1,721,007 research outputs found
XylFeed – Analysing DC-EPG waveform variables for European spittlebugs and sharpshooters
No full textThe software “XylFeed” is designed as MS Excel macro, developed to analyse essential DC-EPG (Direct Current-Electrical Penetration Graph) waveform variables for European xylem sap-feeding insects (spittlebugs and sharpshooters). DC-EPG waveforms must be manually marked in ‘Stylet+a’ (EPG Systems, Wageningen, Netherlands) or comparable software previously to allow a calculation in “XylFeed”. The software enables the analysis of the probing and feeding activities of European xylem sap-feeding insects through a calculation of sequential and non-sequential EPG variables. A detailed description of the software usage is provided in the Supplementary Material of the connected publication, while software output variables are listed and defined within the software.Peer reviewe
Philaenus spumarius: when an old acquaintance becomes a new threat to European agriculture
No full textThe unique color pattern polymorphism and the foamy nymphal case of the meadow spittlebug Philaenus spumarius have
attracted the attention of scientists for centuries. Nevertheless, since this species has never been considered a major threat to
agriculture, biological, ecological and ethological data are missing and rather scattered. To date this knowledge has become
of paramount importance, in view of the discovery of P. spumarius main role in the transmission of the bacterium Xylella
fastidiosa in Italy, and possibly in other European countries. The aim of this review is to provide a state of the art about this
species, with particular focus on those elements that could help developing environmental friendly and sustainable control
programs to prevent transmission of X. fastidiosa. Moreover, recent findings on the role of the meadow spittlebug as vector
of the fastidious bacterium within the first reported European bacterium outbreak in Apulia (South Italy) will be discussed
Analysis of vector behavior as a tool to predict xylella fastidiosa patterns of spread
Full text linkThe most likely scenarios for Xylella fastidiosa introduction in Central Europe is through infected ornamental plants, with a successive spillover from gardens and parks to cultivated orchards. Given its polyphagy and wide distribu-tion, the meadow spittlebug Philaenus spumarius, the only ascertained vector of X. fastidiosa in Europe so far, might play an important role in such a scenario. Here, we combined and analyzed spittlebug’s behavioral data obtained through Electrical Penetration Graph (EPG), preference and survival tests as well as field surveys, in order to infer possible bacterium patterns of spread. For our case study, we selected oleander and rosemary as potential introductory hosts and grapevine and cherry as economically important threatened plants. Philaenus spumarius was collected in field near all the four plant species, although choice and no-choice tests indicated that the spittlebug rather prefers to settle on cherry and grapevine than on rosemary and oleander. Considering the results of the EPG, the duration of xylem sap ingestion was longer in cherry, grapevine and rosemary than in oleander. However, P. spumarius spent on rosemary most of the time in resting activities, this implying a lower duration of xylem sap ingestion compared to grapevine and cherry. Overall, our data suggest that cultivated plants as grapevine and cherry could be more relevant than oleander and rosemary as X. fastidiosa source plants; therefore, P. spumarius might acquire the bacterium from cultivated plants, then first spread it within cultivated orchards, and successively to ornamental plants during its dispersal
Transmission of Xylella fastidiosa to Grapevine by the Meadow Spittlebug
Full text linkThere is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the aphrophorid Philaenus spumarius as a vector to estimate the effect of plant access time on X. fastidiosa transmission to plants; in addition, bacterial population estimates in the heads of vectors were determined and correlated with plant infection status. Results show that transmission efficiency of X. fastidiosa by P. spumarius increased with plant access time, similarly to insect vectors in another family (Hemiptera, Cicadellidae). Furthermore, a positive correlation between pathogen populations in P. spumarius and transmission to plants was observed. Bacterial populations in insects were one to two orders of magnitude lower than those observed in leafhopper vectors, and population size peaked within 3 days of plant access period. These results suggest that P. spumarius has either a limited number of sites in the foregut that may be colonized, or that fluid dynamics in the mouthparts of these insects is different from that in leafhoppers. Altogether our results indicate that X. fastidiosa transmission by spittlebugs is similar to that by leafhoppers. In addition, the relationship between cell numbers in vectors and plant infection may have under-appreciated consequences to pathogen spread
Feeding behavior in relation to spittlebug transmission of Xylella fastidiosa
Full text linkHere, we provide the first insights into the transmission dynamics of the bacterium Xylella fastidiosa by the meadow spittlebug
Philaenus spumarius, gathered through DC EPG (electrical penetration graph)-assisted transmission tests and comparative
observations of the probing and feeding behavior of infective versus non-infective vectors on healthy olive plants.
Bacterial cells binding to P. spumarius’ foregut occurred at a very low rate and in a time as short as 15 min spent by the
insect in xylem ingestion or activities interspersed with xylem ingestion (interruption during xylem ingestion and resting).
P. spumarius inoculation of bacterial cells into the xylem was exclusively associated with an early (ca. 2 to 7 min after the
onset of the first probe) and occasional behavior, provisionally termed waveform Xe, presumably related to egestion regulated
by pre-cibarial valve fluttering. Infective spittlebugs compared to non-infective ones exhibited: (i) longer non-probing
and shorter xylem ingestion; (ii) longer duration of single non-probing events; (iii) fewer sustained ingestions (ingestion
longer than 10 min) and interruptions of xylem activity (N); and (iv) longer time required to perform the first probe. These
observations suggest difficulties in feeding of infective P. spumarius probably caused by the presence of X. fastidiosa within
the foregut. Overall, our data indicate that likely short time—few minutes—is required for X. fastidiosa transmission by
P. spumarius; thus, vector control strategies should aim at preventing spittlebug access to the host plant. Furthermore, our
findings represent an important contribution for further research on the disruption of spittlebug–bacterium interactions
No evidence for cicadas’ implication in Xylella fastidiosa epidemiology
Full text linkCicadas are prominent insects in the Mediterranean basin environments, including in olive orchards. The bacte- rium Xylella fastidiosa is a xylem-limited vector-borne plant pathogen that was introduced into southern Italy, causing significant losses of olive trees. Cicadas are xylem-sap feeders and potential vectors of X. fastidiosa; however, knowledge of their role in the transmission of this bacterium is limited. We carried out two separate experiments: the first in California (USA), where we verified the capability of Platypedia minor to transmit X. fastidiosa from infected to healthy grapevines; the second in Apulia (South Italy), where we evaluated if Cicada orni collected on infected olive plants were able to trans- mit the bacterium to healthy olives. In California, transmission was not achieved for the 19 grapevines caged each with a group of two to three P. minor; moreover, none of the 19 insects (out of the 47 used for the transmission test) tested by culturing resulted positive for X. fastidiosa. In Italy, none of the olive recipient plants either caged with groups of three C. orni individuals per plant confined in sleeve cages (55 plants) or placed inside a mesocosm with cicadas free to move among the recipient plants (30 plants), were infected with the bacterium. Moreover, out of the 314 field collected C. orni tested by qPCR, only 4 (1.27%) were positive for the bacterium. Our data suggest that the cicada species we tested likely have no or a negligible role in the natural spread of X. fastidiosa
Exploring the role of vibrational cues in a parasitoid-host interaction
No full textThe green peach aphid, Myzus persicae Sulzer (Aphididae, Hemiptera), is a major agricultural pest worldwide, and an efficient vector of several plant viruses, whose control still majorly relies on pesticides. However, the need to reduce pesticide use, given their side effects on non-target organisms and human health, and their inefficacy for containing the spread of aphid-borne viruses, call for research on alternative tools for pest control, such as biological control. Aphidius colemani Viereck (Braconidae, Hymenoptera) is a parasitoid that is commonly used as a biological control agent of M. persicae, but little is known about the behavioral interaction with its host.
The potentiality of Biotremology for pest control has already been highlighted by several studies. However, the role of substrate-borne vibrations in inter- and intra-specific communication in some insect taxa, including aphids and parasitoids, has never been addressed, and further studies may pave the way for the sustainable control of species currently representing major threats for food safety and security.
Therefore, the aim of this study is to characterize the role of substrate-borne vibrations in: i) the inter-specific communication between M. persicae and its parasitoid A. colemani; ii) the intra-specific communication between an “attacked” aphid and its conspecifics. Thereafter, the impact of previously recorded vibrational cues or signals on the aphid feeding behavior will be assessed using the Electrical Penetration Graph (EPG) technique, with a particular focus on the patterns conducive to viruses’ acquisition and inoculation.
Two are the major outcomes expected from the present study: i) insights into the role of substrate-borne vibrations in aphids intra-specific communication and parasitoid foraging behavior; ii) a proof of concept of the applicability of semiophysicals as an alternative to pesticides for aphids and aphid-borne viruses control
Behavioral effects induced by organic insecticides can be exploited for a sustainable control of the Orange Spiny Whitefly Aleurocanthus spiniferus
Full text linkThe Orange Spiny Whitefly (OSW) Aleurocanthus spiniferus (Hemiptera: Aleyrodidae) represents a new serious threat to Citrus spp., grapevine and ornamental plants in the whole Mediterranean area. Such threat urgently calls for the development of a sustainable control strategy, including insecticides compatible with biological control, and applicable also in organic citrus farming that represent an essential part of Mediterranean agricultural economy. Therefore, we evaluated the toxicity and the effects on host searching, oviposition, and probing and feeding behavior exerted on OSW by organic insecticides supposed to have limited side effects on environment and ecosystem services, i.e. sweet orange essential oil (EO), extract of Clitoria ternatea (CT), mineral oil, pyrethrin and azadirachtin. Despite none of the compounds caused a significant mortality of any of the OSW instars, we observed interesting effects on whitefly behavior: (i) EO and pyrethrin showed a relevant repellent effect, with impairment of both adults landing and oviposition on treated plants; (ii) CT and pyrethrin strongly affected probing behavior. Here, in the light of our findings, we discuss possible OSW sustainable control strategies and further research perspectives
assisted comparison of European spittlebugs and sharpshooters feeding behaviour on grapevine
Full text linkXylem-feeding is apparently the only requirement making an insect a competent vector of the bacterium Xylella fastidiosa, an organism responsible for the devastation of the Southern Italian olive forest and nowadays considered one of the most feared threats to agriculture and landscape in Europe, including vineyards. Here, we used the direct current-electrical penetration graph (DC-EPG) technique to compare and describe the feeding behaviour on grapevine of four xylem-feeding species considered candidate vectors of X. fastidiosa widespread in Europe, namely two spittlebugs (the meadow spittlebug Philaenus spumarius and the spittlebug Neophilaenus campestris) and two sharpshooter leafhoppers (the rhododendron leafhopper Graphocephala fennahi and the green leafhopper Cicadella viridis). We created a standard for the analysis of EPG waveforms recorded with a DC-EPG device, describing feeding activities performed by these insects from stylet insertion into the plant to withdrawal. This standard, along with freely available software, has been developed to harmonize the calculation of feeding behavioural parameters in xylem-feeders. The most relevant differences between the two vector taxa were the probing frequency and the dynamics of xylem ingestion. Sharpshooters tended to perform significantly more probes than spittlebugs. In contrast, the latter spent longer times in low-frequency xylem ingestion, characterized by scattered contractions of the cibarial dilator muscle interspersed with periods of pump inactivity. Cicadella viridis was the species displaying the highest frequency of the electrical pattern found to be associated with X. fastidiosa inoculation in spittlebugs (Xe). Feeding behavioural data presented here represent an important step forward for deepening our knowledge of xylem-sap feeding insects' interaction with both the host plants and the bacterium they transmit
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