Impact of multiple natural enemies on immature <Emphasis Type="Italic">Drosophila suzukii</Emphasis> in strawberries and blueberries

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) oviposits in ripening fruit, larvae render crops unmarketable, and significant economic losses can occur. Biological control research has focused on individual natural enemy species against immature D. suzukii. Here we combine two predators and an entomopathogenic nematode, expecting species complementarity and increased control of D. suzukii. In strawberries, Orius insidiosus (Say) (Hemiptera: Anthocoridae) plus Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) resulted in fewest D. suzukii (81% reduction), and in blueberries, results were similar (60% reduction), although H. bacteriophora was not as effective as in strawberries, which was likely due to drier substrate conditions. There was neither strong complementarity nor interference between predators, O. insidiosus and Dalotia coriaria Kraatz (Coleoptera: Staphylinidae). Inclusion of O. insidiosus resulted in 50% fewer D. suzukii than combinations without O. insidiosus. Control of D. suzukii can be improved with multiple natural enemies, and combinations of O. insidiosus with other agents (parasitoids, fungal entomopathogens) should be tested.     

Identification of active components from volatiles of Chinese bayberry, <Emphasis Type="Italic">Myrica rubra</Emphasis> attractive to <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is native to Southeast Asia and now has become a severe pest of several soft fruits in Europe and the Americas. It causes considerable damage to Chinese bayberry, Myrica rubra, in China. In the present study, we employed gas chromatograph–electroantennographic detection (GC–EAD) together with behavioural bioassays and trapping experiments to identify volatile semiochemicals emitted by Chinese bayberry attracting D. suzukii. Electrophysiological experiments revealed the presence of six EAD-active compounds from ripe bayberry fruits, including methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate, α-ylangene, α-humulene and an unidentified compound that elicited consistent antennal response. In two-choice bioassays, bayberry fruits attracted all responding flies, and significantly more flies responded to the volatile extract of bayberry fruits. Four EAD-active compounds were attractive to mated female D. suzukii at lower doses (0.01 and 0.1 µg), but showed repellency at higher doses (10 and 100 µg). Mixtures of these four compounds at different ratios attracted D. suzukii flies at all test doses (0.1, 1 and 10 µg). Both male and female flies were trapped by a mixture of synthetic methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate and α-humulene in a ratio of 1:1.3:1:6.4 in the field trapping experiment. Significantly more males than females were captured in the trap baited with the synthetic blend, and the percentages of D. suzukii captured out of all flies by the traps baited with lure were higher than that baited with blank control. Our findings may provide insights into the olfactory responses of D. suzukii to specific host plant volatiles, and contribute to further development of an effective lure for monitoring D. suzukii in the field.     

A preliminary study on distributions and oviposition sites of <Emphasis Type="Italic">Drosophila suzukii</Emphasis> (Diptera: Drosophilidae) and its parasitoids on wild cherry tree in Tokyo,central Japan

Distributions and oviposition sites of Drosophila suzukii (Matsumura) and its parasitoids on wild cherry tree were studied in early summer in a suburb of Tokyo, central Japan. Adults of D. suzukii occurred in the foliage layer as well as in the undergrowth layer. The number of D. suzukii that emerged did not significantly differ between wild cherry fruit collected from the foliage layer and those from the undergrowth layer. In addition, the number of D. suzukii that emerged per fruit decreased when fruit were left on the ground longer. It is therefore assumed that D. suzukii females rarely oviposit eggs in fallen wild cherry fruit. The suzukii-associated type of Ganaspis brasiliensis (Ihering) was the major parasitoid that emerged from D. suzukii in the study area. The rate of parasitism by this parasitoid did not significantly differ between larvae in fresh fruit from the foliage layer and those in fallen fruit from the undergrowth layer. This may also suggest that this wasp rarely attacks D. suzukii larvae in fallen fruit. Adults of the suzukii-associated type of G. brasiliensis, Asobara sp. TK1, and Leptopilina japonica that attack D. suzukii were mainly collected from the foliage layer. On the basis of the present results, some proposals for the control of D. suzukii were discussed.     

<Emphasis Type="Italic">Gr</Emphasis> and <Emphasis Type="Italic">hp</Emphasis>-<Emphasis Type="Italic">1</Emphasis> tomato mutants unveil unprecedented interactions between arbuscular mycorrhizal symbiosis and fruit ripening

Main conclusion

Systemic responses to an arbuscular mycorrhizal fungus reveal opposite phenological patterns in two tomato ripening mutants depending whether ethylene or light reception is involved. The availability of tomato ripening mutants has revealed many aspects of the genetics behind fleshy fruit ripening, plant hormones and light signal reception. Since previous analyses revealed that arbuscular mycorrhizal symbiosis influences tomato berry ripening, we wanted to test the hypothesis that an interplay might occur between root symbiosis and fruit ripening. With this aim, we screened seven tomato mutants affected in the ripening process for their responsiveness to the arbuscular mycorrhizal fungus Funneliformis mosseae. Following their phenological responses we selected two mutants for a deeper analysis: Green ripe (Gr), deficient in fruit ethylene perception and high-pigment-1 (hp-1), displaying enhanced light signal perception throughout the plant. We investigated the putative interactions between ripening processes, mycorrhizal establishment and systemic effects using biochemical and gene expression tools. Our experiments showed that both mutants, notwithstanding a normal mycorrhizal phenotype at root level, exhibit altered arbuscule functionality. Furthermore, in contrast to wild type, mycorrhization did not lead to a higher phosphate concentration in berries of both mutants. These results suggest that the mutations considered interfere with arbuscular mycorrhiza inducing systemic changes in plant phenology and fruits metabolism. We hypothesize a cross talk mechanism between AM and ripening processes that involves genes related to ethylene and light signaling.

     

Effect of entomopathogenic nematodes on different developmental stages of <Emphasis Type="Italic">Drosophila suzukii</Emphasis> in and outside fruits

Drosophila suzukii Matsumura (Diptera: Drosophilidae) is a harmful invasive fruit pest, which is currently spreading in Europe. Since its arrival in 2008, the spotted wing drosophila has caused major losses in several soft-skinned fruit crops. This critical situation urgently requires efficient practices of residue-free pest control. In the present laboratory study, entomopathogenic nematodes (EPNs) were investigated for their ability to infect larvae and pupae of D. suzukii within directly sprayed fruit, fruit placed on soil, and soil. Steinernema feltiae Filipjev (Rhabditida: Steinernematidae), and Steinernema carpocapsae Weiser (Rhabditida: Steinernematidae) were more efficient at infecting soil-pupating host larvae than Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) at application rates ranging from 25 to 400 EPN cm^?2. Applied as a soil drench, S. feltiae and S. carpocapsae were able to infect D. suzukii larvae in the soil as well as hidden inside fruit. Direct application of EPNs on the fruit was less successful, although emergence of flies was significantly reduced.     

<Emphasis Type="Italic">Drosophila suzukii</Emphasis> in Southern Neotropical Region: Current Status and Future Perspectives

Non-native insect pests are often responsible for important damage to native and agricultural plant hosts. Since Drosophila suzukii Matsumura (Diptera: Drosophilidae) has become an important pest in North America and Europe (i.e., in 2008), the global production of soft thin-skinned fruits has faced severe production losses. In the southern Neotropical region, however, the first record of D. suzukii occurred in 2013 in the south of Brazil. It has also been recorded in Uruguay, Argentina, and Chile. Despite its recent occurrence in the southern Neotropical region, the fast dispersion of D. suzukii has inspired local research efforts in an attempt to mitigate the consequences of this insect pest invasion. In this forum, we explore the current status of D. suzukii in southern Neotropical regions, discussing its future perspectives. Additionally, we attempt to draft activities and a research agenda that may help to mitigate the losses caused by D. suzukii in native and commercial soft-skinned fruits produced in this region. Currently, D. suzukii appears to be well established in the south of Brazil, but considering the entire southern Neotropical region, the invasion panorama is still underinvestigated. The lack of studies and regulatory actions against D. suzukii has contributed to the invasion success of this species in this region. Considering several peculiarities of both the pest biology and the environmental of this region, the authors advocate for the need of intensive and integrative studies toward the development and implementation of area-wide integrated pest management programs against D. suzukii in the southern Neotropical region.     

<Emphasis Type="Italic">Diplazium</Emphasis> hybrids involving <Emphasis Type="Italic">D. plantaginifolium</Emphasis> and <Emphasis Type="Italic">D</Emphasis>. <Emphasis Type="Italic">ternatum</Emphasis> from Mexico and Central America

Here we evaluate the origins and relationships of Mexican and Central American Diplazium hybrids derived from crosses involving either D. plantaginifolium or D. ternatum. Based on study of live plants and herbarium specimens, we distinguish D. ×verapax from the similar D. riedelianum and present evidence that the former is a sterile hybrid derived from a cross between D. plantaginifolium and D. werckleanum. We also describe new hybrids, D. ×torresianum and D. ×subternatum from Mexico and northern Central America. Both involve D. ternatum as one parent. Diplazium. cristatum is the other putative parent of D. ×torresianum, and D. plantaginifolium is the second parent of D. ×subternatum. We also designate lectotypes for D. cordovense and D. dissimile.     

Functional Analysis of <Emphasis Type="Italic">VvBG1</Emphasis> During Fruit Development and Ripening of Grape

β-glucosidase (BG) was believed to take part in abscisic acid (ABA) synthesis via hydrolysis of ABA glucose ester to release active ABA during plant growth and development. However, there is no genetic evidence available to indicate the role of genes during fruit ripening. Here, the expression patterns of three genes (VvBG1, VvBG2, and VvBG3) encoding β-glucosidase were analyzed during grape fruit development, and it was found that β-glucosidase activity increased in grape fruit in response to various stresses. Furthermore, to verify the function of β-glucosidase during fruit ripening, heterogeneous expression of the VvBG1 gene in strawberry fruit was validated, and the results showed that the VvBG1 over-expression increased β-glucosidase and promoted the fruit ripening process in strawberry. In addition, we found that ABA contents increased in the VvBG1 over-expression of strawberry fruit, which induced fruit anthocyanin, soluble solid accumulation, and fruit softening. Moreover, genes related to coloring (CHS, CHI, F3H, and UFGT), softening (PG1, PL1, and EXP1), and aroma (SAAT, and QR) were up-regulated. This work will elucidate the specific roles of VvBGs in the synthesis of ABA and provide some new insights into the ABA-controlled grape ripening mechanism.     

<Emphasis Type="Italic">Drosophila</Emphasis> as models to understand the adaptive process during invasion

The last few decades have seen a growing number of species invasions globally, including many insect species. In drosophilids, there are several examples of successful invasions, i.e. Zaprionus indianus and Drosophila subobscura some decades ago, but the most recent and prominent example is the invasion of Europe and North America by the pest species, Drosophila suzukii. During the invasive process, species often encounter diverse environmental conditions that they must respond to, either through rapid genetic adaptive shifts or phenotypic plasticity, or by some combination of both. Consequently, invasive species constitute powerful models for investigating various questions related to the adaptive processes that underpin successful invasions. In this paper, we highlight how Drosophila have been and remain a valuable model group for understanding these underlying adaptive processes, and how they enable insight into key questions in invasion biology, including how quickly adaptive responses can occur when species are faced with new environmental conditions.     

Trail Chemicals of the Convergens Ladybird Beetle, <Emphasis Type="Italic">Hippodamia convergens</Emphasis>, Reduce Feeding and Oviposition by <Emphasis Type="Italic">Diaphorina citri</Emphasis> (Hemiptera: Psyllidae) on Citrus Plants

We investigated feeding and oviposition behavior of the Asian citrus psyllid, Diaphorina citri, when exposed to the foraging trails of the convergens ladybird beetle, Hippodamia convergens. Diaphorina citri females feeding on citrus leaves directly exposed to the ladybird adults or treated with trail extract excreted significantly less honeydew droplets than controls. The trail chemicals of the ladybird beetle also decreased oviposition by D. citri females on citrus. In a no-choice experiment, D. citri females preferred to oviposit on control flush and plants than those with ladybird trail-extract treatments. In two-choice experiments, 68.0% of D. citri released into cages exhibited strong selection preference for settling and eventual oviposition on control plants than plants treated with ladybird trail extract. Diaphorina citri eggs were found on all new leaf flush of control plants, whereas only 29.5% of flush on treatment plants were selected for oviposition. The trail chemical deposited by the convergens ladybird beetle elicits repellency of D. citri feeding and oviposition. Therefore, the trail chemicals my contain components that could be useful for behavior-based management of D. citri and HLB disease by reducing psyllid feeding and oviposition.     

Search for Canonical <Emphasis Type="Italic">P</Emphasis> Element in Genomes of Drosophilinae Subfamily Species

Using the FISH method and PCR analysis, the presence of canonical P element was studied in the genomes of a number of laboratory lines isolated from nature in different years from the Zaprionus genus (Z. indianus) and Drosophila genus, Sophophora subgenus (D. ananassae, D. eugracilis, D. simulans, D. immigrans), Drosophila subgenus (D. virilis, D. mercatorum, D. hydei, D. funebris, D. pseudoobscura), Lordiphosa subgenus (L. magnipectinata), and Dorsilopha subgenus (D. busckii) in a search for new cases of horizontal transfer. According to our data, the L. magnipectinata genome contains sequences homologous to terminal regions of canonical P element, as well as the sequence with a weak homology from the central part of canonical P element. The P-element hybridization sites adjacent to the chromocenter were found in the D. pseudoobscura genome; this can indicate an ancient origin of the sequences homologous to the P element. The P element is absent in old D. simulans lines, except for the line isolated from nature in 2014 (in which the P element was found); this confirms data of other researchers about recent cases of horizontal P-element transfer in this species. No new cases of horizontal transfer were detected in the analyzed lines.     

Genome-wide identification and evolution of <Emphasis Type="Italic">TC1</Emphasis>/<Emphasis Type="Italic">Mariner</Emphasis> in the silkworm (<Emphasis Type="Italic">Bombyx mori</Emphasis>) genome

TC1/Mariner transposons belong to class II transposable elements (TEs) that use DNA-mediated “cut and paste” mechanism to transpose, and they have been identified in almost all organisms. Although silkworm (Bombyx mori) has a large amount of TC1/Mariner elements, the genome wide information of this superfamily in the silkworm is unknown. In this study, we have identified 2670 TC1/Mariner (Bmmar) elements in the silkworm genome. All the TEs were classified into 22 families by means of fgclust, a tool of repetitive sequence classification, seven of which was first reported in this study. Phylogenetic and structure analyses based on the catalytic domain (DDxD/E) of transposase sequences indicated that all members of TC1/Mariner were grouped into five subgroups: Mariner, Tc1, maT, DD40D and DD41D/E. Of these five subgroups, maT rather than Mariner possessed most members of TC1/Mariner (51.23%) in the silkworm genome. In particular, phylogenetic analysis and structure analysis revealed that Bmmar15 (DD40D) formed a new basal subgroup of TC1/Mariner element in insects, which was referred to as bmori. Furthermore, we concluded that DD40D appeared to intermediate between mariner and Tc1. Finally, we estimated the insertion time for each copy of TC1/Mariner in the silkworm and found that most of members were dramatically amplified during a period from 0 to 1 mya. Moreover, the detailed functional data analysis showed that Bmmar1, Bmmar6 and Bmmar9 had EST evidence and intact transposases. These implied that TC1/Mariner might have potential transpositional activity. In conclusion, this study provides some new insights into the landscape, origin and evolution of TC1/Mariner in the insect genomes.     

Association between <Emphasis Type="Italic">cagA</Emphasis>, <Emphasis Type="Italic">vacAi</Emphasis>, and <Emphasis Type="Italic">dupA</Emphasis> genes of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> and gastroduodenal pathologies in Chilean patients

In addition to the already known cagA gene, novel genetic markers have been associated with Helicobacter pylori (H. pylori) virulence: the dupA and vacAi genes. These genes might play an important role as specific markers to determine the clinical outcome of the disease, especially the vacAi gene, which has been expected to be a good marker of severe pathologies like gastric adenocarcinoma. In the present study, the association of cagA, dupA, and vacAi genes with gastroduodenal pathologies in Chilean patients was studied. One hundred and thirty-two patients positive for H. pylori were divided into two groups—non-severe and severe gastric pathologies—and investigated for the presence of cagA, dupA, and vacAi H. pylori virulence genes by PCR. The cagA gene was detected in 20/132 patients (15.2%), the vacAi1 gene was detected in 54/132 patients (40.9%), the vacAi2 gene was detected in 26/132 patients (19.7%), and the dupA gene was detected in 50/132 (37.9%) patients. Logistic regression model analysis showed that the vacAi1 isoform gene in the infected strains and the severity of the diseases outcome were highly associated, causing severe gastric damage that may lead to gastric cancer (p < 0.0001; OR = 8.75; 95% CI 3.54–21.64). Conversely, cagA (p = 0.3507; OR = 1.62; 95% CI 0.59–4.45) and vacAi2 (p = 0.0114; OR = 3.09; 95% CI 1.26–7.60) genes were not associated with damage, while the dupA gene was associated significantly with non-severe clinical outcome (p = 0.0032; OR = 0.25; 95% CI 0.09–0.65). In addition, dupA gene exerts protection against severe gastric pathologies induced by vacAi1 by delaying the outcome of the disease by approximately 20 years.