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For additional information about this publication click this link. http://hdl.handle.net/2066/145528 Please be advised that this information was generated on 2021-10-10 and may be subject to change. «3>> 4 % Ы ¿Л •i Biological control of the mushroom sciarid Lycoriella auripila and the pho Mesaselia halterata l>\ entomopathoeenic nematodes • Biological control of the mushroom sciarid Lycoriella auripila (Sciaridae) and the phorid Megaselia halterata (Phoridae) by entomopathogenic nematodes Biological control of the mushroom sciarid Lycoriella auripila and the phorid Megaselia halterata by entomopathogenic nematodes een wetenschappelijke proeve op het gebied van de Natuurwetenschappen, Wiskunde en Informatica Proefschrift ter verkrijging van de graad van doctor aan de Katholieke Universiteit Nijmegen, volgens besluit van het College van Decanen in het openbaar te verdedigen op maandag 25 januari 1999 des namiddags om 1.30 uur precies door Jacqueline Wilhelmina Andrea Scheepmaker geboren op 30 oktober 1959 te Uithoorn Promotor: Prof. Dr. LJ.L.D. Van Griensven Co-promotores: Dr. P.H. Smits IPO-DLO, Wageningen Dr. F.P. Geels Proefstation voor de Champignoncultuur, Horst Manuscriptcommissie: Prof. Dr. M.W. Sabelis (UvA) Prof. Dr. Ir. E.A. Goewie (LUW) Dr. Ir. F.J. Gommers (LUW) ISBN 90-6464-017-3 Cover: SEM: IPO-DLO Design by Caroline Buiskool Printed by Ponsen & Looijen BV, Wageningen Acknowledgements The work presented in this thesis was financed by the Dutch mushroom growers through the Agriculture Board, which enabled the employment of Jacqueline Scheepmaker as a PhD-student at the Catholic University of Nijmegen, Department of Microbiology. The study was carried out at the Mushroom Experimental Station, Horst, The Netherlands and at the DLO-Research Institute for Plant Protection (IPO-DLO), Wageningen, The Netherlands. Financial support for the publication of this thesis was given by Brinkman BV and MicroBio Division, Agricultural Genetics Company ((MBI-AGC, UK). Nemasys is produced by MicroBio and distributed in The Netherlands by Brinkman BV. CONTENTS Chapter page 1 Introduction 1 2 Substrate dependent larval development and emergence of the 21 mushroom pests Lycoriella auripila and Megaselia halterata 3 Location of immature stages of the mushroom insect pest 31 Megaselia halterata in mushroom-growing medium. 4 Susceptibility of larvae of the mushroom fly Megaselia halterata 39 (Diptera: Phoridae) to the entomopathogenic nematode Steinernema feltiae (Rhabditida: Steinernematidae) in bioassays 5 Comparison of the efficacy of entomopathogenic nematodes for 53 the biological control of the mushroom pests Lycoriella auripila (Sciaridae) and Megaselia halterata (Phoridae). 6 Influence of Steinernema feltiae and diflubenzuron on yield 67 and economics of the cultivated mushroom Agaricus bisporus in Dutch mushroom culture. 7 Effects of hosts and C02 on dispersal and persistence of 77 entomopathogenic nematodes used as biocontrol agents of sciarids and phorids in mushroom compst and casing. 8 Control of the mushroom pests Lycoriella auripila (Diptera: 93 Sciaridae) and Megaselia halterata (Diptera: Phoridae) by Steinernema feltiae (Nematoda: Steinernematidae) in field experiments. 9 General discussion 105 Summary 117 Samenvatting 120 List of publications 124 Curriculum vitae 125 Dankwoord 126 1 CHAPTER 1 Introduction 2 Chapter 1 Introduction When mushroom culture first became of significant economic importance, entomological research was focused on the identification of insect pests and other fauna. Sciaridae, Phoridae and Cecidomyiidae were identified as the main insect pests (Austin, 1933a; 1933b; 1937; Broekhuizen, 1938; Jary & Austin, 1934; Thomas, 1939; Flachs, 1941; Schmitz, 1948; Brauns, 1950). In the UK, Wyatt (1959), Binns (1973) and Hussey (1959) were active in elucidating the insects' life cycles. In the USA, similar work was done by Chung & Snetsinger (1965; 1968). It became commonly accepted that insect pests can be largely avoided by observance of good hygiene (Ganney, 1973) and strict use of insecticides. Disadvantages such as resistance, chemical residues in the mushroom and the mushroom waste, health danger to the grower during application and yield reduction were among the main reasons to find other, safer ways to control insects. In 1996, yearly production of the white button mushroom (Agaricus bisporus) in the Netherlands was 240 min kg, representing a production value of around NLG 600 min. After tomatoes, mushrooms are the second most valuable vegetable crop, with cucumbers a close third. When processed mushrooms are included, mushrooms are leader with a turn­ over 1998 value that exceeds an amount of NLG 1 billion. Such a figure justifies any research that might result in a safer control method that can protect the crop from insect pest infestations. Reduction of the use of pesticides Under increasing pressure from the general public the Dutch government developed a policy to cope with a multitude of environmentally related problems in agriculture and horticulture. In 1991 the Multi-Year Crop Protection Plan was presented (Meerjarenplan Gewasbescherming, MJP-G) which had to lead to a sustainable, safe and competitive agriculture by the year 2000 (Baerselman, 1992). By then, the use of pesticides should be halved relative to the level in 1988. For each sector the exact reduction to be attained was calculated, which meant, specifically, a 52% reduction in pesticide use for mushroom culture. Research plans were initiated by the individual sectors and financed by the government or by the sector itself. In 1991, the research project on biological control of insect pests with entomopathogenic nematodes, described in this thesis, was started. In 1992, different research was initiated concerning the development of new strains resistant to Verticillium fungicola var. fungicela, causing "dry bubble" in mushrooms. Both projects were financed by the Agricultural Board (Landbouwschap). The mushroom industry itself significantly reduced pesticide use with the increased use of full-grown compost. By using centrally produced full-grown compost, the farmers could skip the spawn-running period, which is most susceptible to infection by insect pests and moulds. Skipping the spawn-running period resulted in a major reduction of the total amount of pesticides. In the new situation, spawn-running was performed indoor in tunnels, under highly controlled conditions and void of insect infestations. Further reduction of the use of chemicals Introduction 3 was expected from better sealing of the cells and book-keeping of applicated pesticides. Already in 1995, the use of insecticides was reduced by 75% and the use of fungicides by 40%, together, an average reduction of 64% relative to the use in 1988 (Van Keulen, 1997). Further reductions can possibly obtained by installation of proper filters in air inlets and outlets and application of control methods at the right moment. A threshold value of the severity of pests is useful in determining the necessity of chemical control. Preventive control methods then become unnecessary. Cultivation of the mushroom Agaricus bisporus The two essential basic materials used for the cultivation of the common white mushroom Agaricus bisporus are compost and casing soil. The preparation of mushroom compost in the Netherlands The production of mushrooms requests a special compost. Conventionally, its preparation can be subdivided in two phases. Phase I is an outdoor composting process in which a mixture of horse manure, wheat straw, chicken manure and gypsum (Fermor et al. 1985; Gerrits, 1987) is wetted and piled in dikes. During a 3- wk period, easy degradable substrates are consumed by the bacterial microflora. At the start of this process, this microflora is mesophyllic, but during the rapid temperature increase, it is substituted by a thermophilic microflora. Simultaneously, ammonia (NH3) and unpleasant-smelling compounds are emitted into the environment. Phase II is an indoor process which starts with pasteurization of the compost during 6-8 h at 57°C. All harmful organisms that were able to survive Phase I, such as mites, saprophytic nematodes and insects are then killed. Pasteurization is followed by conditioning at approximately 45-50°C during a period of 7 days. At this temperature a thermophilic microflora of actinomycetes and moulds is able to develop (Fergus, 1964). This microflora incorporates part of the remaining NH3. At the end of Phase II the compost has reached the state of 'selectivity'. This term refers to ecological properties of the compost, selectively enabling A. bisporus to colonize the compost. It implies that A. bisporus has a lead over the much reduced mesophyllic microflora. Also, the thermophilic fungus Scytalidium thermophilum, which is predominantly present at the end of Phase II (Straatsma et al., 1989) provides for selectivity by protecting against negative effects of compost bacteria on mycelial growth of Λ. bisporus. In the highly populated country of the Netherlands, outdoor composting was no longer tolerated due to emission of NH3 (leading to acidification of the soil) and unpleasant-smelling compounds into the environment. Experiments by Gerrits (1987, 1993) showed that Phase I could be carried out indoors during only 6 days, in tunnels. Nowadays, Phase I and II take place in tunnels where airwash installati­ ons withdraw ammonia from the