Health effects of predatory beneficial mites and wasps in greenhouses
2 Biology of the selected species of arthropods
- 2.1 The predatory mite Amblyseius cucumeris
- 2.2 The predatory mite Amblyseius californicus
- 2.3 The predatory mite Phytoseiulus persimilis
- 2.4 The predatory mite Hypoaspis miles
- 2.5 The parasitoid Aphidius colemani
- 2.6 The parasitoid Encarsia Formosa
- 2.7 The two-spotted spider mite Tetranychus urticae
- 2.8 The mould mite Tyrophagus putrescentiae
Below is given a brief biological character of relevance of the 6 beneficial species Amblyseius cucumeris, Amblyseius californicus, Phytoseiulus persimilis, Hypoaspis miles, Aphidius colemani and Encarsia formosa, as well as of the 2 pest species, the two-spotted spider mite Tetranychus urticae and the mould mite Tyrophagus putrescentiae.
The descriptions encompass methods for release, frequently treated cultures, biological parameters (survival, reproductive capacity, and population growth rate), possible remains from the species and the possibility to survive and reproduce at the consumers place.
In the descriptions, information on survival and reproduction pertains to normal glasshouse conditions, here defined as 20-25°C, 70-80 % rh. Only crops relevant for Denmark are mentioned. When referring to the possibility for the species to survive at the consumers place, the following conditions are assumed: in hobby glasshouses: as in the industry; in windowsills, patios etc.: 25-40°C, 20-50 % rh. It should be noted that glasshouse products prior to their arrival at retailers and consumers are subjected to transport conditions different from those during production. These transport conditions vary depending on producer, product and destination. In addition, season will influence the actual conditions in the refrigerated vans used for transport – during summer it will be more difficult to maintain a specific low temperature than during winter. Generalising, however, the conditions during transport are 1-4 days at 10-17°C for pot plants (Lene Petersen, DEG; Niels Peter Bach, GASA Group) and ½-1 day at 10-15°C for tomatoes and cucumbers (GASA Odense Frugt & Grønt). These conditions may affect the ability of pests and beneficials on the products to survive during transport hereby influencing their potential establishment at the consumers place.
An overview of the collected information is found in table 2-1.
2.1 The predatory mite Amblyseius cucumeris
(Synonym Neoseiulus cucumeris)
Photo: H.F. Brødsgaard, DJF
2.1.1.1 Overview
Predatory mite primarily used for control of thrips. Also eats various mites (Malais & Ravensberg, 2003) and may survive on pollen (Matsuo et al., 2003).
2.1.1.2 Cultures
The mite is used in a number of cultures, including cucumber and various pot plants (e.g. Chrysanthemum, Gerbera, and Cyclamen).
2.1.1.3 Systems for release
Several systems for release. Direct releases are often used preventively (i.e. before the appearance of the target pest, thrips). This means that distribution of the mites often are repeated at short intervals (2-3 weeks) in case no other food sources are available.When breeding units are used, these may be replaced continuously throughout the cultural period with 4-5 week intervals.
Direct release 1: sprinkler bottles with several thousand adults or adults and nymphs (numbers varies from 10,000 up to 500,000), mixed with bran and mould mites (T. putrescentiae) as prey during transport (ratio between predatory mites and mould mites is approximately 1: 2-5). The content of the bottle is distributed evenly by hand in the crop, on leaves or in small piles on rock wool[1].
Direct release 2: as above but vermiculite[2] is added which makes the product suited for distribution with mechanical blowers. A. cucumeris is the only beneficial mite for which distribution may take place with blowers.
Breeding units: sachets with different stages of the mite (numbers 200-1,000), as well as bran and mould mites (ratio between predatory mites and mould mites is approximately 1: 15:30). The sachets are placed evenly in the crop by hanging them from the plants. The mites reproduce within the sachets and migrate slowly out in the culture over a period of up to 5-8 weeks.
2.1.1.4 Release rates
Direct releases: preventively: 50-100 mites /m² every 2 weeks; curatively: 100-250 mites /m² every week. Breeding units: 1 sachet /2-3m² in ornamentals (to be replaced every 4-5 week); 1 sachet /3. cucumber plant (to be used twice per cucumber planting)[3].
2.1.1.5 Survival and reproduction
The population of released mites will survive for up to 3-4 weeks (Zhang et al., 2003) and will reproduce in the culture (both provided that suitable prey is available). Reproduction characteristics: 30-35 eggs/female (Castagnoli & Simoni, 1990; Zhang et al., 2003); sex-ratio ca. 65 % females (Castagnoli & Simoni, 1990; Zhang et al., 2003) population growth rate (rm) 0.15-0.18 day-¹ [i.e. doubling time 3.8-4.6 days; finite rate of increase 1.2 (for every individual in one generation there will be 1.2 present the next)] (Castagnoli & Simoni, 1990; Cloutier et al., 1995; Li et al., 2003). Development from egg to adult last ca. 10 days (Castagnoli et al., 1990).
Minimum temperature for development is around 8°C and maximum temperature approx. 35°C (Castagnoli et al., 1990; Malais & Ravensberg, 2003). Optimum temperature for development and reproduction is 25-30°C (Castagnoli et al., 1990; Cloutier et al., 1995; Li et al., 2003; Malais & Ravensberg, 2003). Optimum humidity for survival of adults and juveniles is approx. 75-95 % rh (Shipp & van Houten, 1997). Survival of juveniles and adults decreases with temperature above 25°C and with humidity below ca. 55 % (Shipp & van Houten, 1997).
The commercially available strain of A. cucumeris does not enter diapause (i.e. hibernation).
For survival and reproduction of mould mites, see the section on T. putrescentiae.
2.1.1.6 Possible remains
A. cucumeris passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adults. Between each stage the old cuticle is shed and will remain in the crop on leaves and in flowers until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in the crop until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
For remains of mould mites, see the section on T. putrescentiae.
2.1.1.7 Survival at consumers
In the absence of food A. cucumeris may survive for some time (Malais & Ravensberg, 2003); (no further specifications found).
The survival with access to prey or pollen/nectar is stated above. A. cucumeris is likely to thrive in hobby glasshouses but may find it difficult to sustain population development in more interior places due to a generally high temperature and low humidity.
For survival and reproduction of mould mites see the section on T. putrescentiae.
2.2 The predatory mite Amblyseius californicus
(Synonym Neoseiulus californicus)
Photo: BioBest, www.biobest.be
2.2.1.1 Overview
Predatory mite used primarily for control of spider mites (Malais & Ravensberg, 2003). In the absence of spider mites the predatory mite may survive on thrips (Malais & Ravensberg, 2003), other mites (Castagnoli & Falchini, 1993) and pollen (Dindo, 1995).
2.2.1.2 Cultures
The mite is used in a number of different glasshouse cultures, both vegetables and ornamentals.
2.2.1.3 Systems for release
The mite is marketed in bottles with 2,000 individuals (nymphs and adults) mixed with vermiculite[4]. The content of the bottle is distributed evenly by hand in the crop on leaves[5].
2.2.1.4 Release rates
Preventively: 1-2 mites /m² every 2-3 weeks; curatively: 6 mites /m² one time[6]. Some recommend the simultaneous use of both A. californicus and P. persimilis when spider mites are present in the culture[7].
2.2.1.5 Survival and reproduction
The population of released mites will survive for up to 4-8 weeks (de Courcy Williams & Kravar-Garde, 2002; El-Laithy & El-Sawi, 1998) and will reproduce in the culture (provided that suitable prey is available). Reproduction characteristics: 60-65 eggs/female (Castagnoli & Simoni, 1991; El-Laithy & El-Sawi, 1998); sex-ratio 50-65 % females (Castagnoli & Simoni, 1991; Castagnoli & Falchini, 1993); population growth rate (rm) 0.12-0.26 day-¹ [i.e. doubling time 2.7-5.8 days; finite rate of increase 1.1-1.3 (for every individual in one generation there will be 1.1-1.3 present the next)] (Castagnoli & Simoni, 1991; Rencken & Pringle, 1998). Development from egg to adult last ca. 6-7 days (Castagnoli & Simoni, 1991).
Lower temperature threshold for development, survival and reproduction is around 8-9°C (Castagnoli & Simoni, 1991; Rencken & Pringle, 1998) and populations can still develop at 33°C (Malais & Ravensberg, 2003). No information can be found on the upper temperature threshold. Optimum temperature for development and reproduction seems according to (Castagnoli & Simoni, 1991) to be around 28-32°C. Relative humidity below 60 % has a negative effect on population growth (Malais & Ravensberg, 2003).
The commercially available strain of A. californicus does not enter diapause (i.e. hibernation).
2.2.1.6 Possible remains
A. californicus passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adults. Between each stage the old cuticle is shed and will remain in the crop on leaves or in flowers until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in the crop until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
2.2.1.7 Survival at consumers
In the absence of food A. californicus may survive for some time ((Malais & Ravensberg, 2003); no further specifications found).
The survival with access to prey or pollen/nectar is stated above. A. californicus is likely to thrive in hobby glasshouses and perhaps also in more interior places, provided that temperature and humidity conditions are not too server.
2.3 The predatory mite Phytoseiulus persimilis
Photo: F. Lind, DJF
2.3.1.1 Overview
Predatory mite used for control of spider mites (Malais & Ravensberg, 2003).
2.3.1.2 Cultures
The mite is used in a number of different glasshouse cultures, including cucumbers and ornamentals (e.g. Gerbera). On tomato a special strain adapted to tomato is marketed[8].
2.3.1.3 Systems for release
Several systems for release exist.
Release only of predatory mites:
Mixed with carrier material. Here the mite is delivered in bottles with 1,000-2,000 individuals (nymphs and adults) mixed with vermiculite[9] or wood chips. The content of the bottle is distributed by hand in the crop on leaves[10]. The strain used for bio control of spider mites on tomato is formulated in this way.
Release of both spider mites and predatory mites[11]:
1) On leaves with spider mites. Here the mite is delivered in packages with 2,000 individuals (adults and nymphs) on bean leaves, with spider mites serving as food during transport and establishment (ratio between predatory mites and spider mites is approximately 1: 5). The leaves are distributed in the crop.
2) Bottles with predatory mites and with spider mites, respectively. Here both spider mites and predatory mites are delivered. Spider mites are released and for every second dose of spider mites, predatory mites are added.
2.3.1.4 Release rates
(valid for both the usual strain of P. persimilis and for the tomato-adapted strain)
Preventively: 1-2 mites /m² every 2-3 weeks[12]; curatively for light infestations: 3-10 mites /m² once a week for 2 or more weeks; curatively for heavy infestations: 20-50 mites /m² once a week for 2 or more weeks[13]. When using the mites curatively for light infestations they are placed on plants with symptoms, as well as on plants without[14]. When used curatively for heavy infestations they are introduced only in the infested areas[15].
2.3.1.5 Survival and reproduction
The population of released mites will survive for up to 3-4 weeks (Cho et al., 1995; Galazzi & Nicoli, 1996; Laing, 1968) and will reproduce in the culture (both provided that spider mites are available). Reproduction characteristics: 40-75 eggs/female (Gillespie & Quiring, 1994; McClanahan, 1968; Schulten et al., 1978); sex-ratio 60–80 % females (Kilincher et al., 1996; Toyoshima & Amano, 1998); population growth rate (rm) 0.2-0.4 day-¹ [i.e. doubling time 1.7-3.5 days; finite rate of increase 1.2-1.5 (for every individual in one generation there will be 1.2-1.5 present the next)] (Hance, 1988; Kilincher et al., 1996; Laing, 1968; Mesa et al., 1988). Development from egg to adult last ca. 5-7 days (Mesa et al., 1988; Sabelis, 1981).
Minimum temperature for development is around 11°C (Morewood, 1992) and maximum temperature ca. 30-35°C (Ashihara et al., 1976; Hamamura et al., 1976; Malais & Ravensberg, 2003). Optimum temperature for development and reproduction is around 25-27°C (Santi & Maccagnani, 2000; Stenseth, 1979). Lower humidity threshold is around 65 % rh. (Perring & Lackey, 1989).
P. persimilis does not enter diapause (i.e. hibernation).
For survival and reproduction of spider mites either present in the culture, where P. persimilis is released, or released together with the predatory mites, see the section on T. urticae.
2.3.1.6 Possible remains
P. persimilis passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adult. Between each stage the old cuticle is shed and will remain in the crop on leaves or in flowers until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in the crop until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
2.3.1.7 Survival at consumers
In the absence of spider mites, P. persimilis will first act cannibalistic and subsequently starve and die after a short time (2-4 days or 1-2 weeks without and with water, respectively (de Courcy Williams & Kravar-Garde, 2002; Mori & Chant, 1966; Sabelis, 1981)). In the absence of food, egg laying ceases (Sabelis, 1981).
The survival with access to prey is stated above. Spider mites will thrive in consumers’ hobby glasshouses and are, in addition, able to survive on plants in windowsills, patios and similar interior parts of the homes of consumers. P. persimilis will likewise thrive in hobby glasshouses but normally finds it difficult to sustain population development in more interior places, due to a generally high temperature and low humidity.
2.4 The predatory mite Hypoaspis miles
Photo: S. Ydergaard, DJF
2.4.1.1 Overview
Soil-dwelling predatory mite used for control of arthropods with soil-dwelling stages, e.g. sciarids, fly larvae, spring tails, mites and thrips (Malais & Ravensberg, 2003).
2.4.1.2 Cultures
The mite is used in a variety of glasshouse cultures, especially ornamentals (e.g. Poinsettia, Cyclamen).
2.4.1.3 Systems for release
The mite is marketed in bottles with 10,000-50,000 individuals (nymphs and adults) mixed with peat and vermiculite[16]. Some products also contain the mould mite, T. putrescentiae (ratio between predatory mites and mould mites is approx. 1: 1-2). The content of the bottle is distributed evenly by hand in the crop on the compost or on rock wool cubes[17]. The mite may be introduced below the tables to help control of sciarids[18].
H. miles is completely soil-dwelling in all stages inhabiting the top layer of the soil (at a depth of 1-4 cm). The mite seldom occurs on the above-ground plant parts.
2.4.1.4 Release rates
Preventively: 100 mites /m² once or twice[19]; curatively: 200-1000 mites /m² applied at least once[20].
2.4.1.5 Survival and reproduction
The population of released mites will survive for up to 9-16 weeks (Enkegaard et al., 1997; Ydergaard et al., 1997) and will reproduce in the culture (both provided that suitable prey is available). Reproduction characteristics: 45-55 eggs/female (Enkegaard et al., 1997; Ydergaard et al., 1997); sex-ratio 60-90 % females (Enkegaard et al., 1997; Ydergaard et al., 1997); population growth rate (rm) 0.07-0.13 day-¹ [i.e. doubling time 5.3-9.9 days; finite rate of increase 1.1 (for every individual in one generation there will be 1.1 present the next)] (Enkegaard et al., 1997; Ydergaard et al., 1997). Development from egg to adult last ca. 13-20 days (Enkegaard et al., 1997; Ydergaard et al., 1997).
Minimum temperature for population development is around 10-12°C (Ydergaard et al., 1997) and maximum temperature approx. 33°C (Wright & Chambers, 1994). Optimum temperature is around 22-25°C (Ydergaard et al., 1997). Population development requires that the soil medium is moist but not too wet[21].
H. miles does not enter diapause (i.e. hibernation).
For survival and reproduction of mould mites, see the section on T. putrescentiae.
2.4.1.6 Possible remains
H. miles passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adults. Between each stage the old cuticle is shed and will remain in or on the soil until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in or on the soil until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit in or on the soil. No information is available on the durability of this material.
For remains of mould mites, see the section on T. putrescentiae.
2.4.1.7 Survival at consumers
H. miles brought to the home of consumers (hobby glasshouses, windowsills, patios and similar interior parts) in the soil of potted plants are likely to be able to survive and reproduce provided that the above mentioned conditions are met and provided that the soil contains prey items suited for the mite. In the absence of food, the mite may survive for 3-4 weeks. In the absence of food, egg laying ceases (Malais & Ravensberg, 2003).
For survival and reproduction of mould mites, see the section on T. putrescentiae.
2.5 The parasitoid Aphidius colemani
Photo: Jack Kelly Clark, University of California,
2.5.1.1 Overview
Parasitoid used for control of aphids (Malais & Ravensberg, 2003). Parasitoids are obligatory parasites that for reproduction require hosts in which the eggs are laid and in which development to adults takes place. Adult A. colemani feeds on honeydew[22].
2.5.1.2 Cultures
The parasitoid is used in a number of cultures where suitable host aphids (e.g. cotton aphids, Aphis gossypii and peach-potato aphids, Myzus persicae) occur, including tomato and cucumber and various pot plants (e.g. Chrysanthemum, Gerbera).
2.5.1.3 Systems for release
Two systems for release.
Direct release: sprinkler bottles with 500-5,000 parasitoids (a few adults, the rest in the mummy stage (parasitized aphids in the last stage of parasitisation)) mixed with sawdust or wood chips. The content of the bottle is distributed evenly by hand in the crop on leaves, growing media or rock wool[23].
Banker plants: an open rearing system created by placing wheat plants infested with approx. 500 cereal aphids, Rhopalosiphum padi in the glasshouse and introducing A. colemani onto these. The parasitoids will reproduce on the cereal aphids and disperse to the glasshouse crop[24].
2.5.1.4 Release rates
Direct releases: preventively: 0.15 parasitoids /m² every week [25] or ½-1 parasitoids /m² every 2 weeks[26]; curatively: ½-1 parasitoids /m² every ½ week or every week for 3-6 weeks[27].
Banker plants: min. 5 banker plants /1,000 m² [28] which are substituted every 2-3 weeks. A. colemani is introduced at 0.1-0.15 parasitoids /m² each time.
2.5.1.5 Survival and reproduction
The population of released parasitoids will survive for up to 1 week (Hofsvang & Hagvar, 1975; van Steenis, 1995) and will reproduce in the culture provided that suitable aphid species are present. Reproduction characteristics: 300-390 eggs/female (Hofsvang & Hagvar, 1975; van Steenis, 1993; van Steenis, 1995); sex-ratio ca. 66 % females (Gucuk & Yoldas, 2000); population growth rate (rm) 0.3-0.35 day-¹ [i.e. doubling time 2-2.3 days; finite rate of increase 1.35-1.4 (for every individual in one generation there will be 1.35-1.4 present the next)] (Ahmad & Hodgson, 1997; van Tol & van Steenis, 1994). Development from egg to adult last ca. 10-13 days (van Steenis, 1993).
Minimum temperature for population development is around 3-5°C (Elliott et al., 1995; Prinsloo et al., 1993; Sampaio et al., 2003) and maximum temperature 25-30°C (Ahmad & Hodgson, 1997; Guenaoui, 1991; Malais & Ravensberg, 2003). Optimum temperature for development and reproduction is around 22-25°C (Ahmad & Hodgson, 1997; Sampaio et al., 2003).
A. colemani does not enter diapause (i.e. hibernation).
2.5.1.6 Possible remains
The development of an individual A. colemani takes place within an aphid. In the process, the entire aphid is consumed and all that remains after the parasitoid has emerged is the outer cuticle of the parasitized aphid. No information is available on the durability of these remains. The adult parasitoids produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
2.5.1.7 Survival at consumers
Without access to hosts or honeydew the lifespan of A. colemani is reduced to 1-2 days at temperatures around 25°C (Gucuk & Yoldas, 2000). Supplement of sugar solutions prolongs longevity to about 2-4 days (Gucuk & Yoldas, 2000).
The survival with access to hosts is stated above. Aphids will thrive in consumers’ hobby glasshouses and are, in addition, able to survive on plants in windowsills, patios and similar interior parts of the homes of consumers. A. colemani will likewise thrive in hobby glasshouses but normally finds it more difficult to sustain population development in more interior places, due to a generally high temperature and low humidity.
2.6 The parasitoid Encarsia Formosa
Photo: F. Lind, DJF
2.6.1.1 Overview
Parasitoid used for control of whiteflies (Malais & Ravensberg, 2003). Parasitoids are obligatory parasites that for reproduction require hosts in which the eggs are laid and in which development to adults takes place. Adult E. formosa feeds on honeydew, as well as on host body fluid[29].
2.6.1.2 Cultures
The parasitoid is used in a number of glasshouse vegetables (tomato, cucumber) and various pot plants (e.g. Poinsettia, Gerbera).
2.6.1.3 Systems for release
The parasitoids are supplied as parasitized whitefly pupae glued to cards (100-500 pupae per card) that are hung from the plants in an even distribution[30].
2.6.1.4 Release rates
Preventively: 1½ parasitoids /m² every week or every second week[31]; curatively: 3-10 parasitoids /m² every week until sufficient parasitisation is achieved (minimum 5 weeks)[32]. For treatment of “hot-spots” (areas with high infestation of whiteflies) more than 10 parasitoids /m² may be needed[33].
2.6.1.5 Survival and reproduction
The population of released parasitoids will survive for up to 2-3 weeks (Burnett, 1949; Dindo, 1995; Enkegaard, 1993; Yoldas, 2001; Di Pietro, 1977) and will reproduce in the culture provided that suitable whitefly species are present. Reproduction characteristics: 100-350 eggs/female (Gast & Kortenhoff, 1983; Kajita, 1979; Madueke, 1979; Parr et al., 1976; van Lenteren et al., 1987; Yoldas, 2001); sex-ratio ~100 % females (Ghahhari & Hatami, 2001; Heimpel & Lundgren, 2000; van Roermund & van Lenteren, 1992); population growth rate (rm) 0.13-0.28 day-¹ [i.e. doubling time 2.5-5.3 days; finite rate of increase 1.14-1.32 (for every individual in one generation there will be 1.14-1.32 present the next)] (Arakawa, 1982; Enkegaard, 1993; Lopez & Botto, 1995; van Roermund, 1995). Development from egg to adult last ca. 15-25 days (Arakawa, 1982; Di Pietro, 1977; Jansen, 1974; Madueke, 1979).
Minimum temperature for population development is around 10-11°C and maximum temperature approx. 38°C (van Roermund & van Lenteren, 1992). Optimum temperature for development and reproduction is around 25°C (van Roermund & van Lenteren, 1992; van Roermund, 1995), and optimum humidity is 50-85 % rh (Malais & Ravensberg, 2003).
E. formosa does not enter diapause (i.e. hibernation).
2.6.1.6 Possible remains
The development of an individual E. formosa takes place within a whitefly. In the process the entire whitefly is consumed and all that remains after the parasitoid has emerged is the outer cuticle of the parasitized whitefly. No information is available on the durability of these remains. The adult parasitoids produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
2.6.1.7 Survival at consumers
Without access to hosts or honeydew E. formosa only survives for few days (ca. 3) at temperatures around 20°C (Gast & Kortenhoff, 1983; van Lenteren et al., 1987). In the absence of hosts, but supplied with honeydew or other sugar solutions, the parasitoids can sustain life 4 weeks or more (Gast & Kortenhoff, 1983; van Lenteren et al., 1987; Vet & van Lenteren, 1981).
The survival with access to hosts is stated above. Whiteflies will thrive in consumers’ hobby glasshouses and are, in addition, able to survive on plants in windowsills, patios and similar interior parts of the homes of consumers. E. formosa will likewise thrive in hobby glasshouses, but normally finds it more difficult to sustain population development in more interior places, due to a generally high temperature and low humidity.
2.7 The two-spotted spider mite Tetranychus urticae
Photo: Jack Kelly Clark, University of California,
2.7.1.1 Cultures
Spider mites occur as pests in a number of different glasshouse cultures, including tomato, cucumber and ornamentals (e.g. Hedera, Aster, Chrysanthemum). In connection with the use of the predatory mite, P. persimilis, spider mites may be part of the product or recommended to be released simultaneously to serve as prey during establishment and/or transport. The mite feed on the underside of the leaves and produce webbing that at high infestation levels may cover the plants. The mites spread through the culture by migration between plants or along wires or by use of silk threads that are carried by air currents. Also mechanical spread, via movement of infested plant material or on clothes or other objects, occurs.
2.7.1.2 Survival and reproduction
Spider mites survive and reproduce where sufficient plant material is available. Uncontrolled infestations of spider mites will lead to the collapse of the culture. Adult spider mites live for 12-20 days (Ahn et al., 1997; Rao et al., 1996) and the reproduction characteristics are: 60-130 eggs/female (Ahn et al., 1997; Rao et al., 1996; Sabelis, 1981); sex-ratio 70-80 % females (Ho & Lo, 1979; Kim et al., 2001; Margolies & Wrensch, 1996); population growth rate (rm) 0.12-0.4 day-¹ [i.e. doubling time 1.7-5.8 days; finite rate of increase 1.1-1.5 (for every individual in one generation there will be 1.1-1.5 present the next)] (Ahn et al., 1997; Ho & Lo, 1979; Rao et al., 1996; van Impe & Hance, 1991). Development from egg to adult last ca. 10-22 days (Ahn et al., 1997; Rao et al., 1996; Sabelis, 1981).
Minimum temperature for development is around 11-12°C (Kim et al., 2001; Lu et al., 2002; Malais & Ravensberg, 2003) and maximum temperature ca. 35-40°C (Candolfi et al., 1991; Malais & Ravensberg, 2003). Optimum temperature for development and reproduction is around 24-30°C (Chen, 2000; Malais & Ravensberg, 2003; Sabelis, 1981). Optimal humidity is around 40-80 % rh (Ferro & Chapman, 1979).
When environmental conditions change adversely (decreased daylenght, reduced temperatures, decline or deterioration of food supply), female spider mites enter diapause and remain hidden in the glasshouse structures (Malais & Ravensberg, 2003). When conditions become more favourable, diapause is broken and feeding and egg laying resumes.
2.7.1.3 Possible remains
T. urticae passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adults. Between each stage the old cuticle is shed and will remain in the crop on leaves or in flowers until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in the crop until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
2.7.1.4 Survival at consumers
Spider mites will thrive in consumers’ hobby glasshouses and are, in addition, able to survive on plants in windowsills, patios and similar interior parts of the homes of consumers.
2.8 The mould mite Tyrophagus putrescentiae
Photo: USDA
Mould mites occur in various environments e.g. in grain stores, in soil or litter feeding on organic material and on mould. The mites often occur in the soil of potted plants in glasshouses and are, in addition, added to some products of beneficial organisms (e.g. A. cucumeris and H. miles) serving as prey during transport and first establishment. In glasshouses they may establish in e.g. shoots and flowers of some crops (e.g. cucumber, Begonia, Gerbera) and cause damage (Malais & Ravensberg, 2003).
2.8.1.1 Survival and reproduction
Adult mould mites live for about 30-50 days (Eraky, 1992; Li et al., 1998; Malais & Ravensberg, 2003) and the reproduction characteristics are: 300-500 eggs/female (Boczek, 1974; Eraky, 1992; Li et al., 1998); sex-ratio ca. 50 % females (Eraky, 1992; Ignatowicz, 1986). No information has been found regarding population growth rate (rm). Development from egg to adult last ca. 13-21 days (Li et al., 1998).
Minimum temperature for development is around 6-10°C (Sanchez-Ramos & Castanera, 2001) and maximum temperature ca. 35-37°C (Sanchez-Ramos & Castanera, 2001). Optimum conditions for development and reproduction are around 30°C and 85-95 % rh (Sanchez-Ramos & Castanera, 2001). Lower humidity threshold for survival is around 65 % rh (Ree & Lee, 1997). The conditions of the substrate in which the mites live are also of importance for survival and reproduction (Malais & Ravensberg, 2003).
2.8.1.2 Possible remains
T. putrescentiae passes through 4 stages (egg, larva, protonymph, deutonymph) in its development to adults. Between each stage the old cuticle is shed and will remain in the crop on leaves or in flowers until it deteriorates. Dead individuals will shrink and shrivel but the outer cuticle being hardier will remain in the crop until deterioration. No information is available on the durability of these remains. The feeding stages of the mites produce faeces that deposit on plants and the surroundings. No information is available on the durability of this material.
T. putrescentiae does not enter diapause (i.e. hibernation).
2.8.1.3 Survival at consumers
Mould mites can under high humidity conditions be found in house dust and food items such as flour, oats and grain[34]. Mould mites brought to the consumers place in the soil of potted plants will be able to survive and reproduce here, provided that conditions are suitable.
Table 2-1 Overview of the 8 different glasshouse arthropods.
Footnotes
[1] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[2] Vermiculite may cause sensitisation by inhalation at mechanical application – dust masks are recommended.
[3] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[4] Vermiculite may cause sensitization by inhalation at mechanical application – dust masks are recommended.
[5] (Biobest, http://www.biobest.be; Koppert http://www.koppert.nl/e002.shtml)
[6] (Biobest, http://www.biobest.be; Koppert http://www.koppert.nl/e002.shtml)
[7] (Biobest, http://www.biobest.be)
[8] (Biobest, http://www.biobest.be; EWH BioProduction http://www.bioproduction.dk/)
[9] Vermiculite may cause sensitisation by inhalation at mechanical application – dust masks are recommended.
[10] (Biobest, http://www.biobest.be; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[11] (Biobest, http://www.biobest.be; EWH BioProduction http://www.bioproduction.dk/)
[12] (EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[13] (Biobest, http://www.biobest.be; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[14] (EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[15] (Koppert http://www.koppert.nl/e002.shtml)
[16] ¹Vermiculite may cause sensitisation by inhalation at mechanical application – dust masks are recommended.
[17] (Biobest, http://www.biobest.be; Koppert http://www.koppert.nl/e002.shtml)
[18] (EWH BioProduction http://www.bioproduction.dk/)
[19] (EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[20] (Biobest, http://www.biobest.be; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[21] (Koppert http://www.koppert.nl/e002.shtml)
[22] (Biobest, http://www.biobest.be/)
[23] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[24] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[25] (Biobest, http://www.biobest.be/; Koppert http://www.koppert.nl/e002.shtml)
[26] (EWH BioProduction http://www.bioproduction.dk/)
[27] (Biobest, http://www.biobest.be/; Koppert http://www.koppert.nl/e002.shtml)
[28] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/) or 5 banker plants /10,000 m² (Koppert http://www.koppert.nl/e002.shtml)
[29] (Biobest, http://www.biobest.be/)
[30] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[31] (Koppert http://www.koppert.nl/e002.shtml)
[32] (Biobest, http://www.biobest.be/; EWH BioProduction http://www.bioproduction.dk/; Koppert http://www.koppert.nl/e002.shtml)
[33] (EWH BioProduction http://www.bioproduction.dk/)
[34] (Danish Pest Infestation Laboratory http://www.dpil.dk/frames/spom_frm.htm)
Version 1.0 August 2007, © Danish Environmental Protection Agency