Arthropod-Plant Interactions最新文献

The cucurbit beetle, Diabrotica speciosa larvae are subterraneous and feed on plant roots, mainly Poaceae and Solanaceae. Although they are not gregarious, these larvae are often grouped in the root, triggering holes and galleries. The rhizophagy carried out by D. speciosa larvae induces the plant defense mechanisms, which can modify the behavior and development of other belowground larvae. Here, we present an induction method by natural rhizophagy of D. speciosa, which separates groups of insects into different parts of the root system. This methodology allows the prior rhizophagy by a larval group and the subsequent behavioral and performance evaluation of a larval group late affected. We cultivated maize plants in voile bags, into which 8-day-old Diabrotica speciosa larvae were inoculated. In order to determine the efficiency of the system, the weight of the larvae was measured before and after inoculation into the system. The proposed system enables normal root development of maize plants, even after their roots are wrapped in voile bags, which is possible given the porosity of the fabric used. Concerning the insects that fed on the roots inside and outside the voile bags, the fact that they presented similar weight gain indicates that they did not undergo food restriction and that the portion of the root they fed on did not influence their development during the evaluation period. Thus, insect feeding occurred normally, even if they consumed different portions of the roots. Our methodology can be used in any system that needs the simulation of rhizophagy by larvae of D. speciosa, needing to separate individuals that cause plant induction from those individuals that will be exposed to the effects of rhizophagy.

Plant resistance to herbivores is largely dependent on its ability to defend through biochemical mechanisms. Present study deciphered constitutive and Chilo partellus damage-induced levels of defensive phytochemicals in thirty maize lines, including susceptible and resistant checks. The association of these biochemicals with various indices of C. partellus was computed to comprehend the antibiosis mechanism and group the maize lines in to resistant/susceptible categories. The findings revealed significant variation in antibiosis, growth, and fitness indices of C. partellus when fed on different male and female maize lines, owing to significant differences in the quantity of nutritional (sugars and proteins), antinutritional (phenols, tannins, FRAP and total antioxidants), and enzymatic (TAL, PAL, AO, APX and CAT) components among the test maize lines. Resistant maize lines contained significantly lower quantities of nutritional components, while higher antinutritional and enzymatic components as compared to susceptible lines. Nutritional compounds were positively associated with antibiosis, fecundity and fitness indices, suggesting that these compounds favor growth and reproduction of C. partellus. Conversely, both constitutive and induced levels of antinutritional and enzymatic components were negatively associated with these indices, indicating their detrimental effect on the developmental biology of C. partellus. Additionally, these biochemicals accounted to 70.8 to 79.0% variability in various growth and fitness indices of C. partellus. The A-lines CML 565, AI 501, AI 196, C 70 and DDM 2309-O, and R-lines AI 125, AI 542 and AI 1100 were identified as best sources of resistance, and could be utilized in the breeding program to develop C. partellus resistant maize hybrids.

Bees play an essential role as pollinators in both natural and agricultural ecosystems. The Africanized honey bee (Apis mellifera Linnaeus, 1758) is a common species in modified ecosystems being an important pollinator for many crops, such as pepper (Capsicum spp.). In this study, we assessed the individual variation in floral resource foraging by examining the pollen loads in the corbiculae of A. mellifera workers. We sampled the bees in a pepper experimental crop for two months. We found between two and 17 pollen types in the bees' corbiculae, with a high abundance of the Fabaceae, Asteraceae, and Rubiaceae families. The pollen types ranged from 18 to 19 over the months. A. mellifera collected floral resources mainly from arboreal plants providing nectar and pollen. Our findings highlight the importance of understanding the ecological interactions between bee and plant species in agricultural areas to inform management and conservation strategies aimed at sustaining bee populations and enhancing pollination services.

The Megachilidae are among the bees that most depend on plant resources, since they need them both for food provisioning and for nest building. However, pollen and leaf specializations in the large genus Megachile have been largely unexplored, both in natural and urban habitats. Here, their botanical origin was studied in more than 20 cells from eight nests of Megachile susurrans in a temperate city of Argentina during four consecutive summers when adults were active, identifying a strong link for pollen (Styphnolobium japonicum) and leaf (Robinia pseudoacacia) hosts, caused by local preference. They were identified at light and stereoscopic microscopes comparing to reference collections from pollen and leaves surrounding the nesting area. Pollen resources were almost exclusively from S. japonicum, and three nests also contained important quantities of Syagrus romanzoffiana and Punica granatum, the remaining five only S. japonicum. The nest architecture was the typical for most Megachile, with cylindrical brood cells made of leaf pieces of two shapes disposed in linear series. Each nest had two to four cells composed only of leaf pieces of the exotic R. pseudoacacia. The abundant pollen of flower types with diverse configurations indicates versatile foraging behavior: keel flowers (Styphnolobium, Fabaceae Papilionoideae), multiple stamen brush flowers (Punica, Punicaceae) and open small radially symmetric flowers (Syagrus, Arecaceae). Although only three families were abundant in the diet, its composition with exotic species “unknown to bees” and flower type versatility suggest polylecty. Megachile susurrans was also generalist in the choice of nesting substrates, and generalist with occasional (local) preference in leaf and pollen hosts. The link to any papilionoid legume might also extend to its whole geographical distribution.

The corn leafhopper, Dalbulus maidis, transmits phytopathogens that cause significant economic losses in Zea mays. The maize bushy stunt phytoplasma (MBSP) indirectly affects insect vectors behavior through morphological and physiological changes in host plants. This study evaluated the effect of MBSP-infected and sham-infected maize plants on the host selection of D. maidis. Dual-choice tests were performed with non-infected D. maidis females using a Y-tube olfactometer. Volatile organic compounds (VOCs) from MBSP-infected and sham-infected genotypes were collected and characterized. Our results showed that MBSP infection altered the VOC profiles of both maize genotypes. In the P4285VYHR hybrid maize, MBSP infection induced the release of six new compounds and increased the levels of nine others. Non-infected D. maidis discriminated between MBSP-infected and sham-infected P4285VYHR plants, showing a preference for VOCs emitted by infected plants. In contrast, MBSP infection in the SCS156 Colorado genotype led to the emission of three new compounds and increased the release of two others. For this genotype, non-infected females preferred the odors of sham-infected plants over clean air. Our findings show that non-infected D. maidis recognizes maize VOCs and selectively responds to MBSP-infected plants, particularly in a hybrid genotype.

Plants experience a wide variety of mechanical stimuli in their environment, some of which indicate the presence of herbivory. Insect feeding vibrations elicit direct and primed increases in levels of defensive compounds. Touch is also a mechanical stimulus arising from rain, wind, and the movement of herbivores and pollinators. In this study, we compared the effect of insect feeding vibrations on flavonoid defenses with two other mechanical stimuli, a silent sham treatment and an active touch treatment. Feeding vibrations caused a direct increase in the concentration of anthocyanins compared to silent sham and active touch, and elicited no priming effects on response to methyl jasmonate. Silent sham caused a priming increase in the concentration of flavonols compared to feeding vibrations and active touch, and there were no direct effects. Although these results provide additional evidence for plant discrimination among mechanical stimuli, we discuss the common intertwining of touch and vibration in what plants experience in natural environments. We propose that touch and vibration are likely perceived by plants as related mechanical stimuli, and encourage broader exploration of this core feature of plant sensory ecology.

Pollination maintains natural communities and agricultural production by allowing and/or improving fruit and seed sets. Understanding local plant-pollinator interactions is important for enhancing crop pollination. This study investigated relationships between co-flowering crops and pollinators using six crops (pumpkin, watermelon, melon, gherkin, tomato, and sweet pepper) in NE Brazil. Questions raised include: What is the network’s structural pattern? Which bee groups are shared among co-flowering crops? 3) What is the functional role of the different species within the network? Field data were collected through focal observations. The network structure was described by connectivity and modularity calculations, and the role of species. A total of 27 bee species, across 19 genera and three families, were recorded. Apidae (15 species), Halictidae (nine), and Andrenidae (three) were the families observed. The network was modular, with four modules related to floral attributes. No bee species was a network hub. Paratrigona incerta and Ceratina sp. were module hubs. Paratrigona incerta had the highest number of interactions, visiting all crops except pumpkin. Apis mellifera, although not a key pollinator, had the second-highest number of interactions, connecting to all Cucurbitaceae. We recommend promoting pollinator-friendly conservation practices, including Paratrigona incerta and Ceratina sp., and testing the management of efficient native bees for crops.

Bees are exposed to a range of stressors in agricultural environments. One of them is introducing rapeseed monocultures that reduces the diversity of available pollen sources and increases the likeliness of pollen diet homogeneity. Nutritional stress can impair bees’ development and is highly likely to reflect in their phenotype. One of the means to assess the effect of environmental stress on bees is measuring wing asymmetry. We hypothesized that low pollen diversity of provisions collected by polylectic bee Osmia bicornis impairs the development of the bees’ offspring. We checked pollen composition, diversity, percentage of dominant pollen type, content of Brassica napus and Quercus pollen in the provisions. Then we modeled how these pollen traits impact wing size and asymmetry. Palynological analyses both from this study and cross-reference analysis revealed that even when placed in the center of rapeseed field, O. bicornis do not form homogeneous provisions from rapeseed pollen. Adversely, the content of Quercus pollen in pollen provisions is relatively high. The pollen composition of larval provision has an influence on the size of wings, but not on the fluctuation asymmetry in O. bicornis. Our results support earlier reports that wing size reflects response to nutritional stress better than wing asymmetry.

Spotted lanternfly (Lycorma delicatula White, (Hemiptera: Fulgoridae)) is a non-native, invasive pest with a broad host range that has rapidly spread since its discovery in the United States in 2014. Managing emerging invasive pests can be challenging as repeated insecticide inputs can lead to resistance and impact non-target organisms. Alternative strategies, such as biological control, reduce risks but require extensive investigation before implementation. A recent community science study suggests that arthropods are major predators of L. delicatula. However, this pest can sequester toxins from its preferred host, tree of heaven (Ailanthus altissima), which may defend it from predation. Thus, we tested a variety of predatory arthropods against all life stages of L. delicatula to determine if they would avoid prey fed on A. altissima compared to other host plants. Predatory arthropods did not show a preference when given a choice between L. delicatula reared with access to A. altissima compared to those reared on alternative hosts. We then tested 10 commercially available or easily field-collected generalist predators to determine if these potential biological control agents could reduce L. delicatula populations. Spined soldier bugs (Podisus maculiventris (Say, Hemiptera: Pentatomidae)), Carolina mantids (Stagmomantis carolina (Johansson, Mantodea: Mantidae)), and Chinese mantids (Tenodera sinensis (Saussure, Mantodea: Mantidae)) were the most effective at reducing prey populations, indicating they have promise as effective natural control agents. Our results also suggest that conservation and/or augmentation biological control using generalist predators already present in the landscape could be a useful management strategy for L. delicatula.

The role of nocturnal pollinators has been globally understudied, particularly in agriculture, but growing evidence suggests that crops often assumed to be pollinated during the day also receive additional pollination by night-active animals. In our study, we assessed six different types of evidence to determine whether blueberry flowers, which are typically associated with diurnal pollinators, could also be pollinated at night. We used observational and experimental approaches commonly used and validated for assessing nocturnal pollination, including variation in stigma receptivity and pollen viability at day and night, nectar standing crop dynamics, temporal effects of pollen germination, pollinator exclusion experiments and the presence of pollen on the bodies of potential nocturnal pollinators (moths). Stigma receptivity and pollen viability were similar between our day and night sample points. We found no negative effects of time of pollination on pollen germination. Nectar availability was strongly associated with time of day, and although nectar was available both day and night, nectar volume was highest at night. Fruit set was highest in flowers with unrestricted access to pollinators, but we are unable to determine the relative importance of nocturnal versus diurnal pollination as these treatments gave the same result as our control. Moths caught in blueberry orchards carried pollen from 25 plant species, with blueberry pollen being the fifth most abundant. Our results show that blueberry flowers have floral traits that allow pollination at night as well as during the day, and that moths, along with other nocturnal insects, may be contributing to this. However, the importance of nocturnal pollination relative to diurnal pollination remains unknown.