbstractAcrolepiopsis assectella(Zeller), leek moth, is a widespread and common pest of species ofAlliumL. (Liliaceae) in the western Palaearctic subregion. The establishment ofA. assectellain eastern North America has resulted in economic losses to garlic (Allium sativumL.), leek (Allium porrumL.), and onion (Allium cepaL.) growers, especially to organic producers in eastern Ontario and southern Quebec.Acrolepiopsis assectellawas first recorded in the Ottawa area in 1993. By 2010,A. assectellahad expanded its range into eastern Ontario, southwestern Quebec, Prince Edward Island, and New York. A bioclimate model, using CLIMEX simulation software, was developed to produce mapped results that closely approximated known distributions forA. assectellain central Europe. This model was then validated with recorded distribution records in eastern Europe, Asia, and North America. Model output predicted thatA. assectellawill readily survive in southeastern Canada and the eastern United States of America. Other areas potentially suitable forA. assectellainclude coastal regions of the Pacific Northwest, the interior of southern British Columbia, and north-central Mexico. The continued range expansion ofA. assectellainto otherAllium-growing areas of eastern North America appears to be inevitable. Establishment in these areas presents the risk of substantial production losses toAlliumspp. producers.

Biology and development ofAcrolepiopsis assectella(Lepidoptera: Acrolepiidae) in eastern Ontario

AbstractLeek moth,Acrolepiopsis assectella, recently became established in the Ottawa Valley, where it significantly damages garlic, leek, and onion (AlliumL., Liliaceae) crops. At a threshold of 7 °C, populations in eastern Ontario require 444.6 day-degrees to develop from egg to adult. Pheromone-trap data identify spring, early-summer, and late-summer flight periods of overwintered 1st- and 2nd-generation adults, respectively. Depending on ambient temperatures, the life cycle takes 3–6 weeks in the field, with three generations possible. Management strategies such as application of reduced-risk foliar insecticides and use of row covers require precise timing to target appropriate life-cycle stages. Implementation windows can be determined by incorporating pheromone-trap data and ambient air temperature into a life-cycle development model. A proposed integrated pest management program will involve the use of pesticides, mechanical barriers, and classical biological control.

Pre-release analysis of the overwintering capacity of a classical biological control agent supporting prediction of establishment

This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding short periods of temperatures as low as −5°C or −10°C, but even much higher temperatures were lethal if sustained for several weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime50 at −12°C, simulating winter temperatures without snow cover, was 4–5 and 6–7 days for males and females, respectively. The LTime50 at −4°C, simulating winter temperatures beneath an insulating snow layer, was 1–2 and 2–3 weeks for males and females, respectively, with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity. Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec.

Native range assessment of classical biological control agents: impact of inundative releases as pre-introduction evaluation

Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae) is a pupal parasitoid under consideration for introduction into Canada for the control of the invasive leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Since study of the parasitoid outside of quarantine was not permitted in Canada at the time of this project, we assessed its efficacy via field trials in its native range in central Europe. This was done by simulating introductory releases that would eventually take place in Canada when a permit for release is obtained. In 2007 and 2008, experimental leek plots were artificially infested with pest larvae to mimic the higher pest densities common in Canada. Based on a preliminary experiment showing that leek moth pupae were suitable for parasitism up to 5-6 days after pupation, D. pulchellus adults were mass-released into the field plots when the first host cocoons were observed. The laboratory-reared agents reproduced successfully in all trials and radically reduced leek moth survival. Taking into account background parasitism caused by naturally occurring D. pulchellus, the released agents parasitized at least 15.8%, 43.9%, 48.1% and 58.8% of the available hosts in the four release trials. When this significant contribution to leek moth mortality is added to previously published life tables, in which pupal parasitism was absent, the total pupal mortality increases from 60.1% to 76.7%. This study demonstrates how field trials involving environmental manipulation in an agent's native range can yield predictions of the agent's field efficacy once introduced into a novel area.

Symbiotic virus at the evolutionary intersection of three types of large DNA viruses; iridoviruses, ascoviruses, and ichnoviruses.

BackgroundThe ascovirus, DpAV4a (family Ascoviridae), is a symbiotic virus that markedly increases the fitness of its vector, the parasitic ichneumonid wasp, Diadromus puchellus, by increasing survival of wasp eggs and larvae in their lepidopteran host, Acrolepiopsis assectella. Previous phylogenetic studies have indicated that DpAV4a is related to the pathogenic ascoviruses, such as the Spodoptera frugiperda ascovirus 1a (SfAV1a) and the lepidopteran iridovirus (family Iridoviridae), Chilo iridescent virus (CIV), and is also likely related to the ancestral source of certain ichnoviruses (family Polydnaviridae).Methodology/Principal FindingsTo clarify the evolutionary relationships of these large double-stranded DNA viruses, we sequenced the genome of DpAV4a and undertook phylogenetic analyses of the above viruses and others, including iridoviruses pathogenic to vertebrates. The DpAV4a genome consisted of 119,343 bp and contained at least 119 open reading frames (ORFs), the analysis of which confirmed the relatedness of this virus to iridoviruses and other ascoviruses.ConclusionsAnalyses of core DpAV4a genes confirmed that ascoviruses and iridoviruses are evolutionary related. Nevertheless, our results suggested that the symbiotic DpAV4a had a separate origin in the iridoviruses from the pathogenic ascoviruses, and that these two types shared parallel evolutionary paths, which converged with respect to virion structure (icosahedral to bacilliform), genome configuration (linear to circular), and cytopathology (plasmalemma blebbing to virion-containing vesicles). Our analyses also revealed that DpAV4a shared more core genes with CIV than with other ascoviruses and iridoviruses, providing additional evidence that DpAV4a represents a separate lineage. Given the differences in the biology of the various iridoviruses and ascoviruses studied, these results provide an interesting model for how viruses of different families evolved from one another.

Comparative life tables of leek moth,Acrolepiopsis assectella(Zeller) (Lepidoptera: Acrolepiidae), in its native range

Leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae), is an invasive alien species in eastern Canada, the larvae of which mine the green tissues of Allium spp. This study was designed to construct and analyse life tables for leek moth within its native range. Stage-specific mortality rates were estimated for the third leek moth generation at three sites in Switzerland from 2004 to 2006 to identify some of the principle factors that inhibit leek moth population growth in areas of low pest density. The contribution of natural enemies to leek moth mortality was measured by comparing mortality on caged and uncaged leeks. Total pre-imaginal mortality on uncaged plants was 99.6%, 99.1% and 96.4% in 2004, 2005 and 2006, respectively. Variation in mortality was greater among years than among sites. Total larval mortality was greater than that in the eggs and pupae. This was due largely to the high mortality (up to 83.3%) of neonates during the brief period between egg hatch and establishment of the feeding mine. Leek moth pupal mortality was significantly greater on uncaged than on caged leeks, indicating an impact by natural enemies, and this pattern was consistent over all three years of study. In contrast, the other life stages did not show consistently higher mortality rates on uncaged plants. This observation suggests that the pupal stage may be particularly vulnerable to natural enemies and, therefore, may be the best target for classical biological control in Canada.

Phytophagous Entomofauna Occurring on Onion Plantations in Poland in Years 1919-2007

Phytophagous Entomofauna Occurring on Onion Plantations in Poland in Years 1919-2007 In years 1919-2007 on domestic onion plantations 37 phytophagous species taxons belonging to 7 insect orders: Thysanoptera, Homoptera, Heteroptera, Lepidoptera, Coleoptera, Diptera and Orthoptera were noted. Among these groups 22 species were stated as phytophagous, additional taxons were indentified to 5 genus (Thrips, Mamestra, Polia, Agrotis, Agriotes) and 3 families: fungus gnats (Sciaridae), march flies (Bibionidae), crane flies (Tipulidae). Furthermore 7 species of saprophagous Diptera were collected from damaged onions during harvest. The most common dominant species occurring in all regions of onion production were: onion fly (Delia antiqua Meig.), onion thrips (Thrips tabaci Lind.), onion weevil (Ceutorhynchus suturalis Fabr.), leek moth (Acrolepiospis assectella Zell.) and cutworms (Noctuidae). The population density of: onion beetle (Lilioceris merdigera L.), garlic fly (Suillia lurida Meig.) and leek miner fly (Napomyza gymnostoma Loew) were only a seasonal danger, especially in southern regions of Poland. On wet and rich in organic matter soils some soil dwelling insects such as larvae of Melolontha species (Scarabaeidae), larvae of Agriotes (Elateridae), flies (Diptera) from Tipulidae and Bibionidae families were also occurring periodically. The species and population changes of above mentioned pests allowed to elaborate effective pest control methods of onion plantations. The pest control was performed after field monitoring on the basis of constantly updated short - and long-term forecasting.