Arthropod-Plant Interactions最新文献

Many pollinating animals visit a variety of flowering plant species. Rare plant species pollinated by such generalists may experience a low quality or quantity of pollination, depending on the pollinators’ foraging behaviour. How plants cope with this rarity disadvantage is not well understood. One possibility would be to offer a higher floral reward, for example, a higher nectar sugar concentration. However, since nectar production is costly, rare plants may only be able to increase their nectar concentration for a limited time and offer little reward afterwards. In this study, we performed a laboratory experiment with bumblebees (Bombus terrestris) foraging on artificial flowers of two colours to investigate whether the bees’ foraging behaviour produces a rarity disadvantage and if so, whether the rare flower type could improve its pollination success through temporal variation of its nectar sugar concentration, i.e. a temporary increase of nectar sugar followed by a period with low concentration. We found that when both flower colours offered equal rewards, the rare colour received only slightly fewer visits per flower, but had a considerably lower expected pollination success based on the bumblebees’ visitation sequences. Temporal variation of the rare colour’s sugar concentration increased both the quantity and quality of visits it received. This positive effect was reduced when there were fewer rare flowers or when two bumblebees foraged simultaneously. Our results suggest that temporal variation of floral rewards can alleviate, but not completely eliminate the rarity disadvantage.

Invasive plants are often released from herbivore pressure in their secondary range, but native herbivores can adapt to feed on them over time. Impatiens glandulifera and I. parviflora are two invasive species, whose leaves in the secondary range have been severely damaged by leaf miners in recent years. The leaf miner attack rates for these species and a native congener, I. noli-tangere, were examined. Molecular analysis shows that all three impatiens species are affected by the same leaf miner Phytoliriomyza melampyga (Agromyzidae) without signs of divergence between populations living on different plant species. The native I. noli-tangere is more often damaged by the leaf miner, whilst I. parviflora is attacked more often than I. glandulifera. The largest mined area was found in I. glandulifera leaves and the smallest in I. noli-tangere. The nitrogen content, indicative of food quality, was similar in all three species, and there were no differences in ¹⁵N enrichment between miners from three impatiens species. We suppose that observed differences in attack rates and mined area in P. melampyga on three Impatiens species can be explained mainly by different levels of antiherbivore defence and recent host shift from native species to invasive ones.

Arbuscular mycorrhizal fungi (AMF) and herbivore insects are essential elements of ecosystems. They can influence each other on their common host plant. AMF support the plant growth by protecting against herbivore insect stresses. Opuntia ficus-indica (L.) miller is a multipurpose species which is under serious threat by cochineal insect (Dactylopius coccus (C.). The AMF and cochineal insect interaction on O. ficus-indica plants were not studied. This paper analyzed AMF spore density and root colonization of O. ficus-indica population in cochineal-infested and uninfested cultivated areas. Soil depth, season, and altitude were main environmental factors for the result observations. Soil and root samples were collected from the rhizosphere of O. ficus-indica plants. AMF spore density and root colonization were higher in uninfested plants than cochineal infested. AMF genus significantly varied along altitude and soil depth. Root colonization was higher during the rainy season than dry season, while spore density was lower in the rainy season. In the cochineal infested populations, spore density did not significantly varied with seasons. Spore density and root colonization were significantly higher on the upper soil depth than lower depth. Rhizosphere soil properties varied with altitude and soil depth. Soil available phosphorus (AVP) was significantly higher in the cochineal-infested populations. AVP showed significant negative correlation with mycorrhizal colonization. AMF–cochineal interaction in O. ficus-indica populations needs to be experimentally tested to understand the facilitative role of AMF to increase the performance of O. ficus-indica plants and to defend against the infestation of cochineal.

Coffee berry borer (CBB) Hypothenemus hampei is the major pest of coffee fruits worldwide. Bioregulators have been applied in crop plants with the aim of changing their physiology and metabolism for better yield and quality of produce, but little knowledge exists on the effects on insect pests. This study evaluated application of ethylene synthesis inhibitor in arabica coffee on CBB field infestation, preference, and performance in function of application time and dose. Field experiments were conducted in Lavras, Brazil, and the effects of ethylene synthesis inhibitor Mathury™ on CBB were evaluated using five treatments: control (water); Time1 + Dose1; Time1 + Dose2; Time2 + Dose1; and Time2 + Dose2. The first and second applications were performed at 80 and 110 days after flowering, respectively, using the doses of 2 and 15 L ha⁻¹. CBB field infestation was recorded through time as the percent bored fruits, and the colonization in the beans and degree of fruit maturation were evaluated at harvest. CBB preference and colonization were assessed in dual-choice bioassay and the performance under no-choice condition in the lab. Plants treated with the bioregulator overall presented fruits less suitable for CBB preference and performance in terms of females choice and survival in the lab, but varying effects were found between field experiments for bored fruits (%), which increased with fruit maturation. In the second field experiment, reduced larvae and pupae infestations were found in bioregulator-treated fruits. Application of ethylene synthesis inhibitor is promising to complement CBB management in sustainable coffee crops. Future research should evaluate the underlying induced-resistance mechanisms.

Galls are products of anatomical, metabolic, and chemical alterations in host plant tissues, caused by parasitic organisms named gall inducers. Gall inducers can potentiate chemical and structural specializations of their host plants for their own benefit, such as the accumulation of bioactive and antioxidant secondary metabolites, which should be tested. This could lead to increased protection against natural enemies, pathogens, and different abiotic stressors. Based on data in the literature, we listed the gall morphotypes found in restingas (threatened coastal vegetations) in Rio de Janeiro State, Brazil, and reunited the anatomical, phytochemical, and medicinal information of the host plants. Superhost plants, capable of hosting more than one gall-inducing species, represented 51% of the hosts, with 80% of the listed galls. Phytochemical and pharmacological potentials were confirmed for 80% of the gall superhosts. Most of the non-medicinal superhosts belong to species or families of toxic plants. These facts indicate the high percentage of superhost species capable of producing and accumulating secondary metabolites. Anatomical, phytochemical, and pharmacological potentials of the 17 most widely distributed superhosts are discussed in detail. These plants have metabolites with antimicrobial and antioxidant activity, among several other pharmacological properties. Data gathered here revealed that superhost plants of galling organisms have wide distribution in restingas, accumulate diverse secondary metabolites, and several of them are reported to have bioactive or pharmacological properties. Families of superhost plants not necessarily are those richer and more diverse in restingas, indicating that specific chemical and structural features of host plants are preponderant in galling arthropod–plant interactions. Based on our results, we indicated some superhosts as study models to test the potentiation of such features in galls, which were selected based on the number of associated galls, the types of secondary metabolites detected, and the presence of bioactive substances.

The role of secondary metabolites (SMs) in Amaranthus plant defense is a poorly studied field. Different cultivars of amaranth have shown varying degrees of susceptibility to insect attack in the field, and previous research has discussed the potential role of these compounds as insect phagodeterrents. In this study, we measured the content of five hydroxybenzoic acids, three hydroxycinnamic acids, and three flavonoids in 30-days-old undamaged plants, over two consecutive years. In addition, we examined the impact of SM content in the leaves of amaranth cultivars on food preference and the rate of plant tissue utilization by the generalist insect Spodoptera frugiperda. In the first year, experiments were conducted using two cultivars: A. cruentus (1) and A. mantegazzianus (1), while the second-year experiments included three cultivars of A. hypochondriacus (a total of five cultivars). Our results showed that, under identical growth conditions and in the absence of stress, flavonoid content emerged as the most consistent trait for distinguishing between cultivars, with rutin being the key variable accounting for the observed variability. In contrast, the contents of hydroxybenzoic and hydroxycinnamic acids exhibited significant variability among cultivars and between years. Additionally, we observed that high concentrations of phenolic acids in plant tissue correlated with lower rates of food utilization by S. frugiperda, without affecting preference indices. The potential defensive capabilities of these SMs for mitigating insect herbivory damage in amaranth crops are discussed in this work.

Agroforestry systems in the tropics exhibit high heterogeneity in plant species composition and structural configuration. However, few studies evaluated the seasonal shift in arthropod alpha diversity and abundance in agroforestry systems in the tropics. This study was designed to analyze the composition, abundance, and alpha diversity of arthropod orders in five agroforestry systems in the humid tropic of Tabasco, Mexico. The agroforestry systems compared were shade trees in plantations (ShTP), living fences (LF), alley farming (AF), slash-and-burn agriculture (SBA), and grazing plantations (GP) during dry and rainy seasons. Arthropods were collected using pitfall traps, classified at the order level, and counted to estimate the abundance. A total of 10,271 arthropod individuals were collected that belong to seven orders. Hymenoptera was the most abundant group, accounting for 64.7% of the total count, followed by Coleoptera, Collembola, Araneae, Hemiptera, Diptera, and Orthoptera. Arthropod alpha diversity and abundance varied significantly among the agroforestry systems and between the rainy and dry seasons. The agroforestry systems AF, GP, and ShTP showed a higher diversity (Shannon index) and dominant orders (Simpson index) in the rainy season compared to the dry season. The seasonal shift of the different arthropod orders varied among agroforestry systems, while the Orthoptera did seasonally vary across the agroforestry systems. This study suggests the interactive effects of seasons and agroforestry systems on arthropod abundance and diversity.