Since birds do not eat coffee cherries, bio-control by birds would only occur during the brief dispersal period when CBB are vulnerable. There is a rich bird community during this period of time as both resident and migratory birds are present . Neotropical migrants are potentially more abundant on coffee farms than resident species that may prefer forest habitat due to higher prey abundances . Many migratory warbler species of the Setophaga genus that frequent coffee farms have been confirmed as CBB predators, as have resident bird species such as the rufous-capped warbler and common tody flycatcher This positive density-dependent relationship between population growth and density is an Allee effect , and escape from predation is one mechanism for this phenomenon . In general, predator-driven Allee effects can occur when predators are the main driver of prey dynamics and when predators are generalists as are insectivorous Neotropical migrants . Additionally, predators can exert strong pressure when prey availability is not temporally or spatially limited—a potential limiting factor in the coffee system, since CBB are only available to birds during dispersal. The degree to which birds exert an Allee effect on CBB might depend on the starting population size of the pest. Variation in starting population size is likely dependent on how recently CBB have colonized in an area, timing of trapping , the size of the farm , and the extent to which farmers used control measures the previous year . We found that only under very low initial population sizes of CBB could birds be expected to suppress pest numbers by 50%. We note that earlier, nursery pots stronger CBB suppression by birds would lead to lower infestation numbers later in the coffee season, but this might require selective foraging by birds, depending on relative abundances of other prey species.
In conclusion, our models suggest that birds can control CBB under some circumstances, depending on the relative size of the starting CBB population and existing local bird density. To put this idea into practice it is important to remember that managing farms for bird habitat does not always result in pest reduction. Birds may not prey on the pest of interest or birds might cause pest numbers in increase by preying on insect predators that normally regulates the pest population . Aside from predators, pest species are also impacted by the agricultural environment directly . In fact, on coffee farms where bird densities are higher in shade, CBB infestations are also higher , possibly because CBB native range is in humid, shade forests of Africa . It is important that future modeling include such habitat-specific factors to understand Our research helps quantify the densities under which birds have the potential to control CBB populations. Putting these numbers into practice will require understanding how management practices affect both bird and CBB densities.Synsepalum Daniell and Englerophytum K. Krause are two closely related genera of the sub-family Chrysophylloideae in the family Sapotaceae. These two genera comprise 35 and 19 recognized species respectively and are predominantly distributed across West-Central tropical Africa. Both genera share the frequent presence of stipules, usually 5-merous flower with the irregular presence of small staminodes, similar seeds, and embryos. They are however considered to be different genera due to the consistent striate brochidodromous venation and strong fusion of the filaments into a staminal tube found in species of Englerophytum, whereas in species of Synsepalum leaf venation tends to be eucamptodromous and the filaments are free. In their study of the SynsepalumEnglerophytum complex, reported six lineages from combined data from nuclear DNA, chloroplast DNA and morphology analyzed using parsimony. The views of [2] are however different from the previously obtained results from in which the two genera formed a single heterogeneous clade where species of Synsepalum genus were grouped within species of Englerophytum. The differences between the two genera are a call for concernas the decision to either merge the two genera or separate them is yet to be reached.
Also, [5] in their multi-gene phylogeny study, found support for the monophyly of the Synsepalum–Englerophytum clade but did not sample either genus extensively, only very limited sampling of the two genera.Synsepalum has undergone several taxonomic changes throughout history as new species have been discovered. It is comprised of trees and shrubs native to tropical lowland areas of Africa. It was described in 1852 and currently consists of about 35 species, including the very popular miracle berry plant, S. dulcificum Daniell which is the type species on which the genus is based. Like the genus Diploon Cronquist, Synsepalum has glabrous staminodes and imbricate to valvate corolla lobes. A very common feature in the genus is their fused sepals, a character that gave the name to the genus. Synsepalum can also be characterized by its long spreading corolla lobes and large stipules. The current 35 recognized species in the genus are a combination of species from previously recognized smaller genera, including Afrosersalisia A.Chev., Pachystela Radlk, Vincentella Pierre, Synsepalum, and Tulestea Aubrév. & Pellegr. Previous generic classifications were considered unsatisfactory and therefore the genera were united under Synsepalum. The small genera were merged using overlapping characters to form the currently recognized genus. The combination of the following characters was used to describe Synsepalum: frequent occurrence of large stipules, eucamptodromous venation, 5-merous flowers, corolla nearly always rotate, cyathiform or shortly tubular with wide-spreading lobes, corolla lobe aestivation imbricate or induplicate valvate, stamens fixed at or near the top of the corolla tube, exserted with well-developed filaments. The seed is broad and not laterally compressed, with a broad adaxial scar that sometimes extends to cover most of the surface. The embryo has plano-convex cotyledons and endosperm is known to be generally absent in the genus. Due to the inconsistency in the characters of the small genera that were merged, species in the genus are often individually very distinct.
This has complicated the taxonomic revision of the genus and caused many synonyms to have emerged. With the emergence of molecular technique, the lumping of these genera to form the genus Synsepalum has been disputed by many authors as the conclusion was purely based on morphological characters.Englerophytum K. Krause was described as a genus, with Englerophytum stelechanthum as the type species. Five species were added to the genus, two of which were newly described while the other three were products of new combinations of species previously classified in different genera. As opposed to the views of [11], who advocated for the distinct status of the genera Englerophytum, Wildemaniodoxa Aubrév. & Pellegr. and Zeyherella Aubrév. & Pellegr, united the genera based on the fusion of their filaments and the number of floral parts. Although considered Synsepalum to be closely related to Englerophytum because of the frequent presence of stipules, usually 5-merous flowers, irregular presence of small staminodes, and similar structure of seeds and embryo, he considered Synsepalum distinct genus from Englerophytum.The Sapotaceae classification of was purely morphological as that was the standard used then in reaching taxonomic conclusions. Nuclear DNA and plastid trnH-psbA were used by to estimate phylogeny within the Synsepalum–Englerophytum clade. Their results do not support the classification by Pennington, and the species of the two focal genera of this study that they analyzed were resolved in a polytomy of six clades: two comprising the species of Englerophytum and four of Synsepalum. However, plastic planters their result cannot be considered final due to incomplete sampling, as only 11 out of the 35 accepted species of Synsepalum and 8 out of the 19 species of Englerophytum were used for the study. They also recommended that more work is required before a comprehensive taxonomic conclusion about the clade can be reached. Aside from the work of [2], there are no published reports on phylogenetic relationships within the Synsepalum-Englerophytum clade. In their studies of the SynsepalumEnglerophytum complex, reported that four of the six lineages comprised Synsepalum species, and three out of the four lineages of Synsepalum corresponded to the smaller genera of the earlier generic classification by [9]. There are, however, some concerns with the lineages reported. Some of the lineages had just a single species, which was not the type species of the small, segregated genus . More species need to be investigated to better understand the phylogenetic relationships among species currently classified in Synsepalum and Englerophytum and to determine the number, names, and circumscriptions of genera that should be recognized in a phylogenetically based classification.In general, plant phylogenetic studies provide a framework for understanding the fundamental processes of evolution and help in organizing the diverse plants of the earth in a way that will make sense to all. In the genus Synsepalum, although the presence of stipules and 5-merous flowers has been suggested as diagnostic characters for the genus, the presence of stipules is not consistent. They are missing in some species, these may represent secondary losses, however. Phylogenetic analyses based on molecular data should make it possible to evaluate relationships among species in the group and compare them with the ancient generic concept. Moreover, not much has been done in resolving the divergent views of researchers on the merging of the small genera by Pennington to form Synsepalum sensu lato. This research proffers a solution to taxonomic problems in the Synsepalum–Eglerophytum complex.
It is generally believed that fresh materials from the field are more reliable for DNA extraction but due to the outbreak of the Covid-19 pandemic, getting to the field to sample materials was not an option to be explored for this study. Thus, materials for both Synsepalum and Engleropytum were mostly accessed from herbarium material. Materials were obtained as loans through the University of California Davis Herbarium . Samples were collected from Missouri Botanical Gardens , New York Botanical Gardens , Harvard University Herbarium and The Conservatory and Botanical Garden of the city of Geneva . A few other samples were collected in silica gel from people who grow them in their gardens. Leaf material sufficient for use in extracting DNA was removed from the herbarium samples.To avoid the destructive removal of leaf samples, leaves already placed in the fragmented packet in the herbarium sheets were first used. Where there were no leaves in the fragment packet, a single leaf was removed and used for the experiment. A total of 103 leaf samples were used for this study, comprising 43 from different herbaria in the United States , 56 from Switzerland and France , and four were fresh samples, see Supplementary Materials, Table S1.The amplified fragments for both regions were controlled for their quality by electrophoresis. 1.8 g of powdered agarose gel was added to 100 mL of 1X TAE buffer. The mixture was shaken vigorously to ensure the agarose gel was completely immersed in the 1X TAE buffer. After heating, 1 µL of Sybrsafe DNA gel stain is added to the beaker containing the agarose gel, which is placed in a bath containing water for a few seconds until the beaker is cool enough to be handled with the hand using hand gloves. The gel solution was poured into a tray fitted with combs and allowed to stay for 20 min until it solidified. After solidification, the comb is removed, and the wells are loaded with PCR. The chamber containing the loaded DNA is connected to power at 76 KVA and allowed to run for 1 h. The gel is then visualized under UV light. Wells that produce bands are considered successful. The bands are excised using a razor blade. DNA was extracted from the bands and purified by application of a QIA quick PCR purification kit from Qiagen .To obtain DNA sequences, extracted purified DNA from the gel was sent to the UC Davis sequencing center. For each direction of the primer, six micro-liters were used. Raw data from the facility were opened on Sequencher 5.4.6 which was used to assemble contigs and edit the sequences. The first nucleotides of each end of the sequences were trimmed until readable bases were obtained. After trimming up the sequences, BLAST searches were performed to ensure the results obtained were that of Sapotaceae. In cases of contamination, blast results give different plant families and in some cases insects. Whenever contamination was observed the experiment was repeated to be sure the right species was used for the research. Alignment was done using muscle in MEGA X. For the GenBank codes of sequences used in our phylogenetic analyses, see Supplementary Materials, Table S2.The evolutionary history was inferred using the Bayesian Inference and Maximum Likelihood methods.