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When assessing changes in populations of species, it is essential that the methods used to collect data have some level of precision and preferably also good accuracy. One commonly used method to collect pollinators is colour pan traps, but this method has been suggested to be biased by the abundance of surrounding flowers. The present study evaluated the relationship between pan trap catches and the frequency of flowers on small (25 m2) and large (2–6 ha) spatial scales. If pan traps work well, one should assume a positive relationship, that is, more insects caught when they have more food. However, in contrast, we found that catches in pan traps were often negatively affected by flower frequency. Among the six taxa evaluated, the negative bias was largest in Vespoidea and Lepturinae, while there was no bias in solitary Apoidea (Cetoniidae, Syrphidae and social Apoidea were intermediate). Furthermore, red flowers seemed to contribute most to the negative bias. There was also a tendency that the negative bias differed within the flight season and that it was higher when considering the large spatial scale compared to the small one. To conclude, pan trap catches may suffer from a negative bias due to surrounding flower frequency and color. The occurrence and magnitude of the negative bias were context and taxon dependent, and therefore difficult to adjust for. Thus, pan traps seem less suited to evaluate differences between sites and the effect of restoration, when gradients in flower density are large. Instead, it seems better suited to monitor population changes within sites, and when gradients are small. Colour pan traps are often recommended for pollinator monitoring. We report that pan trap catches may suffer from a negative bias due to surrounding flower frequency and color. The occurrence and magnitude of the negative bias were context and taxon dependent, and therefore difficult to adjust for. Thus, pan traps seem less suited when gradients in flower density are large. Instead, it seems better suited to monitor population changes within sites, and when gradients are small.

The abundance and diversity of three taxa of citrus pest predators, syrphids (Diptera), coccinellids (Coleoptera), and chrysopids (Neuroptera) and their association with flowering weed species in commercial citrus orchards in southern California were investigated. The occurrence and frequency of adult predators were determined with vertical yellow sticky traps and by performing 3 min visual counts on flowering weeds from May through November 2021. Syrphid abundance peaked in June and September, with the dominant species being Allograpta obliqua (Say), Toxomerus marginatus (Say), and Paragus tibialis (Fallen). Peak collections of coccinellids occurred in May, June, and September on sticky traps and during September and October in flowering weedy plants. Peak flowering of weed species occurred during May and declined sharply over summer into fall (June–November). The efficacy of yellow 355 mL glycol pan traps, yellow 1774 mL water pan traps, and yellow sticky traps orientated either horizontally or vertically with respect to capturing key natural enemies was evaluated in 2021 and 2022. Significantly more syrphids were captured on the horizontal yellow sticky traps than on the vertical yellow sticky traps or the yellow pan traps filled with glycol or water. Coccinellids were most frequently captured on vertical yellow sticky traps and yellow water pan traps. Numbers of chrysopids captured in all studies were not significant, which was most likely attributable to their nocturnal behavior. Collectively these results suggest that syrphid and coccinellid activity in southern California citrus orchards displayed two seasonal peaks, one in spring and the other in the fall. In the context of future conservation biological control, insectary plantings in spring (April–June) and fall (September–October) would be most beneficial to these predators and would coincide with population peaks of a key citrus pest, Asian citrus psyllid, Diaphorina citriv Kuwayama (Hemiptera: Liviidae). Se investigó la abundancia y diversidad de tres taxones de depredadores de plagas de cítricos, sírfidos (Diptera), coccinélidos (Coleoptera) y crisópidos (Neuroptera) y su asociación con especies de malezas en flor en huertos comerciales de cítricos en el sur de California. Se determinó la aparición y frecuencia de depredadores adultos con trampas adhesivas amarillas verticales y realizando recuentos visuales de 3 minutos en malezas en flor desde mayo hasta noviembre del 2021. La abundancia de sírfidos alcanzó su punto máximo en junio y septiembre, siendo las especies dominantes Allograpta obliqua (Say), Toxomerus. marginatus (Say) y Paragus tibialis (Caído). Las recolecciones máximas de coccinélidos ocurrieron en mayo, junio y septiembre en trampas adhesivas y durante septiembre y octubre en plantas de malezas en flor. La floración máxima de las especies de malezas se produjo durante mayo y disminuyó drásticamente durante el verano hasta el otoño (junionoviembre). En 2021 y 2022 se evaluó la eficacia de las trampas amarillas de bandeja de glicol de 355 ml, las trampas amarillas de bandeja de agua de 1774 ml y las trampas adhesivas amarillas orientadas horizontal o verticalmente con respecto a la captura de enemigos naturales clave. Se capturaron significativamente más sírfidos con las trampas adhesivas amarillas horizontales que con las trampas adhesivas amarillas verticales o las trampas de bandeja amarillas llenas de glicol o agua. Los coccinélidos fueron capturados con mayor frecuencia en trampas adhesivas amarillas verticales y en trampas de agua amarillas. El número de crisópidos capturados en todos los estudios no fue significativo, lo que probablemente se debió a su comportamiento nocturno. En conjunto, estos resultados sugieren que la actividad de sírfidos y coccinélidos en los huertos de cítricos del sur de California mostró dos máximos estacionales, uno en primavera y el otro en otoño. En el contexto del futuro control biológico de conservación, las plantaciones de insectarios en primavera (abril-junio) y otoño (septiembreoctubre) serían más beneficiosas para estos depredadores y coincidirían con los maximos de población de una plaga clave de los cítricos, el psílido asiático de los cítricos, Diaphorina citri Kuwayama (Hemíptera: Liviidae).

The use of coloured pan traps (bee bowls, Moericke traps) for sampling bees (and other pollinators) has continuously increased over the last two decades. Although a number of methodological studies and conceptual frameworks offer guidance on standardised sampling, pan trap setups vary widely in characteristics even when optimised for capturing bees. Moreover, some uncertainty persists as to how local flower abundance and diversity influence sampling. We systematically reviewed peer‐reviewed studies that used pan traps for bee collection and that were listed in the Web of Science core collection. To gauge methodological variation, we identified a set of relevant methodological criteria and assessed the studies accordingly. For obtaining evidence that pan trap samples and floral environment around traps are correlated, we screened the relevant studies for such correlations. While some aspects of pan trapping (e.g., trap coloration and elevation) were similar in the majority of studies, other aspects varied considerably (e.g., trap volume/diameter and sampling duration). Few studies used floral abundance and/or diversity as an explanatory variable in their analyses of bee samples. Among these studies, we found a considerable variation in key aspects of floral survey methods, such as time and space between vegetation surveys and pan trap sampling, abundance measures (quantitative, semi‐quantitative and presence–absence), and processing of raw data prior to analysis. Often studies did not find any correlation between the floral environment and bee samples. Reported correlations varied markedly across studies, even within groups of studies applying a similar method or analysing a similar group of bees. Our synthesis helps to identify key issues of further standardisation of pan trap methodology and of associated floral surveys. In addition to the few aspects that have been standardised over the past decades, we suggest methodological direction for future research using pan traps as a better standardised method for the collection of wild bees. We encourage further studies to illuminate if and how varying floral resources around traps bias bee samples from pan traps. More generally, our synthesis shows that trapping methodologies should be reviewed regularly when their use increases to ensure standardisation. Although a number of methodological studies and conceptual frameworks offer guidance on standardised sampling, pan trap setups vary widely in characteristics. To gauge methodological variation, we systematically reviewed peer‐reviewed studies that used pan traps for bee collection and assessed the studies using a set of relevant methodological criteria. For obtaining evidence that pan trap samples and floral environment around traps are correlated, we screened the relevant studies for such correlations.

Although pan traps are an established method for sampling bees across a wide range of habitats and geographical regions, uncertainty persists as to how pan-trap characteristics influence sampling results. We investigated the effect of pan-trap diameter (23 cm versus 12 cm), interacting with trap colour, on sampled bee communities and bycatch in wildflower strips within agricultural landscapes in Germany, using fluorescent blue, white and yellow pan traps. Based on 1147 collected bee individuals identified on a species level (69 species), we observed interacting effects of pan trap colour and size on the number of sampled bee individuals and species. Large pan traps collected significantly more bee individuals (white and yellow pan traps) and species (all colours) than small pan traps. Large pan traps also collected significantly more bycatch biomass than small pan traps, irrespectively of pan trap colour. The estimated number of sampled species based on the same number of sampled individuals (individual-based rarefaction) was higher for larger pan traps than for smaller pan traps at all sampling sites. Implications for insect conservation: using larger pan traps for sampling bees increases trap efficacy (absolute numbers of sampled individuals and species) and efficiency (sampled species per sampled individuals), but larger traps also capture more bycatch biomass. Particularly in long-term monitoring schemes, we encourage a limitation of this potential impact on the non-target insect fauna by employing methodological refinements. The option to use more small traps per site versus fewer large traps remains to be explored.

Context Increased cocoa cultivation ( Theobroma cacao ) has led to the conversion of over 6 million hectares of rainforest to cocoa farmlands in West Africa. Globally, pollinator decline has been driven by land use changes. Though land use change through cocoa expansion may affect insect pollinators and, by extension, pollination services, this has rarely been assessed. Objectives Our study examined the relationships between the proportion of natural forest in the landscape (reduced primarily due to cocoa expansion) and flower-visiting insect abundance, and bee abundance, richness, diversity and community composition. The effect of pan trap type (aerial or ground) was also tested. Methods Eighteen sites were selected along a gradient of an increasing proportion of natural forests in the surrounding landscape (from 9 to 100%). Ground and aerial pan traps were deployed in each site to sample flower-visiting insects. Two sampling sessions were conducted; during the rainy season in 2021 and during the dry season in 2022. Results The abundances of Coleoptera, Hymenoptera and Hemiptera increased with increasing proportion of natural forests in the landscape, while Diptera decreased. Natural forest and trap type did not significantly influence bee abundance, species richness, and Shannon diversity. However, bee community composition differed along the forest gradient, indicating that forests and cocoa farms harbour different bee communities. Ground pan traps captured more insects (61% of 19,927 flower-visiting insects) than aerial pan traps, which was driven by the Diptera as the abundances of the other orders were not significantly related to trap type. Conclusions Preserving natural forest in cocoa-growing landscapes is important to sustain the coexistence of diverse flower-visiting insect communities owing to their differential responses to the proportions of natural forests.

The annotated checklist includes 309 species from the families Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae, and Mycetophilidae. In addition to the previous records, 242 species have been recorded for the fauna of the Republic of Mordovia for the first time. Among these are species new to Russia (Orfelia boreoalpina, Mycetophila rudis, Neoclastobasis draskovitsae, Novakia scatopsiformis) and a species new to the Palearctic (Sciophila emarginata). The collection sites are described. For the first time, 242 species are recorded for the fauna of the Republic of Mordovia. Over the course of the study, 275 species were noted in the Mordovia Nature Reserve, 91 species in National Park \"Smolny\", and 47 species in other locations within the region. Data on trapping methods for the collected fungus gnats are provided. Comparative data on species abundance in neighboring regions are also discussed.

In order to study regional faunas, one or two methods of studying Coleoptera are often used. However, a comparison of several ways of studying shows that it is more expedient to use more than one of them. Six different methods of catching Coleoptera used in studies of the biodiversity of regional faunas were compared. This research employed pitfall traps (PfT), beer traps (BT), freely hanging flight intercept traps or window traps (FWT), Malaise traps (MT), pan traps (PT), and sweep net (SN). The goal was to assess the effectiveness of these methods in evaluating the biodiversity of this insect group. Studies were conducted from 2011 to 2017 and 2019 to 2023 in the Ryazan region (the central part of European Russia). A total of 27,892 specimens of Coleoptera (927 species from 64 families) were collected. Specifically, 17,659 specimens were collected using PfT (396 species from 36 families), 4971 specimens using BT (146 species from 30 families), 1014 specimens using FWT (221 species from 51 families), 109 specimens using MT (43 species from 16 families), 2220 specimens using PT (357 species from 42 families), and 1919 specimens using SN (265 species from 32 families). The maximum number of families was observed with FWT, while the minimum number of families was registered with MT. Interestingly, the highest number of rare species from both protected lists was obtained using BT and PfT. The Margalef index was higher for Coleoptera collections using PT and PfT, while the largest Shannon index values were recorded for samples using SN and PT. The Berger–Parker index was the highest for catches using BT, which was characterized by the highest dominance of one or more species. In our study, four species of Coleoptera were found that are included in the protected lists of the Russian Federation and 14 species of Coleoptera were listed in the protected species of the Ryazan region. Considering the results of this study, the Coleoptera fauna of the Ryazan region currently accounts for 1674 species.

The relationship between insect diversity and crop production has been of continuous scientific interest. Understanding insect community dynamics using various sampling and monitoring methods at different crop phenology stages is crucial for enhancing pest management and ecosystem service functioning. The present study assessed the influence of four trap types (Blue, Yellow, White, and Malaise) applied at four tomato developmental stages (start of planting, flowering, flowering fruit development and harvest) on insect diversity in northeastern Tunisian open-field conditions. A total of 1771 insect individuals belonging to seven orders and 31 families were trapped, with the order Hymenoptera being the most common in the sampled plots, which was represented by 25 families. Trap type exerted a strong effect on both abundance and alpha diversity parameters. Yellow pan traps showed the highest diversity, with family richness (S) ranging from 1 to 16, Shannon diversity (H) reaching 2.54, Simpson (Is) diversity ranging from 0.72 to 0.90 and Pielou’s evenness (J) ranging from 0.83 to 0.98. Blue and white traps displayed intermediate diversity (Blue: S = 6 and H = 1.7; White: S = 7 and H = 1.6), while Malaise traps captured the least diverse assemblages (S = 4, H = 1.2 and Is = 0.65). These differences were highly significant (p < 0.05). Phenological stage significantly structured Hymenoptera diversity. Richness peaked at the start of planting (S = 1–16 and H up to 2.54) and declined sharply at harvest (S = 1–6). Pollinator families (Apidae, Halictidae, Megachilidae) were the most abundant during flowering, whereas parasitoid families (Braconidae, Eulophidae) dominated during the fruit development stage. Beta diversity analyses (NMDS, stress = 0.25) and PERMANOVA showed that trap type and phenological stage jointly explained 15.5% of the variation in community composition (R2 = 0.155, p = 0.014). Although a strong taxonomic overlap among traps was observed, Indicator Value analysis revealed significant trap-specific associations, including the family Andrenidae with Blue traps and the family Scoliidae with White and Yellow traps. Overall, the results of the present study demonstrate that both trap type and crop phenology significantly influence insect population diversity. A multi-trap sampling strategy combining colored pan traps and Malaise traps could be recommended to accurately characterize insect communities and associated ecosystem services in Mediterranean open-field tomato systems.

The diversity and biology of the moss and leaf litter-inhabiting flea beetles are still poorly known. In this study, three new species of Benedictus are described from China: Benedictus fuanensis Ruan & Konstantinov, sp. nov. , Benedictus quadrimaculatus Ruan & Konstantinov, sp. nov. , and Benedictus wangi Ruan & Konstantinov, sp. nov. Comments on their biology are given. Benedictus quadrimaculatus has a highly unusual morphological feature not reported before in flea beetles: black spots on the abdominal tergites that are visible through the elytra. Traditional and modified ethanol traps were tested and proven useful for collecting leaf litter- and moss-inhabiting flea beetles. Based on our tests, eight traps could collect one specimen each day in the testing sites in Fujian Province; three traps could collect one specimen each day in the testing sites in Guangdong Province.

Clear-cuts in production forests provide an open, sunny environment, with an abundance of nectar, as well as exposed soil and woody debris. This makes them a potential habitat for several groups of insects that typically use open habitats like grassland, including those species that visit fl owers. In the current study, we used colour pan traps to catch fl ower-visiting species. Study sites were selected according to age (2-8 yrs since clear-cut) and land-use history (forest or meadow 150 yrs ago). We caught and identifi ed solitary bees (395 specimens belonging to 59 species), social bees (831/16), other Hymenoptera (367/66), Syrphidae (256/31), and beetles (Lepturinae & Cetoniinae; 11,409/12). Age of the clear-cut strongly affected species composition as well as several groups and species, with most species caught mainly in the younger clear-cuts. Flower abundance statistically affected several groups and species, but inferring causation is diffi cult due to the fl ower-richness bias in pan trap catches. Bare soil and woody debris were important for the insect assemblage sampled, while bare rock was not. Although the majority of the insects caught were forest species, about one third of the species were associated with open, agricultural sites and hence seem to be able to locate and exploit resources in clear-cuts.