FR005 Biology and management of field pests of mangoes

Dr Ian Cunningham Queensland Department of Primary Industries

danikahStamp

FROOS

This report is published by the Horticultural Research and Development Corporation to pass on information concerning horticultural research and development undertaken for the mango industry.

The research contained in this report was funded by the Horticultural Research and Development Corporation with the financial support of the Queensland Fruit & Vegetable Growers.

All expressions of opinion are not to be regarded as expressing the opinion of the Horticultural Research and Development Corporation or any authority of the Australian Government.

The Corporation and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this Report and readers should rely upon their own inquiries in making decisions concerning their own interests.

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HRDC ISBN 1 86423 326 5

Published and Distributed by:

Horticultural Research and Development Corporation Level 6 7 Merriwa Street Gordon NSW 2072

Telephone: (02) 9418 2200 Fax: (02) 9418 1352

Copyright 1996

FINAL REPORT

Biology studies and control of mango

pests in north Queensland

HRDC PROJECT FR005

QDPI Mareeba

I.C. Cunningham S. DeFaveri B. Pinese

August 1996

COLOUR PLATE

MANGO PESTS STUDIED FOR THIS REPORT

Colony of mango scale on leaf. Female scales on fruit note the pink skin

discolouration due to the scale

Mango seed weevil, Sternochetus mangiferae adult and larvae and damage to the seed cotyledons

arvae of mango tipborer Chlumetia euthystica showing damage to terminal shoot

CONTENTS

Page

Colour plate

Summary 1

Industry 1

Technical 3

Recommendations 4

Extension/Adoption 4

Directions for future research 5

Financial/commercial benefits 5

Technical Report 6

Introduction 6

Materials and methods 8

Results 11

Discussion of results 17

Bibliography 21

1

SUMMARY

(I) INDUSTRY SUMMARY

The project involved field, laboratory and glasshouse studies towards development of a sound pest management system for mangoes. Major emphasis was focused on the two major pests, mango seed weevil (MSW) and mango scales. The former is a pest of quarantine importance. Mango scales cause loss of tree vigour and fruit blemish.

Infested fruit are also unacceptable for export markets. A preliminary evaluation of

the impact on yield following mango tip borer damage was also undertaken.

The biology, ecology and control of these pests had not been researched in the rapidly

expanding mango growing areas of north Queensland. Surveys of mango fruit revealed the heaviest infestations of MSW occurred in fruit from large urban trees.

Commercial orchards were either not infested or had lower infestation levels than

urban trees.

A sampling procedure was developed to detect MSW in orchards. Non-infested

orchards were issued with a phytosanitary certificate. Phytosanitary certificates were

useful in export market development.

The biology and ecology of MSW in north Queensland was elucidated through field and laboratory life histories. Trapping of adults was attempted with unsatisfactory

results.

Insecticide screening trials to test the efficacy of several insecticides against MSW

were conducted. Insecticidal/cultural control was part of a strategy to reduce the risk

of spread of MSW to non-infested orchards and reduce populations in infected

orchards.

Fenvalerate (0.025% ai) applied as two cover sprays before and after flowering was considered the preferred treatment. This pesticide reduced the populations of MSW to

2

low levels but did not eradicate the pest. Cultural methods for MSW control (removal of fallen fruits) were found to be ineffective.

Insecticide screening trials were also conducted to test the efficacy of several

promising insecticides against mango scales. Data on scale mortality and survival of

beneficial insects was recorded. All treatments were equally effective and low

viscosity mineral oil (Lo-vis) and chlorpyrifos were registered for control of mango scale.

3

(II) TECHNICAL SUMMARY

The project aimed to: 1. determine the incidence of mango seed weevil, Stemochaetus mangiferae (Fabricius) in north Queensland and to develop fruit sampling protocols to allow the issue of phytosanitary certificates; 2. develop a field

control spray programme for mango scales, Phenacaspis dilatata (Green) and Aulacaspis tubercular is Newstead and to determine the level of natural control;

3. obtain registration of new products for control of mango scales and 4. determine

the impact of damage from the mango tip borer, Chlumetia euthysticha (Turner) on fruit yield.

A sampling procedure using a 1:400 fruit sample was developed to detect the

presence/absence of weevils in orchards. This protocol was used as the basis for

issuing phytosanitary farm certificates to allow the development of export markets.

Fenvalerate (0.025% ai) sprays and cultural control methods (fruit removal) were evaluated as methods for eradicating MSW but both of these techniques reduced the

incidence of the pest only.

Buprofezin was effective against mango scale for up to five months at 60 ml/100 L.

Buprofezin was also specific to the mango scale and therefore is superior to

methidathion. Imidachloprid was also tested but was not as effective as buprofezin

and methidathion. Sprays of low viscosity oil used alone and in conbination with low

rates of buprofezin (30 ml/lOOL) were not as effective as buprofezin used at the higher rate. Imidachloprid as a foliar spray and as a paint treatment to the trunk was

not effective and appeared to cause an increase in scale.

Our results indicate that for best results, buprofezin should be applied when fruit is

pigeon egg size and again one month later.

Results from a tip removal experiment to simulate mango tip borer damage were

inconclusive due to erratic bearing of the test trees. Results tended to indicate that

yield responses were more sensitive to removal of the early flush (early February) than the removal of the late flush (late March). The severity of tip removal (from 1 to

4

5 tips per shoot) did not provide consistant results in relation to yield. Size of remaining shoots appeared to be unrelated to the level of prior shoot removal.

RECOMMENDATIONS

(I) EXTENSION / ADOPTION

(a) A 1:400 fruit sampling protocol can be adopted as a means of determining farm freedom from mango seed weevil. Since farm freedom has been recognised by

exporters as a valid criteria for export of mangoes, this sampling procedure can be

used by growers wishing to enter markets where mango seed weevil is a quarantine

pest.

(b) Sprays of fenvalarate can be used to suppress field populations of mango seed weevil. These may not result in eradication but sustained well timed applications over a

number of seasons may result in achieving farm freedom status.

(c) Mango scale can be controlled by individual sprays of low viscosity oil, chlorpyrifos or buprofezin. Data from this project was used to support the registration of chlorpyrifos against mango scale. Registration for buprofezin should be finalised for

the 1997.

5

(II) DIRECTIONS FOR FUTURE RESEARCH

(a) Although this project identified a range of native parasites and predators effective against the mango scale, the level of control attributed to these beneficials is

inadequate. Augmentation via the introduction of exotic beneficials is considered

necessary if adequate levels of biological control are to be realised.

(b) Evaluate Chilocorus circumdatus as a mango scale predator.

(c) Improved knowledge of the seasonal population dynamics of mango scale and its beneficial complex is essential to develop a more target oriented insecticide spray

programme.

(d) A collaborative research programme involving Australia and Thailand should be undertaken to develop mutually acceptable area freedom and control protocols for

mango seed weevils to allow the expansion of mutually beneficial mango trade

between the two countries. This work will also be valuable in opening new markets

into other countries where mango seed weevils are quarantine pests.

(e) The study to determine the economic impact of mango tip borer should be repeated to demonstrate the need (or otherwise) for specific insecticide treatments.

(f) The possible phytotoxic effect of mineral oil sprays and the impact of their use on flowering and fruit set (as reported in the literature) needs investigation.

(Ill) FINANCIAL/COMMERCIAL BENEFITS

Not applicable.

6

TECHNICAL REPORT

INTRODUCTION

The mango industry ($60 m current value to north Queensland) has come into prominence in the last decade. Expansion is continuing. Most of the crop is sold as

fresh fruit on the domestic market. Overseas markets are becoming very important to

the overall economy of the mango industry as supply exceeds domestic demand.

Access to some important markets has been denied to Australian mangoes because of

mango seed weevil, Sternochaetus mangiferae.

The pest status of the mango seed weevil results from quarantine limitations rather

than commodity damage. Fruit quality is unaffected by oviposition, larval feeding,

and development. Only seed germination is adversely effected.

The life history of S. mangiferae has been reported by Balcock and Kozuma (1964) Schoeman (1977), De Villiers (1984) and Cunningham (1989). In north Queensland, egg laying commences when the fruit has reached 30 mm in September/October and

continues until one month before fruit maturity in November, (Cunningham, 1989). One or more eggs are laid on a fruit. Development from egg to adult occurs in 5-6

weeks. Adult weevils emerge from fallen fruit in January-February and move to

sheltered sites, usually tree crotches on the parent tree. They remain inactive until

swelling of the flower bud occurs. Movement from resting sites to the outer canopy is

by flight. Adult longevity of 21 months has been recorded by Balcock and Kozuma

(1964).

Jarvis (1946) considered damage to be of more concern to nurserymen than fresh fruit producers and stated control was impractical in Queensland. A change from low to high pest status occurred in the 1970's in response to quarantine limitations on some

foreign markets.

7

Brooks and Snyman (1986) and De Villiers (1987) in South Africa developed mango seed weevil management strategies based on fruit hygiene, removal of fallen fruit and

fenvalerate, parathion or prothiofos sprays.

Two species of Diaspidid scales; Phenacaspis dilatata (Green) and Aulacaspis tubercularis Newstead, are important economic pests of mangoes in Queensland. Scales infest the twigs, leaves and fruit.

In the nursery a severe infestation of mango scale will retard growth. Young trees in

the field are particularly vulnerable to excessive leaf loss and death of twigs due to

scale infestation. The stress is exacerbated during hot dry weather.

Infested areas on leaves turn pale green or yellow and ultimately become necrotic.

Scale infestations on the fruit cause a conspicuous pick blemish. Both the blemish

and presence of scale downgrade quality and scale infested fruit is unacceptable for

export markets.

The biology of A. tubercularis has been discussed by De Villiers (1984) Vilujoen and De Villiers (1987) and Cunningham (1989). Continuous breeding occurs throughout the year in north Queensland. The rate of increase is highest in spring and summer. In South Africa, De Villiers (1984) developed mango scale management strategies based on prothiophos and parathion sprays but both insecticides are disruptive to

beneficial insects.

The work reported here had the following aims: (1) to determine the incidence of S. mangiferae in the study area and to establish whether area freedom could allow the issue of phytosanitary certificates, (2) to elucidate the efficacy of cultural control and combinations of cultural practices and insecticide sprays in suppressing S. mangiferae populations, (3) to develop a pest management strategy for mango scale, and (4) determine the economic importance of mango tip borer.

8

2. MATERIALS AND METHODS

2.1 Mango seed weevil (MSW)

2.1.1 Incidence of MSW in the far north Queensland study area.

The study area was a roughly triangular area between Cairns, Mossman and Dimbulah

between latitudes 1706'S and 1630'S in north Queensland.

Preliminary sampling had shown that mango trees fell into three broad categories.

These were:

(1) shade trees in urban areas and adjoining dwellings on farms,

(2) orchard trees, usually > 10 years old, growing within long established farming areas, and

(3) recently developed orchards isolated from trees in categories 1 and 2 and usually < 10 years old.

Mangoes, within two weeks of maturity, were harvested at random and cut longitudinally into

halves. Cotyledons were examined for the presence of larvae, pupae and adult MSW. Fruit

was scored for the presence or absence of MSW. Fruit were destructively sampled at five

sites in each of the tree location categories. Sample size was 200 fruit. Due to irregular

bearing of mangoes the same trees in each category were not always sampled.

2.1.2 Evaluation of orchard freedom from MSW

A sampling procedure based on destructively sampling 1:400 randomly selected fruit within

one month of harvest was employed.

9

2.1.3 Management of MSW

(a) Experiment 1

An experimental area of 100 trees, in an orchard known to be infested with S. mangiferae, was divided in half (5 rows x 10 trees). From one half, fallen fruit more than 20 mm long was removed twice weekly until harvest. Fallen fruit were not removed from the other half.

In the succeeding year 200 fruit per block were sampled in the manner previously described,

from the three central rows, two weeks before harvest and the number of infested fruit

recorded.

(b) Experiment 2.

A 5 x 4 randomised block of 25 trees per plot was established in an orchard of 700 trees

infested with S. mangiferae. Datum area within plots was 9 trees in the centre of the plot. Treatments were:

(1) nil treatment,

(2) trunk and scaffold branch spray with fenvalerate 0.05% a.i. in April,

(3) trunk and branch spray with fenvalerate 0.05% a.i. in April plus canopy sprays with fenvalerate 0.025% a.i. before (July) and after flowering (October) and

(4) remove debris from base of trunk to the drip line and spray and cleared area, trunk and scaffold branches in April with fenvalerate 0.05% a.i. plus the canopy before and after

flowering with fenvalerate 0.025% a.i.

Sprays were applied between 5 and 7 am with a misting machine. Four hundred random fruit

per treatment were destructively sampled two weeks prior to harvest and the number of

mango seed weevil recorded.

10

2.2 Mango scale

The efficacy of several insecticides against mango scales were tested in a 6 x 3 randomised

block experiment. Treatments were:

(1) prothiophos 0.05% a.i.,

(2) methidathion 0.05% a.i.,

(3) low viscosity oil 1.0% a.i.,

(4) buprofezin 0.05% a.i.,

(5) chlorpyrifos 0.1% a.i.

(6) nil treatment.

Treatments were applied on February 24, March 21 and October 22.

Four leaves were sampled from the canopy of the single tree plots in April, May, July,

September, October and December. Numbers of live female scales and beneficial insects

were recorded.

11

3 . RESULTS

3.1 Mango seed weevil

3.1.1 Incidence of MSW in the far north Queensland study area

Results are presented in Table 1.

Infestation levels were higher in urban shade trees (category 1) than in trees under orchard management (categories 2 and 3). Infestation levels in orchard trees in older established farming areas (category 2) declined during the study period. Mango orchards (category 3) established some distance from infested trees category (1 and 2) remained free from infestation during the period of the study.

TABLE 1. Percentage of mango fruit infested with S. mangiferae

Year Category 1 Category 2 Category 3

(shade trees in (orchard trees in (orchard trees in urban area) established farming newly cultivated

areas) areas)

1982 80 30 nil

1983 89 35 nil

1984 76 20 nil

1985 77 16 nil

1986 70 9 nil

1987 79 3 nil

12

No fruit set occurred at one site (category 1) Dimbulah in 1985 due to frost during flowering. Infestation levels in 1986 were similar to 1984 levels despite the absence of fruit for 18

months.

3.1.2 Management of MSW

(a) Experiment 1. Infestation values for the hygiene and untreated blocks are 64 and 52 percent respectively. Field hygiene during one season did not influence the

percentage infestation level in the subsequent season. The experiment was

discontinued due to the high labour requirement.

(b) Experiment 2. The mean number of mango seed weevil per treatment are presented in Table 2.

TABLE 2. The efficacy of several fenvalerate treatments against mango seed weevil

Treatment No. of infested fruit (sample size 400 fruit)

Back transformed mean (%)

1. nil treatment 16 3.3a

2. trunk and branch spray with fenvalerate 0.05% a.i. in April

4 0.8b

3. As 2 above plus canopy sprays of fenvalerate 0.025% a.i. before and after flowering

4 0.8b

(con. Over)

13

Treatment No. of infested fruit (sample size 400 fruit)

Back transformed mean (%)

4. Two canopy sprays of fanvalerate 0.025% a.i. before and after flowering

3 0.6b

5. Debris removed from under tree spray drip area plus spray treated area, as in 2 and 3 above

5 1.0b

Means not followed by a letter in common differ significantly (P

14

3.2 Mango scale

Results of chemical control trial are presented in Tables 3.

All insecticides tested were efficacious against mango scales, Aulacaspis tubercularis and

Phenacaspis dilatata.

The data presented in Table 4 shows numbers of beneficial insects collected from mango

scales from scale infested leaves collected from sprayed or unsprayed trees. Sample size was

72 leaves collected on six occasions between April and December. Two thousand one

hundred and fifty live female scales were examined.

Predators were: Coccinellidae {Rhyzobius sp. and Chilocorus(J)baileyi Blackburn); Neuroptera (Chrysopidae) (Chrysopa otalatis Banks and Oligochrya lutea Walker); Thysanoptera (Phaeothripidae) (Aleurodothrips faciapennis (Franklin)) and Lepidoptera (Noctuidae) (Catoblemma dubia (Butler). Only one parasite, Hymenoptera (Aphelinidae), Aphytits sp. was recorded. While predation levels could not be quantified, parasitism was

only 1.7 percent.

15

TABLE 3. Number of live female scales on old leaves and old stems after treatments in

Treatment April May July September

Treatment Old Leaves

Old Stems

Old Leaves

Old Stems

Old Leaves

Old Stems

Old Leaves

Old Stem

Prothiophos

Buprophezin

Mineral oil

Methidathion

Chlorpyrifos

Control

12.0

4.3

5.0

1.7

2.3

94.0

1.0

0.3

2.3

0.7

0.3

6.7

31.3

10.7

16.0

9.3

7.0

111.7

2.3

1.3

1.3

1.0

0.3

8.0

33.0

18.3

49.7

12.3

3.0

63.3

2.0

1.0

0.0

0.0

0.7

10.3

100.0

7.7

31\0

23.3

22.3

112.3

3.7

2.7

2.0

3.0

3.3

17.3

LSD 5%

LSD 1%

22.3

31.8

NS

NS

64.2

91.3

2.6

3.6

33.2

47.3

5.3

7.5

60.4

85.9

9.3

13.2

LSD = Least Significant Difference at 5 and 1% level of probability.

16

TABLE 4. Number of beneficial insects recorded from scale infested mango leaves following tr March & October

SAMPLE DATE APRIL MAY JULY SEPTEMBER OC Beneficials C N H T. L C N H T L C N H T L C N H T L C N

Treatment

C N H T L C N H T L C N H T L C N

Prothiophos 1 - 3 1 - 1 . . . . 3 -

Buprophezin 1 _ _ . - -Buprophezin

Mineral Oil 1 1 - 3 - - - - - - 1 . . . . 3 -

Methidathion . . 1 . - - - 2 - - - - -

Chlorpyrifos 1 _ 2 -Chlorpyrifos 2 -

Control 1 - 4 3 - - - 3 7 3 3 - 1 10 - 4 - - 12 - 5 -

TOTAL 3 2 7 8 - - - 3 7 3 4 - 3 10 - 6 - - 12 - 13 -

C = Coccinellidae H = Hymenoptera L = Lepidoptera N = Neuropte

17 4. DISCUSSION OF RESULTS

Insect cycles and phenological development in mangoes in north Queensland

Following harvest in December-January trees are pruned in January-February. New growth

flushes occur in late February and late March. These flushes are attacked by the

lepidopterous tip borers, Chlumetia euthysticha (Turner) and Penicillaria jocosatrix Guenee and mango scales.

Two insecticide sprays are recommended in February and March to protect the new growth

from damage. Following flowering in July-August, mango fruit develop on the tree. By

October these fruit are 30mm diameter. At this stage oviposition by mango seed weevil

commences and continues until one month before fruit maturity. Mango scale and mango

plant hopper Colgaroides acuminata (Walker) cause fruit blemish during October-December. Mango seed weevil hatch from fallen fruit in January-February.

Mango Seed Weevil management

High levels of mango seed weevil (MS W) in urban trees is most probably due to the absence of insecticide sprays and also because a high percentage of the fruit is left unharvested. Our

results indicated that collection and destruction of fallen fruit does not control MSW. Also

populations of MSW are not reduced by the removal of infested fruit during harvest.

Urban trees are a focus for spreading MSW. Circumstantial evidence suggests infestations

spread passively by movement of infested fruit for propagation and consumption rather than

by flight of adult weevils.

Eradication of urban trees is not an option because of the costs and objections of landholders. Similarly pest management with insecticides is impractical. An education program to

increase awareness of the dangers of spreading MSW through movement of fruit is

warranted. This is particularly valid where several growers may use a shared packing facility.

Circumstantial evidence suggests that population decline after 1983 (Table 1) in infested orchards is due to methidathion and chlorpyrifos sprays applied in the pre and post flowering

period for mango scale control.

18

A two fold approach to managing MSW has been adopted. The program involves

identification of orchards free of the pest and suppression of populations in infested orchards.

The sampling procedure based on destructively sampling 1:400 fruit (approximately one fruit from each alternate tree) has been a valuable guide to presence or absence of MSW. The sample size is a compromise between accuracy and the cost to the grower of fruit loss due to

sampling.

Phytosanitary certificates issued following sampling have been a valuable guide to exporters,

of orchards which are free of MSW. Exporters have been requesting phytosanitary

certificates from growers. A long term approach to developing export markets is necessary.

In years of low domestic production and high domestic prices, growers are less enthusiastic

of destructive sampling to demonstrate low levels of MSW. Continuity of sampling to

maintain a history of freedom from infestation is important irrespective of short term market

trends.

Acceptance by the Japanese and Middle East countries of the orchard freedom concept has

opened markets to Australian mangoes.

The technique developed in this study for assessing farm freedom was used successfully in

Thailand to survey the incidence of a related MSW, Sternochaetus oliveri.

There are no known alternative host plants for MSW. At one location sampled, frost killed

the flowers and no fruit developed. Although the population of MSW was denied the

opportunity to reproduce for 18 months.the adults survived during this extended non fruiting

period. Longevity of adults (over several seasons if required) is an important survival mechanism in mangoes which are erratic bearers. Consequently removal of fallen fruit,

stressed by De Villiers (1984) and Schoeman (1987) as a cultural control technique, is unlikely to give significant population suppression in the short term. The cost of removing

fruit twice weekly over several months and at least two seasons would be high. A mechanical

method of fallen fruit collection would be an advantage.

19 Suppression of MSW to < 1 percent fruit infestation was achieved in one season using

fenvalerate sprays (0.025 % a. i.) applied in July and October. Fenvalerate treatment repeated over several seasons will most likely reduce mango seed weevil to very low levels which

would not be detected by sampling. Fenvalerate sprays will most likely be necessary on a

continuing basis to prevent resurgence of MSW. Fenvalerate sprays can be used as a

mechanism for reducing field populations and limiting the spread of MSW to non-infested

orchards but cannot be used as a tool for MSW eradication.

Natural enemies are also extremely sensitive to fenvalerate sprays. Mango scale populations

increased in fenvalerate treated plots. Because the pest status of MSW results from export

quarantine limitations rather than commodity damage and fenvalerate sprays are disruptive of

biological control of mango scale, fenvalerate should not be sprayed in orchards producing

mangoes for the domestic market.

Mango scale management

Since the successful biological control of pink wax scale, Ceroplastes rubens Maskell by the

introduced parasite Anicetes beneficus Ishii & Yasumatsu, mango scale control is the biggest single factor influencing the frequency of insecticide sprays on mangoes.

Beneficial insects presently in Queensland are ineffective as biocontrol agents in preventing economic losses from mango scales. However they do collectively suppress mango scale

populations. Use of a broad spectrum insecticide such as fenvalerate will kill beneficials and

induce a rapid increase in mango scale populations.

During this study a literature review of beneficial insects on mango scales in overseas

localities was conducted with a view to finding candidate species for introduction. De

Villiers (1987) lists four natural control agents of mango scales in South Africa. These are Aspidiotiphagus citrinus Craw (Aphelinidae) Rhizobius lophanthae (Blaisdell) and Chilocorus nigritus (F) (Coccinelidae) and an unidentified Cecidimyiidae. Schoeman (1987) recorded parasitism levels of 17.7% for A. citrinus and considered the insect to have

biocontrol potential. Samways (1984) has successfully employed C. nigritus against Diaspidid scales on citrus. The taxonomic status of Aspidiotiphagus is being revised. Until the revision is published, Aspidiotiphagus cannot be a candidate for introduction.

20

An application to the Department of Primary Industries and Energy to introduce Chilocorus

nigritus (F.) from South Africa for host specificity testing was refused. The recent fortuitous arrival of Chilocorcus circumdatus, which is proving to be a useful predator against

Diaspidid scales in citrus, may be advantageous to biological control of mango scales. The

interaction between C. Circumdatus and mango scales is being studied.

Augmentation of the biological arsenal against mango scales is desirable. Selection of

beneficial-friendly insecticides for mango scale control will enhance control and prevent

rapid resurgence of mango scales which can follow the use of broad spectrum insecticides.

Two insecticides tested in the mango scale insecticide screening trial are selective on a

limited range of insects, mainly scale insects. These insecticides are low viscosity oil and

buprofezin. The latter is an insect growth regulator. Buprofezin causes the death of scales at

moulting and suppresses oviposition. Both low viscosity oil and buprofezin were efficacious

against mango scales in the insecticide screening trial conducted during this study (Table 3). Low viscosity oil is the preferred insecticide for mango scale control.

Buprofezin has not been registered for control of mango scale because product development

was not pursued by the manufacturer. The organophosphorous (OP) insecticides chlorpyrifos and methidathion are also efficacious against mango scales and tip borers, C. Euthysticha and

P. Jososatrix, which damage new growth in February-April. Efficacy data presented here

(Table 3) was used to support registration of chlorpyrifos for mango scale control.

To achieve integrated pest management in mangoes, augmentation of parasitoids by

introduction of beneficials and the use of beneficial-friendly scale pesticides is desirable.

Elucidation of economic injury levels and seasonal population cycles would assist in the formulation of an effective integrated pest management program for mangoes.

21 BIBLIOGRAPHY

Cunningham, I.C. (1989). Management of Mango Insect Pests - A Review. Proceedings of the 3rd International Mango Symposium, Darwin.

Cunningham, I.C. (1989). Mango seed weevil in Queensland. Proceedings of the 3rd International Mango Symposium, Darwin.

Cunningham, I.C. (1989). Common mango scales in Queensland. Proceedings of the 3rd International Mango Symposium, Darwin.

De Villiers, E.A. (1987). Beheer van die mangodophuis met mineral olie. South African Mango Growers Association Yearbook Vol. 7.

Samways, M.J. (1984). Biology and economic value of the scale predator, Chilocorus nigritus (F) (Coccinellidae). Biocontrol News and Information 5(2)91-105.

Schoeman (1987). First record of a parasitoid of the mango scale, Aulacaspis tubercularis Newstead. J.ent.Socof Southern Africa, 50: 1,259.

Viljoen, Helena M.-and De Villiers, E.A. (1987). Doeltreff end heid van fenvaleraat en monokratafos teen die mangodopluis, Aulacaspis tubercularis Newstead. Subtropica

8: 1:19-23.