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The first step to better understand the relationship between natural enemy communities and pest control is to know which, when, and how frequently different natural enemies interact with their prey. In alfalfa fields of central Chile, aphids are the most common pests and are consumed by predators such as coccinellids, syrphids, and spiders. In this study, through video recording, we analyzed how natural enemy communities visiting aphid sentinel cards vary between scenarios of low and high abundance of aphids in alfalfa in spring. On 15 occasions, during the day, we monitored the natural enemies visiting cards with sentinel aphids (60 cards per field; total 900) located in fields with high (n = 6) and low (n = 9) aphid abundance. We also analyzed whether the abundance of coccinellid species visiting sentinel cards was related to their abundance in each field. In 750 h of video recording, we found 2749 natural enemies visiting the sentinel cards; 86.2% of them were coccinellids of five species. Total natural enemies and coccinellid visits were three times higher in low than in high aphid abundance scenarios. In contrast, the species richness and diversity of natural enemies and coccinellids visiting cards did not differ between aphid scenarios. The abundance of coccinellids in the field was positively associated with the abundance of coccinellids visiting cards, for the three most abundant species. Our study shows that video recording is useful for identifying changes in the communities of natural enemies of aphids in alfalfa, providing important new insights into trophic interactions in field situations. [ABSTRACT FROM AUTHOR]

The trophic interactions between predators can vary depending on the abundance of their prey. In the alfalfa fields of central Chile, coccinellids (Coleoptera: Coccinellidae) are the main natural enemies of aphids (Hemiptera: Aphididae), whose populations vary throughout the season. Coccinellids can forage for alternative prey, remaining in the crops when target pests are scarce, favoring their presence before the pest arrives and improving biological control. Therefore, knowledge of the different predator–prey interactions in different scenarios of prey availability has gained great importance. Based on DNA metabarcoding analysis, we describe the diet of the most abundant coccinellid species in alfalfa fields and how food web varies in scenarios of higher and lower aphid abundance. Additionally, we analyzed the consumption of alternative prey, such as pollen. The results revealed a set of generalist predators with high stability in their trophic interactions regardless of aphid abundance. However, Hippodamia variegata (Goeze) is less generalist than Eriopis chilensis Hofmann and Harmonia axyridis (Pallas). The native E. chilensis has a stable consumption of aphids, and other important pests are exclusively preyed by this species. Pollen is frequently consumed by these coccinellids, E. chilensis and H. variegata, which remain in alfalfa throughout the season, increasing its consumption during periods of lower aphid abundance. Aphids are the key prey for the permanence of H. axyridis in these crops. This study shows that coccinellids consume a variety of prey and alternative resources, allowing some species to persist in the fields when aphids are scarce. [ABSTRACT FROM AUTHOR]

Breeding natural enemies to generate populations with improved characteristics is an attractive idea, particularly nowadays with the increase in use of biological control and the availability of modern molecular and genetic tools. A first step in the process is to characterize traits which can be important for biological control and their intraspecific variation. In this study we characterized fecundity, longevity and dispersal-related traits of four endogamic and three exogamic laboratory populations (lines) of Mastrus ridens, an important parasitoid of the codling moth (Cydia pomonella (L.)). We found that several traits were positively correlated and that there was variability among lines and between endogamic and exogamic lines. Exogamic lines presented a better combination of trait values than endogamic lines. The absence of trade-offs among the traits studied in M. ridens would be advantageous for a breeding program. Nevertheless, it would be important not to lose genetic variability in the process, because of the presence of complementary sex determination (CSD) and negative effects of inbreeding on other traits. The results of this study could be useful for the selection of M. ridens lines with better traits and as preliminary information for breeding programs. [ABSTRACT FROM AUTHOR]

The rhodesgrass mealybug, Antonina graminis (Maskell, 1897), is reported for the first time from Chile, in the northern region of Tarapacá. This legless mealybug is widely distributed in tropical and subtropical regions around the world, and yet mentioned in the neighbouring countries. It feeds on a large variety of grasses (Poaceae), and can be considered as pest. The species identification was based on morphological and molecular data using the 28S gene as barcode marker. Of the five sites sampled, A. graminis was found in only one, indicating it may correspond to a recent introduction. Thus, it would be important to survey more closely its distribution within the country. A key to the genera of Pseudococcidae from Chile is provided, including relevant genera considered as pest, and not established in the country. This key is of direct interest to stakeholders in Chile, such as national phytosanitary services, and farm advisors. [ABSTRACT FROM AUTHOR]

Environmental risk assessments (ERAs) are required before utilizing exotic arthropods for biological control (BC). Present ERAs focus on exposure analysis (host/prey range) and have resulted in approval of many specialist exotic biological control agents (BCA). In comparison to specialists, generalist arthropod BCAs (GABCAs) have been considered inherently risky and less used in classical biological control. To safely consider exotic GABCAs, an ERA must include methods for the analysis of potential effects. A panel of 47 experts from 14 countries discussed, in six online forums over 12 months, scientific criteria for an ERA for exotic GABCAs. Using four case studies, a three-tiered ERA comprising Scoping, Screening and Definitive Assessments was developed. The ERA is primarily based on expert consultation, with decision processes in each tier that lead to the approval of the petition or the subsequent tier. In the Scoping Assessment, likelihood of establishment (for augmentative BC), and potential effect(s) are qualitatively assessed. If risks are identified, the Screening Assessment is conducted, in which 19 categories of effects (adverse and beneficial) are quantified. If a risk exceeds the proposed risk threshold in any of these categories, the analysis moves to the Definitive Assessment to identify potential non-target species in the respective category(ies). When at least one potential non-target species is at significant risk, long-term and indirect ecosystem risks must be quantified with actual data or the petition for release can be dismissed or withdrawn. The proposed ERA should contribute to the development of safe pathways for the use of low risk GABCAs. [ABSTRACT FROM AUTHOR]

Identifying the main routes followed by an invasive species has significant management implications and may help to understand its colonization process. The obscure mealybug, Pseudococcus viburni (Signoret, 1875), is an important agricultural pest native to South America that infests fruit crops worldwide. The genetic diversity and structure of P. viburni samples collected around the globe was investigated here, and the most likely invasion routes were inferred using state-of-the-art population genetics methods. The results obtained include: (1) identification of low intrapopulation genetic diversity (mean number of alleles per locus below 4 and heterozygosity below 50%) and high genetic differentiation among populations (average FST = 0.29); (2) strong evidence of an initial colonization from South America towards Europe and secondary introductions from Europe towards other continents, (3) evidence of population structure within Europe and, (4) support for introductions from North America and Europe to South Africa. These results improve our understanding of the worldwide distribution and invasion pathways of P. viburni and suggest further exploring South America as the best source for potential biological control agents. [ABSTRACT FROM AUTHOR]

The harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) has rapidly spread in several continents over the past 30 years and is considered an invasive alien species. The success of H. axyridis as an invader is often attributed to weak control by natural enemies. In this paper, we provide an overview of current knowledge on predators and parasitoids of H. axyridis. The common feature of predators and parasitoids is that they directly kill exploited organisms. Currently available data show that H. axyridis, displaying a variety of chemical, mechanical, and microbiological anti-predator defenses, is usually avoided by predators. However, some birds and invertebrates can eat this ladybird without harmful consequences. The primary defenses of H. axyridis against parasitoids include immune response and physiological and nutritional unsuitability for parasitoid development. These defenses are probably relatively efficient against most ladybird parasitoids, but not against flies of the genus Phalacrotophora. The latter are idiobiont parasitoids and hence can evade the host’s immune response. Indeed, rates of parasitism of H. axyridis by Phalacrotophora in the Palaearctic region (both in the native range in Asia and in Europe) are relatively high. While strong evidence for enemy release on the invasive populations of H. axyridis is lacking, several cases of parasitoid acquisition have been recorded in Europe, North America, and South America. We conclude that enemy release cannot be excluded as a possible mechanism contributing to the spread and increase of H. axyridis in the early stages of invasion, but adaptation of parasitoids may lead to novel associations which might offset previous effects of enemy release. However, further work is required to elucidate the population-level effects of such interactions. [ABSTRACT FROM AUTHOR]

Due to typesetting errors, Table 5 was not displayed correctly in the initial online publication. The original online article has been corrected. [ABSTRACT FROM AUTHOR]

Maconellicoccus hirsutus (Green) (Hemiptera:Pseudoccidae) is an important pest in many countries being responsible for considerable economic loses. Although it is not currently present in Chile, the chance that it could be accidentally introduced rises with the list of infested countries increasing over the last years. In addition, climate change projections indicate that a larger region would fit as potential habitat for this pest, allowing it to persist over time and colonize a larger proportion of the Chilean territory. In this study the geographic distribution and the number of generations this mealybug would develop in Chile were determined, under current temperatures and under two projected climatic scenarios. Cumulative degree days were calculated for current and future scenarios using a lower temperature threshold of 14.5 °C, with 624.5 degree-days as the thermal requirement for the species to complete one generation. The results show that under current climate conditions M. hirsutus could develop up to three generations in the north of the country (i.e. 18° South) and one generation in the region near 37° South. Under future scenarios' conditions the pest could develop up to five generations in the north, and one generation around the 42° South. Present climate conditions in Chile would allow the establishment of the pink hibiscus mealybug, if the pest enters the country. Climate change conditions would allow the potentially invaded area to expand south, and would promote the development of more generations per year of the mealybug in the studied territory. [ABSTRACT FROM AUTHOR]

The absolute configuration of the sex pheromone of the citrophilous mealybug, Pseudococcus calceolariae, was determined to be ( 1R,3R)-[2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl ( R)-2-acetoxy-3-methylbutanoate. NMR, derivatization reactions, chiral gas chromatography-mass spectrometry, and comparison with synthetic chiral reference compounds, were used to determine the absolute configuration of this compound. This activity of this compound was further confirmed by testing synthetic stereoisomers of the compound as lures in traps for adult male mealybugs. Traps baited with 1,000 μg of the pheromone compound caught 36 times more males than traps baited with virgin females. A mixture of stereoisomers of the pheromone compound can be used for field trapping without adverse effects on trap catch. A comparison with the structures of other sex pheromones of mealybugs is presented. [ABSTRACT FROM AUTHOR]

We conducted an experimental landscape study to test the hypotheses that: (1) habitat removal results in short-term increases in population density in the remaining habitat patches (the crowding effect); (2) following habitat removal, density is higher in landscapes with more, smaller patches and more habitat edge (i.e., a higher level of habitat fragmentation per se) than in less fragmented landscapes, for the same total amount of habitat on the landscapes; (3) this positive effect of fragmentation per se on density is larger in landscapes with smaller inter-patch distances; and (4) these last two effects should be reduced or disappear over time following habitat removal. Our results did not support the first hypothesis, but they provided some support for the other three hypotheses, for two of the four Coccinellid species studied. As in other empirical studies of fragmentation per se on population density, the effects of fragmentation per se were weak and positive (when they did occur). This is the first study to document a transient effect of fragmentation per se on population density, and to show that this effect depends on inter-patch distances. We suggest that fragmentation per se increased the rate of immigration to patches, resulting in higher population densities in more fragmented landscapes. [ABSTRACT FROM AUTHOR]

The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader. [ABSTRACT FROM AUTHOR]