Aleksandro Stulginskio Universitetas

ALEKSANDRO STULGINSKIO UNIVERSITETAS

Povilas Mulerčikas

SPRAGŠIŲ (COLEOPTERA, ELATERIDAE) PAPLITIMAS SKIRTINGOSE AGROCENOZĖSE IR GAUSIAUSIŲ RŪŠIŲ ŽALINGUMAS MIGLINIAMS JAVAMS

Daktaro disertacijos santrauka Žemės ūkio mokslai (A 000), agronomija (01 A)

Akademija, 2013

Disertacija rengta 2008–2012 metais Aleksandro Stulginskio universitete.

Mokslinis vadovas: Doc. dr. Vytautas Tamutis (Aleksandro Stulginskio universitetas, žemės ūkio mokslai, agronomija – 01 A).

Disertacija ginama Aleksandro Stulginskio universitete Agronomijos mokslo krypties taryboje:

Pirmininkas: Prof. habil. dr. Zenonas Dabkevičius (Lietuvos agrarinių ir miškų mokslų centras, žemės ūkio mokslai, agronomija 01 A).

Tarybos nariai: Doc. dr. Aušra Marcinkevičienė (Aleksandro Stulginskio universitetas, žemės ūkio mokslai, agronomija 01 A). Dr. Jolanta Rimšaitė (Ekologijos institutas, Gamtos tyrimų centras, biomedicina, zoologija 05B). Prof. habil. dr. Rimantas Rakauskas (Vilniaus universitetas, biomedicina, zoologija 05B). Prof. dr. Kęstutis Romaneckas (Aleksandro Stulginskio universitetas, žemės ūkio mokslai, agronomija – 01 A)

Oponentai: Prof. habil. dr. Jonas Rimantas Stonis (Lietuvos edukologijos universitetas, biomedicina, zoologija 05B). Prof. dr. Vytautas Pilipavičius (Aleksandro Stulginskio universitetas, žemės ūkio mokslai, agronomija 01 A).

Disertacija bus ginama viešajame Agronomijos mokslo krypties tarybos posėdyje 2013 m. gruodžio 19 d., 14 val. Aleksandro Stulginskio universiteto IV rūmų posėdžių salėje (211 kab.), Adresas: Universiteto g. 8 A, Akademijos mstl., LT – 53361, Kauno r. tel.: (8–37) 752 254, faks.: (8-37) 397 500.

Daktaro disertacijos santrauka išsiuntinėta 2013 m. lapkričio 19 d.

Disertaciją galima peržiūrėti Aleksandro Stulginskio universiteto ir Lietuvos agrarinių miškų mokslų centro, Žemdirbystės instituto bibliotekose.

INTRODUCTION

Relevance of the topic. Species composition, distribution, habitat preference of click beetle detected in Lithuanian agrocenoses, their need for certain soil properties and as well as food ration has not been yet fully explored in Lithuania. Every year, farmers suffer huge losses in relation to damage caused by click beetle larvae. They injure germinating seeds of the variety of plants, seedlings, underground parts of the plants, tubers, and roots. Damaged seeds do not sprout up, seedlings perish, and crops become sparse. The trade value gets worse and fungal or bacterial infection pervades through the injuries into potato tubers or vegetables during the storage period and finally the stored production gets rotten. There is a lack of data concerning click beetle bioecology and harmfulness under Lithuanian environmental conditions. In order to increase the efficacy of plant protection measures against these pests it is necessary to establish prevalent click beetle species composition, to explore their bioecological characteristics and the level of harm in agrocenoses under Lithuanian agroclimatic conditions. On the other hand, not every click beetle species is herbivorous and makes damage. There are species which are recognized as predators. In this respect, they may be eligible as natural enemies of pests for an integrated pest management approach. Hypothesis of the research. Click beetle species composition, distribution and abundance should depend on granulometric structure of soil and on the state of agrocenosis as well. It is likely that the variety of click beetle species and the abundance of individuals are greater in agrocenoses with lighter granulometric structure of the soil and minimal tillage. Click beetle larvae are characterized as polyphagous. Thus larvae of all click beetle species should be equally destructive to cereals. Objective of the research – to determine composition, distribution, abundance dynamics of the click beetle species detected in Lithuanian agrocenoses, and harmfulness of the most abundant species for certain cereals. Tasks of the research. It was pursued by the research: 1. To determine in agrocenoses with different granulometric structure of the soil and different soil tillage: 1.1. Click beetle species composition and its alterations; 1.2. Abundance of click beetle individuals and its alterations; 1.3. Dynamics of the number of click beetle specimens during the growing period and in the process of succession; 2. To evaluate the harmfulness of the most common in agrocenoses click beetle species to maize, wheat and barley under laboratory conditions. Propositions to be defended: 1. Click beetle species composition depends on the soil granulometric structure and the state of agrocenosis has no significant effect. 2. Abundance of click beetle individuals depends on the soil granulometric structure and on the state of agrocenosis. 3. Duration of the activity period and dynamics of adult click beetles is more dependent on biological characteristics of the species than on the ambient air temperature.

4. Harmfulness of larvae of various click beetle species is different for maize, wheat and barley, and its intensity depends on the number of click beetle larvae in the substrate. Originality of the research work. For the first time under Lithuanian agroclimatic conditions, click beetle species composition that were detected in agrocenoses, their distribution, abundance and alterations have been established in agrocenoses with different state in loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)), sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)), hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)), and sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)). The harmfulness of click beetle species Agiotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus for maize, wheat and barley under laboratory conditions has been evaluated. Studies have demonstrated that Cidnopus aeruginosus injures all investigated plants, however their damage is two times fewer than caused by A. obscurus and S. aeneus larvae. Practical value of the research. Every year, due to the damage caused by click beetles farmers suffer huge losses. Conventional plant protection measures including chemicals are not effective enough due to specific click beetle larvae lifestyle. Pursuing better plant protection against these pests the necessity of the development of crop cultivation strategies considering bioecology of both the crop and click beetles injuring the crop. Results of the research which revealed that the composition of click beetle species and their abundance depend on soil type and agrocenosis state will enable more appropriate selection of composition of cultivated plant species in order to avoid yield losses. The peculiarities of the abundance dynamics of click beetle adults were clarified due to investigations which will enable more efficient application of chemical plant protection measures against these pests. The established harmfulness of the most common click beetle species in agrocenoses will launch a more accurate determination of the economic damage threshold for these pests. Approval of the research work. Three articles concerning topic of the dissertation have been published, and one among them is the publication, which is assessed in the database of the Institute for Scientific Information (ISI WOS) with a citation index. The other two articles have been published in journals which are refereed by the database of the Institute for Scientific Information (ISI Master Journal List). The results of the research have been presented at The Fifth International Scientific Conference “Research and Conservation of Biological Diversity in Baltic Region” (Latvia, Daugavpils, 2009) and at the Twenty-eighth Nordic-Baltic Congress of Entomology “XXVIII Nordic-Baltic Congress of Entomology” (Lithuania, Birštonas, 2010). The structure of the dissertation. The dissertation is written down in Lithuanian. The work consists of the following parts: introduction, literature review, research conditions and methods, results, conclusions, list of references on the topic and summary in English. The volume is - 121 pages, 8 tables, 31 figures, 365 references have been cited.

EXPERIMENTAL OBJECT, CONDITIONS AND METHODS

Experimental object – click beetles prevalent in agrocenoses in the Republic of Lithuania (Coleoptera, Elateridae). Experimental site and soil type. Investigations were carried out in 2009-2012 in Kaunas, Marijampolė and Druskininkai regions with four different types of soil in agrocenoses. Four stationary sites according to the granulometric structure of the soil were selected with four different soil types as follows: sandy soil (A1) (SDp-n Dystri- Haplic Arenosols (Arh-dy)), sandy loam soil (A2) (SDp-b Eutri- Haplic Arenosols (Arh-eu)), loamy soil (A3) (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)), hard loamy clay soil (A4) (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)) (Table 1).

Table 1. Soil characteristics of the research locations, 2009–2012 Coordinates Quantity of the mobile nutrients pH Soil type of the Nitrogen Potassium Phosphorus of

(by Buivydaitė et al., 2001) locations (N %) (K2O) (P2O5) the (WGS mg/kg mg/kg soil system) A1 (SDp-n Dystri- Haplic 54°53'46"N, 0.17 73.8 117.1 5.37 Arenosols (Arh-dy)) 23°29'02"E A2 (SDp-b Eutri- Haplic Arenosols 54°5'28"N 0.24 168.6 190.2 6.6 (Arh-eu)) 23°51'39"E A3 (Calc(ar)i- Epihypogleyic 54°53'06"N 0.21 86.4 46.7 6.65 Luvisol LV-g-p-w-cc (sc)) 23°50'15"E A4 (RDg-8-k2- Eudocaleari- 54°29'33"N 0.48 152.4 40.0 7.0 Epihypogleyic Cambisols (CMg-p- 23°44'31"E w-can))

The research was carried out in agrocenoses with four different statuses over each stationary site: 1. Intensively cultivated land - B1 (these were fields where all the tillage operations (deep ploughing, spring cultivation and harrowing, sowing and etc.) were applied before as well and during investigations as well; various gramineous cereals were cultivated in these fields during the research period); 2. Reclaimed pasture - B2 (these were fields where perennial grasslands were ploughed in autumn 2008, prior to performing the research and during the research period these fields have been cultivated in conventional way; various gramineous cereals were cultivated in these fields during the research period); 3. Perennial grasses - B3 (these were fields where arable land was until spring of 2008, when perennial grasses have been sown; during the research period these fields have been mowed regularly (1-2 times) and the animals were grazing; clovers and gramineous forage grasses dominated in these fields);

4. Seminatural meadow - B4 (these were fields with more than 20 years of growing perennial grasses; during the research period these fields have not been regularly mowed and grazed; gramineous grasses dominated in these fields). Laboratory investigations were carried out in 2010-2011 at Aleksandras Stulginskis University, Institute of Biology and Plant Biotechnology, Laboratory of Plant Protection methods.

Experimental methods

The research, observations, assessments and analyses were conducted by applying the following methods: Methods for investigation for the abundance and species composition of click beetle adults. Barber pitfall traps have been used for the collection of click beetles crawling on the soil surface (Фасулати, 1971; Burakowski, 1993, McEwen, 1997, Brunner et al., 2005; Tarnawski, Buchholz, 2000, 2008). 5 pitfall traps have been installed in each research site. Pitfall traps were set out randomly within 10 meters of each other. Distances from the edges of the field in all treatments were more than 10 meters. During the research period pitfall traps were active from the last decade of April to the last decade of September. Pitfall trap inspections were performed regularly every 2 weeks. During the inspection insects that entered into the trap were removed and placed in the special containers, which were recorded by the number of the trap, the title of the treatment and the date of the inspection. All collected click beetles species were identified by means of a binocular microscope “Nikon” and in accordance with the identification guides (Черепанов, 1965; Бобинская et al, 1965; Долин, 1978, 1982, Гурева 1979; Tarnawski, Buchholz, 2000, 2008). Species classification has been presented according to a catalogue of the Palearctic beetles (Cate, 2007). Methods for investigation for the abundance and species composition of click beetle larvae. Whereas click beetle larvae are soil dwelling, the method of soil sample analysis (squares) was used (Черепанов, 1965; Бобинская et al, 1965; Burakowski, 1993; Šurkus, Gaurilčikienė 2002, Brunner et al., 2005; Tarnawski, Buchholz, 2000, 2008). For this purpose, soil samples were collected, which consisted of a soil (30 cm in depth of soil surface layer) taken from 0.16 m2. 12 soil samples (6 in spring and 6 in autumn) were analysed in each treatment every year. Samples were collected randomly in various locations of investigated sites, though never closer than 10 meters to the edge of the field. Excavated soil sample was poured onto a dark colour sheet and thoroughly inspected crushing clods or turf. Detected click beetle larvae were collected and placed into special containers, where they were fixed applying 70% ethanol solution. Number of the sample, title of the treatment, sampling date and location were recorded on the cover of each container. Collected click beetle larvae were identified to species by means of a binocular microscope “Nikon” and in accordance with the identification guides (Черепанов, 1965; Бобинская и др., 1965; Долин, 1978, 1982, Гурева 1979; Tarnawski, Buchholz, 2000, 2008). Research methods of the harmfulness of the most abundant click beetle larvae to maize, wheat and barley in agrocenoses. Three cereal species were involved into research: maize (Zea mays), the variety - ‘Auxxel’; wheat (Triticum aestivum), the variety – ‘Zentos’; and barley (Hordeum vulgare), the variety – ‘Barke’. The harmfulness of 3 click beetle species

Agiotes obscurus (Linnaeus, 1758), Selatosomus aeneus (Linnaeus, 1758), Cidnopus aeruginosus (Olivier, 1790) larvae was investigated. Plastic containers of 2.7 litre volume (30 cm of length, 30 cm of width and 10 cm of depth) were applied for the research. Containers by ¾ of volume were filled with sandy soil (A1) (Table 1). Large plant debris was removed from the soil prior to pouring into containers. During the research, with an average ambient temperature of 20°C, the moisture content of the soil was observed by means of Tensis - Technik humidity meter, and soil moisture content was maintained at 50% threshold by using tap water. All treatments of the experiment were carried out with 5 replications. Click beetle larvae for the experiment were collected in the nature in the same location where the soil for containers has been taken. Until the experiment click beetle larvae were kept in the refrigerator at the temperature of +5°C or less and in the soil with 50% moisture content. The head capsule width of Agriotes obscurus larvae used for the experiment was around 1-1.5 mm, and body length - 10-15 mm. Selatosomus aeneus larval head capsule width reached around 1.5-2 mm, and body length - 15-20 mm. Finally, Cidnopus aeruginosus larval head capsule width fluctuated between 0.5-1 mm, and body length - 5-10 mm. Determining injuries caused by click beetle larvae, seedlings and growing plants in the containers were observed. Under observations damaged (drop-out) and normal- growing plants were assessed. At the end of the experiment the inspection has been performed whether all the larvae, embedded into containers, have been survived. Containers where at least one larva perished were eliminated of the experiment. The experiment was carried out by two stages. During first stage of the experiment the aim was to compare the susceptibility of maize, wheat and barley to injuries caused by click beetle larvae. For this purpose, in the containers 20 seeds of each plant species were sown and certain number of the same instar click beetle larvae (1, 3, 5, 7 pcs.) were released. Thus, this stage of the experiment consisted of 13 treatments: 1 - control (containers without larvae), 2-5 - containers with Agriotes obscurus larvae, 6-9 - containers with Selatosomus aeneus larvae, 10-13 - containers with Cidnopus aeruginosus larvae. During the second stage of the experiment the purpose was to establish the harmfulness to the plants of click beetle larvae, depending on larval species and quantity. For this purpose, in the containers 20 seeds of one plant species were sown and certain number of the same instar click beetle larvae (1, 3, 5, 7 pcs.) were released. Thus, 39 treatments comprised this stage of the experiment: 1-3 - control (containers with different plants and without larvae); 4-15 - containers with barley and Agriotes obscurus (4-7), Selatosomus aeneus (8-11), Cidnopus aeruginosus (12-15) larvae; 16-27 - containers with wheat and the appropriate species and number of click beetle larvae; 28-39 - containers with maize and the appropriate species and number of click beetle larvae. Chemical composition of the soil. Samples for the assessment of the chemical properties of the soil were collected in each site in spring and in autumn. Bulk samples were taken from ten locations of the site. Analyses of the soil have been performed at the Laboratory of Raw Food Materials, Agronomical and Zootechnical Research. The total nitrogen content in the soil has been determined by the Kjeldahl method. While the quantity of mobile phosphorus assessed by CAL method using a spectrophotometer. The quantity of

7 available potassium was defined by CAL method as well, though by using a flame photometer (Hoffman, 1991). Methods for the statistical analysis of the research data. In order to exclude dominant click beetle species the index of dominance was calculated: D = n/N 100%, where n – number of specimens of the species in agrocenosis, N - total number of specimens. Using the index of dominance (D) five classes of dominance are determined: D5 - eudominants (> 10%) - very abundant species; D4 - dominants (5.1–10%) - abundant species; D3 - subdominants (2.1–5%) - moderately abundant species; D2 - recedents (1.1–2%) - scarce abundant species; D1 - subrecedents (<1%) - solitary species (Tamutis et al., 2007; Górny, Grüm 1981). Cluster analysis was used for similarity of species composition in different treatments of the research assessment. Program Biodiversity Pro 2.0. was applied for designing of the similarity (difference) dendrograma (McAleece et al. 1997). Research data about the dependence of click beetle abundance on soil and on agrocenosis types were statistically estimated by applying the method of two factors quantitative traits analysis of variance. The influence for click beetle abundance of the soil (factor A) and agrocenosis type (Factor B) was assessed by distribution analysis with Fisher’s exact test. Differences between the treatments under interaction of the factors of the experiment AB were evaluated according to the least significant difference (LSD 0.05). In order to reduce data variation the transformation ( X 1 ) of the data was carried out. The reliability of the obtained data was calculated by statistical analysis method by using computer program for statistical data evaluation ANOVA for EXCEL vers. 4.0, author - dr. Pavel Tarakanov form the „SELEKCIJA“ package (Tarakanovas, Raudonius, 2003). Harmfulness of Agriotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus larvae to maize, wheat and barley was evaluated by method of three factors quantitative traits analysis of variance (Raudonius, 2008). The data of the research were assessed statistically by using a computer program DISVEG of the statistical data processing software package „SELEKCIJA“.

ANALYSIS OF THE EXPERIMENTAL RESULTS AND DISCUSSION Qualitative analysis of the click beetle species composition

During the research performed in 2009-2012 by means of pitfall traps 2295 click beetle adults were caught and during the analysis of the soil samples 1739 click beetle larvae were detected. All detected click beetle specimens belonged to 16 species, 10 genera: Actenicerus, Adrastus, Agriotes, Agrypnus, Athous, Cidnopus, Hemicrepidius, Oedestethus, Negastrius, and Selatosomus. Click beetle species composition in studied agrocenoses was different. Only two species, such as Agriotes lineatus and Agriotes obscurus, were detected in all agrocenoses (Table 2). Analysis of click beetle species preference to different soil types strongly suggested that click beetle species composition depended on granulometric structure of the soil (P <0.05). Cidnopus aeruginosus might be recognized as a species which is very sensitive to the soil type, while the specimens of the species were detected only in sites with sandy soil.

Table 2. Composition of detected click beetle species and their relative abundance in investigated agrocenoses in 2009-2012 S A1 A1 A1 A1 A2 A2 A2 A2 A3 A3 A3 A3 A4 A4 A4 A4 Name of the species L B1 B2 B3 B4 B1 B2 B3 B4 B1 B2 B3 B4 B1 B2 B3 B4 Actenicerus sjaelandicus S - + - - + - - ◙ ------◙ (Muller, 1764) L ------◙ ------× Adrastus limbatus S ------+ ------(Fabricius, 1777) L ------× - - × ------Adrastus rachifer S ------× ------(Geoffroy, 1785) L ------Adrastus palens S ------(Fabricius, 1792) L ------+ Agriotes lineatus S × ◙ × ◙ ◙ ◙ ◙ ◙ × ◙ ◙ ◙ ◙ ◙ ◙ ◙ (Linnaeus, 1767) L × × × × × × ◙ × - × × ◙ × ◙ ◙ × Agriotes obscurus S ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ (Linnaeus, 1758) L ◙ ◙ × ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ ◙ Agriotes sputator S - - + - ◙ - - × × - + ◙ ◙ × ◙ × (Linnaeus, 1758) L - + + ------× + - - - + Agrypnus murinus S + × × × × ◙ - ◙ - - - × - + - × (Linnaeus, 1758) L - + + × × ◙ × × - - - × × - - + Athous haemorrhoidalis S ------× (Fabricius, 1801) L - - + - - - - × × ------◙ Cidnopus aeruginosus S × × ◙ × ------(Olivier, 1790) L ◙ ◙ ◙ ◙ × × × ------Dalopius marginatus S ------(Linnaeus, 1758). L - - - - × - - + ◙ - × - - - - - Hemicrepidius hirtus S + - - - + - - × × ◙ ◙ × × × × × (Herbst, 1784) L - - - + - + - × - ◙ ◙ × - - - × Hemicrepidius niger S + + - + + × - - × × - + - × × × (Linnaeus, 1758). L - - + × - - - ◙ ◙ × ◙ × × ◙ × ◙ Negastrius pulchellus S ◙ ◙ - - × × ◙ + × ------(Linnaeus, 1758). L ------Oedostethus quadripustulatus S - - - - ◙ - ◙ - ◙ × ◙ ◙ ◙ × × - (Fabricius, 1792). L ------Selatosomus aeneus S ◙ ◙ ◙ ◙ × - × ------(Linnaeus, 1758) L ◙ ◙ ◙ ◙ ◙ × ◙ + ------Total number of species S 8 8 6 6 10 5 5 7 9 5 5 7 5 7 6 8 L 4 6 8 7 6 6 6 9 4 5 6 6 3 3 3 8 Total number of specimens S 270 248 160 325 101 74 206 159 62 105 63 184 37 141 72 88 L 155 201 348 179 44 53 86 130 23 37 78 107 25 46 37 190 General number of species 8 9 8 7 12 8 8 11 11 6 7 7 7 7 6 9 General number of specimens 425 449 508 522 145 127 292 289 85 142 141 291 62 187 109 278 Remarks: A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)). B1 - intensively cultivated land; B2 - reclaimed pasture; B3 - perennial grasses; B4 – seminatural meadow. ◙ - eudominants (>10%) – very abundant species; × - subdominants and dominants (2.1–10%) – abundant species; + - subrecedents and recedents (<1%–2%) – scarce abundant species; - any specimen has not been detected; S – click beetle adults; L – click beetle larvae.

A similar preference tendency to the soil type was shown by Selatosomus aeneus which dominated in the investigated sites with sandy soil. Negastrius pulchellus distinguishes by slightly better tolerance to soil granulometric structure. The specimens of the species have been detected in sandy soil and also in the soil of heavier granulometric structure A3. Meanwhile, Oedostethus quadripustulatus was found only in those sites where the soil was with heavier granulometric structure and any specimen of the species have not been detected in the sandy soil (A1). Clear preference tendency of Agriotes sputator to the soil with heavier granulometric structure has been determined. Results of the research showed the stronger preference of the species of Hemicrepidius genus to heavier soils rather than to sandy soil. Click beetle species composition of the studied agrocenoses was supplemented by species of which only 1-2 specimens were found. Adrastus palens, A. rachifer, A. limbatus should be assigned to such species. The latter two species are considered as rare in Lithuania (Pileckis, Monsevičius, 1995). Only one specimens were found for A. limbatus and A. rachifer species in loamy soil (A3) (Table 2). Apparently, these two species could be accidental, since they are usually found in natural habitats (Pileckis, Monsevičius, 1995; Tarnawski, Buchholz, 2008). Two additional species specific for open and grassy biotopes were discovered in some studied agrocenoses: Athous haemorrhoidalis and Actenicerus sjaelandicus. By the way, the latter was quite abundant in seminatural meadow (B4) with sandy loam soil (A2) and hard loamy clay soil (A4) as well (Table 2). Review of the click beetle species distribution in different agrocenoses revealed that agrocenoses type (tillage intensity) did not have significant effect to the species composition. Most click beetle species, including the most abundant Agriotes lineatus and A. obscurus, and those that preferred only certain soils Cidnopus aeruginosus, Selatosomus aeneus, Oedostethus quadripustulatus, Agriotes sputator, Negastrius pulchellus, Agrypnus murinus, Hemicrepidius hirtus, and H. niger were found in various agrocenoses and any regular preference to any of them has not been defined. Only some species, such as Actenicerus sjaelandicus and Athous haemorhoidalis were discovered in seminatural meadow (B4), since these species are specific for natural open biotopes. On the contrary, larvae of the euritopic species Dalopius marginatus which usually occurs in natural biotopes were found only in intensively cultivated agrocenoses (Table 2). After performance of Bray Curtis analysis when the similarity of click beetle communities were assessed in stationary sites the obtained results showed that they were different (Fig. 1). In the dendrogram they deploy into three clades. The most similar click beetle communities were in A3 and A4 stationary sites (73% of similarity), where the soil was with heavier granulometric structure. The most varied click beetle communities were in the stationary site A1, which differed over 30% from the communities in A3 and A4 stationary sites and by 20% in A2 stationary site where the soil type was sandy loam soil (A2). This evidently shows that click beetle species composition depends on the granulometric structure of the soil.

Fig. 1. Bray - Curtis cluster dendrogram of the similarity of click beetle species composition in investigated treatments, 2009-2012 Remarks: A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)).

Quantitative analysis of click beetle species

The summarised results of the research showed that significantly higher (P <0.05) number of click beetle species was found in stationary site A1 where during the season specimens on average 4 click beetle species entered per one trap. Meanwhile, the average number of the click beetle species specimens per one trap in other stationary sites was twice fewer. Similar tendency of the number of the click beetle species might be observed in the analysis of the quantity of click beetle larval species.

A. B1 B2 B3 B4 B. B1 B2 B3 B4 5 4,5

4,5 4

4 3,5 3,5 3 3 2,5 2,5

one trap one

one trap one 2 2

1,5 1,5

1 1

Average number of click beetle species per per species beetle of click number Average Average number of click beetle species per per species beetle of click number Average 0,5 0,5

0 0 A1 A2 A3 A4 A1 A2 A3 A4 LSD=0.61 Agrocenoses type LSD=0.61 Agrocenoses type

Fig. 2. The average number of click beetle adult (A) and larval (B) species over the entire research period 2009-2012 Remarks: transformed data ( X 1); A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)). B1 - intensively cultivated land; B2 - reclaimed pasture; B3 - perennial grasses; B4 – seminatural meadow.

A reliable tendency was not observed while analysing the dependence of the number of the click beetle species on the soil tillage that were found in the trap per season. However, while analysing the number of the species of click beetle larvae, found in the samples, significantly higher number of click beetle larval species was defined in the seminatural meadow (B4) as compared to the intensively cultivated land (B1).The number of the detected species of the click beetles between B2 and B3 agrocenoses did not differ significantly (Fig. 2B). By the way, a similar tendency can be observed in the analysis of the overall number of the adult click beetle species, although only in soils of heavier granulometric composition (Fig. 2A).

ABUNDANCE OF THE CLICK BEETLES Abundance analysis of the adult click beetles

During the research period, there were discovered 2295 adult click beetles in the investigated agrocenoses. Their amount in the course of the research varied in different soil types and in agrocenoses of different intensity.

4 3,53 3,5

3 2,56 2,5 2,31 2,15 2

1,5

Average number of specimens per trap per of specimens number Average 0,5

0 A1 A2 A3 A4 LSD=0.95 Soil type

Fig. 3. The average number of specimens of adult click beetles in different soil types in 2009-2012 Remarks: transformed data ( X 1); A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)).

During the period of the research, significantly the biggest number of the adult click beetles was detected in the agrocenoses, which was dominated by sandy soil (A1), and on average 3.53 specimens entered into one trap during the period of activity of the traps. This number was significantly higher as compared to other types of soil in agrocenoses. Meanwhile, there were no significant differences in the number of click beetles among agrocenoses with the sandy loam soil (A2), loamy soil (A3) and hard loamy clay soil (A4).The least number of the click beetles was caught in the soil A4 – on average of 2.15 specimens per one trap (Fig. 3).

After the analysis of the data about the abundance of the adult click beetles, it was found that the greatest abundance of specimens characterized four species: - Agriotes obscurus (543 specimens, 24%), Selatosomus aeneus (418 specimens, 18.2%), Agriotes lineatus (394 specimens, 17, 2%) and Negastrius pulchellus (233 specimens, 10.2%) (Fig. 4). However, in the course of the research it was determined that these species were equally abundant in different agrocenoses (Table 2). Some species of them were the background and comprised for most of the specimens detected in all the locations that were researched, while other species were dependent only on certain conditions, such as granulometric structure of the soil or type of the agrocenoses.

Agriotes obscurus Selatosomus aeneus 4,5% Agriotes lineatus 24% Negastrius pulchellus 6,3% Oedostethus quadripustulatus Agrypnus murinus 8,32% Cidnopus aeruginosus Hemicrepidius hirtus 10,2% 18,2% Agriotes sputator Actenicerus sjaelandicus 17,2% Hemicrepidius niger Other species Fig. 4. Abundance of the species of click beetles (%) during the research 2009-2012

In all the researched agrocenoses two species were distinguished as having the highest abundance of specimens - A. obscurus and A. lineatus, while N. pulchellus and S. aeneus species were found only in agrocenoses characterized in certain conditions, they were assigned as eudominants only in the treatments of the research with sandy soils, in other treatments they were less abundant or were not found at all (Table 2). Two click beetle species were assigned to dominant class: Oedostethus quadripustulatus (191 specimens, 8.32%) and Agrypnus murinus (144 specimens, 6.3%). More than a half of O. quadripustulatus specimens (125 pcs.) were detected in treatment A3. A. murinus was detected in treatments of the research where the soil was of lighter granulometric structure. Four species were attributed to the subdominants: Cidnopus aeruginosus, Hemicrepidius hirtus, Agriotes sputator and Actenicerus sjaelandicus. C. aeruginosus specimens were only found in treatment A1 (103 specimens, 4.48%). The highest number of them was detected in agrocenosis B3 (35%) and the lowest – in agrocenosis B2 (9.7%). The largest number of H. hirtus (77 specimens in total, 3.3%) was detected in treatment A3 (43 pcs.), only one specimen was found in A1. During the research click beetles of Agriotes sputator species (74 specimens, 3.2%) were more frequently detected in soil types with heavier granulometric structure, treatment A4 (29 pcs.). A. sjaelandicus (64 specimens, 2.8%) - it is a species of the purely natural habitat, whereas the highest proportion of them was found in seminatural meadows, while only a few specimens

13 occurred in other agrocenoses during the research. Most specimens were detected in treatment A2 of the research (35 pcs.). The species H. niger was assigned to scarce recedent species - in total 47 specimens were defined, which comprised for only 2.04%. The abundance of the click beetles in seminatural meadows (B4) was significantly higher only in A1 and A3 soils as compared to the intensively cultivated land (B1). In the remaining agrocenoses the number of detected adult click beetles was different, although significant differences were not defined (Fig. 5.).

B1 B2 B3 B4 4,5 4,1 4,0 3,7 3,5 3,5 3,1 2,9 2,8 3,1 3,0 2,8 2,3 2,4 2,5 2,0 2,0 1,9 2,0 2,3 2,0 1,6 1,5

1,0

0,5 Average number of specimens per trapper of specimens number Average 0,0 A1 A2 A3 A4 LSD=0,95 Soil type

Fig. 5. The average number of the adult click beetle specimens in different agrocenoses in 2009-2012 Remarks: transformed data ( X 1); A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)). B1 - intensively cultivated land; B2 - reclaimed pasture; B3 - perennial grasses; B4 – seminatural meadow.

3.2.2. Analysis of the abundance of click beetle larvae

1739 larvae of the click beetle were detected during the research, their abundance in different treatments was different. Significantly highest number of the click beetle larvae was detected in A1 treatment, dominated by the sandy soil (A1), here an average of 4.2 click beetle larvae were found in one sample. Meanwhile, the number of the larvae in other treatments did not differ significantly. The least number of click beetle larvae was detected in treatment A4, with an average of only 2.3 larvae of the click beetles in one sample (Fig. 6.). Three species of click beetle larvae were distinguished as being the most abundant: Agriotes obscurus, Cidnopus aeruginosus and Selatosomus aeneus, which have been attributed to the abundance of eudominant class (Fig. 7.). However, these species of click beetle larvae in different treatments of the research were distributed very unevenly (Table 2.). Only larvae of A. obscurus dominated in all the treatments of the research. In total 547 specimens of A. obscurus larvae were detected, which comprised for 31.5% of the total number of detected larvae of the click beetles. Most larvae of this species were found in seminatural meadow (B4), 192 specimens (Fig. 7.).

4,5 4,2 4

3,5

3 2,7 2,3 2,5 2,4

1,5

1 Average number of larvae per sample sample per of larvae number Average 0,5

0 A1 A2 A3 A4 LSD=0,41 Soil type

Fig. 6. The average number of the click beetle larvae in different agrocenoses in 2009-2012 Remarks: transformed data ( X 1); A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)).

Agriotes obscurus Cidnopus aeruginosus 7,7 Selatosomus aeneus 31,5% Hemicrepidius niger 9,08 Agriotes lineatus Hemicrepidius hirtus Actenicerus sjaelandicus 20,53% Agrypnus murinus 21,33% Athous haemorrhoidalis Other species

Fig. 7. Abundance of the click beetle larvae (%) during the research in 2009-2012

The larvae of C. aeruginosus also dominated only in treatment A1, while in treatment A2 there were only few larvae. There were no larvae found in other treatments. Larvae of Agriotes lineatus species were assigned to dominant class (134 pcs. - 7.7%), and the largest number of this species of larvae was detected in treatment A1 of the researched agrocenoses, in total 46 larvae and this comprised for 5.2% of the total quantity of the larvae. Comparing the data obtained by analysing individual agrocenosis, most larvae of this species were detected in B4 agrocenosis. Two click beetle species were assigned to subdominant class: Actenicerus sjaelandicus and Hemicrepidius hirtus. Larvae of species Agrypnus murinus, Athous haemorrhoidalis, Agriotes sputator, Dalopius marginatus, Adrastus limbatus and Adrastus palens were found only as single specimens (Fig. 7.). Comparing the distribution of the quantity of all species of click beetle larvae in different agrocenoses, a tendency can be observed that the number of the click beetle larvae

15 in intensively cultivated land (B1) was significantly lower than in seminatural meadow (B4) (Fig. 8.). By the way, the number of the click beetle larvae that were detected in the latter agrocenosis was significantly highest except in treatment A3, where the differences in the number of the larvae between agrocenoses B2 and B4 were insignificant. Significantly higher number of the click beetle larvae in treatment A3 also was detected in reclaimed pasture (B2) as compared to the intensively cultivated land (B1).

6 B1 B2 B3 B4 5,4 5,5

4,5 4,3 3,9 4 3,8 3,4 3,3 3,7 3,5

3 2,4 2,5 2,6 2,5 2 2,1 2,2 2 1,9 1,5 1,6 1,5

1 Average number of larvae per sample sample per of larvae number Average

0,5

0 A1 A2 A3 A4 LSD=1,1 Soil type

Fig. 8. Average number of the click beetle larvae during the research in 2009-2012 Remarks: transformed data ( X 1); A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)). B1 - intensively cultivated land; B2 - reclaimed pasture; B3 - perennial grasses; B4 – seminatural meadow.

Above mentioned distribution tendency of the quantity of the click beetle larvae remained throughout the research period, however the number of the larvae in seminatural meadow (B4) was significantly highest only in treatment A4. Meanwhile, the quantity of larvae varied in other treatments during the different periods of the research.

3.3. SEASONAL DYNAMICS OF THE ABUNDANCE OF THE CLICK BEETLES (IMAGO) The first specimens of click beetle adults got into the traps in the first decade of May, when the average air temperature was of approximately 13°C (Fig. 9.). Subsequently, their abundance increased rapidly and reached the peak in the first half of June. During the period from mid-May to mid-June an average of approximately 6 specimens got into one trap. In July the activity of adult click beetles declined and in August only single specimens got into the traps. The beginning of the activity of the adult click beetles was different in investigated treatments. In treatments A1 and A2, where the soil had lighter granulometric structure, the first click beetles were detected in the traps approximately two weeks earlier than in treatments A3 and A4, where the soil was heavier (Fig. 9.). This suggests that the activity of the adult click beetles depends on the temperature of the soil surface. In the spring light soils warm up faster than the heavier ones, therefore the beginning of the activity of the click beetles is earlier there.

Activity peaks of the adult click beetles in three treatments A1, A2 and A4 of the research did not differ, while in the variant A3 it was recorded two weeks later. Reviewing activity period of the adult click beetles it is noted that in all three treatments its length differed slightly and lasted from the end of May until the beginning of August. Single specimens got into the traps until September although (Fig. 9.).

A1 A2 A3 A4 T-DV A1, A3 - T-4 A2-T-4 A4-T-4 16 22 15 21 20 14 19 13 18 17 12 16 11 15 10 14 13 9 12 8 11 7 10

9 temperatureAir °C 6 8 5 7 6 4 5 3

Average number of specimens per trapper specimens ofAverage number 4 2 3 2 1 1 0 0

II-April I-May II-May I-June II-June I-July II-July I-August II-August I-September II-September

Fig. 9. Seasonal dynamic of the general number of adults of click beetles in 2009-2012 in different locations of the research and means of average air temperature of the season Remarks: A1 - sandy soil (SDp-n Dystri- Haplic Arenosols (Arh-dy)); A2 - sandy loam soil (SDp-b Eutri- Haplic Arenosols (Arh-eu)); A3 - loamy soil (Calc(ar)i- Epihypogleyic Luvisol LV-g-p-w-cc (sc)); A4 - hard loamy clay soil (RDg-8-k2- Eudocaleari- Epihypogleyic Cambisols (CMg-p-w-can)). T-DV - average of the multiannual air temperature; T - average of yar air temperature;

By comparing the dynamics of the activity of the adult click beetles during the different year of the research, it was observed that it was irregular. A very sudden increase in the abundance of the click beetles was recorded in the end of May and early June of 2009 and 2012 (Fig. 10.).

2009 2010 2011 2012 T-2009 T-2010 T-2011 T-2012 12 24

11 22

10 20

9 18

8 16

7 14

6 12

5 10

Air temperature °C Air temperature 4 8

3 6

2 4

Average number of specimens per trap trap per number of specimens Average 1 2

0 0 II-April I-May II-May I-June II-June I-July II-July I-August II-August I-September II-September

Fig. 10. Seasonal dynamic of the general number of adults of click beetles in different years in all treatments of the research and means of average air temperature of the season Remarks: T-DV - average of the multiannual air temperature; T - average of year air temperature;

Meanwhile, there was no such increase in their abundance during the same period of 2010 and 2011. There were no consistent patterns found by relating aforementioned changes in the abundance of the click beetles to the air temperature during this period. This could have been influenced by other factors, related to the biological characteristics of the click beetles. It is likely that, as other multi-generational beetles (cockchafers), click beetles expose increases in the abundance of the adults that repeat in a certain frequency. Abundance dynamics of Agriotes obscurus and Selatosomus aeneus were slightly different. During the growing period the abundance of A. obscurus was significantly lower, but it continued for a longer period without greater variations. Meanwhile, adults of S. aeneus are characterized by a sudden increase in activity in late May, early June, but this high activity takes a short time in comparison. The beginning of the activity of both species of adult click-beetles coincided at all the years of the research, however, adults of S. aeneus were no longer detected in August, and A. obscurus were active in almost all years of the research until September.

HARMFULNESS OF THE MOST FREQUENTLY IN AGROCENOSES DETECTABLE CLICK BEETLE SPECIES TO SOME GRAMINEOUS CEREALS

Results of the research performed under laboratory conditions demonstrated that the harmfulness of the most common in agrocenoses click beetle species Agriotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus larvae to maize, wheat and barley was different. It depended both on the plant (F = 4.17*), click beetle species (F = 3.22*) and on the number of larvae as well (F = 11.41**). Maize, wheat and barley crops that were growing in the same vegetative pot were not damaged evenly by the larvae of the click beetles. The larvae of all click beetle species damaged maize in significantly greater manner. Significant differences in the number of plants damaged by the click beetle larvae were not found among wheat and barley (Table 3.). Studies have revealed that the most significantly investigated plants were damaged by larvae of Agriotes obscurus and Selatosomus aeneus, however, there were no significant differences found when comparing these two species.

Table 3. Average number of damaged plants (%) depending on the species of plants and number of click beetle larvae under laboratory conditions, Akademija, 2011 Number Average quantity of the damaged plants% Influencing factors of treats T N Factor A (plant species) 1. Corn 2.17 5.98 2. Wheat 1.7 3.08 3. Barley 1.69 2.78 LSD05 0.374 1.927 Factor B (species of click-beetle larvae) 1. Agiotes obscurus L. 2.02 4.98 2. Selatosomus aeneus L. 1.97 4.34 3. Cidnopus aeruginosus Ol. 1.58 2.52 LSD05 0.374 1.927

Number Average quantity of the damaged plants% Influencing factors of treats T N Interaction of the factor B (species of click-beetle larvae) and factor C (number of click-beetle larvae) 1. Agiotes obscurus L. 0 larva 1 0 2. Agiotes obscurus L.1 larva 2.12 3.69 3. Agiotes obscurus L. 3 larva 3.05 7.01 4. Agiotes obscurus L. 5 larva 4.57 7.93 5. Agiotes obscurus L. 7 larva 5.25 12.04 6. Selatosomus aeneus L. 0 larva 1 0 7. Selatosomus aeneus L. 1 larva 1.51 2.88 8. Selatosomus aeneus L. 3 larva 2.46 5.3 9. Selatosomus aeneus L. 5 larva 3.33 8.3 10. Selatosomus aeneus L. 7 larva 3.96 8.8 11. Cidnopus aeruginosus Oliv.0 larva 1 0 12. Cidnopus aeruginosus Oliv.1 larva 1.32 1.2 13. Cidnopus aeruginosus Oliv.3 larva 1.57 2.91 14. Cidnopus aeruginosus Oliv.5 larva 1.95 4.6 15. Cidnopus aeruginosus Oliv.7 larva 2.29 6.58 LSD05 0.505 5.518 Remarks: T - transformed data ( X 1); N - non-transformed data;

The analysis of the second stage laboratory research data revealed that click beetle larvae were feeding evenly on maize, wheat and barley seedlings as well, when plants were grown in distinct pots, since significant differences between the percentage of damaged plants have not been defined (F = 1.61). Whereas the level of plants’ damage has been influenced by click beetle larval species (F = 94.67**) and number of larvae (F = 123**). According to the statistical analysis the interaction of click beetle larval species and number of larvae also affected damage of the plants (F = 11.98**). Strong dependence of the quantity of damaged plants on the number of click beetle larvae has been defined. However, the dependence varied among different click beetle larval species. The increase of A. obscurus and S. aeneus larvae by two specimens in the sample significantly enhanced the quantity of damaged plants. Meanwhile, the quantity of C. aeruginosus larvae damaged plants significantly increased when the number of larvae was enlarged up to 4 specimens. The results of the experiment show that A. obscurus and S. aeneus larvae were at least two times more harmful than larvae of C. aeruginosus. This should be taken into consideration and the economic damage thresholds have to be established for each click beetle species individually.

CONCLUSIONS

1. During the research period totally 4034 click beetle specimens (imago and larvae) were caught, which belonged to 16 species: Actenicerus sjaelandicus, Adrastus rachifer, A. limbatus, A. palens, Agriotes lineatus, A. obscurus, A. sputator, Agrypnus murinus, Athous haemorrhoidalis, Cidnopus aeruginosus, Dalopius marginatus, Hemicrepidius hirtus, H. niger, Negastrius pulchellus, Oedostethus quadripustulatus, Selatosomus aeneus. Agriotes lineatus and A. obscurus were found in all types of agrocenoses. Such click beetle species as Cidnopus aeruginosus and Selatosomus aeneus were discovered only in sandy soil (A1) and sandy loam soil (A2) soils. While Oedostethus quadripustulatus was detected in loamy soil (A3) and hard loamy clay soil (A4) soils. Agrocenosis state had no significant effect on the click beetle species composition. Significantly higher number of click beetle species was defined in agrocenoses with sandy soil (A1). 2. Click beetle abundance in agrocenoses has been influenced significantly by granulometric structure of the soil. The number of specimens detected in soils with lighter granulometric structure was significantly higher in comparison with number of specimens caught in heavier soils. The state of agrocenosis did not influence significantly the number of click beetle adults, however, it had substantial effect on the abundance of the click beetle larvae. Significantly highest number of the click beetles was detected in seminatural meadows, and the least – in intensively cultivated land. During the entire research period click beetle species Agriotes obscurus and Selatosomus aeneus distinguished in the highest click beetle abundance of both larvae and adults in all treatments. 3. The activity of click beetle adults during the growing season was variable. First specimens entered into the traps during the first decade of May when the average air temperature reached 13°C. Activity of click beetles attains a peak in the first half of June. The period of activity of click beetles in lighter soils started two weeks earlier in average. The activity of Agriotes obscurus was significantly lower in comparison with activity of Selatosomus aeneus. Therefore, Agriotes obscurus activity was longer and more stable. Meanwhile, a sharp increase of the activity in late May and early June was specific for adults of Selatosomus aeneus. By the way, such a high activity takes comparably short time. Dependence of the activity dynamics of click beetles on the ambient air temperature during the growing season has not been defined. The ambient air temperature was specific for each click beetle species. 4. Results of the research under laboratory conditions showed that damage to maize caused by larvae of Agiotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus was significantly greater. Significant differences among the numbers of click beetle larvae damaged wheat and barley have not been defined. Agriotes obscurus and Selatosomus aeneus larvae injured significantly highest number of the investigated plants. The quantity of damaged plants depended on the number of click beetle larvae. Agriotes obscurus and Selatosomus aeneus larvae were double more harmful in comparison with larvae of Cidnopus aeruginosus.

LIST OF PUBLICATIONS ON THE SUBJECT OF THE DISSERTATION Articles in the journals indexed in ISI WOS List database: Leidiniuose, referuojamuose Mokslinės informacijos instituto duomenų bazėje „ISI Web of Science“ ir turinčiuose citavimo indeksą.

1. MULERČIKAS, P.; TAMUTIS, V.; KAZLAUSKAITĖ, S. Species composition and abundance of click – beetles (Coleoptera, Elateridae) in agrobiocenozes. Polish Journal of Environmental Studies. 2011, vol. 21, no. 2 (2012), p. 425 – 433.

In the peer-reviewed scientific publications, indexed in other data bases Recenzuojamuose mokslo leidiniuose, referuojamuose kitose duomenų bazėse

1. TAMUTIS, V.; FERENCA, R.; IVINSKIS, P.; MULERČIKAS, P. New data on little known species of click beetles (Coleopters: Elateridae) in Lithuania. Baltic Journal of Coleopterology, 2010, 10(1) ISSN, p. 45-60. 2. MULERČIKAS P.; KAZLAUSKAITĖ S.; TAMUTIS V. The new data on seven protected and two rare beetle (Insecta: Coleoptera) species detected in Lithuania in 1997- 2011. New and Rare for Lithuania Insect Species. Records and Descriptions, 2011, vol. 23, p. 30 – 33.

Brief information about the author of the dissertation

Povilas Mulerčikas was born on 15th of July in 1984 in Druskininkai. He finished Druskininkai I high school in 2002 and entered into the Lithuanian University of Agriculture, Faculty of Forestry. The author of the dissertation graduated from the LUA in 2004 and obtained a BSc degree in Ecology. During the period of 2004-2006 studies at the same university were continued, and Master’s of Science degree in Forest Ecology was gained. Since 2008 P. Mulerčikas was a PhD student at Lithuanian University of Agriculture (ASU since 2011), Department of Plant Protection (Institute of Biology and Plant Biotechnology since 2013).

Reziumė

Temos aktualumas. Lietuvos agrocenozėse aptinkamų spragšių rūšinė sudėtis, paplitimas, prieraišumas buveinėms, poreikis tam tikroms dirvožemio savybės jų maisto racionas Lietuvoje iki šiol nebuvo išsamiai tirti. Kasmet dėl spragšių daromos žalos ūkininkai patiria didelius nuostolius. Spragšių lervos apgraužia įvairių augalų dygstančias sėklas, daigus, požemines augalo dalis, gumbus, šakniavaisius. Pažeistos sėklos nedygsta, daigai žūva, pasėliai išretėja. Pablogėja ne tik produktų prekinė vertė, bet laikymo metu, į pažeidimo vietą patekus bakterinei ar grybinei infekcijai, daržovės ir bulvės saugyklose greičiau sugenda. Trūksta duomenų apie spragšių bioekologiją ir žalingumą Lietuvos gamtinėmis sąlygomis. Siekiant didesnio augalų apsaugos priemonių nuo šių kenkėjų efektyvumo yra būtina nustatyti Lietuvos agroklimatinėmis sąlygomis agrocenozėse

21 paplitusių spragšių rūšinę sudėtį, ištirti jų bioekologijos ypatumus bei žalingumo lygį. Kita vertus, ne visos spragšių rūšys yra augalėdės ir kenkia. Yra rūšių, kurioms būdingas grobuoniškumas. Šiuo aspektu jos gali būti svarbios taikant integruotos augalų apsaugos metodą kaip natūralūs augalų kenkėjų priešai. Tyrimų hipotezė. Spragšių rūšinė sudėtis, paplitimas ir gausumas turėtų priklausyti tiek nuo dirvožemio granuliometrinės sudėties, tiek nuo agrocenozės būklės. Tikėtina, kad spragšių rūšių kiekis ir individų gausumas yra didesnis agrocenozėse, kur dirvožemis yra lengvesnės granuliometrinės sudėties ir žemės dirbimas yra minimalus. Spragšių lervoms būdinga polifagija, todėl visos rūšys turėtų būti vienodai žalingos migliniams javams. Tyrimų tikslas – Nustatyti Lietuvos agrocenozėse aptinkamų spragšių (Coleoptera: Elateridae) rūšinę sudėtį, paplitimą, gausumo dinamiką ir gausiausių rūšių žalingumą kai kuriems migliniams augalams. Tyrimų uždaviniai. Tyrimais siekta: 1. skirtingų dirvožemių ir skirtingo žemės dirbimo agrocenozėse nustatyti: 1.1. Spragšių rūšinę sudėtį bei jos pokyčius; 1.2. Spragšių individų gausumą bei jos pokyčius; 1.3. Spragšių individų kiekio dinamiką vegetacijos periodu bei sukcesijos eigoje; 2. Įvertinti dažniausių agrocenosėse aptinkamų spragšių rūšių žalingumą kukurūzams, kviečiams ir miežiams laboratorinėmis sąlygomis.

Ginamieji disertacijos teiginiai: 1. Spragšių rūšinė sudėtis priklauso nuo dirvožemio granuliometrinės sudėties, o agrocenozės būklė jai esminės įtakos neturi. 2. Spragšių individų gausumas priklauso nuo dirvožemio granuliometrinės sudėties ir agrocenozės būklės. 3. Spragšių suaugėlių aktyvumo periodo trukmė bei dinamika labiau priklauso nuo rūšies biologinių savybių nei nuo aplinkos oro temperatūros. 4. Skirtingų rūšių spragšių lervų žalingumas kukurūzams, kviečiams ir miežiams yra skirtingas, o jo intensyvumas priklauso nuo spragšių lervų kiekio substrate. Mokslinio darbo naujumas. Pirmą kartą Lietuvos agroklimatinėmis sąlygomis, nepasotintame paprastajame smėlžemyje, pasotintame paprastajame smėlžemyje, karbonatingame stagniškame išplautžemyje ir giliau karbonatingame sekliai glėjiškame rudžemyje nustatyta agrocenozėse aptinkamų spragšių rūšinė sudėtis, rūšių paplitimas, individų gausumas bei jų pokyčiai skirtingos būklės agrocenozėse. Laboratorinėmis sąlygomis įvertintas Agiotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus spragšių rūšių žalingumas kukurūzams, kviečiams ir miežiams. Tyrimais nustatyta, kad Cidnopus aeruginosus kenkia visies tirtiems augalams, tačiau jų žalingumas yra du kartus mažesnis nei A. obscurus ir S. aeneus. Darbo praktinė vertė. Kasmet dėl spragšių daromos žalos ūkininkai patiria didelius nuostolius. Dėl specifinio spragšių lervų gyvenimo būdo įprastinės augalų apsaugos priemonės tame tarpe ir cheminės nėra pakankamai efektyvios. Siekiant geriau apsaugoti augalus nuo šių kenkėjų būtina parengti augalų auginimo strategiją atsižvelgiant tiek į auginamų augalų, tiek į jiems kenkiančių spragšių bioekologiją. Atliktų tyrimų rezultatai

22 atskleidę spragšių rūšinės sudėties, gausumo priklausomybę nuo dirvožemio tipo ir agrocenozių būklės leis tinkamiau parinkti auginamų augalų rūšių sudėtį, siekiant išvengti mažiausių derliaus nuostolių. Tyrimais išaiškinti spragšių suaugėlių gausumo dinamikos ypatumai įgalins efektyviau panaudoti chemines augalų apsaugos priemones prieš šiuos kenkėjus. Nustatytas labiausiai agrocenozėse paplitusių spragšių rūšių žalingumas leis tiksliau nustatyti šių kenkėjų ekonominio žalingumo ribą.

Išvados

1. Iš viso tyrimų metu aptikta 4034 spragšių individai (imago ir lervos), kurie priklausė 16 rūšių: Actenicerus sjaelandicus, Adrastus rachifer, A. limbatus, A. palens, Agriotes lineatus, A. obscurus, A. sputator, Agrypnus murinus, Athous haemorrhoidalis, Cidnopus aeruginosus, Dalopius marginatus, Hemicrepidius hirtus, H. niger, Negastrius pulchellus, Oedostethus quadripustulatus, Selatosomus aeneus. Agriotes lineatus ir Agriotes obscurus buvo aptiktos visose tirtose agrocenozėse. Tik smėlžemio dirvožemiuose buvo aptiktos tokios rūšys, kaip Cidnopus aeruginosus ir Selatosomus aeneus, o Oedostethus quadripustulatus aptikta karbonatingame stagniškame išplautžemyje ir giliau karbonatingame sekliai glėjiškame rudžemyje. Agrocenozės būklė esminės įtakos spragšių rūšinei sudėčiai neturėjo. Patikimai didesnis spragšių rūšių kiekis buvo aptinkamas nepasotinto smėlžemio dirvožemio agrocenozėse. 2. Dirvožemio granuliometrinė sudėtis esmingai įtakojo spragšių gausumą agrocenozėse. Lengvesnės granuliometrinės sudėties dirvožemiuose individų kiekis buvo esmingai didesnis lyginant su sunkesniais dirvožemiais. Agrocenozių būklė spragšių suaugėlių kiekiui esminės įtakos neturėjo, tačiau esmingai įtakojo spragšių lervų gausumą. Patikimai daugiausiai spragšių buvo aptikta ilgametėse sėtinėse pievose, o mažiausiai ariamose dirvose. Per visą tyrimų laikotarpį, visuose tyrimų variantuose didžiausiu tiek suaugėlių, tiek lervų individų gausumu pasižymėjo Agriotes obscurus ir Selatosomus aeneus rūšys. 3. Spragšių suaugėlių aktyvumas vegetacijos periodo eigoje kito. Pirmieji spragšių suaugėliai į gaudykles patekdavo gegužės pirmąją dekadą, vidutinei oro temperatūrai pasiekus 13°C. Birželio mėnesio pirmoje pusėje pragšių aktyvumas pasiekia piką. Lengvesnėse dirvose spragšių aktyvumo periodas prasidėjo vidutiniškai dviem savaitėm anksčiau. A. obscurus aktyvumas lyginant su S. aeneus buvo žymiai mažesnis, tačiau tęsiasi ilgesnį periodą ne itin kisdamas. Tuo tarpu S. aeneus suaugėliams būdingas staigus aktyvumo padidėjimas gegužės pabaigoje, birželio pradžioje, tačiau toks aukštas aktyvumas trunka palygus trumpai. Spragšių aktyvumo dinamikos priklausomybė nuo aplinkos oro temperatūros vegetacijos periodo metu nenustatyta, ji buvo savita kiekvienai spragšių rūšiai. 4. Laboratorinėmis sąlygomis nustatyta, kad Agiotes obscurus, Selatosomus aeneus, Cidnopus aeruginosus rūšių lervos esmingai labiau pažeidė kukurūzus. Esminių spragšių lervų pakenktų augalų kiekio skirtumų tarp kviečių ir miežių nebuvo nustatyta. Patikimai daugiausiai tirtų augalų pažeidė A. obscurus ir S. aeneus lervos. Pažeistų augalų kiekis priklauso nuo spragšių lervų kiekio. A. obscurus ir S. aeneus lervos yra dvigubai žalingesnės lyginant su C. aeruginosus lervomis.

Trumpos žinios apie disertantą

Povilas Mulerčikas gimė 1984 m. Liepos 15 d. Druskininkuose. 2002 m. baigė Druskininkų I–ąją vidurinę mokyklą. 2002 įstojo į Lietuvos žemės ūkio universiteto Miškų fakultetą. 2004 m. baigė studijas ir įgijo Ekologijos bakalauro kvalifikacinį laipsnį. 2004– 2006 m. tęsė studijas tame pačiame universitete, įgijo ekologijos mokslų magistro kvalifikacinį laipsnį. Nuo 2008 m. – Lietuvos žemės ūkio universiteto (ASU, 2011) Augalų apsaugos katedros doktorantas (nuo 2013 metų Biologijos ir augalų biotechnologijos institutas).

SPRAGŠIŲ (COLEOPTERA, ELATERIDAE) PAPLITIMAS SKIRTINGOSE AGROCENOZĖSE IR GAUSIAUSIŲ RŪŠIŲ ŽALINGUMAS MIGLINIAMS JAVAMS

Povilas Mulerčikas

Daktaro disertacijos santrauka Žemės ūkio mokslai (A 000), agronomija (01 A)

SL 399. 2013.11.18. Sp. 1,5. Tiražas 30. Užsakymo Nr. 58. Leido ir spausdino ASU Leidybos centras – 2013. Studentų g. 11, LT–53361 Akademija, Kauno r.