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ISSN / EISSN : 2075-4450 / 2075-4450
Published by: MDPI (10.3390)
Total articles ≅ 3,617
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Published: 17 May 2022
by MDPI
Abstract:
The striped cucumber beetle (SCB) Acalymma vittatum (F.) (Coleptera: Chrysomelidae) is a prime problem in North American cucurbit crops. While certain chemical pesticides efficiently control SCB in conventional cucurbit fields, alternative solutions are required due to the ever-evolving regulations on pesticides. For organic producers, very few control methods exist. A novel mass trapping method demonstrates the potential of controlling SCBs using floral-based semiochemical baited traps in cucurbit crops. The goals of this study were to (1) determine whether baited traps capture more SCBs than unbaited ones, and (2) optimize the trapping method by comparing different trap types and different commercially available attractants to maximize SCB captures while minimizing non-target species captures. The results of a first experiment showed that baited traps captured significantly more SCBs than unbaited ones. Baited traps also captured significantly more bees and hoverflies than unbaited ones. In a second experiment these unwanted captures were drastically reduced by using traps with ten 4 mm in diameter holes per side. Finally, a third experiment demonstrated that the attractant 40CT313 was the most efficient at capturing SCB compared to other tested lures. Overall, the optimized mass trapping technique demonstrated a potential to effectively control SCB populations in organic cucurbit crops.
Published: 17 May 2022
by MDPI
Abstract:
Urban agriculture is practiced in spatially fragmented landscapes with unique characteristics that can impact species occurrence in time and space. As a result, biological control services, an ecosystem service from naturally occurring arthropod natural enemies, can be negatively impacted. Many urban farms forgo pesticides and utilize agroecological pest-management strategies that rely on natural enemies to help regulate pest populations. Understanding how these enemies are affected by landscape composition and on-farm management practices is critical to understanding agroecological pest management in UA and furthering our understanding of landscape-mediated population dynamics. Over two growing seasons, we sampled brassica crops in urban agriculture sites occurring on a spectrum of surrounding landscape imperviousness, spatial composition, size, and management practices to better understand parasitic Hymenoptera abundance, richness, and parasitism rates on the common cabbage aphid (Brevicoryne brassicae). We found that on-farm agroecological pest-management practices such as mulch coverage, floral richness, and overall crop-plant richness impacted parasitic Hymenoptera abundance. Larger proportions of on-farm noncrop area increased parasitoid abundance on urban farms. Aphid parasitism increased in relation to on-farm management practices, including increased crop-plant richness. These findings add to a growing understanding of urban agroecosystem function and support the enemies hypothesis in urban agroecosystems.
Published: 16 May 2022
by MDPI
Abstract:
This study investigated the species composition and density of sand flies in the Lombardy region (Northern Italy). Sand flies were collected using CDC traps baited with CO2 (CO2–CDC traps) between June and August 2021. A total of 670 sand flies were collected. The specimens were identified as seven species belonging to two genera, Phlebotomus and Sergentomyia, namely, S. minuta, Ph. perniciosus, Ph. perfiliewii, Ph. neglectus, Ph. mascitti, Ph. papatasi, and Ph. ariasi. Phlebotomus perniciosus was the most abundant species (87.76%), followed by Ph. perfiliewii (7.31%), Ph. neglectus (3.13%), S. minuta (0.75%), Ph. mascitti (0.6%), Ph. papatasi (0.3%), and Ph. ariasi, for which only one specimen was identified. Among these identified species, five are considered vectors of Leishmania, which causes cutaneous and visceral leishmaniasis. As vector presence increases the risk of vector-borne leishmaniasis, these results suggest that Northern Italy could be a potential area of pathogen circulation over the next few years. These preliminary results suggest that the risk of borne leishmaniasis is high in this region of Northern Italy. Monitoring the distribution of sand fly species in areas suitable for their persistence is important for control programs aimed at reducing the risk of leishmaniasis infection.
Published: 16 May 2022
by MDPI
Abstract:
Neuropterida is a relatively primitive group of Holometabola. There are about 6500 extant species. Many species of this group are natural enemies and can prey on a variety of agricultural pests. In order to understand the leading research institutions, researchers and research contents, and to predict the future research directions of Neuropterida, the Web of Science core database, from January 1995 to September 2021, was searched with the theme of “Neuropterida or Neuroptera or Megaloptera or Raphidioptera or Lacewing”. The results showed that the United States and China published relatively more publications than other countries. In addition, researchers from these two countries had more cooperation with other countries. China Agricultural University ranked the highest in the number of publications and centrality in this field. In addition, it was found that the early research focused on the biological control of Neuropterida by analyzing the keyword burst, whereas the more recent research focused on the phylogeny of Neuropterida. As the first representative chromosome-level genome of Neuropterida has been published, the future research of Neuropterida will focus on the genomic studies and molecular mechanisms of their morphological characters, behavior, historical evolution and so on.
Published: 14 May 2022
by MDPI
Abstract:
The cotton-melon aphid, Aphis gossypii Glover, is a polyphagous insect pest with many host-specialized biotypes, such as the Cucurbitaceae- and Malvaceae-specialized (CU and MA) biotypes. Bacterial symbionts were reported to determine the host range in some aphids. Whether this is the case in A. gossypii remains unknown. Here, we tested the host specificity of the CU and MA biotypes, compared the host specificity between the wingless and winged morph within the same biotype, and analyzed the composition of the bacterial symbionts. The reproduction of the CU and MA biotypes reduced by 66.67% and 82.79%, respectively, on non-native hosts, compared with on native hosts. The composition of bacterial symbionts was not significantly different between the CU and MA biotypes, with a Buchnera abundance >95% in both biotypes. Meanwhile, the winged morph produced significantly more nymphs than the wingless morph on non-native hosts, and the Buchnera abundance in the winged morph was only about 10% of that in the wingless morph. There seemed to be a relationship between the Buchnera abundance and host specificity. We regulated the Buchnera abundance by temperature and antibiotics, but did not find that a low Buchnera abundance resulted in the high reproduction on non-native hosts. We conclude that the host specificity of A. gossypii is not controlled by specific bacterial symbionts or by Buchnera abundance.
Published: 13 May 2022
by MDPI
Abstract:
This study investigates the effect of wing planform shape on the aerodynamic performance of insect wings by numerically solving the incompressible Navier-Stokes equations. We define the wing planforms using a beta-function distribution and employ kinematics representative of normal hovering flight. In particular, we use three primary parameters to describe the planform geometry: aspect ratio, radial centroid location, and wing root offset. The force coefficients, flow structures, and aerodynamic efficiency for different wing planforms at a Reynolds number of 100 are evaluated. It is found that the wing with the lowest aspect ratio of 1.5 results in the highest peaks of lift and drag coefficients during stroke reversals, whereas the higher aspect ratio wings produce higher lift and drag coefficients during mid half-stroke translation. For the wings considered, the leading-edge vortex detachment is found to be approximately at a location that is 3.5–5 mean chord lengths from the wing center of rotation for all aspect ratios and root offsets investigated. Consequently, the detachment area increases with the increase of aspect ratio and root offset, resulting in reduced aerodynamic coefficients. The radial centroid location is found to influence the local flow evolution time, and this results in earlier formation/detachment of the leading-edge vortex for wings with a smaller radial centroid location. Overall, the best performance, when considering both average lift coefficient and efficiency, is found at the intermediate aspect ratios of 4.5–6; increasing the centroid location mainly increases efficiency; and increasing the root offset leads to a decreased average lift coefficient whilst leading to relatively small variations in aerodynamic efficiency for most aspect ratios.
Published: 13 May 2022
by MDPI
Abstract:
Under the influence of various circulation systems, the Holocene humidity conditions on the Mongolian Plateau are spatially heterogeneous and the underlying mechanism is still ambiguous. The complexity of climate change may affect the accuracy of assessing lake ecosystem evolution. In this study, based on the precise chronology, a chironomid assemblage sequence from the Darhad Basin in northern Mongolia is analyzed to elucidate the hydroclimate variation during the early-middle Holocene. The results show that the chironomid communities changed suddenly from littoral taxa to sublittoral/profundal taxa at about 9 cal kyr BP, reflecting an environmental transition from a river or shallow lake condition to a deep lake environment. Thereafter, most parts of the paleolake remained at a relatively high level until 4.5 cal kyr BP. This hydrological pattern resembles the typical humidity variations in the Westerlies affected regions, except that the onset of wetter conditions occurred one thousand years earlier as reflected in our results. The melting of glaciers and permafrost in the basin resulting from the early increased summer solar insolation could be a feasible explanation for these time advances.
Published: 13 May 2022
by MDPI
Abstract:
The Wiedemannia zetterstedti species group is revised after examination of all available type specimens and includes one new species (W. ulrichi Ivković & Sinclair sp. nov.) and four redescribed species (W. czernyi (Bezzi), W. longipennis (Mik) stat. rev., W. rufipes (Oldenberg) stat. rev. and W. zetterstedti (Fallén)). The following new synonyms are proposed: W. (Roederella) ouedorum Vaillant, 1952 = W. czernyi (Bezzi, 1905); Paramesia riparia Robert, 1836 = W. zetterstedti (Fallén, 1826). Lectotypes are designated for the following species/subspecies: Atalanta hirtiloba Speiser, Brachystoma escheri Zetterstedt, Clinocera czernyi Bezzi, Clinocera longipennis Mik, Paramesia riparia Robert, and Roederia czernyi rufipes Oldenberg. In addition to morphological evidence, molecular species concepts were investigated using a molecular phylogenetic divergence-based species delimitation (bPTP) and results confirmed the morphological conclusions. A key to species is presented and geographic distributions are mapped.
Published: 12 May 2022
by MDPI
Abstract:
Although transposable elements (TEs) are usually silent in somatic tissues, they are sometimes mobilized in the soma and can potentially have biological consequences. The mariner element is one of the TEs involved in somatic mobilization (SM) in Drosophila and has a high rate of somatic excision. It is also known that temperature is an important factor in the increase of the mariner element SM in the fly. However, it is important to emphasize that excision is only one step of TE transposition, and the final step in this process is insertion. In the present study, we used an assay based on sequencing of the mariner flanking region and developed a pipeline to identify novel mariner insertions in Drosophila simulans at 20 and 28 °C. We found that flies carrying two mariner copies (one autonomous and one non-autonomous) had an average of 236.4 (±99.3) to 279 (±107.7) new somatic insertions at 20 °C and an average of 172.7 (±95.3) to 252.6 (±67.3) at 28 °C. In addition, we detected fragments containing mariner and others without mariner in the same regions with low-coverage long-read sequencing, indicating the process of excision and insertion. In conclusion, a low number of autonomous copies of the mariner transposon can promote a high rate of new somatic insertions during the developmental stages of Drosophila. Additionally, the developed method seems to be sensitive and adequate for the verification and estimation of somatic insertion.
Published: 12 May 2022
by MDPI
Abstract:
The Colorado potato beetle Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) is an internationally recognized destructive pest which has caused serious losses to the potato industry. To clarify the impact of repeated short-term heat exposure on CPB egg hatching and adult fecundity under climate change, CPB eggs and adults were treated with repeated short-term heat exposure in this study. We found that the hatching rate of CPB eggs, the total number of eggs laid per female, the oviposition period, the intrinsic rate of population increase (rm), finite rate of increase (λ), and the net reproductive rate (R0) of CPBs decreased with increasing temperature. The hatching rate and fecundity of CPBs were significantly lower than those of control (CK) after repeated short-term heat exposure. Our research has found that repeated short-term heat exposure is not conducive to the development and reproduction of CPBs.
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