A Performance Index as a Measure of the Host Suitability to Drosophila suzukii Matsumura (Diptera: Drosophilidae).

Drosophila suzukii Matsumura, known as spotted wing drosophila (SWD), is an Asiatic invasive fruit pest that has spread over the world in the last 15 years, due to its high reproductive rate, its tolerance to different environmental conditions, the international fruit trade, and its wide range of host plants. In Buenos Aires, Argentina, blueberry is a major susceptible crop, although other cultivated and non-cultivated fruit species are frequent. The aim of this study was to evaluate the host suitability of commercial and non-cultivated fruit species (blueberries, plums, mulberries, and cherries) at two stages of maturity by estimating an index that takes into account biological and biometric parameters. The development and survival of SWD cohorts reared on different fruits were followed from egg to adult emergence. Then, adults were sexed and some biometric traits were measured. The indices: Wing loading, Wing aspect, and the Relative Performance Index (RPI) were estimated. The shortest developmental time and the maximum egg to adult survival were observed in the specimens developed in mulberry, in both stages of maturity. Only the length of the thorax showed significant differences between treatments in both sexes, and the largest adults were those reared in the ripe mulberries. The RPI, which relates performance and biometric variables, was the best index to evaluate the host suitability of SWD. So, it could be used as an indicator of the nutritional quality of fruits available in a region and to evaluate the importance of alternative hosts in the population dynamic of SWD.

A georeferenced database of the edaphic biota currently available for Argentina.

Background: Soils have been studied and classified in terms of their physical and chemical characteristics, while the knowledge about biodiversity and the ecosystem processes that they support is lagging behind. Furthermore, the advance in scientific knowledge contributed by different researchers is dispersed and it is necessary to collect it to bring the big picture into focus. Today, it is possible to have the findings and data collected by different researchers, compile them and, based on technological advances, have tools that allow the information to be analysed in its entirety. The main objective of this work is to compile and systematise all the bibliographic information available on the main organisms that make up biodiversity in the soil: Acari, Collembola and Crassiclitellata in Argentina. This information will then allow us to link the composition and structure of the soil community with processes and flows in the ecosystem, and to estimate them at different scales and in soils with different anthropic impact. The database presented here gathers presence information on the mentioned taxa, their geographical location for the entire country, while preserving the identity and authorship of each scientific work retrieved. The taxonomic range of the organisms of the edaphic biota collected in this database ranges from class to subspecies and are registered, based on the taxonomic level reported by the original author in their research. The publications were obtained from Google Scholar, Scopus and JSTOR. In addition, records were added from INEDES theses, library searches, information requested from authors cited in other articles and unpublished works. In total, information was collected from 224 scientific publications, as well as personal information requested directly from some authors. The total number of registered individuals so far is 4838 of which 3049 specimens correspond to Acari, 944 to Classiclitellata and 845 belong to Collembola. New information: This work is the first to gather, in a single publication, the entire dataset for all the Acari, Collembola and Clitellata recorded for Argentina.

Trophic resources of the edaphic microarthropods: A worldwide review of the empirical evidence.

Ecosystem sustainable use requires reliable information about its biotic and abiotic structure and functioning. Accurate knowledge of trophic relations is central for the understanding of ecosystem dynamics, which in turn, is essential for food web stability analyzes and the development of sustainable practices. There is a rapid growth in the knowledge on how belowground biodiversity regulates the structure and functioning of terrestrial ecosystems. Although, the available information about trophic relationships is hard to find and fragmented. Most of the information available worldwide about the food resources of soil microarthropods suggested that out of 3105 hits of initial research on this aspect only a total of 196 published works related particular species, genera, and families to particular trophic resources, the majority of them dealing with soils of the Palearctic region. From the 196 publications we extracted 3009 records relating specific taxonomic groups to their trophic resources, 20 percent mention saprophytic fungi as a food resource, 16 percent cite microfauna, 11 percent mention bacteria, 10 percent litter and 8 percent cite Springtails. The available information was highly skewed, the 73.71 percent comes from Acari, and within these, 50.62 percent correspond just to Sarcoptiformes. The literature on Collembola is very scarce and most of the information is on arthropleona. The review also highlights that available research on the use of trophic resources comes from European sites and the information on this aspect from other parts of the soils of the world is still at large but unknown.

Size spectra of the edaphic fauna of typical Argiudol soils of the Rolling Pampa Region, Argentina.

Background: Soil-dwelling organisms populate the spaces-referred to as interstices-between the litter on the soil surface and the pores in the soil's organo-mineral matrix. These organisms have pivotal roles in soil ecosystem functions, such as the breakdown and decomposition of organic matter, the dispersal of bacterial and fungal spores and biological habitat transformation. These functions, in turn, contribute to broader ecosystem services like carbon and nutrient cycling, soil organic matter regulation and both chemical and physical soil fertility.This study provides morphological data pertaining to a range of soil organism sizes, specifically in Argiudol soils subjected to varying levels of agricultural activity in the Rolling Pampas Region, one of the world's most extensive and fertile plains.The primary focus is on soil microarthropods-namely, Acari (mites) and Collembola (springtails)-with a body width of less than 2 mm. These organisms constitute the majority of life in the intricate soil pore network. Additionally, the study documents species of earthworms (Oligochaeta, Crassiclitelata), recognised as ecosystem engineers for their ability to create physical channels in the soil matrix and to distribute organic matter. Moreover, the study includes measurements of morphological traits of soil-dwelling "macrofauna" (organisms with a body width greater than 2 mm), which are also implicated in various soil ecosystem functions. These include population regulation by apex predators, organic matter decomposition, biogenic structure formation, nutrient mobilisation and herbivory. New information: In this paper, we report both the geographical locations and individual measurements of key morphological traits for over 7,000 specimens, covering a range of soil-dwelling organisms. These include springtails (Entognatha, Collembola), mites (Arachnida, Acari), earthworms (Oligochaeta, Crassiclitellata) and additional soil macrofauna. All specimens were collected from typical Argiudol soils located in three distinct agricultural systems characterised by varying levels of land-use intensity. To our knowledge, no other dataset exists providing this information for the Argentinian Pampas.

Surfactantless Emulsions Containing Eugenol for Imidacloprid Solubilization: Physicochemical Characterization and Toxicity against Insecticide-Resistant Cimex lectularius.

Synthetic insecticides have been used for a long time as one of the most effective tools for insect pest control. However, the re-emergence of insect pests and their fast development of resistance, as has occurred for pyrethroid-resistant bed bugs Cimex lectularius L., make it necessary to develop new and safe strategies for effective pest control. This has fostered the research on new eco-sustainable formulations based on essential oils, which allows reducing the impact associated with the intensive use of synthetic insecticides on the environment and their effects on human health. This research explores the stability of water/eugenol/ethanol surfactantless emulsions loaded with imidacloprid (0.003 wt%), and their toxicity against a resistant bed bug strain. The results have shown that these emulsions enable the solubilization of a poorly water-soluble drug, such as the imidacloprid, without any significant modification of their stability. Furthermore, the application of the obtained formulations against the pyrethroid-resistant bed bug results in mortality in the 50-85% range upon topical and spray applications, with the increase of the eugenol content enhancing the effectiveness of the formulations. It may be expected that the ternary water/eugenol/ethanol mixtures could be further developed in the preparation of ready to use formulations, enabling the dispersion of insecticides for pest control.

First Evidence of Thaumastocoris peregrinus (Heteroptera: Thaumastocoridae) Feeding From Mesophyll of Eucalyptus Leaves.

The bronze bug, Thaumastocoris peregrinus Carpintero & Dellapé, 2006 (Heteroptera: Thaumastocoridae) originally restricted to Australia, is an important emerging pest of Eucalyptus plantations in the Southern Hemisphere. It feeds on mature leaves, causing the loss of photosynthetic surface area and defoliation and, according to some studies, even tree death. In this work, feeding activities of T. peregrinus on Eucalyptus camaldulensis Dehn leaves and its primary food resources were identified. In cross sections of leaves, solid salivary deposits on epidermal cells and in the vicinity of stomata cells were detected. In subepidermal cells of the palisade parenchyma near the stylet penetration point, disorganization and removal of chloroplasts were also observed. The presence of chlorophyll in guts of adults and nymphs was analyzed using spectrophotometry and confocal laser scanning to obtain in situ fluorescent spectra. Both spectra showed chlorophyll absorbance peaks. In addition, the presence of chlorophyll in guts of T. peregrinus using fluorescence microscopy was identified. These results provide the first evidence that T. peregrinus feeds from the palisade parenchyma (chlorenchyma) of Eucalyptus leaves.

Differential contribution of soil biota groups to plant litter decomposition as mediated by soil use.

Plant decomposition is dependant on the activity of the soil biota and its interactions with climate, soil properties, and plant residue inputs. This work assessed the roles of different groups of the soil biota on litter decomposition, and the way they are modulated by soil use. Litterbags of different mesh sizes for the selective exclusion of soil fauna by size (macro, meso, and microfauna) were filled with standardized dried leaves and placed on the same soil under different use intensities: naturalized grasslands, recent agriculture, and intensive agriculture fields. During five months, litterbags of each mesh size were collected once a month per system with five replicates. The remaining mass was measured and decomposition rates calculated. Differences were found for the different biota groups, and they were dependant on soil use. Within systems, the results show that in the naturalized grasslands, the macrofauna had the highest contribution to decomposition. In the recent agricultural system it was the combined activity of the macro- and mesofauna, and in the intensive agricultural use it was the mesofauna activity. These results underscore the relative importance and activity of the different groups of the edaphic biota and the effects of different soil uses on soil biota activity.

Reproductive biology and functional response of Dineulophus phtorimaeae, a natural enemy of the tomato moth, Tuta absoluta.

The tomato moth, Tuta absoluta (Lepidoptera: Gelechiidae), is a major pest in South America and is at present an important invasive species in the Mediterranean Basin. The larval stadium mines leaves, stems, and fruits, and chemical control is the most used control method in both its original range and the invaded distribution regions. Since current T. absoluta control strategies seem limited, biological control is a prominent tool to be applied abroad. The naturally occurring larval ectoparasitoid in Argentina and Chile Dineulophus phtorimaeae (Hymenoptera: Eulophidae) has been reported to have potential biocontrol efficiency. In this study, the ovigeny strategy of D. phtorimaeae was analyzed throughout the adult female lifetime, and the functional response of females offered a range of 2-15 T. absoluta larvae was measured over a 48-hour period. Mean D. phtorimaeae egg load was 4.15 eggs, and egg production resulted in extremely synovigenic behavior. Meanwhile, a decreasing number of eggs, due to resorption, was found. Proportions of attacked (host-fed and/or parasitized) and only host-fed hosts by the ectoparasitoid were density independent for the tested host range, exhibiting a type I functional response to T. absoluta, with an attack rate of 0.20 host larvae. Meanings of this reproductive strategy in evolutionary time as well as the consequences for augmentative biological control programs are discussed.

Feasibility of tracking within-field movements of Homalodisca coagulata (Hemiptera: Cicadellidae) and estimating its densities using fluorescent dusts in mark-release-recapture experiments.

A mark-release-recapture technique was developed and tested for use in tracking the field movements of adult glassy-winged sharpshooters, Homalodisca coagulata (Say) (Hemiptera: Cicadellidae), in various agricultural and urban plantings. Greenhouse experiments in which adult H. coagulata were marked with one of five colored fluorescent dusts (Aurora Pink-All, Horizon Blue-A19, Blaze Orange-A15N, Saturn Yellow-A17, and Corona Magenta-A21) and released into cages with citrus seedlings showed that their mortality rates during a 30-d period were statistically similar to that of the undusted controls. Adults marked with a sixth dust color (Signal Green-A18N) suffered higher rates of mortality than did the undusted controls and thus were eliminated from further consideration. Adult H. coagulata marked with one of the five accepted colors of fluorescent dust were able to fly beyond 100 m in a field devoid of vegetation within minutes of their release, and the marking did not affect overall flight behavior significantly compared with that of the undusted controls. However, at wind speeds above 5 m/s, percentage recapture was significantly reduced, which indicates that both dusted and undusted adults were unable to orient their flight. In total, 41,124 marked and unmarked adults were released in the three field experiments in southern California (Riverside and Kern counties) during 2000 and 2001 to evaluate flight dispersal and estimate densities of H. coagulata. The mark-release-recapture and feral data obtained during the June, July, and August 2001 studies, when coupled with the Lincoln index, yielded estimates of adult H. coagulata of 1.2 and 2.2 million per ha, respectively, at a San Joaquin Valley (Kern Co.) and a southern California (Riverside Co.) citrus grove. The use of colored dusts to mark H. coagulata proved to be reliable, cost-effective, and time-efficient for mark-release-recapture studies with this insect within a citrus grove, but they are less likely to be useful for studies of adult H. coagulata movements among plantings.

Plant allocation to defensive compounds: interactions between elevated CO(2) and nitrogen in transgenic cotton plants.

Plant allocation to defensive compounds in response to growth in elevated atmospheric CO(2) in combination with two levels of nitrogen was examined. The aim was to discover if allocation patterns of transgenic plants containing genes for defensive chemicals which had not evolved in the species would respond as predicted by the Carbon Nutrient Balance (CNB) hypothesis. Cotton plants (Gossypium hirsutum L.) were sown inside 12 environmental chambers. Six of them were maintained at an elevated CO(2) level of 900 micromol mol(-1) and the other six at the current level of approximately 370 micromol mol(-1). Half the plants in each chamber were from a transgenic line producing Bacillus thuringiensis (Bt) toxin and the others were from a near isogenic line without the Bt gene. The allocation to total phenolics, condensed tannins, and gossypol and related terpenoid aldehydes was measured. All the treatments were bioassayed against a non-target insect herbivore found on cotton, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Plants had lower N concentrations and higher C:N ratios when grown in elevated CO(2). Carbon defensive compounds increased in elevated CO(2), low N availability or both. The increase in these compounds in elevated CO(2) and low N, adversely affected growth and survival of S. exigua. The production of the nitrogen-based toxin was affected by an interaction between CO(2) and N; elevated CO(2) decreased N allocation to Bt, but the reduction was largely alleviated by the addition of nitrogen. The CNB hypothesis accurately predicted only some of the results, and may require revision. These data indicate that for the future expected elevated CO(2) concentrations, plant allocation to defensive compounds will be affected enough to impact plant-herbivore interactions.