Insecticidal effect of deltamethrin, dinotefuran and spiromesifen against the sugarcane whitefly Neomaskellia andropogonis on CP69-1062 sugarcane cultivar

SummaryThe sugarcane whitefly, Neomaskellia andropogonis Corbett (Homoptera: Aleyrodidae), is one of the important pests of sugarcane in Iran. The use of selective chemical insecticides helps to suppress whitefly infestations. Although several insecticides from various groups have been registered to control whiteflies, this is the first study to test the efficacy of deltamethrin, dinotefuran and spiromesifen insecticides against eggs, second instar nymphs and pupae of the sugarcane whitefly on CP69-1062 sugarcane cultivar. Five concentrations of the tested insecticides were applied in a leaf dipping bioassay under laboratory conditions. Probit analysis indicated that deltamethrin and dinotefuran with LC50 values of 50.1 and 49.5 ppm were the most toxic insecticides against eggs of N. andropogonis. Deltamethrin controlled nymphal and pupal stages more effective than the other two tested insecticides and the LC50 values were 49.7 and 5.44 ppm on nymphs and pupae, respectively. The LC50 values of dinotefuran on second instar nymphs and pupae were 564.7 and 78.7 ppm and the values were 270.9 and 18.3 ppm for spiromesifen, respectively. The results support the use of the insecticides in rotation according to their different mode of action in integrated pest management programs of the sugarcane whitefly N. andropogonis.

Tomato bacterial endophytes in controlling Verticillium wilt and their advantage on biostimulation

SummaryA total of 688 bacterial endophytes were isolated from both greenhouse and field-grown tomatoes in the Tehran and Alborz provinces, Iran in order to obtain effective bacterial endophytes against the fungus Verticillium dahliae. 128 bacterial isolates, with respect to their different phenotypic characteristics were further analysed. All bacteria with positive hypersensitivity reaction on tobacco and geranium leaves and potato soft rot were eliminated, and totally 39 isolates were selected for in vitro antagonism and greenhouse tests. The potential biocontrol isolates were evaluated using seed treatment and soil drench methods on two tomato cultivars. The results indicated that seven bacterial isolates had a high potential for the control of the fungus and reduced the severity disease to 95-98%. This reduction was coincided with an increase in some growth factors like plant dry weight, root dry weight, plant height, root length, root fresh weight and plant fresh weight ranged between 92-98%. The seven antagonists’ preliminary identification was confirmed using 16SrRNA gene sequencing analysis. The BLAST analysis was performed, and the bacteria were also identified as Bacillus pumilus (two isolates), Bacillus subtilis, Bacillus safensis, Enterobacter ludwigi, Serratia marcesens and Pseudomonas beatica. Biocontrol mechanisms examination indicated that protease production was positive for all isolates and differentiated isolates E. ludwigii and P. beatica as higher producers with protease levels up to 65%. The three bacteriocins producing isolates inhibited the phytopathogenic mycelium up to 70% in dual culture assay. Also, five of the isolates produced siderophores and P. baetica, S. marcesens and E. ludwigii produced remarkable amount of auxin hormone.

Infections of bean plant and field soil are linked to region, root rot pathogen, and agro-ecosystem

SummaryUnderstanding pathogen-agrosystem interaction is particularly essential when applying a control method to minimize pathogen prevalence prior to plant infection. To meet this requirement, frequency of major root rot pathogens isolated from bean root and seed, and their soil populations were examined in farmers’ fields. Multivariate analyses evidenced more frequent isolations of Fusarium solani and Rhizoctonia solani from root and seed compared to Macrophomina phaseolina and Fusarium oxysporum. Two Fusarium species had denser soil populations than R. solani and M. phaseolina. More frequent isolations of pathogens were detected in root and seed collected from Abhar and Khodabandeh compared to Kheirabad region. Agronomic and soil variables corresponded less closely to root infections compared to soil infestation and seed infections. Bean market class, herbicide application, and planting depth were linked to root, seed and soil infestations. Such information provides a basis for increased confidence in choosing appropriate control strategies for a pathogen and region in sustainable agriculture.

The scale insect Coccus pseudomagnoliarum (Kuwana) (Hemiptera: Coccomorpha: Coccidae) on citrus in Greece

SummaryPhenology and parasitism of the scale insect, Coccus pseudomagnoliarum (Kuwana) (Hemiptera: Coccomorpha: Coccidae), infesting Citrus sinensis (Rutaceae), were studied in Papagou area, in northeastern Athens, from June 2015 to June 2017. Coccus pseudomagnoliarum is a univoltine, viviparous, parthenogenetic species. It overwintered as settled 1st instar nymph on the shoots of the trees. The 2nd instar nymphs appeared between the beginning of April and the end of May, and the mature females were recorded from the beginning of May until the middle of June. The crawlers appeared between the middle of May and the middle of June and the 1st instar nymphs settled on the shoots at the end of May, where they remained during the whole summer period, winter, until the beginning of April next year. Parasitism of the scale was recorded between the beginning of May and the middle of May and reached a maximum rate of 35%. The recorded parasitoid species were Coccophagus shillongensis Hayat and Singh (Hymenoptera: Aphelinidae), Coccophagus spp. and Metaphycus dispar (Mercet) (Hymenoptera: Encyrtidae).

Effect of rhizobacteria strains on the induction of resistance in barley genotypes against Cochliobolus sativus

SummaryEnhancement of the resistance level in plants by rhizobacteria has been proven in several pathosystems. This study investigated the ability of four rhizobacteria strains (Pseudomonas putida BTP1 and Bacillus subtilis Bs2500, Bs2504 and Bs2508) to promote the growth in three barley genotypes and protect them against Cochliobolus sativus. Our results demonstrated that all tested rhizobacteria strains had a protective effect on barley genotypes Arabi Abiad, Banteng and WI2291. However, P. putida BTP1 and B. subtilis Bs2508 strains were the most effective as they reduced disease incidence by 53 and 38% (mean effect), respectively. On the other hand, there were significant differences among the rhizobacteria-treated genotypes on plant growth parameters, such as wet weight, dry weight, plant height and number of leaves. Pseudomonas putida BTP1 strain was the most effective as it significantly increased plant growth by 15-32%. In addition, the susceptible genotypes Arabi Abiad and WI2291 were the most responsive to rhizobacteria. This means that these genotypes have a high potential for increase of their resistance against the pathogen and enhancement of plant growth after the application of rhizobacteria. Consequently, barley seed treatment with the tested rhizobacteria could be considered as an effective biocontrol method against C. sativus.

Effect of the endophytic plant growth promoting Enterobacter ludwigii EB4B on tomato growth

SummaryThis study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.

Lavandula angustifolia and Oxalis pes-caprae, hosts of Meloidogyne hapla and Meloidogyne javanica - A note for Meloidogyne luci in Greece

SummaryRoot-knot nematodes (RKN), Meloidogyne spp., have a wide host range and are common in the Mediterranean area. Cultivated lavender (Lavandula angustifolia) was found naturally infested by M. hapla in Kozani area, the first documented infestation of this crop by RKN in Greece. Oxalis pescaprae, a common winter weed in Crete, was found to be a host of M. javanica under artificial inoculation. This weed acts as a potential winter host of the nematode in fields cultivated with vegetable crops. Two populations of M. ethiopica were found in kiwi and maize in Greece in the past. Recently, populations of M. ethiopica from Europe were re-classified as M. luci, based only on the population isolated from kiwi for Greece. In the current work, the RKN populations originating from kiwi and maize and maintained on tomato, were identified as M. luci. Nematode species identification was determined by electrophoretic analysis of protein extracts obtained from females.

Effect of the olive fruit size on the parasitism rates of Bactocera oleae (Diptera: Tephritidae) by the figitid wasp Aganaspis daci (Hymenoptera: Figitidae), and first field releases of adult parasitoids in olive grove

SummaryThe olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is the major pest of olives worldwide. The figitid wasp, Aganaspis daci (Hymenoptera: Figitidae), is a larval-prepupal endoparasitoid of fruit fly species, and it was found to successfully parasitize medfly larvae in field-infested figs in Greece. To assess the potential of A. daci as a biological control agent against B. oleae, we studied the effect of olive fruit size on parasitism rates of A. daci on 2nd and 3rd instar larvae of B. oleae, by using fruit of different size (cultivar ‘Chalkidikis’) and wild olive fruit. In addition, we conducted releases of A. daci females in a pilot olive grove in Volos, Magnesia. From July to October, we released 200 A. daci females/0.1 ha/week, followed by olive fruit sampling to estimate olive fruit infestation levels and the parasitism rates of A. daci. Laboratory trials revealed that fruit size and larvae instar were predictors of parasitism success of A. daci, with parasitism rates higher for small-size fruit of the cultivar “Chalkidikis” and the 3rd instar larvae of B. oleae. In field trials, no A. daci adults emerged from the olive fly infested fruit.

Prototype Spatio-temporal Predictive System of pest development of the codling moth, Cydia pomonella, in Kazakhstan

SummaryA prototype for pest development stages forecasting is developed in Kazakhstan exploiting data from the geoinformation technologies and using codling moth as a model pest in apples. The basic methodology involved operational thermal map retrieving based on MODIS land surface temperature products and weather stations data, their recalculation into accumulated degree days maps and then into maps of the phases of the codling moth population dynamics. The validation of the predicted dates of the development stages according to the in-situ data gathered in the apple orchards showed a good predictivity of the forecast maps. Predictivity of the prototype can be improved by using daily satellite sensor datasets and their calibration with data received from a network of weather stations installed in the orchards.

A qualitative and quantitative comparison of mite fauna between bifenthrin-treated and non-pesticide treated alfalfa hay fields in Central Greece

SummaryThe mite fauna in foliage and litter of a sprayed alfalfa hay field with the acaricide-insecticide bifenthrin, was studied based on monthly samplings from foliage and litter in Central Greece between 2008–2009. Potential differentiations between this field and two adjacent alfalfa hay fields, which were not subjected to pesticide applications and were managed with different number of cuttings, were also evaluated in terms of population fluctuation over time, population density, species richness, diversity and spatial distribution. The sprayed field hosted 50 and 68 species and morphospecies in foliage and litter respectively, depicting high relative abundance of oribatid and prostigmatic mites. Neoseiulus aristotelisi Papadoulis, Emmanouel and Kapaxidi, was a new record for alfalfa, previously found in rice in Macedonia, Greece. The seasonal fluctuation of mites, particularly in foliage, was similar in all fields. The spatial distribution of a Zygoribatula species, which was common and dominant in all fields, was also aggregated. Finally, the sprayed field shared similar mite diversity with the two non-sprayed fields, but not similar species richness.