Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

OCCURRENCE OF BEAUVERIA BRONGNIARTII (SACC.) PETCH IN ROMANIAN FOREST NURSERIES INFESTED WITH MELOLONTHA MELOLONTHA (L.)

Constantin Ciornei1, Ana-Maria Andrei2, Daniela Lupaştean3, Otilia Pavel4, Maria Tudorache2

1Forestry Research Station, Bacãu, , [email protected] 2Research-Development Institute for Plant Protection, Romania 3Faculty of Forestry, , Romania, [email protected] 4Museum of Natural Sciences, Bacãu, Romania

Abstract

The studies developed in 116 forest nurseries from eastern part of Romania – 38 forest districts from 8 forest National Forest Administration (NFA) Branches – revealed different infestation levels with Melolontha melolontha larvae (13% low, 7% medium, 15% high and 24% very high) during the year 2005. In 10% of nurseries, mainly those from the northern part, very highly infested by M. melolontha, there were observed natural infections produced in different stages of the pest (larvae L3, pupa, and adult) by Beauveria brongniartii, playing an important role in the natural reduction of scarabeid populations.

Keywords: Beauveria brongniartii, Melolontha melolontha, forest nurseries

1. Introduction

Melolontha melolontha (L.) (Coleoptera: Scarabeidae) is well known as serious pest in the Romanian forest nurseries and therefore studies of the natural enemies are important for biological control. This paper deals with the existance of naturally occurring microorganisms with entomopathogenic features for the root pests; we present the results of a mycological research on European cockchafer and soil in some Romanian forest nurseries. Among the entomopathogenic fungi, Beauveria brongniartii (Sacc.) Petch (Deuteromycotina: Hyphomycetes), an important and specific natural enemy of the European cockchafer, is receiving a great deal of attention for the management of soil-inhabiting insect pests in forestry. The aim of the present study is to isolate local strains of B. brongniartii participating in the natural reduction of scarabeids and originating from the same habitat with the host, taking into account that fungi which are adapted to the particular environmental conditions and belong to the same biocenose as the host, would more easily play the role as a factor limiting the numbers of a given pest (Bajan, Kmitowa, 1998). Observations carried out in the eastern part of Romania in 2005 (116 nurseries from 38 forest districts from 8 NFA Branches) emphasized the level of infestation with M. melolontha larvae and, in certain conditions, the presence of natural infections with Beauveria sp. on L3 larvae (11 nurseries) and on pupae and adults (5 nurseries), which contributes to decreasing of pest populations.

IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 253 Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

2. Material and methods

Entomological and soil samples were collected from forest nurseries, digging hollows of 100 x 100 cm and 50 (100) cm deep, at the end of August, but especially at the beginning of September (10 samples/hectare). In the field, determinations were made regarding the species of cockchafer, the instars of the larvae and there were selected the specimens covered with mycelia. Sick and dead larvae together with soil samples were incubated in moist conditions favourable for infection by B. brongniartii: Petri dishes with filter paper soaked with water, at 27ºC, for 7-14 days; the samples placed in moist chambers result in fungal growth. When mycelium and conidia occurred, we inoculated them on potato-dextrose-agar medium, using dilution plate method. The pathogenity of all B. brongniartii isolates were tested by Postulate Koch method.

3. Results and discussions

3.1. Level of infestation with cockchafers

The observations were made in forest nurseries from eastern part of Romania ( County), mainly situated in the basin of the river, at the end of the vegetation season 2005, in order to establish the level of infestation with root pests (figure 1). The most of them are placed on medium texture soils (clays) with some exceptions (for instance, the nursery Tudor Vladimirescu from NFA Branch Galati, placed on sand dunes). The elevation of the experimental places varies between 100 m and 850 m.

10 11 LEGEND

13 medium infestation with M. Melolontha

12 high infestation with M. Melolontha very high infestation with M. Melolontha very slow infection with Beauveria brogniartii slow infection with Beauveria brogniartii medium infection with Beauveria brogniartii high infection with Beauveria brogniartii very high infection with Beauveria brogniartii 1, 2, ...13 forest nurseries (table 2)

Figure 1 - Distribution of forest nurseries naturally infected by Beauveria brogniartii on Melolontha melolontha

IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 254 Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

Soil samples were collected from 116 nurseries, meaning 38 forest districts from 8 NFA Branches (table1). Fifty-nine percent of these were infested by cockchafer larvae (mainly M. melolontha) in different infestation levels (13% low, 7% medium, 15% high and 24% very high) and 29% were infested by the adults ( 8% low, 9% medium, 6% high and 5% very high). Most of the M. melolontha larvae were found in the upper 10-50 cm of soil. The highest infestations with Melolontha larvae were registered in September of 2005 in the nurseries from NFA Branch Botosani (60% nurseries, of these 27.5% high and very high infested), Suceava (73% nurseries, of these 58% high and very high infested) and Neamt (80% nurseries, of these 60% high infested). In one of the nurseries from Botosani NFA Branch were present Amphimalon solstitialis L. larvae and on the sandy soil from Hanu Conachi we have identified larvae of Polyphylla fullo F..

Table 1: The infestation of forest nurseries from Romania (Moldova) with Melolontha melolontha during the autumn of 2005

Number of nurseries (infection levels) 2 2 Larvae (transformed L3)/m Pupae (adults)/m NFA Branch Forest district Non Low Me- High Very Non Low Me- High Very Total infes- ≤0.25 dium 0.51- high infes- ≤0.2 dium 0.51- high > ted 0.26- 1.0 > 1.0 ted 0.21- 1.0 1.0 0 0.5 0 0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 Botosani Botosani 16 13 - 2 1 - 13 1 1 1 - Darabani 5 2 1 1 - 1 3 2 - - - Dorohoi 16 1 5 1 A.s. 2 7 12 - 2 1 1 Flamanzi 2 - 2 - - - 2 - - - - Trusesti 1 - - 1 - - - - - 1 - Total Botosani 40 16 8 5 3 8 30 3 3 3 1 Suceava Adancata 1 - 1 ------1* 6 - - - 1 5 6 - - - - Falcau 1 - - - 1 - 1 - - - - Falticeni 1 - - - 1* - - - 1* - - 15 11 - 1* 2 1* 14 1 - - - Gura 2 - 1* - - 1 - - - 1* 1 Moldovita 4 - - - - 4** 1 1 1 1 - Patrauti 1 - - - 1 - - - - - 1 Putna 2 - - - 1 1* 1 - 1 - - Rasca 1 - - - - 1* 1 - - - - 4 - - 1 2 1 1 1 1 1 - Tomnatec 3 - - - 1 2* 2 1* - - - Total Suceava 41 11 2 4 9 15 27 4 4 3 3 Neamt Borca 1 - - - 1 - 1 - - - - Galu 1 1 - - - - 1 - - - - Garcina 1 - 1 - - - 1 - - - - Roman 1 - - - 1* - - 1* - - - Tg. Neamt 1 - - - 1* - - - 1 - - Total Neamt 5 1 1 - 3 - 3 1 1 - - Iasi Ciurea 1 1 - - - - 1 - - - - Dobrovat 1 1 ------1 - - Harlau 1 1 - - - - 1 - - - - Iasi 4 4 - - - - 4 - - - - Pascani 1 - - - 1 - 1 - - - - Raducaneni 1 - - - 1 - 1 - - - - Total Iasi 9 7 - - 2 - 8 - 1 - -

IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 255 Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

Table 1 (continued) 1 2 3 4 5 6 7 8 9 10 11 12 13 Bacau Darmanesti 4 2 1 - - 1 4 - - - - Livezi 4 2 - - 1 1 4 - - - - Moinesti 5 3 - - - 2 1 1 2 1 - Traian 1 1 - - - - 1 - - - - Total Bacau 14 8 1 - 1 4 10 1 2 1 - Vaslui Bacesti 2 2 ------2 Focsani Focsani 1 1 - - - - 1 - - - - Neruju 1 1 - - - - 1 - - - - Soveja 1 - 1 - - - 1 - - - - Total Focsani 3 2 1 - - - 3 - - - - Galati Hanu Conachi 1 - - - - 1 P.f. 1 - - - - Tecuci 1 1 - - - - 1 - - - - Total Galati 2 1 - - - 1 2 - - - - Total Moldova 116 48 13 9 18 28 83 9 11 7 6 A. s.= Amphimalon solstitialis; P. f. = Polyphylla fullo; * = Beauveria brongniartii present

A flight of M. melolontha was registered in the spring of 2006, especially in Botosani and Suceava regions, at the altitudes of 200-400 m. Its intensity varied from slow to very high.

3.2. Natural infection with Beauveria brongniartii

In some forest nurseries, mainly those being very high infested by M. melolontha, there were observed natural infections produced on different stages of the pest (larva L3, pupa, adult) by B. brongniartii. The infections were more frequent in NFA Branches Suceava and Neamt (north of Moldova) in conditions of a very rainy year. High soil moisture favored the development of mycelia outside the bodies of infected insects. The appearance of decay was probable possible because of chemical treatments with Sinolintox 10G (100 kg/ha) and Counter 5G (50 kg/ha), which sensitized the survival specimens and influenced the fungal persistence in soil. It considers that there are differences in abundance of occurrence of entomopathogenic fungi in the soil in relation to the way of their utilization (Kleepsis et al., 1989). A number of 11 nurseries from NFA Branch Suceava infested by M. melolontha (37% from total infested) has registered infections with B. brongniartii (table 2, figure 1). Decay occurred, especially on old larvae L3 (82% of nurseries), and sometimes also, on pupae (18% in the nurseries Plopi-Falticeni and Corhana -Tomnatic) or on adults (18% in the nurseries -Adancata and Miloseni-). The level of infection varied in the larval stage from 0% (the nurseries Salcea and Corhana) to 100% (the nursery Salatruc), in the pupal stage from 0% to 12.5% (the nursery Plopi) and in the adult stage from 0% to 33.3% (the nursery Miloseni). In NFA Branch Neamt, only two nurseries (40%) were infected by B. brongniartii. So, the infection level was 15.7% on larvae and 2% on adults in the nursery Basta-Roman and 40% on larvae in the nursery Dumbrava-Tg.Neamt.

IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 256 Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

Table 2: The level of natural infection with Beauveria brongniartii in some forest nurseries from Romania (Moldova)

Infestation Infection with B. brongniartii NFA with No Forest district Nursery (%) Branch Melolontha melolontha L3 P A ∑ 0 1 2 3 4 5 6 7 8 1 Suceava Adancata Salcea Very high - - 7.7 7.7 2 Suceava Brodina Tabara Very high 20.0 - - 20.0 3 Suceava Falticeni Plopi High 37.5 12.5 - 50.0 4 Suceava Frasin Bucsoita Very high 55.5 - - 55.5 5 Suceava Frasin Salatruc Medium 100.0 - - 100.0 6 Suceava Gura Humorului Miloseni High 33.3 - 33.3 66.6 7 Suceava Moldovita Paltin Very high 3.1 - - 3.1 8 Suceava Moldovita Rasca Very high 4.0 - - 4.0 9 Suceava Rasca Calugara Very high 30.8 - - 30.8 10 Suceava Tomnatec Carbuna Very high - 10.0 - 10.0 11 Suceava Tomnatec Demacusa Very high 20.0 - - 20.0 12 Neamt Roman Basta Medium 15.7 - 2.0 17.7 13 Neamt Tg. Neamt Dumbrava Very high 40.0 - - 40.0

The larval stage was most susceptible to the fungal infection, confirming observations of Cisneros & Vera (2000) for Andean potato weevil, Premnotrypes spp., and earlier observations of Rojas (1981) and Vera (1992); the least susceptible stage was the adult.

Figure 2 – Melolontha melolontha larvae, natural infected with Beuveria brogniartii in Romanian forest nurseries

In laboratory conditions, B. brongniartii was isolated in large quantities from cadavers placed in moist chambers and profusely covered with white compact mass of mycelium. The development of the mycelium started after 2-4 days. We also isolated the fungus from several apparently healthy larvae of M. melolontha. On PDA, B. brongniartii showed good growth of white aerial mycelium with red-violet reverse of colonies, a characteristic feature which assisted rapid identification of fungal colonies. Blue-cotton lactophenol was used for microscopic observations. B. brongniartii are also found in soil. No differences were observed in the abundance of B. brongniartii in soil originated from different samples in relation to the kind of soil. The result of the mycological analysis revealed 23 isolates of B. brongniartii. Strains are stored on PDA medium in test tubes at 4°C, in order to select virulent, ecologically competent

IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 257 Ciornei et al.: Occurrence of Beauveria brongniartii (Sacc.) petch in Romanian forest nurseries infested with Melolontha melolontha (L.)

B. brongniartii strains. Due to the long persistence in infected larval stages of scarabeids, fungus-covered specimens are also kept under cool, dry conditions. Under laboratory conditions, the fungal isolates caused 100% mortality on the larvae of M. melolontha exposed to B. brongniartii conidia. In laboratory bio tests, pathological diagnosis was based on post-mortem symptoms, in order to discriminate between cases of mycosis and other causes of death; only those dead larvae which were covered by aerial mycelium were attribute to B. brongniartii infection.

4. Conclusions

Given the analysed material, it can be appreciate that B. brongniartii is a relatively widely distributed fungus in northern Romanian forest nurseries, infecting most commonly over- wintering larvae and pupae of M. melolontha and playing a role in the natural reduction of hibernating scarabeids. This enables us to open up new biological forestry protection opportunities.

5. References

BAJAN C. & KMITOWA K. 1968: Possibilities to use entomogenous fungi in the biological control of insects. Post. Nauk. Roln. 3 : 21-25.

CISNEROS F. & VERA A. 2000: Mass - Producing Beauveria brongniartii Inoculum, an Economical, Farm-Level Method. CIP Program Report 1999-2000. 155-159.

KLEESPIES R., BATHON H. & ZIMMERMANN G. 1989: Untersuchungen zum natürlichen Vorkommen von entomopathogenen Pilzen und Nematoden in verschiedenen Böden in der Umgebung von Darmstadt. Gesunde Pflanzen. 41: 350-355.

ROJAS, C.I. 1981: Studio de la susceptibilidad del Premnotrypes suturicallus al hongo Beauveria sp. Master’s thesis. Universidad Nacional del Centro del Peru, Huancayo, Peru.In : Cisneros F., In : Vera A. – 2000. Mass-Producing Beauveria brongniartii Inoculum, an Economical, Farm-Level Method. CIP Program Report 1999-2000. 155-159.

VERA, R.A. 1992.: Patogenicidad de cinco aislamentos del hongo Beauveria brongniartii sobre los estados de desarrollo del gorgojo de los Andes Premnotrypes latithorax. Master’s thesis. Universidad Nacional de San Augustin de arequipa, Crusco, Peru. In: Vera A. – 2000. Mass-Producing Beauveria brongniartii Inoculum, an Economical, Farm-Level Method. CIP Program Report 1999-2000. 155-159.

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