Species Of Megachile Research Articles

A cytochrome P450 insecticide detoxification mechanism is not conserved across the Megachilidae family of bees.

Recent work has demonstrated that many bee species have specific cytochrome P450 enzymes (P450s) that can efficiently detoxify certain insecticides. The presence of these P450s, belonging or closely related to the CYP9Q subfamily (CYP9Q-related), is generally well conserved across the diversity of bees. However, the alfalfa leafcutter bee, Megachile rotundata, lacks CYP9Q-related P450s and is 170-2500 times more sensitive to certain insecticides than bee pollinators with these P450s. The extent to which these findings apply to other Megachilidae bee species remains uncertain. To address this knowledge gap, we sequenced the transcriptomes of four Megachile species and leveraged the data obtained, in combination with publicly available genomic data, to investigate the evolution and function of P450s in the Megachilidae. Our analyses reveal that several Megachilidae species, belonging to the Lithurgini, Megachilini and Anthidini tribes, including all species of the Megachile genus investigated, lack CYP9Q-related genes. In place of these genes Megachile species have evolved phylogenetically distinct CYP9 genes, the CYP9DM lineage. Functional expression of these P450s from M. rotundata reveal they lack the capacity to metabolize the neonicotinoid insecticides thiacloprid and imidacloprid. In contrast, species from the Osmiini and Dioxyini tribes of Megachilidae have CYP9Q-related P450s belonging to the CYP9BU subfamily that are able to detoxify thiacloprid. These findings provide new insight into the evolution of P450s that act as key determinants of insecticide sensitivity in bees and have important applied implications for pesticide risk assessment.

Species of Megachile (Chrysosarus) with a partial cutting edge in the female mandible in Argentina, Chile and Uruguay (Hymenoptera, Megachilidae)

Species of Megachile (Chrysosarus) with a partial cutting edge in the female mandible in Argentina, Chile and Uruguay (Hymenoptera, Megachilidae)

Megachile sculpturalis, a Novel Host for the Cuckoo Bee Stelis costalis (Hymenoptera: Megachilidae)

Stelis costalis Cresson is an anthidiine cuckoo bee known from Texas and Mexico. Currently, it is placed in the subgenus Dolichostelis, a small group of seven species (Parker and Bohart, 1979; Gonzalez et al., 2012). To date, its members have only been reported laying their eggs in the nests of various resin-using species of Megachile (Chelostomoides) (Table 1). Here, I report on the successful parasitism of a nest of the introduced resin-using bee, Megachile (Callomegachile) sculpturalis Smith by S. costalis.

Nesting biology of two sympatric species of Megachile (Chrysosarus) (Megachilidae) in Argentina

Leaf cutter bees (genus Megachile) are a diverse group of pollinators of wild and cultivated plants. Many species nest in pre-existing cavities and use diverse building materials to construct their brood cells. For instance, species of subgenus Chrysosarus add a mud layer between two layers of leaves or petals. We studied similarities and differences in their nesting biology from 13 nests of Megachile (Chrysosarus) concava and 72 nests of Megachile (C.) diversa (Megachilidae) obtained in trap nests in northern Argentina. Females of M. concava used trap nests with higher diameters, shorter length, and built a lower number of brood cells per nest compared to females of M. diversa. In the latter species, the sex ratio was female-biased, but we observed male-biased progeny in shorter trap nests, thus the sex ratio of M. diversa could be context-dependent. Reproductive success was different between species: 40.5% for M. concava and 75.8% for M. diversa, desiccation and/or mold being the principal factor of mortality of immature stages. The attack from parasitic species represented 10.8% for M. concava and only 1.2% for M. diversa. Megachile concava, based on observations of a few nests collected during autumn, could be a bivoltine species and oligolectic of Faboideae, while M. diversa is a partially bivoltine or multivoltine, and polylectic species, with a marked turnover of pollen resource throughout its extensive reproductive season. Differences in the trophic niche and, to a lesser extent, in the inner diameter of trap nests used could allow their coexistence in the studied forests.

Possible Epigenetic Origin of a Recurrent Gynandromorph Pattern in Megachile Wild Bees.

Simple SummaryGynandromorphs, i.e., individuals with a mix of male and female body parts, are known for many species of insects and other animals with separate sexes. This anomaly is generally regarded as the result of localized genetic mutations in sex-determining genes. We analyzed the specific mix of male and female characters in naturally occurring gynandromorphs of 21 species of the wild bee genus Megachile and found a recurrent pattern. Based on the regularity of this pattern, and the current knowledge on sex determination and sex differentiation in the relatively closely-related honey bee, we argue that the origin of these composite phenotypes is possibly epigenetic, rather than genetic, i.e., produced by some defects in the maintenance of the regulatory signals that control sex differentiation at the level of single cell lineages, rather than triggered by genetic mutations.Gynandromorphs, i.e., individuals with a mix of male and female traits, are common in the wild bees of the genus Megachile (Hymenoptera, Apoidea). We described new transverse gynandromorphs in Megachile pilidens Alfkeen, 1924 and analyze the spatial distribution of body parts with male vs. female phenotype hitherto recorded in the transverse gynandromorphs of the genus Megachile. We identified 10 different arrangements, nine of which are minor variants of a very general pattern, with a combination of male and female traits largely shared by the gynandromorphs recorded in 20 out of 21 Megachile species in our dataset. Based on the recurrence of the same gynandromorph pattern, the current knowledge on sex determination and sex differentiation in the honey bee, and the results of recent gene-knockdown experiments in these insects, we suggest that these composite phenotypes are possibly epigenetic, rather than genetic, mosaics, with individual body parts of either male or female phenotype according to the locally expressed product of the alternative splicing of sex-determining gene transcripts.

Environmental niche and global potential distribution of the giant resin bee Megachile sculpturalis, a rapidly spreading invasive pollinator

Since alien species may threaten native ecosystems when becoming invasive, one of the main challenges is try to predict their potential spread. Despite bees are essential pollinators and provide important ecosystem services in their native areas, outside these areas they could represent a risk for the local bee fauna, e.g. by competing for resources or by transmitting pathogens, as it was observed for species of Megachile, the bee genus with the highest number of recorded alien species. Here, using two complementary methods (Multidimensional Envelope procedure (MDE) and the Maximum Entropy algorithm (MaxEnt)), we aim to explore environmental niche as well as to identify potential worldwide distribution of the giant resin bee Megachile sculpturalis, native to Asia and recently introduced in North America and Europe. The two methodological approaches predict an important expansion for the species and reveal a preference for areas of Palearctic and Nearctic regions with reduced temperature fluctuations and moderate precipitation regimes. The Southern hemisphere seems not having good conditions for this species. Estimations for the future (2070) predict a further, though limited expansion to northern areas in the North hemisphere. However, during roughly 25 years of spreading outside its native range, M. sculpturalis clearly expanded the range of inhabitable environmental conditions, which may increase its potential invasiveness in a pattern difficult to predict using only correlative methods. Physiological and ecological data are necessary to better assess the potential niche of this bee species and in consequence to better predict its future spreading dynamics.

Clear Plastic Bags of Bark Mulch Trap and Kill Female Megachile (Hymenoptera: Megachilidae) Searching for Nesting Sites

In 2017, we found 17 dead females of Megachile frigida Smith in clear plastic bags of composted bark mulch in a residential yard in Bozeman, Montana, USA. Females apparently entered bags via small ventilation holes, then became trapped and died. To investigate whether this is a common source of mortality, we deployed unmodified bags of mulch and those fitted with cardboard tubes (as potential nest sites) at three nearby sites in 2018. We found two dead M. frigida females and five completed leaf cells in one of these bags of mulch fitted with cardboard tubes; two male M. frigida emerged from these leaf cells. In 2018, we also discovered three dead female M. frigida and three dead females of a second leafcutter bee species, Megachile gemula Cresson, in clear bags of another type of bark mulch. Both mulches emitted nearly identical blends of volatile organic compounds, suggesting their odors could attract females searching for nesting sites. These findings suggest that more research is needed to determine how common and widespread this is for Megachile species that nest in rotting wood and if there are simple solutions to this problem.

Pollination biology of Pongamia pinnata (L.) Pierre: a potential biodiesel plant

Pongamia pinnata, is an important biodiesel plant in India. The seed is an economic part of the plant used for extraction of biodiesel. The reproductive biology of P. pinnata is important for determining barriers in setting pods. The study has been carried out at Central Agroforestry Research Institute, Jhansi, India, during 2017–2019. The observations were made on the floral biology and pollinator activity in P. pinnata for 2 years. Anthesis was noticed between 0800 and 1000 h with peak anthesis between 0800 and 0830 h. Flower longevity was only 1 day. Pollen dehiscence occurred 1–2 h before anthesis. Pollen remained viable throughout the day with maximum germination (96.15%) coinciding anthesis time. Whereas, maximum pollen tube length (0.54 ± 0.10) was observed during 1000 h. Stigma remained receptive for 8 h after anthesis, the maximum receptivity was noticed 2 h after anthesis (82% of pollen germination) and it was coinciding the time where maximum pollen tube length recorded. The style was longer than stamens, indicating that the flower appeared to be adapted for cross-pollination. There were 13 flower visitors recorded, of which Megachile species were more abundant compared to Apis, Xylocopa species and, other flower visitors. The pollinator exclusion experiment was conducted to assess the role of flower visitors on pollination and fruit set. No pod set was noticed in the absence of insect pollinators. Whereas, in an open-pollinated condition, pod set ranged between 15 to 18%.

Taxonomic studies on the subgenus Megachile (Dactylomegachile) in Argentina (Hymenoptera: Megachilidae)

This contribution deals with the most common and frequently collected species of Megachile (Dactylomegachile) in Argentina. The taxonomy of seven species is clarified, presenting sex associations for all but one of the species, M. binota, the male sex of which remains unknown. In most cases sex associations are based on specimens reared from trapnests. The following new synonymies are proposed: M. nigella Vachal is a junior synonym of M. ctenophora Holmberg; M. parsonsiae Schrottky and M. riojanensis Mitchell are junior synonyms of M. infima Vachal; M. trochantina Vachal and M. perspicua Mitchell are junior synonyms of M. leucografa Friese; M. albopunctata Jörgensen is a junior synonym of M. tetrazona Friese; M. suspecta Vachal and M. impudens Mitchell are junior synonyms of M. vagata Vachal. Redescriptions, distributional data, and a key to the studied species are given

Nesting biology of Megachile (Eutricharea) studiosa Bingham, a leafcutter bee

Investigations on nesting biology of Megachile (Eutricharea) studiosa carried out at Pantnagar (India), revealed that this Megachile species is a leafcutter bee that nests in soil and also in trap nests having tunnel with diameter of 4.79 ± 0.24 mm during summer. The female invested an active time of 49.42 ± 4.24 h to complete its nesting activity in 6–7 days, maximum quantum of time (61.28%) being spent in provisioning the brood cells. The female made 1–6 brood cells in a nest and used leaf pieces of three different sizes to construct a single cell. In their natural habitat, the male progeny had development period of 22.29 ± 1.38 days while the female bees emerged in 29 ± 1 days during May–June at an ambient mean maximum temperature between 33.2 and 38.9 °C. The data on detailed nesting activity, nest structure, plants providing nesting material and larval food presented in this communication is the first report on Megachile (Eutricharea) studiosa Bingham which would help in understanding the ecology, behavior, and role of this leafcutter bee in biodiversity pool.

Stamen elongation in sunn hemp appears to allow delayed self-pollination in the absence of pollinators – A case of bet-hedging?

Sunn hemp, Crotolaria juncea L., is an important green manure crop in the tropics. In this species, flowers are hermaphrodite, self-compatible, but herkogamous with the stigma located well above the anthers, and thus appear to be cross-pollinated. Anthers are dimorphic (5 stamens with short and 5 stamens with long filaments) and hidden beneath keel petals. The longevity of flowers was three days. Of the 16 species of bees that visited flowers of sunn hemp, four species of Megachile (M. lanata, M. bicolor, M. disjuncta and M. anthracina) and one species of Xylocopa (X. fenestrata) were effective pollinators and constituted more than 75% of visits. Species of Apis never came in contact with stigma or anther lobes and were not involved in pollination. Open pollination resulted in 78% pod set. However, when flowers were prevented from pollinator visitation, the pod set was still 62%. In the absence of pollinators, filaments of long stamens elongated and reached the level of stigma which presumably led to delayed autonomous self-pollination, a bet-hedging strategy by the plant to set seeds in the absence of pollinators.

Nesting Biology of Sympatric Species of Megachilidae Bees in a Conservation Area in Brazilian Atlantic Forest

Megachilidae bees are important pollinators in the Neotropical region, however information on the ecology and behavior of these species is still scarce. The objective of this study was to analyze the nesting biology of sympatric species in the União Biological Reserve, a remnant of Atlantic Forest in the southeastern Brazil. Our results indicated the occurrence of 17 species, representing significant richness compared to other areas in the Atlantic Forest. Five sympatric species built ¾ of all nests found and the architecture of their nests was studied including, for the first time, nests of a species of Megachile (Ptilosarus). The use of petals or leaf fragments in the construction of the nests was observed for species of Megachile (Chrysosarus), confirming previous data. The nesting activity period in the trap-nests occurred mainly in the rainy season, with different peaks among the species. The results indicate that the distinctive characteristics of the species, such as the type of material used in the nests, the dimensions of cavities, and the asynchronous nesting period, could be important for the niche differentiation of these sympatric species, allowing the maintenance and the survival of the most abundant Megachilidae populations in the area.

Nesting biology of three Megachile (Hymenoptera: Megachilidae) species from Eastern Amazonia, Brazil

Megachile Latreille is a conspicuous genus of solitary bees distributed worldwide. However, the biology of tropical species is still little known. We present data on biology of Megachile brasiliensis Data Torre, Megachile sejuncta Cockerell and Megachile stilbonotaspis Moure found in two remnants of eastern Amazonian forest in northeastern Brazil. The study was conducted using the trap-nest methodology in two different areas during four periods. We collected a total of 24 nests of M. brasiliensis, 26 of M. sejuncta and 28 of M. stilbonotaspis. The differential abundance of collected nests may reflect the population size in each sampled place. The nesting activity was concentrated mainly between July and January and species presented a multivoltine pattern, except for M. sejuncta, which was partly univoltine. Assessed pollen use showed a predominant use of Attalea sp. (Arecaceae) and, for M. stilbonotaspis, Tylesia sp. and Lepidaploa sp. (Asteraceae). Babassu is a very common palm in the studied areas and the studied species seem to have a strong link with it. We also reported change of pollen use by M. sejuncta, probably due to competition with M. brasiliensis, which may have influenced the biased sex ratio observed in M. sejuncta toward males. Parasites reported here were also recorded for other Megachile species, such as Coelioxys, Brachymeria, Meloidae and Pyralidae species. Mites were observed in association with M. stilbonotaspis. The data presented here set up a background that encourages new studies on the ecology of these three Amazonian species, providing tools for proper biodiversity management and conservation.

Notes on a nest of Megachile (Moureapis) apicipennis Schrottky (Megachilidae) constructed in an abandoned gallery of Xylocopa Frontalis (Olivier) (Apidae)

Notes on a nest of the leafcutting bee Megachile (Moureapis) apicipennis Schrottky (Megachilidae) found in an abandoned gallery excavated by the carpenter bee Xylocopa frontalis (Olivier) (Apidae) are presented. A total of four nests were found at the end of the gallery. Brood cells were lined with imbricate pieces of leaves of Centrosema virginianum (L.) Benth. (Fabaceae). Four males and two females of M. apicipennis emerged as well as individuals of three species of natural enemies: Coelioxys otomita Cresson (Megachilidae), Brachymeria paraguayensis (Brèthes) and Melittobia australica Girault (Eulophidae). Our results were similar to the data obtained from other species of Megachile (Moureapis) Raw.

Floral biology of Grewia flavescens Juss.: an underutilized crop

Grewia flavescens is a fruit species found throughout semi-arid and sub-humid parts of the world including India. In contemporary era, emphasis on food supply, market value and medicinal utility of underutilized crops made this fruit species suitable for commercial cultivation. The present study was the first attempt made to study the floral biology of G. flavescens. Anthesis was noticed between 1130 and 1300 h whereas, between 1200 and 1230 h its peak anthesis was observed. Pollen dehiscence occurred 1–2 h prior to anthesis. The maximum pollen viability of 80.34 ± 5.16 per cent with 1% acetocarmine was observed at the time of anthesis and it was coincided with the stigmatic receptivity. After 2 h of anthesis, receptivity of stigma was found maximum and the peak nectar production was between 0 and 2 h after flower opening. A total of 21 flower visitors were recorded, of which Megachile species was more abundant compared to Apis, Xylocopa species and other minor flower visitors. The absence of insect pollination reduce the fruit set 21% from 82% under open pollination. Delayed selfing was observed as a safety mechanism in this species.

Differentiation of Five Species ofMegachile(Hymenoptera: Megachilidae), based on Wing Shape

AbstractIn the present work we used landmark-based geometric morphometrics to compare the wing shapes of five species ofMegachile(belonging to three subgenera) to confirm whether this technique may be used reliably for differentiation of this group. Analyses of wing shape by the use of principal component analysis (PCA), and canonical variate analysis (CVA) led to a clear differentiation among species. We found a close phenotypic similarity in wing shape betweenM. albisecta(belonging to the subgenus Creightonella) andM. picicornis(belonging to the subgenus Eutricharaea). According to the results of UPGMA, a higher degree of divergence betweenM. farinosa(belonging to the subgenus Pseudomegachile) and species belonging to other subgenera, was detected. The results of a cross-validation test indicated that geometric morphometrics is an effective technique to use for distinguishing betweenMegachilespecies. The reliability rate of this technique was between 85.71-100%. Using only two submarginal cell landmarks for generating shape variables, the cross-validation test correctly assigned individuals to their respective species, with a 92.85-100% reliability rate. Significant differences in wing size were obtained among the analysed species.

Distribution and ecology of bees on the Polish Baltic coast (Hymenoptera, Apoidea, Apiformes)

Abstract The present study provides data on the distribution of 128 bee species on the Polish Baltic coast. This brings the total number of species of Apiformes in this region to 164, including those that I reported earlier. The bee fauna of the Polish coast is characterized by a very high proportion of bumblebees and cuckoo bees (locally up to 70-80% of the total catch), and the dominant proportion of Megachilidae, especially Megachile species. The species diversity and dominance structure of the Apiformes differ between the western coast (a very high proportion of bumblebees) and the eastern coast (a large number of dominant species). These results confirm my earlier hypothesis regarding the maritime-continental gradient of bumblebee abundance, indicating that the densities of these insects are higher in NW Poland. This study is the first to assess bee densities on coastal dunes in Poland.

Studies on Megachile Latreille subgenus Callomegachile Michener (Hymenoptera: Megachilidae) from Chandigarh and Haryana plains, India.

Floral associations of three species of Megachile (Callomegachile) from NW India are provided: M. (C.) disjuncta, M. (C.) cephalotes and M. (C.) lerma. Morphological characters of both sexes and the male genitalia of each species are presented and illustrated. All three species are new records for Union Territory (Chandigarh) and Haryana in India.

A review of Megachile (Chelostomoda) Michener (Megachilidae: Megachilini) known from China with the description of a new species

The Chinese species of Megachile (Chelostomoda) Michener, 1962, are treated in this paper. Megachile (C.) guangxiensesp. nov. is described and illustrated. A checklist of the known Chinese species, distribution records, and an updated iden-tification key are provided. The type specimens of M. guangxiense are deposited in the Insect Collection of the Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS, Beijing).

A taxonomic revision of the southern African species of the subgenus Creightonella Cockerell (Apoidea: Megachilidae: Megachile Latreille)

The southern African species of Megachile (Creightonella) are revised. Twelve valid species are recognised, one of whichis new, Megachile serrula sp. n., and four are only known from the female. Ten new synonymies are recorded. Megachilecognata var. claripennis Friese, Megachile natalensis Friese are synonymized with Megachile cognata Smith. Megachileconsanguinea zamelaena Cockerell is synonymized with Megachile ianthoptera Smith. Megachile hopilitis Vachal,Megachile vanderysti Cockerell, Megachile triangulifera kivuicola Cockerell, and Megachile heptadonta Cockerell aresynonymized with Megachile angulata Smith. Four new lectotypes were designated; they are Megachile natalensis Friese,M. discolor Smith, M. cornigera Friese and M. braunsiana Friese. The nomenclatorial history of each species is documented, diagnoses are given, food plants are recorded and distribution maps are provided.