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1 Important Root Mealybug Species

1 Important Root Mealybug Species

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M. Mathew and M. Mani



630

Table 69.1 List of other root mealybugs on different host plants in different countries

Mealybug species

Dysmicoccus brevipes (Cockerell)

Dysmicoccus texensis (Tinsley)

Dysmicoccus vaccinii sp. n.

Ferrisia virgata (Ckll.)

Geococcus johorensis Williams

Geococcus lawrencei Williams

Geococcus oryzae Kuwana

Phenacoccus salviacus Moghaddam

Phenacoccus hordei (Lindeman)

Planococcoides robustus Ezzat &

McConnell

Planococcus citri (Risso)

Planococcus cryptus Hempel

Planococcus ficus Signoret

Planococcus fungicola sp. nov.

Pseudococcus eriocerei Williams

Pseudococcus viburni (Signoret)

Pseudococcus cryptus Hempel

Polystomophora arakensis

Moghaddam

Rhizoecus maasbachi Jansen



Rhizoecus amorphophalli Betrem



Rhizoecus theae sp.n.



Plants

Pigeon pea & groundnut

Pineapple

Coffee

Cassava

Blueberries

Parthenium hysterophorus

Oil palm

Asplenium nidus

Oryza sativa

Salvia bracteata

Grasses, alfalfa, barley, clover, rye &

wheat

Mango



Country

South India

Many countries

Espirito Santo

Paraguay, Bolivia & Brazil

USA

India

Johore & Malaya

Solomon Islands

Japan & Ceylon

Iran

European countries



Coffee

Citrus

Coffee

Grapevine

Coffee

Cacti

Plum

Coffee

Atraphaxis sp.



Kenya/East Africa

Crete

Brazil

South Africa

Kenya

Argentina

Chile

Espirito Santo

Iran



Segeretia theezans

Michelis sp.

Segeretia sp.

Amorphophallus variabilis

Amorphophallus sp.

Gingiber officinale

Diosorea elephantipes

Curcuma domestica

Amorphophallus variabilis

Colocasia esculenta, Curcuma longa

and Kaempferia galangal

Tea



Netherlands

China

England

Java

India



India



Caroline Islands

Philippines

Japan

(continued)



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69 Root Mealybugs

Table 69.1 (continued)

Mealybug species

Rhizoecus hibisci Kawai & Takagi



Rhizoecus kondonis Kuw.

Rhizoecus cynodontis Green

Rhizoecus arabicus Hambleton

Rhizoecus kondonis Kuw.

Rhizoecus aloes sp. Nov

Ripersia speciosa De Lotto

Xenococcus annandalei Silvestri



Plants

Hibiscus rosasinensis

Coffee

Tea, bonsai plant Serissa foetida,

ornamentals: Cuphea, Hibiscus

rosa-sinensis, Nerium, Oleander

largonium, Rhododendron, bonsais

like, Ligustrum ovalifolium, Punica

granatum, Segeretia theezans, Ulmus

parviflora, Zelkova serrata, foliage

plants Calathea, Diffenbachia, ficus,

and various members of Araceae and

dwarf Bermuda grass

Citrus

Cynodon dactylon

Coffee, Gasteranthus atratus & other

ornamental plants

Citrus

Aloe glauca

Coreopsis sp.

Grapes



Country

Japan

Hawaii

East and southeast Asia, Puerto

Rico, Florida and Hawaii, Italy

and the Netherlands



Japan

India

Colombia, Costa Rica &

Florida

China

UK

Congo

India



China and orange in Izu peninsula, Shizuokaken and Japan. It has been reported on the roots

of betel vine from Tamil Nadu (India)

(Muthukrishnan et al. 1958). This species

became an important pest of Nendran variety of

banana in Kerala. A total of 28 collateral hosts

were recorded for Geococcus citrinus in banana

ecosystem (Abraham et al. 2000; Smitha et al.

2005).



Adult females on the roots



69.1.3 Rhizoecus hibisci

Potted palms and other slow-growing plants are

more susceptible to infestation by root mealybug

Rhizoecus hibisci Kawai & Takagi because they

require lengthy bench time to attain marketable

size. Rhizoecus hibisci have been found on palms,

calathea, and Serrisa spp.



69.1.4 Rhizoecus americanus

Rhizoecus americanus Ferris is a soft-bodied,

sucking insect that attacks the tips of roots. It is

very common in Florida and other southern

states. However, if shipped in plants, it continues



632



to thrive indoors and in greenhouses. These creatures are dangerous to the plants and are often



Roots of Euphorbia squarrosa

infested with mealybugs



69.1.5 Rhizoecus falciper

The ground mealybug R. falciper Kunckel d’

Herculais was described in France, and occurs in

scattered locations across the United States. The

ground mealybug feeds on the roots of anemone,

chrysanthemum, gladiolus, iris, and numerous

other flowers, shrubs, and ornamental grasses. At

times, the ground mealybug becomes abundant

enough to damage its host.



M. Mathew and M. Mani



ignored as insignificant or misidentified as

mycorrhiza.



Rhizoecus americanus on

African Violets



African violet, although it is also known to infest

Achillea, Arctostaphylos, Geum, and Polygala.

Pritchard’s mealybug causes devitalization, foliage deterioration, and even death of its host plant.

When infested African violets are irrigated,

Pritchard’s mealybugs crawl out of the drainage

holes and spread throughout the greenhouse. Eggs

are laid in a loose ovisac in clusters of at least six

eggs. All stages can be found on the roots.



69.1.7 Rhizoecus maasbachi

Rhizoecus maasbachi Jansen is known to infest

bonsai plants of Sageretia spp. in China. This

species lives hidden on root hairs and detection

of small population is difficult. Rhizoecus hibisci

and R. maasbachi are the only two species regularly detected on Chinese bonsai and could be

confused with one another. In R. maasbachi, eyes

are present and the antennae are 6-segmented. In

R. hibisci, the eyes are absent and antennae are

5-segmented (Jansen 2003).



69.1.8 Rhizoecus amorphophalli

Rhizoecus falcifer



69.1.6 Rhizoecus pritchardi

Pritchard’s mealybug Rhizoecus pritchardi

Mckenzie is found across the United States.

Pritchard’s mealybug has become a serious pest of



Rhizoecus amorphophalli Betrem was recorded

on roots of elephant foot yam, Amorphophallus

sp. from Trivandrum, Kerala (India) and roots of

ginger Zingiber officinale from Calicut,

Dioscorea elephantipes from Goa, and rhizomes

of Curcuma domestica Zingiberaceae) from

Kohlapur, Maharashtra stored for seed purpose.



69 Root Mealybugs



69.1.9 Rhizoecus cocois

Rhizoecus cocois Williams was reported from

Kazhakkoottam, Kerala infesting coconut palms.

Infested young palms show yellowing and loss of

vigour and discolouration of the roots at the point

of feeding resulting in the drying up of such

roots. The adult female is subglobular, cream

coloured and enclosed within a loose jacket of

pure white cottony felt (Nair et al. 1980).



69.1.10 Rhizoecus kondonis

Rhizoecus kondonis Kuwana is a subterranean

pest of alfalfa (lucerne), prunes (plums, Prunus

domestica) and other crops primarily in the

Sacramento Valley of California. Root feeding by

the mealybug results in chlorotic, stunted lucerne

plants. Rhizoecus kondonis has three generations

per year with peaks in abundance in July-August,

December-January

and

March-April.

Significantly more R. kondonis were found 15.2–

45.7 cm deep in the soil (averaging 8.3/1240 cm

superscript three soil core samples) compared

with depths of 0–15.2 cm (averaging 2.2/sample).

All ten lucerne varieties were examined for susceptibility to this insect and found to be equally

susceptible (Godfrey and Pickel 1998).



633



bugs species namely Planococcus sp.,

Planococcus citri (Risso), P. lilacinus Cockerell,

Dysmicoccus brevipes (Cockerell) and Ferrisia

virgata (Cockerell) are known to infest the roots

and basal region of stem of black pepper vines

(Piper nigrum) (Ventataramaiah and Rehman

1989; Devasahayam et al. 2010).



69.1.13 Planococcoides robustus

Planococcoides robustus sp.nr. was found infesting roots of mango, grapes and the weed plant

Coniza ambigua in the Kolar district of Karnataka,

India. Ants were observed to carry the mealybugs. The affected plants showing desiccation

and leaf fall survived (Puttarudriah and

Eswaramurthy 1976).



69.1.14 Xenococcus annandalei

The grape root mealybug Xenococcus annandalei Silvestri in India also known to cause damage

occasionally by sucking the sap from roots, and

the affected vines show reduced vigour, shortening of fruit bearing canes and reduction in size of

fruit bunches and yield.



69.1.15 Paraputo sp.

69.1.11 Dysmicoccus brevipes

Dysmicoccus brevipes Cockerell is common on

the roots of pineapple, and large colonies develop

on the stems just above ground level. It is associated with pineapple wilt. It was also found on the

roots of the groundnut. It lives in colonies underground, and few may be seen on foliage. They

feed on nodules and cut off the nutrient supply to

plants (Singh et al. 1986).



69.1.12 Pepper Root Mealybugs

Mealybugs are major insect pests of black pepper

plantations in southern parts of India. Five mealy-



Mulberry plantations in hilly areas of Northern

parts of India such as Darjeeling and Kalimpong

are being infested by root mealybug, Paraputo

sp. (Pseudococcidae: Homoptera) causing considerable damage (Mukhopadhyay et al. 2010).



69.1.16 Phenacoccus parvus

Phenacoccus parvus Morrison was recorded

feeding mainly on collar region and subterranean

plant parts of the ornamental China aster in India.

About 25 % of the plants were infested making

the plant stunted without bearing flowers (Sridhar

et al. 2012).



M. Mathew and M. Mani



634



69.1.17 Chryseococcus arecae

The golden root mealybug, Chryseococcus arecae Maskell is a native of New Zealand. It was

found in Britain and can be witnessed on the

roots of outdoor plants all year round. Golden

root mealybug is a sap feeding insect that feeds

on the roots of a wide variety of plants, although

it has only been found on Meconopsis and

Primula in UK. Mealybug infestations have been

noticed on plants lacking vigour.



Chryseococcus arecae



per plant was recorded in Gedeo zone while the

lowest infestation of three mealybugs per plant

was recorded in Yem district. Knowledge about

the biology and distribution of this species has

paramount importance in devising proper management. Enset plants infested with mealybugs

have a retarded growth and dried lateral leaves.

The insects attack all plant age groups but symptoms are more severe on 2 to 4 years old enset

plants. Enset root mealybugs are found on roots

and corms. However, during periods of extreme

drought the mealybugs tend to move towards the

corm when some of the roots drought. The dispersal mechanism of enset root mealybugs is

facilitated by movement of infested suckers, farm

implements during cultivation, repeated transplanting operations and association with ants.

The population density of the mealybugs was significantly (P < 0.05) higher on the roots than the

corms. Enset root mealybugs were found up to a

soil depth of 60 cm and up to 80 cm from the

corm. However, root density as well as mealybug

population numbers decreased with increasing

soil depth. About 99 % of the mealybugs and

96 % of the roots were collected within the upper

40 cm soil layer. In addition, about 90 % of the

mealybugs were found within a 60-cm radius

from the plant (Addis et al. 2008, 2010).



69.1.18 The Enset Root Mealybug

Cataenococcus ensete



69.2

Enset (Ensete ventricosum) was domesticated in

Ethiopia several hundred years ago, and is now

the staple food crop for over 15 million Ethiopians

living in the highlands of southern Ethiopia. The

enset root mealybug Cataenococcus ensete

Williams and Matile-Ferrero is a major pest in

the enset growing regions of southern Ethiopia.

Infestation was high in Amaro, Gedeo, Sidama

and Bench districts with 100, 67, 61 and 57 %

incidence respectively. Low mealybug incidence

was recorded in Gurage, Kembata Tembaro,

Hadyia zones and Yem districts. More than 30 %

of the enset farms were infested with the mealybugs. The highest infestation of 81 mealybugs



Damage



There can be several generations of the root

mealybugs throughout the year and numbers can

multiply under favourable conditions. With

severe infestations, root mealybugs can be found

on the soil surface at the stem base. It is very difficult to detect symptoms of root mealybugs on

the plant. White, cottony-like masses containing

egg-laying females and/or eggs are normally visible on the outside of the root mass when an

infested plant is lifted. Slow plant growth and

leaf deterioration may be signs of the presence of

the pest. Root-bound or under environmental or

nutritional stress, the plants are more susceptible



69 Root Mealybugs



to attack. Once established in the greenhouse,

root mealybugs may spread as crawlers from

plant to plant as the water moves out of the drainage holes to nearby plants and in plant debris. It

is mainly potted plants (especially bonsai plants)

that are concerned during import inspections.

The pot should be removed and roots examined

for waxy secretions. In case of heavy infestations, crawlers may be observed on the soil surface. The mealybugs may be found particularly in

the new feeder roots in the upper layer of the soil.

The resulting damage stifles the ability of roots to

absorb water and nutrients. The only outward

sign of root mealybug feeding may be a decline

in the health of infested plants. When plants are

removed from the pot, the whitish mealybugs

feeding on the roots are then observed. If the

plant seems to be declining in health because it

has yellow foliage or slow growth or is stunted

for what seems to be no particular reason, then it

is to be looked for something that could be lurking below feeding on the plant’s root system. In

case there are mealybugs on bonsai trees, leaves

may be pale (sometimes greyish) or wilted,

despite regular fertilizer and watering. Maybe the

plant growth has slowed down and/or flowering

has ceased. In severe cases, the leaves may be

misshapen. Although they occur throughout the

roots, they are most obvious along the edges.



Mealybugs on the roots



635



The adults and nymphs of Geococcus suck sap

from the lateral roots of banana colonizing at the

junction of laterals with main root resulting in

drying up of such roots. Yellowing and narrowing

of leaves, general weakening of the plant, reduction in bunch weight, etc. were the observed

symptoms. Geococcus citrinus occurs seriously

on banana roots in reclaimed paddy fields. G. coffeae was also associated with banana grown in

uplands.

The adults and immature stages of Rhizoecus

hibisci feed on plant roots particularly new roots

in the upper layer of soil reducing water and

nutrient uptake by host. Feeding reduces plant

growth resulting in shrivelling and crinkling.

Leaves wilt, become pale and turn yellow or

grey; alternatively they can become soft, translucent and brown. Flowers may not be produced.

Mealy bugs (Planococcus sp., P. citri, P.

lilacinus, Dysmicoccus brevipes and Ferrisia virgata) were found infesting the roots and basal

region of stem of black pepper vines (Piper

nigrum). Infested plants show slow or poor

growth. Leaves wilt, become pale or turn yellow

or grey. Wax deposit is seen around the roots, on

the soil or on the side of the pots. The infestation

is generally severe during the post monsoon. The

root mealy bug affects the aerial parts of the black

pepper vines such as the tender shoots, leaves and

berries (Devasahayam et al. 2010).

Parputo sp. cause appreciable damage to

mulberry directly by sucking the sap and indirectly by making way for some fungal infection,

leading to rotting of the root and ultimately

death of the plants. The infested mulberry plants

show vulnerability to the attack of various fungal pathogens such as Fusarium solani,

Phomopsis mori and Colletotrichum gloeosporioides. Due to this, decaying of bark portion of

root and stem occurs with severe anthracnose

disease. Finally, it results in the death of such

severely affected mulberry plants (Biswas et al.

2002).



M. Mathew and M. Mani



636



Symptoms of banana root mealy bug infestation on banana



Roots of banana infested with mealybugs



Banana plants infested with root mealybugs



69.2.1 Mode of Spread

Under moist conditions, young root mealybugs

or nymphs are active. They move short distances

to adjacent plants. They may crawl from pot to

pot via drainage holes. They are slow moving in

irrigation water thereby facilitating the spread.

However their dispersal potential is usually limited. Infestations often begin with the purchase of

infested plant material.



69.2.2 Seasonal Development

Banana root mealybugs: The maximum population of Geococcus spp. was observed within

20–40 cm radius followed by 40–60 cm. In the

case of vertical distribution, more mealybugs

were collected within 20 cm depth. The population increased with the commencement of southwest monsoon in June and reached a peak in July,

followed by a decline in September, reaching a

lower level in January and remained low up to

May (Smitha and Mathew 2010a).

Mulberry root mealybugs: Plantations in hill

are being infested by root mealybug Paraputo sp.



causing considerable damage. It remains in the

root-zone and adjacent to stump portion below the

soil surface up to 20 cm deep, sucks sap and secrets

honey dew, thus inviting the occurrence of several

fungi on the plants. Due to sucking root becomes

stunted, normal growth ceases and leaves become

yellow and appear to be wilting (Das et al. 2004).



69.2.3 Natural Enemies

There is poor natural enemy complex, particularly natural predators or parasites on root mealybugs. Two predators namely Scymnus sp.

(Coccinellidae: Coleoptera) were found feeding

on G. citrinus (Smitha and Mathew 2010a).

Mathew et al. (2010) reported the fungal pathogen, Paecilomyces lilacinus on Geococcus spp. It

was pathogenic to both Geococcus coffeae and

G. citrinus (Smitha and Mathew 2011) and also

isolated Hirsutella sp. infecting G. citrinus. The

larvae of Spalgis sp. were observed to predate on

pepper root mealybug colonies (Planococcus sp.,

P. citri, P. lilacinus, Dysmicoccus brevipes and

Ferrisia virgata) (Devasahayam et al. 2010;

Ventataramaiah and Rehman 1989).



69 Root Mealybugs



Larva of Scymnus sp.



69.3



637



Adult Scymnus



Management



It is very difficult to detect and control root

mealybugs. Every effort should be made to prevent their spread and establishment. Pesticides

applied as dips, drenches, or granules are more

effective for root mealybug control than are foliar

sprays.



69.3.1 Pot Culture Plants

• Infestations usually begin with new plant

material. Inspect roots of newly purchased

plants by removing them from their pots.

• Inspect roots of suspected plants, especially

slow growing ones.

• Avoid pot-bound plants by re-potting when

necessary.

• Use pots with inner coatings of copper

hydroxide which prevents root matting and

thereby minimizes root mealybug infestations. Separate pots from the ground on raised

benches or with plastic film over the soil.

Palm roots in the pot not treated with copper

hydroxide (right) are more compacted and

infested with mealybugs (Hara et al. 2001).



• Do not allow water from infested areas to run

onto clean areas.

• Remove alternate host plants from around the

greenhouse, or control mealybugs on them.

• Use clean pots and soil; if infested, wash pots

with soap and water.

• Keep the growing area clean of plant debris.

• First, isolate the affected plants, especially if

they share a common watering tray with other,

healthy plants. Although soil mealy bugs do

not spread easily, they will travel over moist

surfaces.

• Root mealybugs can be spread by irrigation

water, re-use of previously infested pots, reuse of contaminated media, and crawlers

moving from infested plants to other plants.

• Infestation of greenhouse bench plants by root

mealybugs can occur by introducing nursery

stock that was already infested when purchased or from crawlers that move in from

host plants near the greenhouse.

• For root mealybug in pots, remove all soil and

destroy it. Wash the roots thoroughly and treat

(eventually immersing the whole plant) with

the above mentioned insecticide, letting the

roots dry after treatment and before replanting

in completely fresh, sterilized soil. Always

cleanse and sterilize frames and all other items



638



used when replanting. Regular applications

(weekly for several weeks) of insecticide

watered into the soil are also effective; it is

also possible to immerse the plant pot up to

the top of the soil in a bucket of insecticide.

• A promising alternative to chemical treatments has been found in the use of

Diatomaceous Earth, a fully inert, non-volatile substance that has proven effective in

eradicating certain insect pests. Strictly speaking, Diatomaceous Earth is not an insecticide.

It is made from the skeletal remains of diatoms, a microscopic form of algae. When processed into Diatomaceous Earth, these skeletal

remains form razor-sharp particles which cut

into the bodies of small insects. While eradicating the insects, Diatomaceous Earth does

not harm African Violets. To treat for soil

mealy bugs, repot the African Violet in a soil

that has been mixed with Diatomaceous Earth.

Use about one tablespoon per one litre of soil.

Pasteurize soil before re-potting. To make soil

uninhabitable for future mealy bug infestations, mix about one fourth tablespoon of

Diatomaceous Earth with every litre of soil.

• Hot-water dips are as effective as insecticides

against mealybugs. Submerging the potted

palms in water held at 120 °F (49 °C) until the

internal root ball temperature reached 115 °F

(46 °C) was 100 % effective in killing root

mealybugs. Drenching potted palm roots in

hot water at 120 °F for 15 min will not only

control mealybugs but will also eliminate burrowing nematodes. If an infestation is found

(Rhizoecus hibisci), hot water treatment of

root balls is very effective (Hu et al. 1996).

• Chemical control of root mealybugs requires

saturation of the root ball and potting medium

to a degree that allows the pesticide to penetrate the pests’ white, waxy secretion. Dipping

or drenching with liquid insecticide is more

effective than applying a granular formulation. Chlorpyriphos, applied twice as a drench

or dip at 2-week intervals controls coffee root

mealybug; however, it may take 4–6 months

before the cottony, waxy secretions deteriorate completely. In the dip method, submerging the plant’s entire root ball without the pot



M. Mathew and M. Mani



in a diluted chlorpyriphos solution (1 pint per

100 gal) for about 30 s with slight agitation is

nearly twice as effective as dipping the plant

while still in its pot. Imidacloprid, which can

be applied only as a drench and incorporated

with a surfactant or wetting agent to ensure

thorough distribution of solution in the potting

medium, can also significantly reduce the

number of individuals in an infestation (Hata

et al. 1996).

• Moth ball: As a preventative measure, moth

balls (paradichlorobenzene), added to the potting mix, seem to discourage infestation by

root mealy bug, and probably discourages

other insects. However, the chemicals in the

moth balls can cause damage to plastic plant

pots and are best used with clay pots.

• Traditionally, the only effective treatment for

soil mealybugs (R. amercanus) has been to

spray the soil with acephate (as directed on the

label) or with malathion (1 teaspoon of

Malathion 50 per 4 l of lukewarm water).

While this treatment does work, it usually

takes several applications over a period of

days. Moreover, there is usually some risk to

plants when using any chemical treatment.



69.3.2 Field Conditions

Application of sodium silicate and calcium oxide at

the time of planting effectively reduced the population of banana root mealybug, G. citrinus.

Drenching of the chemical insecticides, chlorpyriphos at 0.05 % at monthly intervals, reduced the

root mealybug population. Among the combinations, without synthetic insecticides, sodium silicate alone and its combination with neem seed

kernel extract (NSKE) and Cephalosporium lecanii Zimm, were effective in reducing the mealybug

population at sixth and seventh month of the crop.

Application of chlorpyriphos gave the highest benefit--cost ratio of 2.46 followed by sodium silicate

(2.30) (Smitha and Mathew 2010b). Application of

neonicotinoids, which include imidacloprid, thiamethoxam, thiocloprid, by way of soil drench can

also be tried against root mealybugs in general.



69 Root Mealybugs



Drenching the affected vines with about

0.075 % chlorpyriphos is effective in controlling

the pepper root mealybug infestation in India. If

the infestation persists, then drenching may have

to be repeated after 20–30 days, “Adequate care

should be taken to ensure that the insecticide

solution percolates down to the roots while

drenching the vines. Farmers should not transplant infested nursery plants in the field and mild

infestations should be controlled in the nursery

itself. Ploughing the interspaces in black pepper

gardens and removal of weeds also help in lowering the level of pest population. The mango root

mealybug Planococcoides robustus sp.nr. was

controlled by application of disulfoton granules

at monthly intervals and watering weekly. The

affected plants showing desiccation and leaf fall

had survived (Puttarudriah and Eswaramurthy

1976).

Under green house and farmers field conditions, insecticides like diazinon 60 % EC and

chlorpyriphos 48 % EC caused at least 98 % mortality of enset mealybug Catenococcus ensete

both under field and green house conditions

(Tadesse et al. 2010a). Seed water suspension of

Millettia ferruginea at 10 % was toxic to C.

ensete, causing 66 % mortality. However, the

efficacy was inferior to diazinon application in

the pot and dipping treatments (Tadesse et al.

2010b). Citronella oil at 5 % performed better

towards controlling mulberry root mealybug

Paraputo sp. followed by 5 % neem oil and 55

neem leaf extract, without any adverse effect on

silkworm rearing (Anonymous 2011). Biswas

et al. (2002) reported that both carbofuran and

endosulfan were effective in controlling mulberry root mealybug for longer period. Diazinon,

oxamyl and granules of aldicarb are recommended for control of Rhizoecus arabicus

Hambleton (Hamon 1982). Phyrinex 48 % EC

and Phostoxin tablet had provided better control

of root mealybug (Paraputo sp.) than the other

insecticides. Phostoxin tablets and Phyrinex

48 % EC resulted in mean pseudostem circumference increases of 23.23 and 32.34 cm, and in

mean plant height increases of 71.09 and

58.11 cm, respectively, over the control (Bekele

2001).



639



69.3.3 Biological Control

Smitha

and

Mathew

(2010b)

found

Cephalosporium lecanii Zimmerman as the best

among the three fungi screened, namely,

Beauveria bassiana Balsomo, Hirsutella sp. and

Cephalosporium lecanii. Entomopathogenic

nematodes (EPNs) have potential for biological

pest control and have been successfully used in

several countries in soil and cryptic pests control,

as for example the coffee root mealybug

Dysmicoccus texensis (Tinsley). Aqueous

suspension of Heterorhabditis on coffee root was

more efficient with 70 % control efficiency when

compared with thiamethoxam (Alves et al. 2009).



69.3.4 Phytosanitary Risk

R. hibisci has spread from Asia to USA (Hawaii

and Florida) and has established in some ornamental glasshouses in Europe. Though there are

also European species of Rhizoecus with similar

biology, R. hibisci is a potentially serious pest in

the EPPO region, particularly on glasshouse pot

plants. Moreover, it has significance as an indicator that pot plants (especially bonsai plants) produced in eastern Asia, and exported to the EPPO

region, have not been grown under adequately

controlled conditions (as defined for example in

EU 2000), and may accordingly be infested by

other non-European pests. Rhizoecus hibisci was

added in 2001 to the EPPO A2 list of regulated

pests. Nurseries producing pot plants for export

to the EPPO region should maintain good standards of hygiene, and in particular should respect

EPPO Standard PM 3/54 growing plants in growing medium prior to export (OEPP/EPPO 1994).

Bonsai plants for export to the EPPO region

should respect the requirements set out in EU

(2000) or equivalent requirements. Consignments

of containerized host species from areas where R.

hibisci occurs should have containers removed

and the roots inspected. Montanucci (2010)

described a safe and inexpensive procedure for

elimination of root mealybugs (genus Rhizoecus)

from a small cactus collection. The procedure

prevents re-infestation by taking advantage of the



640



fact that the root mealybug females and nymphs

are wingless and must crawl to potted plants to

become established. The procedure is expected to

permanently eradicate rather than simply control

these pests.



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