An Integrated System for the Automated Recording and Analysis of Insect Behavior in T-maze Arrays

Host-plant resistance to insects like thrips and aphids is a complex trait that is difficult to phenotype quickly and reliably. Here, we introduce novel hardware and software to facilitate insect choice assays and automate the acquisition and analysis of movement tracks. The hardware consists of an array of individual T-mazes allowing simultaneous release of up to 90 insect individuals from their individual cage below each T-maze with choice of two leaf disks under a video camera. Insect movement tracks are acquired with computer vision software (EthoVision) and analyzed with EthoAnalysis, a novel software package that allows for automated reporting of highly detailed behavior parameters and statistical analysis. To validate the benefits of the system we contrasted two Arabidopsis accessions that were previously analyzed for differential resistance to western flower thrips. Results of two trials with 40 T-mazes are reported and we show how we arrived at optimized settings for the different filters and statistics. The statistics are reported in terms of frequency, duration, distance and speed of behavior events, both as sum totals and event averages, and both for the total trial period and in time bins of 1 h. Also included are higher level analyses with subcategories like short-medium-long events and slow-medium-fast events. The time bins showed how some behavior elements are more descriptive of differences between the genotypes during the first hours, whereas others are constant or become more relevant at the end of an 8 h recording. The three overarching behavior categories, i.e., choice, movement, and halting, were automatically corrected for the percentage of time thrips were detected and 24 out of 38 statistics of behavior parameters differed by a factor 2–6 between the accessions. The analysis resulted in much larger contrasts in behavior traits than reported previously. Compared to leaf damage assays on whole plants or detached leaves that take a week or more to complete, results were obtained in 8 h, with more detail, fewer individuals and higher significance. The potential value of the new integrated system, named EntoLab, for discovery of genetic traits in plants and insects by high throughput screening of large populations is discussed

Evidence for pathotype mixtures on Solanum bulbocastanum in Meloidogyne chitwoodi but not in M. fallax

Variability for pathogenicity on seven Solanum bulbocastanum clones was studied in a collection of isolates of Meloidogyne chitwoodi and M. fallax from a wide range of geographical origins. Four different pathotypes could be distinguished within M. chitwoodi, while no specialisation was found in M. fallax. Meloidogyne chitwoodi isolates from the USA showed the largest variation; those from Europe belonged to one pathotype. In several M. chitwoodi isolates, the occurrence of pathotype mixtures was verified and for the first time reported in automictic Meloidogyne spp. The infrequently formed egg masses in incompatible isolate-plant genotype combinations were not able to reproduce further on various S. bulbocastanum genotypes, suggesting some stability aspects of the resistance. The occurrence of pathotypes and mixtures of pathotypes requires special attention in breeding programmes as well as in disease management

Transmission of escherichia coli from manure to root zones of field-grown lettuce and leek plants

Pathogenic Escherichia coli strains are responsible for food-borne disease outbreaks upon consumption of fresh vegetables and fruits. The aim of this study was to establish the transmission route of E. coli strain 0611, as proxy for human pathogenic E. coli, via manure, soil and plant root zones to the above-soil plant compartments. The ecological behavior of the introduced strain was established by making use of a combination of cultivation-based and molecular targeted and untargeted approaches. Strain 0611 CFUs and specific molecular targets were detected in the root zones of lettuce and leek plants, even up to 272 days after planting in the case of leek plants. However, no strain 0611 colonies were detected in leek leaves, and only in one occasion a single colony was found in lettuce leaves. Therefore, it was concluded that transmission of E. coli via manure is not the principal contamination route to the edible parts of both plant species grown under field conditions in this study. Strain 0611 was shown to accumulate in root zones of both species and metagenomic reads of this strain were retrieved from the lettuce rhizosphere soil metagenome library at a level of Log 4.11 CFU per g dry soil

Factors influencing Ralstonia pseudosolanacearum infection incidence and disease development in rose plants

Glasshouse experiments were conducted to study infection and disease development in rockwool-grown rose plants inoculated with Ralstonia pseudosolanacearum. A R. pseudosolanacearum strain isolated from rose plants was more aggressive than strains from anthurium or curcuma. The three rose cultivars tested, Avalanche, Red Naomi, and Armando, differed in susceptibility. At 20°C, the rose strain caused hardly any symptoms over a 6-week period, whereas at 28°C typical wilt symptoms were observed within 2 weeks after stem inoculation of Armando, the most susceptible cultivar. Inoculating roots with the rose strain resulted only in weak atypical symptoms. Nevertheless, inoculating roots of cv. Armando at a relatively low inoculum dose of 104 cfu/ml led to high densities in the base of stems in one out of two experiments. R. pseudosolanacearum occasionally spread from stem inoculated plants with symptoms in rockwool slabs. This limited spread resulted in a low infection incidence, and only of plants directly adjacent to the plants with symptoms

Mapping tracks of Xanthomonas campestris pv. campestris resulting in Brassica seed infections

In this report research is described, conducted by Wageningen Plant Research (Wageningen Universityand Research) in collaboration with the seed companies Bejo Zaden b.v., Syngenta Seeds b.v., ENZA Zaden Research and Development b.v. and Rijk Zwaan Zaadteelt and Zaadhandel b.v. within the frame of public private partnership project entitled ‘Routes van Xanthomonas campestris pv.campestris die resulteren in zaadinfecties in Brassica in kaart brengen’ (Mapping tracks ofXanthomonas campestris pv. campestris resulting in Brassica seed infections).The project in Netherlands was granted by the Topsector ‘Horticulture and propagation material’ of the Dutch Ministry of Economic Affairs. It was conducted under grant number KV1505 095