IOBC/wprs Bulletin Vol. 28(2) 2005

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Insect Pathogens and Insect Parasitic Nematodes: Melolontha IOBC/wprs Bulletin Vol. 28(2) 2005 pp. 31-35 Development of the Melolontha populations in the canton Thurgau, eastern Switzerland, over the last 50 years Siegfried Keller, Hermann Brenner Agroscope FAL Reckenholz, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland; LBBZ Arenenberg, CH-8268 Salenstein, Switzerland Abstract: Two Melolontha melolontha L. populations each with a three year life cycle exist in the canton Thurgau. The Bernese cycle (III-1) in the western part and the Uranean cycle (III-2) in the central and eastern part of the canton. Two methods were used to monitor their development: The length of forest borders damaged by swarming adults and number and amount of damages done by white grubs. The data show that the Bernese cycle had its peak period 1972-1975, then collapsed and remained stable at a low level. The Uranean cycle had a peak in the early 50s and 1991-1994. The damages done by white grubs are separated between the two flight regimes but show a good correlation with the damages done by adults in the Uranean flight area. Control measures mainly with the fungus Beauveria brongniartii were only done in the Uranean flight area. A comparison between treated and untreated area demonstrate the long lasting efficacy of this method. Nevertheless, it is concluded that a continuous monitoring of the pest population is a prerequisite for a successful Melolontha management. Keywords: Melolontha melolontha, population dynamics, Thurgau, damages. Introduction Two Melolontha melolontha L. populations each with a three year life cycle exist in the canton Thurgau. However, the cycles of the two populations are shifted by one year: The Bernese cycle (III-1) in the western part and the Uranean cycle (III-2) in the central and eastern part of the canton. The development of the Melolontha populations over the last 50 years is well documented mainly by the length of damaged forest borders and by the extent of damages caused by the white grubs. The aim of this work is a documentation of the development of the cockchafer population in an area which permanently suffered from white grub damages since the mid of the 20 th century and to set the population development in relation to control measures with the fungus Beauveria brongniartii. These treatments were mainly carried out in the years 1985 and 1988, when blastospores were sprayed on swarming beetles along forest borders (Keller et al. 1997). In 1985 the Uranean flight area “north” was treated and in 1988 that of the area “south”. The fungus was applied on forest borders in a delimited area where the cockchafers concentrated. In addition to the blastospore treatments, fungus granules (“Beauveria-Schweizer”) were applied in orchards from 1991-1995 followed by the installation of hail nets during subsequent flights (Brenner & Keller, 1996). Material and methods At the end of each cockchafer flight the feeding damage of the swarming adults on oaks and beaches along forest borders was assessed using the scores: undamaged, low, medium and heavy damages. The damages were recorded on a 1:25’000 map and the lengths of the damaged forest borders measured on the map. 31
32 Since 1974 the financial losses due to white grub feeding are reimbursed through a specific fund. The amounts allow to draw conclusions on the densities of white grubs. To set the population development in relation to control measures we chose the Uranean flight area “north” (treated 1985) and compared the length of the heavily damaged forest borders inside the treated area with that outside. Results and discussion Length of damaged forest borders The length of the forest borders damaged by the swarming adults is recorded since 1955 (Uranean cycle) and 1960 (Bernese cycle) respectively. The two cycles did not develop synchronously. According to the damages of forest borders the Bernese cycle had its peak period 1972-1975. From 1981 onwards the population is low and of minor economic importance. The Uranean cycle had two peaks, one in the early 50s at the beginning of the phase with chemical treatments, and the other between 1991 and 1994. With the exception of the period from 1961-1970, this population always caused significant damages especially in orchards. A chemical treatment was planned for 1973, however public concerns prevented the action. The consequences were 1) the creation of a special fund to compensate the damages done by white grubs and 2) the start for the research on biological control. km 500 450 400 350 300 250 200 150 100 50 0 Forest borders damaged by cockchafers, Uranean flight 1955 1958 heavy medium weak total 1961 1964 1967 1970 1973 1976 1979 1982 Year 1985 1988 1991 1994 1997 2000 2003 Figure 2: Development of the Melolontha population in the Bernese flight area from 1960-2002. No data were recorded 1963-1969 and 1981. Payments to the farmers to compensate for damages done by white grubs started 1974. The amount of contributions over the years does not reflect both cycles, it rather correlates with the Uranian cycle only. On average the yearly number of damages from 1974-2004 was 75, the maximum was reached 1992 with 340 cases, the minimum was a single case in 1997. The yearly compensations amounted to an average of CHF 237’604.-. On average a single damage was compensated with CHF 3152.-.
Page 1 and 2: IOBC / WPRS Working group „Insect
Page 3: Preface The Working Group “Integr
Page 6 and 7: iv ERICSSON Jerry University of Bri
Page 8 and 9: vi PÁZMÁNDI Christian Centre for
Page 10 and 11: viii
Page 12 and 13: x Metarhizium anisopliae for white
Page 14 and 15: xii
Page 16 and 17: Insect Pathogens and Insect Parasit
Page 18 and 19: stands (Levine et al. 2002) to feed
Page 20 and 21: In conclusion, the chemical control
Page 22: Kuhlmann, U. & W.A.C.M. Burgt 1998:
Page 25 and 26: 10 Austria, Belgium, Czech Republic
Page 27 and 28: 12 The control strategies used agai
Page 29 and 30: 14 1) Case study: Soil application
Page 31 and 32: 16 2) Case study: Genetic diversity
Page 33 and 34: 18 Bidochka, M.J., Menzies, F.V. &
Page 38 and 39: Results and discussion The first co
Page 40 and 41: Isolation of Beauveria brongniartii
Page 42 and 43: grown in the dark for 3 weeks at 22
Page 44: genotypes (A, B, D, and F) were re-
Page 49 and 50: 34 there is no more a strict three
Page 54 and 55: Numbers of captured beetles were an
Page 56 and 57: Mean captues +/- SE per trap & day
Page 58 and 59: dilution for plating (see above). F
Page 60: 45 “New” white grubs
Page 63 and 64: 48 The goal of this study was to de
Page 65 and 66: 50 In spring 2003 the density of M.
Page 67 and 68: 52 (Germany). The first treatment w
Page 69 and 70: 54 Application timing of H. bacteri
Page 74 and 75: Results and discussion Collection o
Page 76: Discussion During this study the en
Page 79 and 80: 64 Materials and methods Source of
Page 81 and 82: 66 100 80 60 40 20 0 100 80 60 40 2
Page 83 and 84: 68 During this study, selectivity a
Page 86: 71 Wireworms
Page 89 and 90: 74 Solanum tuberosum L. (Solanaceae
Page 91 and 92: 76 % CATEGORIZATION OF MORBIDITY FI
Page 93 and 94: 78 of adults caught can reliably pr
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Insect Pathogens and Insect Parasit
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Results and discussion Before spray
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References Parker, W.E. & Howard, J
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88 insecticide residues. Nonetheles
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90 References Cockbill, G.F., Hende
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92 Results and discussion a. Taxono
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94 published; some information has
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96 C2a: no sensitive crops in the s
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98 Furlan, L., Tóth, M., Ujvary, I
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100 Roberts, A.W.R. 1928: On the li
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102 Results and discussion Crop rot
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104 % damage by wireworms 100 80 60
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106 noticed that grass-clover in cr
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108 % damage by wireworms 60 50 40
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110 Materials and methods Soil Soil
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112 Emigration - deterrence of wire
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114 Table 1. The effect of broadcas
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116
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118 presence and abundance of wirew
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120 Furthermore, A. obscurus larvae
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122 Horton, D.R. & Landolt, P.J. 20
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124 Bait trapping 48 bait traps wer
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126 Acknowledgements We thank Anton
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128 history can be obtained (Scheu
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130 lower left hand corner of fig.
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132 Eggers, T. & Jones, T.H. 2000:
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134 pheromone combinations for each
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136 Fig. 2. Click beetle spp. captu
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138 Fig 4. Click beetle spp. captur
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140 Fig 6. Click beetle spp. captur
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142 Siirde, K., Lääts, K., Erm, A
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Fig. 2. Comparison of several trap
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Fig. 5. Catches of WCR in VARs+ tra
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Table 1. Performance characteristic
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Miscellaneous
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158 Material and methods Field tria
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160 Figure 2: Abundances of Collemb
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162
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164 but also when used against the
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166 based EPN product in this exper
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168
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170 branches. Beetles can walk up t
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172 1999/ 2000, I 1999/ 2000, C 200
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174
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176 Experimental design During the
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178 Acknowledgements We thank Stefa
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180 Spore suspension Conidia of M.
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182 Data about the stability of spo
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184 dence of host presence and appl
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186 Material and methods All habita
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188 Hajek, A.E. & Leger, R. J. St.
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190 Risk Assessment of Fungal Biolo
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192 It is scheduled that our future
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IOBC/wprs Bulletin Vol. 28(2) 2005

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