Potent Attractant for Root-Knot Nematodes in Exudates from Seedling Root Tips of Two Host Species.

Root-knot nematodes (RKN; Meloidogyne spp.) can parasitize over 2,000 plant species and are generally considered to be the most agriculturally damaging group of plant-parasitic nematodes worldwide. Infective juveniles (J2) are non-feeding and must locate and invade a host before their reserves are depleted. However, what attracts J2 to appropriate root entry sites is not known. An aim of this research is to identify semiochemicals that attract RKN to roots. J2 of the three RKN species tested are highly attracted to root tips of both tomato and Medicago truncatula. For both hosts, mutants defective in ethylene signaling were found to be more attractive than those of wild type. We determined that cell-free exudates collected from tomato and M. truncatula seedling root tips were highly attractive to M. javanica J2. Using a pluronic gel-based microassay to monitor chemical fractionation, we determined that for both plant species the active component fractionated similarly and had a mass of ~400 based on size-exclusion chromatography. This characterization is a first step toward identification of a potent and specific attractant from host roots that attracts RKN. Such a compound is potentially a valuable tool for developing novel and safe control strategies

The identification, pathotype, distribution of golden potato cyst nematode (globodera rostochiensis) and status of pale potato cyst nematode (globodera pallida) in lithuanian agroecosystems

Golden (Globodera rostochiensis) and pale (Globodera pallida) potato cyst nematodes are quarantine organisms. Potatoes are by far the most important host crop. Other Solanum spp. and their hybrids can also act as hosts. The aim of this study was to identify G. rostochiensis, G. rostochiensis pathotypes and distribution and also G. pallida status in soil samples from different field of different size and various forecrops in Lithuanian counties. Only G. rostochiensis was present in Lithuania after morphological identification and DNA polymerase chain reaction (PCR) which has been done in Lithuania for the first time. In small field areas up to 5 ha G. rostochiensis is more distributed than in bigger areas up to 30 ha. The presence of host plants in various forecrops, soil type – sands and sandy loams, also have influence on numerous distribution of G. rostochiensis. The experiment of G. rostochiensis pathotypes showed that only Ro1 pathotype is present in Lithuania

Globodera spp. monitoringas Lietuvoje taikant morfometrinę analizę ir polimerazinės grandininės reakcijos metodą

A total of 11,406 soil samples from 2,742 ha were collected in 10 administrative regions of Lithuania during the year 2006. A total of 672 cysts were selected and species were morphologically identified as Globodera rostochiensis. Of these cysts, 117 from 5 administrative regions of Lithuania were identified using polymerase chain reaction (PCR) analysis. Two pairs of species-specific primers were used to distinguish G. rostochiensis from G. pallida. This is the first application of a PCR method for identification of Globodera species in Lithuania

Potent Attractant for Root-Knot Nematodes in Exudates from Seedling Root Tips of Two Host Species.

Root-knot nematodes (RKN; Meloidogyne spp.) can parasitize over 2,000 plant species and are generally considered to be the most agriculturally damaging group of plant-parasitic nematodes worldwide. Infective juveniles (J2) are non-feeding and must locate and invade a host before their reserves are depleted. However, what attracts J2 to appropriate root entry sites is not known. An aim of this research is to identify semiochemicals that attract RKN to roots. J2 of the three RKN species tested are highly attracted to root tips of both tomato and Medicago truncatula. For both hosts, mutants defective in ethylene signaling were found to be more attractive than those of wild type. We determined that cell-free exudates collected from tomato and M. truncatula seedling root tips were highly attractive to M. javanica J2. Using a pluronic gel-based microassay to monitor chemical fractionation, we determined that for both plant species the active component fractionated similarly and had a mass of ~400 based on size-exclusion chromatography. This characterization is a first step toward identification of a potent and specific attractant from host roots that attracts RKN. Such a compound is potentially a valuable tool for developing novel and safe control strategies

Electroantennographic and behavioural responses of European cherry fruit fly, Rhagoletis cerasi, to the volatile organic compounds from sour cherry, Prunus cerasus, fruit

European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is the most important pest of sweet and sour cherry fruit. This fly is difficult to control by insecticide application since most of the conventional insecticides used have been banned in Europe. Traps are used for both the pest’s mass trapping and the detection of the beginning of the flight period. Data on flies’ reactions to host-plant volatile organic compounds (VOCs) can be used to search for new attractants. VOCs were collected from the headspace of sour cherry, P. cerasus, fruit. Gas chromatography–mass spectrometry (GC–MS) resulted in the identification of 51 compounds. Terpenes and esters predominated in two aspects: in the highest diversity of the compounds, and the amount of the total VOC emissions (62.3%). Among the single VOCs, ethyl octanoate prevails, followed by (E)-4,8-dimethyl-1,3,7-nonatriene. GC–electroantennographic detection (GC–EAD) revealed 14 EAG-active compounds and those were identified. In Y-tube olfactometer tests, EAG-active compounds ((E)-β-ocimene, linalool, and (Z)-3-hexenyl 3-methylbutanoate) attracted R. cerasi females in a similar way to the odour of sour cherry fruit