European cherry fruit fly (Rhagoletis cerasi) is the most important pest of sweet cherries (Prunus avium) in Europe. It is a univoltine oligophagous species (Wiesmann, 1933) that attacks also sour cherry (Prunus cerasus) and mahaleb cherry (Prunus mahaleb). It overwinters in a cocoon buried in soil at depth 2-5 cm. Its life cycle is closely adapted to the phenology of host plants. Adults emerge in spring but a portion of the population remains in diapause for 2 or 3 years to prevent population extinction in case of failure of host plants to fruit. After emergence, adults feed on carbohydrates, proteins and water, usually on cherry plants, and maturation to development of gonads is temperature dependent. After mating, females insert a single egg by means of an ovipositor under the skin of young fruit. In order to avoid multiple oviposition within the same fruit and larval competition, during oviposition the female leaves a water soluble pheromone recognised by other females (Katsoyannos, 1975). After embryonic development, freshly hatched larva move to the cherry pit. During the development, the larvae tunnel fruit and feed on fruit tissue. The larvae mature around harvest, and exit through a hole in the fruit skin to pupate in the soil (Daniel and Grunder, 2012).
Plum sawflies are among the most damaging pests of European plum. Current control strategy implies insecticide application. Three species of entomopathogenic nematodes (EPN), Steinernema feltiae Filipjev, S. carpocapsae Weiser and Heterorhabditis bacteriophora Poinar were tested under laboratory and field conditions to assess effectiveness against larval and adult stages. Laboratory tests resulted in up to 100% mortality of last instar larvae before construction of a cocoon. However, the nematodes were not able to penetrate the cocoon. Foliar application did not result in plum sawflies larvae infestation by EPNs. Under field conditions, the nematodes reduced the number of emerging adults by application against sawfly larvae in the previous year before migration into the soil for overwintering by 62%–92%. Application of the nematodes against adults just before their anticipated emergence resulted in reduction of fruit infestation up to 100%. Mean results of 5 trials using caged trees were 47.8% with S. feltiae, 56.3% with S. carpocapsae and 62.9% with H. bacteriophora. In open field trails, control of adults obtained with S. feltiae at 0.5 million nematodes/m2 was 98.2 and 67.8% and at 0.25 million m−2 41.7 and 41.2%. Forecasting adult emergence and optimal soil moisture conditions are essential for success of the nematode application.
Potato cyst nematodes (PCN), the golden cyst nematode Globodera rostochiensis (Woll.) Bahrens, and the pale potato cyst nematode G. pallida (Stone) stand out by their remarkable and efficient parasitic adaptations causing high economic losses in potato production worldwide. They are A2 quarantine pests in EPPO countries as well as in Bosnia and Herzegovina. Up to now, only G. rostochiensis was reported from Bosnia and Herzegovina in 2011 (1). A systematic survey on the presence of PCN on entire territory of Bosnia and Herzegovina started in 2011. During the PCN survey, each year 120 soil samples of 1.5 liters were collected in the Republic of Srpska, one of the two entities of Bosnia and Herzegovina. The samples were collected by soil auger 10 cm in length with a diameter of 1.5 cm consisting of 100 cores. Entire samples were processed by Seinhorst elutriator (4). In autumn of 2012, PCN viable cysts were found in two soil samples originating from one field. From one sample, 12 cysts were extracted, and 2 from another sample. The morphology of cysts and second stage juveniles and molecular analysis established the identity of this species as pale cyst nematode G. pallida (3). In addition, the sequencing of the ribosomal DNA region revealed unequivocal similarity to G. pallida (GenBank Accession No. HF968449), while PCR-RFLP analysis (2) showed European type of G. pallida. The infested field is located in Rogatica, 70 km east of Sarajevo, which is one of the main seed and potato production areas in Bosnia and Herzegovina. The field history revealed that farm-propagated, farm-saved seed potatoes could spread the nematodes to other fields as well. Therefore, 26 additional samples were taken from the fields that belong to the infested field owner and the surrounding fields, but no cysts were found in additional samples. To determine infestation focus and its size, the infested field (1.1 ha) was divided into 46 plots (25 × 10 m) and resampled by taking samples of 60 cores per plot. The detailed sampling of the field revealed a high infestation of 1 cyst per gram of soil in the infestation focus. The high infestation level and the propagation of farm-own seed potatoes suggest that the introduction of G. pallida might have occurred several years ago, probably with imported seed potatoes. The infested field was subjected to the phytosanitary measure of banning potato production for a period of 6 years with the possibility of its prolongation, if cysts with live content are found afterward. It is expected that the nematode is present in other fields due to the farmer's practices of propagating farm-saved seed potatoes and deficient field machinery hygiene. Therefore, the whole area will be intensively monitored for the presence of PCN in the future. An adequate pest management plan will be prepared after PCN pathotype identification. To our knowledge, only one field was found infested with G. pallida during the 3-year PCN survey in Bosnia and Herzegovina. Strict phytosanitary measures for preventing further PCN introductions and spreading should be intensified. References: (1) I. Ostojić et al. Plant Dis. 95:883, 2011. (2) S. Širca et al. Phytopathol. Mediterr. 49:361, 2010. (3) A. M. Skantar et al. J. Nematol. 39:133, 2007. (4) J. van Bezooijen. Methods and Techniques for Nematology, Wageningen University, 2006.
Ophraella communa, a potential biological control agent for Ambrosia artemisiifolia (common ragweed), was recorded from Bosnia and Herzegovina in 2020 for the first time. In the present paper, we report its occurence in other localities in the country.The species was found on A. artemisiifolia, an important invasive alien plant species that causes human health issues and negative impacts on crop yields. All stages of the insect were found in four locations in the northern part of the country where ragweed is highly invasive. A high level of damage on leaves indicates that it has already been established in the area for some time. According to the literature, O. communa might have two generations per year in Bosnia and Herzegovina and relative humidity might play a major role in population development.
Virulence of commercial strains of entomopathogenic nematode (EPN) Steinernema carpocapsae (Weiser), Steinernema feltiae Filipjev and Heterorhabditis bacteriophora Poinar (Rhabditida: Steinernematidae, Heterorhabditidae), were tested on young females of Pulvinaria hydrangeae Steinweden, Partenolecanium corni (Bouché) and Coccus pseudomagnoliarum (Kuwana) (Hemiptera, Coccidae) and a native strain of H. bacteriophora was tested on citricola scale, C. pseudomagnoliarum. The laboratory tests were carried out in small plastic Petri dishes with infective juveniles (IJ) applied on filter paper covering the bottom. Results showed that all EPN tested were virulent to all three soft scale insect species. Recorded mortality of insects at the highest concentration of approximately 50 IJ per cm2 exceeded 64% in all combinations of nematode and scale species tested. Within the same nematode concentration, scales’ mortality of 90% and above was recorded for P. corni with all nematode species, P. hydrangeae with S. carpocapsae (Nemastar) and C. pseudomagnoliarum with native H. bacteriophora strain. All scale species were good hosts for all nematode species. This is the first report of EPNs to parasitize soft scale insects and one of the few among Coccoidea. The level of parasitism recorded is promising for potential use in management of scale insects.
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