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8 Strange Aspects of Ant–Mealybug Associations

8 Strange Aspects of Ant–Mealybug Associations

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15



Ant Association



Another exceptional transport association is

described by Reyne (1954) in Java. In this case,

mealybug Hippeococcus is especially adapted

with long raptorial legs and sucker-like digitules

for clinging of Dolichoderus ants. When disturbed, the highly mobile immature mealybugs

climb onto the bodies of the ants and are carried

into the nest where large colonies of mealybugs

are maintained.

In California, an exceptional relationship

existed between the mealybug, Cryptoripersia

salina (Ehrhorn) and the ant Crematogaster. The

mealybugs are enclosed in a white-felted sac at

maturity under rocks. When a rock was overturned, the mealybugs were all in one large chamber in the ants’ nest and were in great numbers,

mostly matured mealybugs. Once the rock had

been overturned, masses of ants poured from the

lower tunnels of the nest in pursuit of their honeydew “symbionts.” Within a matter of 15 min

the mealybug chamber had been emptied of its

mealybug contents.

Another unusual observation was made in

Modoc County involving an association between

the mealybug Phenococcus colemani Ehrhorn

and the ant Formica subpolita. This mealybug is

very often found in cracks and pits on the underside of larvae rocks. When the mealybug-infested

rock was distributed, associated ants hurriedly

tore the mealybugs, waxy sacs and all, from their

rock habitat and carried them into cracks in the

soil. The ants removed the mealybug so rapidly

that, in order to collect sufficient numbers of the

mealybugs, the ants had to be removed first.

Another unusual observation was made in

Nevada. Ants were busily tending their mealybug

host in the usual fondling manner. In this case,

the mealybugs were withholding their honeydew

supply from the ants. The ants, however, had

overcome this problem by butting the abdomen

of the mealybug with their heads, thus causing

the honeydew to flow from the mealybug ostioles. The ants then consumed the solution.

There was another kind of interrelationships

of big-headed ants, mealybugs, and spread of

mealybug wilt disease. The big-headed ant,

Pheidole megacephala (Fabricius), is the dominant ant species in most of the pineapple fields in



205



Hawaii. Ant and mealybug populations in

infested plots increased gradually and appeared

to be strongly influenced by the phenology of the

pineapple plants during the first fruit crop.

Unusually heavy rainfall caused the dramatic

reduction in ant populations observed then.

Highest ant population levels occurred about 3

years after planting, when all untreated plots

became nearly uniformly infested. The incidence

of mealybug wilt was higher when the ants and

mealybugs were more (John et al. 1982).



15.9



Management of Ants



The association of ants with the mealybugs by

giving protection to natural enemies, transport of

mealybugs, and removal of honeydew from the

mealybug colonies has resulted in an increase in

the mealybug population. It serves the basis to

develop the hypothesis “more the ants, more the

mealybugs.” Hence, it is necessary to check the

activity of ants in the suppression of mealybugs.

According to Mansou et al. (2012), the ants

Tapinoma nigerrimum constitute a threat to biological control of Planococcus ficus (Signoret)

and Pl. citri in the orchards in Italy by either the

encyrtid parasitoids Anagyrus pseudococci

(Girault) and Leptomastix dactylopii (How.) or

larval stage of the coccinellid predator

Cryptolaemus montrouzieri, and hence an adequate control of the ants is highly recommended

before the release of any of these natural

enemies.

General ant control measures may be adopted

to suppress the activity of ants. It has been suggested to apply a band of diazinon granules

around the plant about 1 ft from the main stem.

Other control measures include destruction of ant

holes, red ant nests, and skirting of trees after

fruit harvest, which prevents the ant migration

through side branches. After the patrolling (up

and down) of ants on the trunk is stopped, the

beetles can be released (Singh 1978). It was also

suggested that ants should be prevented by rubbing magnesia or powdered tale in a 4-in.-wide

band at the time of liberation of Cryptolaemus

(Constantino 1935). Mealybug-infested custard



M. Mani and C. Shivaraju



206



apple plants were applied with sticky bands

which had helped to prevent the movement of

ants (Murray 1982). BHC solution (5 g/l) was

poured into the anthills prior to the release of C.

montrouzieri against Ferrisia virgata (Cockerell)

in guava orchards (Mani et al. 1990). In the

orchards where ants were partially excluded, a

significant reduction in citrus mealybug populations and damage could be observed (Villalba

et al. 2006). Applying a 6 % solution of chlorpyriphos to the base of the vine and supporting

stake and to the surrounding soil gave the best

results.

Liquid ant baits were evaluated for the control

of Argentine ants Linepithema humile (Mayr)

and associated mealybug pests (Pseudococcus

species) in commercial vineyards. In all trials,

liquid baits were an insecticide dissolved in 25 %

sugar water. In 2002, a liquid bait – thiamethoxam, mixed at 0.0001 % (active ingredient,

A.I.) – was delivered in ground-based (site 1) and

canopy-based (site 2 and 3) dispensers that were

recharged every 2 weeks and cleaned every 4

weeks, and deployed at rates of 160 (sites 1 and

2) and 620 (site 3) dispensers per hectare. There

was a significant reduction of season-long ant

densities in liquid bait treatments at all sites and

of mealybug densities at two of three sites; crop

damage was significantly lower in the liquid bait

treatment at all sites. Similarly, studies in the

pineapple field showed that eradication of the

ants reduced the population of mealybug

(Beardsley et al. 1982).

Gourmet ant bait (Innovative Pest Control

Products, Florida USA), containing 1 % disodium octaborate tetrahydrate toxicant, dissolved

in 25 % sucrose solution to make 0.5 % A.I., was

overall the most preferred bait for Argentine ants

Linepithema humile (Mayr), common pugnacious ants Anoplolepis custodiens (F. Smith) and

cocktail ants Crematogaster peringueyi (Emery)

during spring, summer, and autumn, and on some

occasions being significantly more preferable to

ants than the control solution. Management of

Argentine ants is important in mealybug management in a vineyard because the ants will protect

the mealybugs. Ant baits, placed in approved dispensers, can reduce Argentine ant populations to



an acceptable level in 2–3 years. The baits need

to be placed in the field during budbreak (March

to June, depending upon location in the state) at a

rate of 15–20 bait stations (UC bait station) per

acre (Nyamukondiwa and Addison 2011). Ants

can also be managed by applying tanglefoot

every 1–2 weeks.



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663 p



Methods of Control



16



M. Mani and C. Shivaraju



Mealybugs pose a serious threat to several agricultural and horticultural crops throughout the

world. They are a major problem in greenhouses

and nurseries, where they often cause severe economic damage. It seems surprising that such a

delicate soft-bodied insect is so difficult to control. There are, however, several reasons which

may account for this fact.

Mealybugs developed several different

defense mechanisms. Many of the species tend to

establish themselves in protected sites, such as

cracks and crevices in bark, leaf axils, root

crowns, nodes of grass stems, under fruit sepals

and within fruit navels, between touching fruits

or fruits and leafs, and in tunnels bored by insect

larvae in roots and stems (Franco et al. 2000;

Kosztarab and Kozár 1988). This cryptic behav-



ior of mealybugs may provide a spatial refuge

from natural enemies and harsh environmental

conditions (Berlinger and Golberg 1978;

Gutierrez et al. 2008a). This type of plant colonization makes mealybugs practically invisible

during the latent population phase. However, during outbreaks, the population “boils over” from

the refuge and becomes conspicuous. In addition,

other species have the habit of spending their

entire lives deep in the soil, protected almost

from insecticidal materials.

Mealybugs are noted for the production of

dermal wax secretions. Adult mealybugs and the

nymphal instars are covered with waxy coating.

Also the eggs of mealybugs, protected by the

waxy filamentous secretions of the ovisac, are

almost impossible to reach with insecticides.



M. Mani (*) • C. Shivaraju

Indian Institute of Horticultural Research,

Bangalore 560089, India

e-mail: mmani1949@yahoo.co.in

© Springer India 2016

M. Mani, C. Shivaraju (eds.), Mealybugs and their Management in Agricultural

and Horticultural crops, DOI 10.1007/978-81-322-2677-2_16



209



M. Mani and C. Shivaraju



210



Eggs protected with waxy ovisac



Adult mealybug covered with

waxy coating



The waxy secretion is the most common conspicuous trait of the mealybug family. It is a complex system that serves different functions, and

which is produced by the epidermal wax glands

and transported to the body surface via ducts,

pores, and secretory setae of various types (Foldi

1983; Gullan and Kosztarab 1997). The main

components of the wax of five mealybug species

(Planococcus citri (Risso), Pl. ficus (Signoret),

Pl. vovae, Pseudococcus cryptus Hempel, and

Nipaecoccus viridis (Newstead)) were trialkyl

glycerols and wax esters. The wax cover is

believed to prevent water loss. The hydrophobic

property of the wax enables the mealybugs to

escape drowning or becoming swamped by water

in their typical cryptic sites. The ovisac, which is

also a wax secretion, is considered to be an adaptation that protects the offspring from both wet

and dry conditions, and that may also provide an

attachment to the host plant. Tubular ducts and

multilocular disc pores, respectively, produce

long hollow and shorter curled filaments, which

make up the ovisac and the male cocoon (Cox

and Pearce 1983; Foldi 1983). The white wax of

mealybugs is strongly light reflective and may

reduce desiccation. In some cases, the wax also

serves to cover the honeydew droplets and to protect the mealybugs from contamination by their

own honeydew and defensive exudates (Gullan

and Kosztarab 1997). Normally, chemicals are

used to control the mealybugs. However, the

crawler stage is not covered with wax, and as a

consequence, this is perhaps one of the most susceptible stages of mealybug to chemicals. On the

other hand, natural enemies have given excellent



Mealybug crawlers not covered

with waxy coating



control of some mealybugs. The purpose of this

study is not to give specific recommendations for

mealybug control. It will be dealt under the

respective crops. General methods of mealybug

control are summarized in this chapter.



16.1



Decision-Making System



The five key elements ought to be considered in a

decision-making system in the management of

mealybug population are (1) information on

mealybug density, perhaps obtained late in the

season, in case of overwintering population; (2)

awareness of the population distribution in the

target area; (3) information about the density of

the relevant natural enemies; (4) the density of

associated insect species, which may increase the

damage or render the activity of the natural enemies; and (5) the risk of the spread of mealybugtransmitted viral disease. In this chapter, the

current knowledge needed to take actions and to

suggest solutions for different situations is

reviewed. Based on such knowledge, the grower

may select the appropriate control tactics.



16.2



Monitoring



Vigilance is important to eliminate them before

there is a major outbreak of mealybugs.

Monitoring for the incidence of mealybugs is a

prerequisite to initiate the management practices.

There are no simple and effective methods to

visually monitor the mealybugs, and the process



16



Methods of Control



itself can be time consuming and laborious. As

exemplified for Pseudococcus maritimus, the

accuracy of monitoring the plant material will

depend on the mealybug population density, and

the number of samples needed for an accurate

count is often high because most of the mealybugs have a clumped distribution pattern, often

being found on only a small percentage of the

plants. The appropriate sampling program will

also vary throughout the season, depending

largely on mealybug location as there are periods

when much of the population is hidden (e.g.,

under bark) rather than exposed (e.g., on leaves).

In addition, as species have different numbers of

annual generations and preferred feeding locations throughout the season, there is not a single

sampling procedure appropriate for all the mealybugs. In most cases, signals of an infested plant

can be used to aid the sampling program. First,

ants are closely associated with the mealybugs,

and their presence can help select the plants for

further sampling. Second, honeydew on the

leaves can also be a good signal; a large population hidden under the bark will excrete enough

honeydew that the infested trunk region will have

a darker, wet appearance. Third, as mealybug

numbers build up, their feeding damage may

cause leaves to turn yellow or brown and drop

from the plant. Finally, during the harvest time,

fruits in direct contact with the spurs or trunk are

more likely to be infested, and by selecting these

fruits, a higher mealybug count can be made A

faster sampling method is to use sticky traps

baited with sex pheromone to lure in and trap the

adult winged males. It has long been known that

sexually mature female mealybugs like

Planococcus citri emit a sex pheromone to attract

the winged adult males. These pheromones can

be synthesized and used in the field for monitoring the mealybugs. Thus, the monitoring provides

essential information for making decisions indicating the presence and the numbers of mealybugs and their enemies occurring in nature; the

degree of natural control by insects, which prey

upon or parasitize the mealybugs; whether the

mealybugs are high enough to require treatment;

the lifecycle stages of any mealybugs present



211



and, therefore, the most effective timing for the

management options.



16.3



Cultural Method



A number of cultural controls are practiced and

these vary greatly among regions. Crop sanitation is useful in reducing the mealybug population. Before applying the insecticides/pesticides,

manual removal of the fluffy nests and most of

the insects is advisable. It greatly increases the

chance on complete elimination of the mealybugs. Removal of the weeds harboring the mealybugs eliminates the source of mealybug

infestation. For example, crop sanitation including the removal of weeds was useful in the control of Heterococcus pulverarius (Newstead)

(Dietz and Harwood 1960) and H. nigriensis

Williams (Harris 1961). Burning and plowing the

crop after harvest result in very little reoccurrence of the mealybugs. The control of certain

garden mealybugs may be done simply by hosting the plants down with a strong stream of water

(Michelbacher et al. 1959). Although this seems

rather unorthodox, the control is fairly successful, especially if this treatment is used at regular

intervals. In the case of woody plants, mealybugs

are found underneath the bark of the trunk, cordon, spurs, and canes. These locations provide

some protection from insecticides, natural enemies, and environmental conditions. Stripping

the bark exposes the mealybugs to these mortality factors. The infested bark should be destroyed

rather than left in the row middles as the mealybugs can move back. Cover crops have been used

to improve soil health and lower-pest densities by

increasing the natural enemy numbers or

diversity.

Parasitoids that attack the mealybugs could

utilize floral nectaries of some cover-crop species

as a food source to increase adult longevity.

Generalist predators, such as the lacewings and

some ladybird beetle species, might also utilize

these floral food resources as well as herbivores

in the cover crop as alternate prey. Overly vigorous plants can increase mealybug populations in



M. Mani and C. Shivaraju



212



two ways. First, excess nitrogen has been shown

to increase the size of mealybug females and the

number of eggs in each ovisac. Second, the

increased foliage associated with overly vigorous

plants provides better shelter for the mealybugs

by reducing temperatures inside the vine leaf

canopy, and may reduce the amount of applied

foliar insecticide that reaches the mealybug.

Controlling plant vigor is, therefore, a practice

that can help improve mealybug control.



16.4



Physical Control



The following physical control measures can be

adopted to reduce the mealybug population on

the plants: (1) flushing mealybugs off the leaves

with water can provide immediate relief but will

simply displace the mealybugs; (2) rubbing off

and crushing the colonies with a cloth; (3) mealybugs can also be removed by dipping a cotton

swab in alcohol or fingernail polish remover; (4)

discarding heavily infested plants; and (5) pruning infested tissue off infested plants.



mealybugs because the mealybug waxy covering

repels polar chemicals (Walton et al. 2004).

Insecticides, with contact and also systemic

activity, are still primarily used to control or regulate the mealybug populations.

Normally chemicals are used to control the

mealybugs. There are great similarities among

the insecticide arsenals used to control mealybug

species on different crops. In principle, three

main modes of insecticide application are

adopted: (1) foliage cover spraying for management of aboveground populations; (2) application of insecticide solution to the soil to enable it

to penetrate to the root zone, so as to combat subterranean colonies; and (3) chemigation by application of systemic compounds via the irrigation

system (Chemigation), for example, drip irrigation. Insecticides are also used against mealybugs

by smearing them on the stem or main branches.

For example, swabbing of grapevine trunk/stem

with chlorpyriphos is recommended to control

the mealybugs. Two other, less common, techniques are fumigation, usually applied for eradication, for example, with methyl bromide, and

slow-release strips to prevent colonization.



16.4.1 Hot Water Treatment

16.5.1 Neonicotinoids

A quarantine treatment is needed to prevent the

entry and spread of mealybugs like Planococcus

citri (Risso) and Pseudococcus odermatti Miller

and Williams infesting limes. A 20-min, 49 °C

hot-water immersion treatment is effective in

killing all the mealybugs without affecting the

fruit quality (Gould and McGuire 2000).



16.5



Chemical Control



Waxy insects such as mealybugs and scale insects

are difficult to kill using contact insecticides

because the waxes produced by these insects

form a physical barrier preventing chemical penetration. It is essential that the mealybug is killed

promptly, but the cotton-wool cover can repel

any insecticide sprayed onto it; therefore, often a

wetting agent in the insecticide spray is required.

Many contact insecticides are ineffective against



More recently, an effective group of compounds

has been found, which combines toxicity to

mealybugs with safety to other non-targeted

organisms; they are the neonicotinoids. These

compounds act on the central nervous system and

easily replace carbamates, organophosphates, or

pyrethroids, since there are no records of crossresistance associated with them. These systemic

compounds show high effectiveness against

mealybugs. Examples include dinotefuran

applied to the canopy; acetamiprid applied by

smearing on the stem or the branches (Gross

et al. 2000; Larrain 1999); and imidacloprid and

thiamethoxam that are introduced by watering

the soil (Daane et al. 2006; Fu Castillo et al.

2004; Grout and Stephen 2005; Martin and

Workman 1999; Sazo et al. 2006). The insecticide arsenal that is both suitable for organic farming and able to cope effectively with mealybug



16



Methods of Control



pests does not exist in practice. Since the growers

will need to treat small hot spots of the mealybug,

it is expected that some soft insecticides will be

used and that more than one application may be

needed to selectively eliminate such hot spots.

When these hot spots are treated, several points

should be taken into account: (1) the hot spots are

expected to be in areas that are practically free of

problematic mealybug populations; they actually

constitute oases for parasitoids and predators;

therefore, the ratio of mealybug to natural enemy

populations in the hot spots should be considered

before initiation of any control operation; (2) an

insecticide will be applied when augmentation

with predators is not useful or cannot be implemented; (3) a low-residue short-life insecticide is

the most appropriate; (4) an augmentation of

natural enemies will be needed if the hot spots

are too numerous.



16.5.1.1 Application Timing

Application timing is critical to control mealybugs with most insecticides. Exposed mealybugs

are more easily killed than those under the bark,

and the smaller stages are more susceptible than

the larger mealybugs. This is especially true for

insecticides with a short residual period. Much

research, therefore, has been aimed at proper

application timing and development of materials

with better penetration into the protected habitats

of mealybugs. Applications with systemic insecticides near bloom are often used, as the insecticide moves quickly in the plants.



16.5.2 Foliar Spray

The dispersive habit of the crawler should make

it more susceptible to insecticides than the later

developmental stages that live in sheltered sites.

Spray application is to be timed to coincide with

the crawler stage as it would be effective and

would also permit the use of less persistent

chemicals.

Not many specific insecticides are available

against all the species of mealybugs, but parathion was primarily used as spray and dust in

commercial agriculture. In the earlier years,



213



organophosphates such as malathion, diazinon,

tetraethyl pyrophosphate (TEPP), and dimefox

have been used with partial success but they are

not in use now due to one reason or the other.

They may be extremely hazardous or can develop

resistance (Madsen and Westgard 1962).

Malathion is primarily used in the control of garden and nursery mealybugs (Michelbacher et al.

1959). TEPP, another organophosphate, has

effectively controlled P. citri, Ps. longispinus,

and Ps. maritimus (Jefferson and Pritchard 1961).

Some old organophosphates, such as dichlorvos

and chlorpyriphos, are still being used against

mealybugs because they certainly are much less

dangerous. Many of the chlorinated hydrocarbons, such as dichlorodiphenyltrichloroethane

(DDT), lindane, aldrin, dieldrin, and endrin, and

the organophosphate (parathion) are not in use

now due to various reasons. Eventually, however,

most of these materials became less effective

also. Organophosphates, such as chlorpyrifos,

acephate, dichlorvos, and diazinon, and, to a

lesser extent, carbamates, such as aminocarb,

carbaryl, thiodicarb, or methomyl, are broadspectrum nerve insecticides, which have been

used against mealybugs that colonize the plant

canopy since the early 1960s (Gonzalez et al.

2001; Shafqat et al. 2007). These insecticides

when applied in high volume could successfully

overcome the obstacles that make mealybugs

hard to kill. The obstacles are as follows: (1) their

hydrophobic wax cover, which repels hydrophilic

insecticides; (2) their tendency to feed in hidden

and protected parts of the plant; (3) their typically

dense colonies; and (4) the frequent overlapping

of generations. Effective control is achieved

when most of the mealybug population is in the

dispersive crawler stage or the young nymphal

instars, and when the host plant does not provide

effective shelter. However, satisfactory control is

often difficult to achieve over an extended period.

These chemicals have detrimental effects on the

environment as a whole and on natural enemies

in particular (Anand and Ayub 2000; Babu and

Ramanamurthy 1998; Meyerdirk et al. 1982).

The multivoltine character of the pest mealybugs

and the frequent application of inefficient control

measures accelerate the development of insecti-



M. Mani and C. Shivaraju



214



cide resistance (Flaherty et al. 1982). Systemic

organophosphates such as dimethoate could

overcome some of these obstacles (Grout and

Stephen 2005; Meyerdirk et al. 1982; Prasad

et al. 1998). Chlorpyrifos-impregnated strips are

applied to protect banana bunches from the

mealybug infestation or applied as stem barriers

for the control of ants (Addison 2002; Gross et al.

2001).

Newer materials, with more novel modes of

action, have also gained in popularity, including

neonicotinoids, insect growth regulators (IGRs),

botanicals,

and

biosynthesis

inhibitors.

Application of spirotetramat 6 fl. oz/acre + adjuvant (Ventre 0.25 % v/v) 44 fl. oz/acre at a spray

volume of 137 gal/ac was able to reduce the

bunch infestation with mealybugs to 3 % fruit

damage and there was little to no honeydew in

that treatment. A major difference between the

older and newer materials is the importance of

coverage. As mentioned, a portion of the mealybug population is often under the bark and, for

some species, on the roots. Many of the older

foliar sprays did not effectively contact and kill

mealybugs in these more protected locations.

Some of the more novel materials have systemic

properties, applied either through the irrigation

system or as a foliar spray. For organic or sustainable farming programs, neem, light mineral oils,

lime sulfur, citrus products, and fatty-acid soaps

have been used.

Another historical difference is that the earlier

materials were often broad spectrum and killed

more than just the targeted mealybugs. The

extensive use of DDT and other synthetic insecticides to control leafhoppers apparently disrupted

the natural control of the mealybug P.

maritimus.



16.5.2.1



Oil Emulsions/Mineral Oils/

Botanicals



Oils

Oils have long been used for the control of scale

insects but they have been ineffective against

mealybugs. However, the integration of narrow

refined oils with other insecticides was suggested

as a means to dissolve the insect’s wax covering



and thereby improve the insecticide efficacy

(Cranshaw et al. 2000; Morishita 2005). Summer

oil emulsions/mineral oils are particularly effective in the control of mealybugs on ornamental

plants. Applications should be made at regular

intervals of 1–3 weeks (Michelbacher et al.

1959). Combinations of these oil emulsions with

contact insecticides are quite effective in the control of garden and household mealybugs. Neem

oil, horticultural oil, and insecticidal soaps are

often regarded as “organic” or non-chemical

methods, but this is not completely accurate.

However, they are safer than the insecticides.

They will not provide absolute control over

mealybugs but can drastically reduce their populations. Chilli–Garlic extract is also used to control the mealybugs.

Botanicals

Neem has natural insecticidal properties but is

biodegradable and non-toxic to several naturally

occurring parasitoids and predators. It works by

making the leaves unpalatable to the mealybugs.

Neem is to be sprayed like other contact insecticides. Spraying should be in such a way that the

undersides of all leaves are covered. In organic

agriculture, azadirachtin, an IGR chitin inhibitor

derived from the Indian neem tree, may be used

in similar modes (Irulandi et al. 2001). Pyrethrins

and rotenone replaced some of the old compounds in organic agriculture with limited effectiveness. Neem products have a repellent effect

on some mealybugs. Neem oil is effective for

mealybug suppression. Neem oil is generally

considered safe for humans, pets, and plants

unlike usual chemical insecticides. Neem oil is

an all-natural organic insecticide. Unlike the

toxic chemicals, neem oil interrupts the pest

reproduction cycle and is, therefore, useful in

eliminating mealybugs from the plants. Mix

5 ml (1 oz) of pure neem oil with 2.5 ml (1/2 oz)

of a mild liquid soap and 1,000 ml of water (four

cups). Mix neem oil and liquid soap first and

then add water. Mix it thoroughly and spray.

Neem oil solution smothers the mealybugs;

therefore, complete coverage of all the plant

parts is essential. Repeat every 5–7 days until the

infestation comes under control. Bug Buster is a



16



Methods of Control



botanical solution for mealybugs. Two sprays of

Bug Buster are recommended; first, at a dose of

4–5 ml/l of water at an interval of 3–5 days and

thereafter, at an interval of 7–15 days. Bug

Buster acts as a contact as well as systemic

against mealybugs; it penetrates the waxy cover

of the insect’s body and eventually kills them;

and it disrupts the structure and permeability of

the insect cell membranes. Disruption of cell

wall damages the cells resulting in quick killing

of the mealybugs. Hence, Bug Buster is very

effective for all the stages of mealybug, as it is

biodegradable and safe for humans; compatible

with most of the bio-pesticides/-fertilizers; free

from harmful synthetic chemicals and water soluble; acts as systemic as well as contact against

mealybugs; non-hazardous; safe to humans and

pests; and non-polluting, eco-friendly, and no

residual toxicity. Because it is a combination of

active natural extracts, there is no possibility of

developing resistance (http://www.ehow.com/

list_7578648_home- remedies- mealybugs.

html#ixzz2sd1mn MBI). Unripe fruit extract of

the plant Balanites aegyptiaca showed inhibition

of the mealybug Ferrisia virgata (Cockerell)

after the third day of spraying. No mealybugs

were observed on the leaf on the seventh day of

the application (Wabale et al. 2010). About 90 %

mortality of Planococcus citri was obtained with

pepper and eucalyptus extract at 3,500 ppm

(Ahmadi et al. 2012).

Horticultural Oil



Horticultural oils are petroleum distillates. They

are to be applied underneath leaves, on pots, and

areas surrounding the plants. These oils (if not

phytotoxic) should not be applied to plants when

temperature is greater than 85 °F or in direct

sunlight.

Insecticidal Soaps



Insecticidal soaps are a solution of synthetic

pyrethroids mixed with a mild detergent made

from petroleum products. These soaps (if not

phytotoxic) should be applied underneath leaves,

on pots, and areas surrounding the plants and

should also be used on greenhouse vegetables.



215



Dishwashing soap can be used as an effective

remedy for mealybugs. According to evergrowing.com, combine one tablespoon of dish soap

with one pint of warm water. Mix the solution in

a spray bottle and coat the plants with a layer of

the solution. The soap penetrates the protective

waxy coat created by mealybugs and kills the

pests. Check all areas of the plant, including the

underside regions, for infestation. Spray every

region of the plant to ensure complete

eradication.



16.5.3 Soil Drench

Soil drenching with malathion and parathion

were partially effective against root mealybugs.

Heavy infestations of Rhizococcus pritchardi

McKenzie on roots of African violet have been

successfully controlled by drenching the potted

plants dimethoate (Snetsinger 1966). At present,

the mealybug management is based on chemical

treatments, primarily with neonicotinoid insecticides (e.g., imidacloprid, thiamethoxam, clothianidin). These are typically applied as a soil

drench directed to the roots. Soil drench applications of imidacloprid is highly effective in reducing the mealybug populations, particularly when

applied at 0.525-g ai/vine makes it extremely

effective. In California, the mealybugs were also

controlled when imidacloprid was applied

through irrigation lines or into furrows (Sazo

et al. 2006). A further benefit of soil drenching is

that the insecticide is transported to the pest without harming the predators and parasitoids and

can be applied before they are active. Under this

condition, imidacloprid could be used to kill

mealybugs on the roots of the plants. Imidacloprid

soil treatments have good residual activity and

the control is sustained even up to 2 years.

Systemic insecticides are applied preventatively to the growing medium as a drench or as a

granule for uptake or absorption via the roots and

then translocated throughout the plant through

the vascular system. Most systemic insecticides

are translocated through the plant via the transpiration stream, which is the movement of water



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