Arthropod-Plant Interactions最新文献

Onion thrips (Thrips tabaci) are a major pest of onion crops, but they can be controlled using syrphid larvae, which are omnivorous, as biological control agents. The introduction of secondary plants may enhance syrphid activity and contribute to the suppression of onion thrips population in onion–barley intercropped fields. Therefore, two experiments were conducted to evaluate the effect of introducing secondary plants on the population of onion thrips and the occurrence of syrphids in onion–barley intercropped fields. In the first 2-year experiment, buckwheat, lacy phacelia, and coriander planted around barley-intercropped onion fields did not result in a significant reduction in the number of onion thrips. However, in the second experiment, which employed mixed intercropping of barley and buckwheat, significantly greater suppression of onion thrips population was observed in the mixed intercropping plots than in plots containing only barley intercropping. In addition, the number of syrphid eggs on intercropped barley was significantly higher in the mixed intercropping plots than in plots containing barley alone, demonstrating that planting flowering plants near barley can attract hoverflies and increase oviposition on barley. Furthermore, three-year experiments revealed more syrphid larvae on onion plants than on barley, with eggs found only on barley. These findings indicate that hoverflies oviposit on intercropped barley; then, the hatched larvae move to onion plants to prey on onion thrips. Overall, this study offers great insights into the potential use of intercropping with flowering plants to boost natural biological control of onion thrips, providing implications for sustainable pest management in onion production.

Kiwifruit (Actinidia chinensis var. deliciosa) has become an important horticultural crop worldwide. Its dioecious nature challenges its commercial production, involving strategies for enhancing cross-pollination to reach a better fruit quality. The explanatory variables that can be linked to improving fruit quality analyzed in this work were pollination (through a hand-pollen application or by Apis mellifera, but also considering the ratio of female:male plants in each plot) and plant competition for resources during fruit development (controlled by thinning, but also considering plant density per plot). The response variables assessed to estimate fruit quality were fruit weight, number of seeds, and shape coefficient. We obtained different models showing how these explanatory variables influence the different indicators for fruit quality (sampling 25 fruits per plot) in seven plots. Results suggest that the female:male ratio and number of plants per hectare are the most influential explanatory variables related to fruit quality in the studied agroecosystem. The kiwifruits from plots with higher amounts of pollen manually added and higher ratios of female:male plants were significantly lighter. We recommend not settling more than 500 plants per hectare at the plot level. The natural pollination for kiwifruit production can be improved if the ratio of female:male plants per plot is ≤ 10/1 when the flowering period of both plant sexes is synchronized. Finally, we recommend that growers follow these numbers in considering the importance of planting male and female plants in close proximity but managing plant density to avoid competition for resources.

Ladybirds (Coleoptera: Coccinellidae) are a significant predator group that plays a role in agricultural contexts. They serve as important biocontrol agents against several agricultural pests. However, there is limited information available about how ladybirds’ populations are regulated by their natural enemies and habitat perturbation. In this study, we evaluated ladybird communities associated with natural and managed areas during the agricultural cycle of 2018 (June–September). We identified seven ladybird species; the most abundant species were Hippodamia convergens (70% individuals) and Cycloneda sanguinea (20% individuals), followed by the exotic species Harmonia axyridis (3.33% individuals), while Paranaemia vittigera, Coleomegilla maculata, Brachiacantha sp., and Olla v-nigrum represented less than 3% each. Ladybirds were more abundant in agricultural fields than in natural habitats. We identified several natural enemies associated with the collected ladybirds, including parasitoids (Dinocampus coccinellae, Hymenoptera: Braconidae), ectoparasitic Acari (Coccipolipus sp., Podapolipidae), and nematodes (Mermithidae). However, none of the natural enemies affected more than 10% of the ladybirds, so natural enemies do not appear to be exerting substantial control over their populations. Our results corroborated that ladybirds can efficiently thrive in anthropogenic habitats in Mexico and therefore may represent good biocontrol agents for agriculture. It is important to consider the ecology of agriculturally important ladybirds in programs for integrated pest management. This includes factors contributing to the mortality of ladybirds, including their natural enemies.

In temperate regions, most insect species overwinter in diapause while others continue to be active, feed, and possibly reproduce despite adverse climatic conditions. For fruit flies which remain active winter long, the presence of winter-available fruit is crucial for population persistence. This study aimed to disentangle the relative effects of climatic, landscape, and local factors on infestation rates of an important winter trophic resource, mistletoe (Viscum album) fruit, by drosophilid flies. Mistletoe fruits were sampled between January and July 2022 in seven regions of France, across a wide range of climatic conditions from Mediterranean to temperate oceanic. The fruits were used both by the invasive Drosophila suzukii and by the native D. subobscura in the latter part of winter and throughout spring, suggesting that this resource may assist these species to overcome the winter bottleneck. Infestations by both flies were positively associated with the presence of fallen mistletoe fruit on the ground and semi-natural (forest, hedgerow) and anthropogenic (garden, park) habitats. The mistletoe’s host tree species also influenced the fruit infestation rate. Drosophila suzukii infestation rate was positively impacted by the accumulated thermal energy (‘degree days’) in the previous 14 days. Mistletoe could act as a catalyst for the development of spring D. suzukii generations and should be considered in the context of integrative pest management strategies to prevent early infestation of crop fruit.

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The Enemy Release Hypothesis posits that invasive plants in secondary ranges are freed from phytophage pressure, yet local phytophages may adapt to these invasive species over time. This study investigated the dietary preferences of Altica oleracea in relation to three native (Chamaenerion angustifolium (L.) Scop., Epilobium montanum L., and E. hirsutum L.) and three invasive (E. adenocaulon Hausskn., Oenothera biennis L., Oe. rubricaulis Kleb.) plant species from the Onagraceae family. A neural network was employed to automate the calculation of leaf damage area for assessing the phytophagous insects' dietary preferences. A. oleracea demonstrated a pronounced preference for Chamaenerion angustifolium compared to other Onagraceae species, irrespective of their invasive status. Among imago, no significant preference was observed between native and invasive Epilobium species or between two Oenothera species. However, the larvae were more discerning and avoided Oe. biennis, rearing on which led to the least weight gain by larvae. The adult beetles' inability to differentiate between plants unsuitable for larvae could lead to an evolutionary trap. The prevalence of Wolbachia infection in the A. oleracea population may influence the further evolution of adaptability to invasive species and the formation of dietary preferences.

The brown citrus aphid, Aphis citricidus, stands out as an important citrus pest that is an efficient vector for Citrus tristeza virus (CTV), the causal agent of important economic losses in citrus. Evidence suggests that aphids deliver salivary effector proteins inside their host cells to modulate plant physiology, suppress defense responses, and consequently favor the establishment and infestation. This study employed deep sequencing of RNA libraries to create a transcriptome of the salivary gland. Screening the transcriptome identified 115 unigenes encoding putatively secreted effector proteins. Eleven A. citricidus effectors exhibiting relatively low sequence identities were selected for gene expression analysis. Among them, six effectors (i.e., AcE1, AcE2, AcE3, AcE5, AcE8, and AcE9) displayed remarkably high expression levels in the head with salivary glands; AcE4 was highly expressed in both head and gut tissue. Further transient overexpression revealed that AcE4 could effectively inhibit INF1/BAX-induced leaf chlorosis in Nicotiana benthamiana leaves, implying its potential role in inhibiting plant defense mechanisms against aphid feeding. The findings of this study demonstrate the in silico identification of effector proteins from A. citricidus. Further investigation and analysis of these effectors, like as AcE4, will provide valuable knowledge regarding the molecular mechanisms that govern the interaction between aphids and plants.

One of the ways to evaluate the success of restoration strategies in degraded areas, in terms of restoring pollination, key process for the reproduction of most angiosperm species, is evaluating species traits, how they respond to changes in the environment and influence their interacting partners. In this study we asked: (i) does the phenological variation, the restoration strategy and the restoration age influence species richness, abundance, species composition and distribution of traits of bees and plants? (ii) do functionally similar species tend to interact with the same mutualistic partners? (iii) what are the most important traits that explain the similarity of interacting partners? We analyzed bee and plant communities in restored areas in the Atlantic Forest. We found that bee richness and abundance did not vary, and plant richness varied temporally. Bee and plant composition changed over time and among restoration strategies. Plant composition also varied with the restoration age. Functional composition, especially of bees, varied little among the tested factors. We also found that species with similar traits tended to interact with similar partners, and bee size, proboscis length and nesting sites were the most important traits to explain the interactions, while for plants, the most important traits were form of life, corolla color and shape. Our study demonstrated that interactions between bees and plants can be mediated by plant phenology and, considering that plant traits filter pollinators’ traits, the choice of plant traits in restoration areas is fundamental for interactions.

Ladybirds (Coleoptera: Coccinellidae) are important predatory insects found in many croplands, but their patterns of diversity and assemblage in diverse crop management practices remain understudied, especially in southeastern Asia. Their existence denotes a crucial need to update the diversity and assemblage pattern in diverse crop management practices. This study aims to (i) delimit ladybird species through DNA barcodes and (ii) compare the abundance of different ladybird taxa from different crop management practices. A total of 2260 ladybirds were collected and barcoded resulting in 12 species representing four subfamilies (Coccidulinae, Coccinellinae, Epilachninae, and Scymninae). Three predatory species dominated and were top contributors to the dissimilarity average for different crop management practices, i.e., Coccinella transversalis, Micraspis discolor, and Cheilomenes sexmaculata. Even though the effect of different crop management practices on ladybird abundance was insignificant (Kruskal Wallis, p-value > 0.05), their diversity significantly varied across different practices (diversity t-test, p-value < 0.05). Organic monocrop resulted in a higher value of Shannon index (H’), and richness than other management practices. Furthermore, monocrops comprised higher ladybird diversity than multicrops. While the species assemblage was not distinct (ANOSIM, p-value > 0.05), a variation in assemblage composition and spatial distribution concerning the different crop management employed (NMDS, stress value = 0.12) was observed. The hierarchical dendrogram distinguished six clusters of ladybirds between organic and conventional management practices. More explorations are required to uncover the various effects of crop management practices on ladybirds’ fitness and survival in different landscapes.

Intercropping faba bean with vegetables provides a possibility to promote pest control and better nutrient cycling in sustainable agriculture. Faba bean produces extrafloral nectar which supports parasitoid wasps that play a role in the biological control of pest insects. However, adult lepidopteran pests also benefit from nectar, increasing their lifespan and the number of offspring they produce. Here, a laboratory-based study was conducted to assess the role of faba bean on the components of a Brassica-based host-parasitoid system. We measured how access to faba bean affected the longevity and fecundity of the brassica pest Plutella xylostella and its parasitoid Cotesia vestalis. It was also studied if odors of flowering faba bean disrupt host finding by C. vestalis in Y-tube bioassays and volatile organic compounds were analyzed to explain the olfaction-based choices made by the parasitoids. The longevity of C. vestalis was 6.6 times longer and the number of pupae produced almost 10 times greater when they had access to faba bean. Meanwhile, the longevity of P. xylostella was 3.6 times longer and it laid 4.6 times more eggs when provided access to faba bean. In Y-tube bioassays, C. vestalis females also oriented toward host-related odors of the damaged cabbage more than intact cabbage when odors of faba bean were mixed with both of them. In conclusion, faba bean provided sustenance to both pest insects and their natural enemies that prolonged their lifespans and their reproductive capacity.

Predatory ladybirds are key natural enemies of a diversity of crop pests. Conserving ladybirds in agroecosystems to benefit from their biocontrol potential requires to understand the ecological interactions between them and functional plants. A diversity of functional plants is known to offer resources improving ladybirds’ fitness and pest control effects. Yet, there is a lack of knowledge on the relationship between a diversity of functional plants found at the field scale and the dynamic of ladybird population. In this study conducted over three consecutive years, we investigated from early May to mid-August, the weekly abundance of predatory ladybirds on 15 functional plants and peach trees (Prunus persica) in a peach orchard agroecosystem in the Beijing Province of China. Seven plant species hosted 90% of the ladybird population throughout the study period. Through them, two abundance peaks of ladybirds were observed, with Vitex negundo and Prunus persica supporting the ladybirds in the first peak, Artemisia sieversiana, Vigna unguiculata, Cosmos bipinnata, Zea mays and Helianthus annuus playing a major role in the second peak. The plant species were either at their seedling, blooming or fructification stage when hosting the ladybirds, suggesting that these lasts used the diversity of resources (prey, nectar and pollen of flowers and extra-floral nectar) offered at the agroecosystem level. The present results enrich the screening of functional plants supporting predatory ladybirds in perennial agroecosystems and emphasize the need to pay attention to the long-standing plants in the surrounding habitats. It suggests that maintaining and managing a diversity of functional plants at the field scale is needed to offer a spatial and temporal continuity of resources to ladybirds.