Two-year (2014-2015) study aimed to determine the effectiveness of entomopathogenic nematode (EPN) Heterorhabditis bacteriophora Poinar, 1976 (Nematoda: Heterorhabditidae) infective juveniles (IJs) ...on sugar beet weevil (Bothynoderes punctiventris Germar, 1824 (Coleoptera: Curculionidae)) larvae and to assess its potential for use in practice. In field experiments, three doses of nematodes were used and an untreated control. In the conditions of moderate larval attack (average infestation of 0.28 larvae per plant), EPNs showed clear dose response being highly effective (92.86% control) when applied in the highest dose. Although the results indicated that H. bacteriophora could have a satisfactory mortality effect on sugar beet weevil larvae, further investigations are needed in order to better determine the optimal dose and application timing. If effective, EPNs could be used as one of the tools in a strategy which aims to reduce sugar beet weevil population levels in a wider area.
The abundance of ground beetles (Coleoptera, Carabidae) in oilseed rape field can be an important indicator of different agricultural measures in arable land fauna. Surveys about ground beetle fauna ...in Croatia are generally very scarce and only few research on oilseed rape were conducted. The aim of this study was to determine the endogaeic ground beetle fauna in oilseed rape field and to determine species abundance and frequency. The study was carried out in Podravina region of Croatia, from the end of May till the mid-September in 2015. Ground beetles were collected using endogaeic traps incorporated in the soil. Altogether, 487 individuals classified into 8 species were collected. Species with the highest abundance and frequency was Brachinus (Brachinus) psophia Audinet-Serville, 1821, which was classified as eudominant and constant species. The highest ground beetle abundance was observed in summer period. All of the species found were spring breeders, except for species Trechus (Trechus) quadristriatus (Schrank, 1781) which breeds in autumn.
Beet nematode is one of the most harmful pests of sugar beet. It was found on 194 ha in the Tovarnik area 37 years ago. As this is the sugar beet intensive production area, the aim of this study was ...to determine the present-day distribution of this pest. Sampling of 1159.49 ha of sugar beet fields and collecting of 692 soil samples were conducted in the period 2012-2014. Soil samples were processed using Spears flotation devices, cysts were identified according to morphological characteristics and population density was determined by crushing cysts in Huysman’s homogenizer. Population density was expressed by g of soil and used to determine the appropriate control measures. H. schachtii was found in 34.54% of the samples and 40% of sampled fields. Total infested area is 867.21 ha being evidence of conservation, but also significant expansion of H. schachtii in the Tovarnik area. Population density ranged from 0.06 to 20.72/ g of soil. By determining the population density and taking appropriate control measures, such as regular crop rotation, weed control, sowing of trap crops and tolerant varieties of sugar beet, increase of pest populations and allow long-term production of sugar beet can be prevented.
The study of the production values of 10 sugar beet hybrids was conducted on chernozem soil type in Eastern Croatia (Tovarniklocation). The used treatments with and without fungicides application ...were investigated in 2013 and 2014. Sugar beet hybrids used in the study originate from three market-leading sugar beet seed companies in Croatia, whose varieties provide disease tolerance to C. beticola. The years of the study were quite warm with higher mean monthly air temperature (°C) and increased amount of rainfall, as compared to the long-term mean. In the second year of the study, due to increased amount of rainfall (mm) in July and August, as well as the total loss ofstrobilurin efficiency and low effectiveness ofthe cyproconazole treatment, the destruction ofthe leaves by C. beticola Sacc. was significantly higher. The results of the study showed a huge coherence of sugar beet yield and quality with leaf conservation through the vegetation (the number of treatment), and with the hybrids. Due to leaves destruction on control treatments, as compared to fungicide application three times, the sugar beet root yield was reduced on the average by 9.79 t ha'1 (10.03%), sugar content by 0.69% (rel. 4.89%) and sugar yield by 2.041 ha1 (17.04%). On the other hand, three fungicide applications increased the root yield by 4.881 ha1 (5.26%), sugar content by 0.52% and sugar yield by 0.99 t ha1 (9.01%) as compared to one fungicide application. All sugar beet hybrids of the study were strongly negatively affected the control treatment, indicating repeated fungicide application against C. beticola as a regular agricultural practices. On the average, for all variations of fungicides applications, the sugar beet hybrid Jadranka had significantly higher root yield in comparison with other hybrids included in the study. Moreover, the highest sugar content achieved Sandor, Marianka and Kundera. Significantly higher sugar yield had a hybrid Jadranka.
The most damaging Noctuidae pests in sugar beets in Croatia are classified into two groups based on the injuries that their larvae produce: the cutting species (Agrotis ipsilon and Agrotis segetum) ...and the surface‐feeding species (Mamestra brassicae, Lacanobia oleracea and Autographa gamma). The flight activity of male moths was detected and monitored using traps baited with sex pheromone. The study aimed to determine the population dynamics of noctuid pests in sugar beet crops and to propose damage forecasts and thresholds based on male moths capture in pheromone traps in specific weather conditions. A strong positive correlation between captured male moths in pheromone traps and the level of damage to sugar beet crops was established. The population densities were extremely affected by the weather conditions that prevailed in the sugar beet growing period. If the weather conditions are not optimal, the population of the second generation of moths and larvae will be smaller, and the level of damage to plants will decrease accordingly. Thus, intensive monitoring of noctuid male moth flights and weather conditions in the sugar beet growing season enabled forecasting of future damage to a larger area, although visual inspections are necessary to plan insecticide applications.
Colorado potato beetle (CPB) is the most notorious and problematic insect defoliator pest of potato. It is well known for its ability to develop resistance to chemical insecticides, so novel ...treatment methods must be developed. A possible solution is the application of newer groups of insecticides (biotechnical and biological insecticides) which are more selective and to which resistance has not yet been recorded. This work investigated the use of ecologically acceptable insecticide treatments: azadirachtin, spinosad and spinetoram, and their combinations against CPB larvae in laboratory and field conditions. Reduced dosing and combinational treatments were used to determine if effective protection against CPB could be achieved while also improving economic results. Our results from laboratory trials showed that combinations of low-dose azadirachtin (25%) and low-dose spinetoram (5%) are suitable for use in CPB integrated pest management. The results of the field trial showed that the use of 50% reduced dosage of spinosad and spinetoram resulted in high efficacy (89–99%) and can be recommended as a treatment method that provides effective control of CPB, improved economic results, and a positive environmental impact. Based on the advantages that these treatments offer compared to chemical insecticides, further work is recommended to determine if these combinational treatments used in other dosages or in combinations with some other ecologically acceptable insecticides can provide satisfactory control of CPB.
Colorado potato beetle (CPB) is an economic pest of potato that has developed resistance to all classes of chemical insecticides, thus requiring alternative control measures. As a potential solution, ...entomopathogenic nematodes (EPNs) have proven effective in suppressing this pest, but their efficacy against overwintering generations of CPB in Croatia has not been sufficiently researched. The aim of this two-year (2018-2019) field study was to determine the efficacy of
and
applied to overwintering CPB adults. EPNs were applied at three doses (7.5 mil./10 m
, 5.0 mil./10 m
(the recommended dose) and 2.5 mil./10 m
) by watering the soil where the adults were overwintering. The first-year results were satisfactory for both EPNs: the efficacy of
ranged from 79.03% to 100.00%, while the efficacy of
ranged from 77.32% to 96.22%. In the second year, the highest efficacy (69.57%) was obtained using the recommended dose of
. Although the results are not consistent across the two years of our study and suggest further research, they indicate that EPNs have great potential in controlling overwintering CPB generations to reduce first generation abundance and damage, and also to prevent the spread of new generations to surrounding potato growing areas.
Overwintering success and weather conditions are the key factors determining the abundance and intensity of the attack of the first generation of European corn borers (ECB). The tolerance of maize to ...the 1st generation of ECB infestation is often considered to be connected with the maize maturity time. The aims of this research were (I) to examine the reactions of different maize FAO maturity groups in term of the damage caused by ECB larvae, (II) to analyze the influence of four climatic regions of Croatia regarding the damage caused by ECB larvae, and (III) to correlate observed damage between FAO maturity groups and weather conditions. First ECB generation damage has been studied in the two-year field trial with 32 different hybrids divided into four FAO maturity groups (eight per group) located at four locations with different climatic conditions. The results showed a lack of correlation between the FAO maturity group and the percent of damage. The percent of damage was positively correlated with the average air temperature in June (r = 0.59 for 2017 and r = 0.74 in 2018, p = 0.0001) within the range from 20 to 24.5 °C and was negatively correlated with the relative air humidity (r = −0.58 in 2017 and r = −0.77 in 2018, p = 0.0001) within the range of 50% to 80%. Our results provide a better understanding of the different factors that influence ECB damage. The obtained data could be used to predict the damage from the first generation of ECB under the weather conditions of different regions.
The codling moth (CM) (Cydia pomonella L.) is the most important apple pest in Croatia and Europe. Owing to its economic importance, it is a highly controlled species and the intense selection ...pressure the species is under has likely caused it to change its phenotype in response. Intensive application of chemical-based insecticide treatments for the control of CM has led to resistance development. In this study, the forewing morphologies of 294 CM (11 populations) were investigated using geometric morphometric procedures based on the venation patterns of 18 landmarks. Finite element method (FEM) was also used to further investigate the dispersal capabilities of moths by modelling wing deformation versus wind speed. Three treatments were investigated and comprised populations from integrated and ecological (susceptible) orchards and laboratory-reared non-resistant populations. Forewing shape differences were found among the three treatment populations investigated. Across all three population treatments, the movement of landmarks 1, 7, 8, 9, and 12 drove the wing shape differences found. A reliable pattern of differences in forewing shape as related to control practice type was observed. FEM revealed that as wind speed (m/s−1) increased, so too did wing deformation (mm) for CM from each of the three treatments modelled. CM from the ecological orchards displayed the least deformation followed by integrated then laboratory-reared CM, which had the highest wing deformation at the highest wind speeds. This study presents an affordable and accessible technique that reliably demonstrates wing shape differences, and thus its use as a population biomarker to detect resistance should be further investigated.
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