Providing key resources to animals may enhance both their biodiversity and the ecosystem services they provide. We examined the performance of annual flower strips targeted at the promotion of ...natural pest control in winter wheat. Flower strips were experimentally sown along 10 winter wheat fields across a gradient of landscape complexity (i.e. proportion non-crop area within 750 m around focal fields) and compared with 15 fields with wheat control strips. We found strong reductions in cereal leaf beetle (CLB) density (larvae: 40%; adults of the second generation: 53%) and plant damage caused by CLB (61%) in fields with flower strips compared with control fields. Natural enemies of CLB were strongly increased in flower strips and in part also in adjacent wheat fields. Flower strip effects on natural enemies, pests and crop damage were largely independent of landscape complexity (8–75% non-crop area). Our study demonstrates a high effectiveness of annual flower strips in promoting pest control, reducing CLB pest levels below the economic threshold. Hence, the studied flower strip offers a viable alternative to insecticides. This highlights the high potential of tailored agri-environment schemes to contribute to ecological intensification and may encourage more farmers to adopt such schemes.
Scouting at key times in the seasonal development of insect pest populations, as guided by degree-day accumulation, is important for minimizing unwarranted insecticide application. Fields of small ...grains in northern Utah were censused weekly from 2001 to 2011, to assess infestation by the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), and develop degree-day guidelines for measuring cereal leaf beetle abundance at peak egg and larval densities in any given year. Even in years of high overall numbers of cereal leaf beetle, relatively few fields were heavily infested (with 20 or more cereal leaf beetle eggs + larvae per 0.09 m2) at either egg or larval peak density during the growing season. In individual fields, the number of immature cereal leaf beetle (eggs + larvae) at peak larval density was positively related to the number of immature cereal leaf beetles present earlier at peak egg density. Although there was large variation among years in when cereal leaf beetle egg and larval numbers peaked during the season as measured by degree-day accumulation from 1 January, much of this variation was accounted for by the warmth of the early spring before significant egg laying occurred. Hence, degree-day estimates that account for early spring warmth can guide growers in scouting grain fields at peak egg densities to identify fields at high risk of subsequent economic damage from cereal leaf beetle larval feeding. The relatively low incidence of fields heavily infested by cereal leaf beetle in northern Utah emphasizes the benefit that growers can gain by scouting early before applying insecticide treatments.
Insecticidal Activity of Lavandula angustifolia Miroslava Kačániová; Simona Kunová; Ladislav Bakay ...
Lucrări științifice zootehnie şi biotehnologii,
06/2023, Letnik:
56, Številka:
1
Journal Article
Odprti dostop
Oilseeds, pulses, and cereals that are kept are seriously harmed by insects. These pests are found all over the globe and result in significant financial losses. Common Palaearctic heteropteran ...Pyrrhocoris apterus produces the macropterous and brachypterous wing morphs, two different wing types. In all of its geographic range, the cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), is a well-known and significant pest of cereals. The volatile chemical mixtures that make up essential oils (EOs) of plants are frequently used as bioactive agents. Effective antifeedants, pesticides, oviposition inhibitors, ovicides, and repellents include EOs. The present work aimed to determine the insecticidal effects of the essential oil (EO) of Lavandula angustifolia (LA) against Pyrrhocoris apterus and Oulema melanopus in different concentration. The best insecticidal activity of LAEO against P. apterus was found in 12.5 % concentration. The greatest insecticidal activity was gained against O. melanopus when LAEO concentration was 50 %. An all-natural alternative to synthetic pesticides, LAEO demonstrated insecticidal properties.
•Tetrastichus julis had a short developmental time and a female-biased sex ratio.•Tetrastichus julis females likely allocate progeny sex ratio based on the instar size of the host.•Sibling mating and ...superparasitism were commonly observed in T. julis.•Tetrastichus julis females can live longer in the absence of its host.
Tetrastichus julis is the key larval endoparasitoid of the cereal leaf beetle, Oulema melanopus. The beetle has recently invaded cereal growing regions of western Canada, and classical biological control with T. julis is a viable management option. Although the general biology of T. julis is known, several knowledge gaps on life history traits still remain particularly in relation to host preferences and their consequences for parasitoid-beetle interactions. We investigated life history parameters and host preferences of T. julis with reference to a number of developmental parameters including survivorship, clutch size, ovipositional preferences for larval stages and their influences on realized clutch size of the parasitoid. Salient features of T. julis biology observed in this study were a short developmental time, a female-biased sex ratio, which is slightly more pronounced in larger instars, extended longevity of females, sibling mating, and more importantly, the capacity of females to live longer in the absence of hosts. The seasonal trend in parasitism rate of T. julis indicated a peak in activity in mid-June. This investigation revealed that T. julis females can discriminate among host instars and can adjust clutch size accordingly and to some extent increase production of females more than males in larger instars. In laboratory and field trials, given a choice, females laid more eggs in fourth instars than in first instars. The sex ratio was female biased and was positively correlated with clutch size. At least one male emerged from most clutches (>2) and sibling mating was common. Parasitism rates were higher after an exposure period of 48 h than 24 h. Mass rearing of T. julis can be enhanced by exposing mated T. julis females for at least 48 h to fourth-instar larvae of O. melanopus. Understanding T. julis biology can enhance mass rearing to relocate parasitoids and improve sustainable management of the cereal leaf beetle as it expands its geographic range.
Ecological intensification aims to reduce environmental costs of agricultural production by increasing biodiversity and using the associated ecosystem services instead of, or in combination with, ...external inputs, so that yields are maintained at high levels or increased. However, to date there are few measures available for which such benefits have already been demonstrated in the field.
In this study, the seeding pattern in winter wheat fields was manipulated to create a diversified crop architecture consisting of ‘unsown-rows’ and ‘densely-sown-rows’ in treatment fields in comparison to ‘conventionally-sown-rows’ in control fields to assess whether (i) in-field structural and microclimatic conditions are more heterogeneous in fields with manipulated crop architecture compared to conventionally managed fields, (ii) a change in crop architecture is related to higher species richness, activity density and altered body size distribution of carabid communities, (iii) this in turn increases natural pest and weed seed control, but (iv) does not lead to yield loss.
In-field structural and microclimatic conditions were more heterogeneous in treatment fields compared to control fields, which was associated with significantly increased body sizes of predatory carabids and a trend for increased predatory carabid species richness (in the ‘unsown-rows’ of treatment fields). These changes were related to significantly stronger pest suppression in the ‘densely-sown-rows’ of treatment fields compared to ‘conventionally-sown-rows’ in control fields, with 10 % higher experimental pest predation rates and 56 % reduced crop damage caused by cereal leaf beetles. Moreover, carabids known to consume weed seeds showed significantly higher activity densities in ‘unsown-rows’ compared to ‘conventionally-sown-rows’, which was related to significantly higher experimental weed seed predation in ‘densely-sown-rows’. Wheat yields were not significantly different in fields with or without manipulated crop architecture.
The results suggest that the simple measure of manipulating the seeding pattern in winter wheat fields creates a diversified crop architecture, thereby promoting carabid diversity and altering their community composition and activity density such that important ecosystem services are increased without yield losses. Thus, beyond fostering biodiversity, this measure has, although not directly tested here, the potential for being used for ecological replacement of pesticides through enhanced ecosystem services without entailing agronomic and economic disadvantages such as land opportunity costs or increased workload.
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•Manipulating crop architecture as new in-field measure for ecological intensification.•Easy applicability by simply closing some sowing coulters without reducing seed quantity.•Higher habitat heterogeneity in manipulated fields with different crop densities.•Changes in carabid communities were positively related to pest control services.•Potential to save pesticides without reducing wheat yield.
Oulema melanopus
L. (
Coleoptera: Chrysomelidae
) is one of the most serious pests of winter wheat that causes peeling of the epidermis and tissue loss. The complex mapping of the physiological ...responses triggered by
O. melanopus
as a biotic stressor in winter wheat has not been fully explored with the help of non-invasive imaging and analytical assays, yet. The aim of the present work was to study the effect of
O. melanopus
on the physiological processes of winter wheat, especially on the extent of lipid peroxidation and antioxidant activity derived from tissue destruction, as well as photosynthetic ability. The results of the measurements enabled the identification of the antioxidant and lipid-oxidation–related physiological reactions, and they were reflected in the dynamics of non-invasive biophoton emissions. Our non-invasive approach pointed out that in the case of
O. melanopus
infestation the damage is manifested in tissue loss and the systemic signaling of the biotic stress may have reached other plant parts as well, which was confirmed by the results of antioxidant capacity measurements. These results indicate that the plant reacts to the biotic stress at a whole organizational level. We identified that the antioxidant and lipid-oxidation–related physiological reactions were reflected in the dynamics of two aspects of biophoton emission: delayed fluorescence and ultra-weak bioluminescence. Our research further supported that the non-invasive approach to stress assessment may complete and detail the traditional stress indicators.
One of the earliest responses of plants to insects’ attack is generation of reactive oxygen species. However, the elevated level of ROS can elicit oxidative burst within plant tissues, and plants ...employ antioxidant systems against these radicals. Due to their chemical structures, polyphenols are able to diminish the level of ROS. Thus, we investigated the role of phenolic compounds in oxidative stress within winter triticale caused by Sitobion avenae and Oulema melanopus. It was found, that infestation by insects induced a high increase in the content of hydrogen peroxide and superoxide anion radical within resistant Lamberto cv. 24 hpi, whereas in sensitive Marko cv., an increase in H2O2 content was found within two days of aphid feeding. Moreover, resistant plants showed earlier and much greater induction of l-phenylalanine and l-tyrosine ammonia lyases and chalcone synthase activities, as well as accumulation of phenolic compounds in response to insect feeding than susceptible Marko. On the other hand, strong positive influence of hydrogen peroxide and superoxide radical contents on chalcone synthase activity and furthermore flavonoid biosynthesis was detected in the susceptible cultivar. Negative relationships between level of o-coumaric acid or flavonoid compounds and content of hydrogen peroxide or superoxide radical suggest their antioxidant capacity. Luteolin and o-coumaric acid may attend in scavenging of hydrogen peroxide, whereas quercetin, apigenin and (+)-catechin probably participate in reduction of superoxide anion radical content.
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•The grain aphid induced in triticale higher levels of H2O2 and O2•− than beetle.•Generation of ROS was earlier and higher in resistant than susceptible plants.•Chalcone synthase in the susceptible cv. is up-regulated by H2O2, O2•−, and TAL.•In the susceptible plants, flavonoids play crucial roles in diminishing of ROS.•In resistant triticale cv., phenolic compounds act as prooxidants against insects.
A microsporidian pathogen was originally identified using molecular techniques from Oulema melanopus L. (Coleoptera, Chrysomelidae) under a “working name” Nosema oulemae, but its description was ...never published. In the present study, a microsporidian infection was detected in the Blue Shieldbug, Zicrona caerulea for the first time, showing 99.9% SSU rRNA sequence similarity to N. oulemae (Genbank accession U27359). Life cycle, tissue tropism, ultrastructure and phylogenetical relationships with other microsporidia species were disclosed. Nymph and adult stages of the host were infected with mature spores produced in the gut, hemocoel and fat body. Spores of the parasite measured approximately 4.50 ± 0.36 μm in length and 2.46 ± 0.18 μm in width on fresh smears. The number of coils of the polar filament was 9–11. Coils were 109.23 ± 22.92 nm (range: 93.75–268.66; n = 50) in diameter and consisted of seven concentric layers of different electron density and thickness. The spores possessed a relatively thick (174.04 ± 57.65 nm) trilaminar spore wall. Developmental sequence and ultrastructure The SSU rRNA and RPB1 gene sequences were deposited GenBank under accession MT102274 and MW538912. Basing upon the sequence similarity, the isolate from Z. caerulea can be attributed to the species from O. melanopus provisionally designated as N. oulemae. The novel species Vairimorpha hostounsky sp. nov. is described, named after Prof. Zdenek Hostounsky who was the first to discover this parasite.
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•Z. caerulea is a useful predatory species which can be used against different pest beetle•To identified the current microsporidium, it was subjected to light, electron microscopy, small subunit ribosomal RNA(SSU rRNA) and the largest subunit of RNA polymerase II (RPB1) gene sequencing•The current microsporidium was the type isolate of Vairimorpha hostounsky sp. nov.•Fresh spores with nuclei arranged in a diplokaryon are oval and measured 4.50 ± 0.36 μm in length and 2.46 ± 0.18 μm in width•Spores have an isofilar polar filament with 9-11 coils
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