Leslie L. Toralba-Ubaub, Ph. D.

Insects

Diseases

Pest

Postharvest

Impact of Insect Pests Reduction of Fruit Quality

Enhances development of diseases

Impede exportation

Fruit flies

Pod borers

Bean Pod Borer

Cacao Pod Borer

Fruit borers

Mealy bugs

Weevils

1. Quarantine- is a legally enforceable restriction for the

importation of produce in order that the introduction or spread of a pest may be prevented or limited or in order that an already introduced pest may be controlled or eradicated.

Quarantine Pest- is a potential pest of crops of economic

importance to the endangered area and which may not yet be present there, or present but not widely distributed and being officially controlled.

2. Declaring areas free from insects and diseases

- these are areas in which a specific pest does not occur as demonstrated by scientific evidence and in which, where appropriate, this condition is being officially maintained.

e.g. „Carabao‟ mango grown in GuimarasIsland.

3. Preventing diseases or insect pests spreading to a country.

e.g. The island of Palawan was placed under special quarantine in 1987 (Administrative Order No. 20), banning the exit of fruits from the island.

4. Regulation on treatment of imported fruits to prevent pests from spreading.

e.g. Mango fruits – Vapor heat treatment (Aus, NZ, USA and Korea)

„Solo‟ Papaya – VHT (Japan)

„Cavendish‟ – treated with fenthion and are require to be shipped at the green mature stage (NZ).

5. Residues of pesticides in food

- a Maximum Residue Level (MRL) established by Codex AlementariusCommission.

- MRL is the highest concentration of a particular chemical that is legally permitted or accepted on food.

6. Certification

- based on the International Plant Protection Convention (IPPC) certification system.

e.g. A quarantine inspector must certify the Mango fruits from Guimaras for export to Aus and USA; and Mango and Papaya for export for Japan.

Quarantine Treatment - is any treatment that kills or otherwise render incapable of establishment quarantine pests at a predetermined level of control (Hallman 2001).

Disinfestation of Phytosanitary Treatment –any treatment that kills, removes or otherwise inactivate pests whether they are of quarantine importance or not, in a commodity, to any level of control.

Quarantine Security – degree of statistical probability needed by a quarantine treatment to disinfest host produce so that upon transport or shipment of the treated pest cannot be established in any area where they do not exist yet (Paul and Armstrong 1994).

Probit Analysis – statistical treatment of quantitative assay data that provides the basis for quarantine security.

Presence of more than one life stage on or in the host commodity.

Location of the insect‟s life stages in the host.

Different Life Stages of an Insects:

1. Egg

2. Larva

3. Pupa

4. Adult

Must kill all stages of the insect present in the commodity.

Rule of thumb:

“No live insects 24 h after treatment”

There should be no detrimental effects on fruit quality.

Must be commercially feasible.

There should be no harmful effects on humans.

e.g. Ethylene dibromide (EDB) to VHT

The treatment should not pose any environmental hazard.

e.g. Methyl bromide scheduled for phase out in 2015 in developing countries.

Fumigation

- use of fumigant, a chemical that at required temperature and pressure can exist in gas form in sufficient concentration to kill an insect or organism.

Insecticide Dust or Spray

e.g. Fenthione

Heat Treatment – is a physical method of controlling insect pests and is therefore more acceptable to consumers.

- can be applied in various ways:

1. Vapor heat treatment

2. Heated dry air or high-temp. forced air or hot forced air.

3. Hot water immersion or extended hot water dip.

Vapor Heat Treatment

Julmar Industrial Sales and Supply Corporation

Hot Water Treatment

Radio Frequency and Microwave Energy Treatment.

Irradiation

Objective: To prevent introduction and spread of regulated pests by:

1. Mortality

2. Aborted development

3. Inability to reproduce

4. Inactivation

Low-Temperature Treatment

- involves exposure of fruit to very low temperature for a specified period and is ideal as in-transit treatment.

Controlled Atmosphere

- modified atmospheric gases can be lethal to quarantined pests yet beneficial for preserving postharvest quality.

- ↑ CO₂ ↓O₂ reduce ATP production in insects.

Use of a screened packinghouse where packing is done.

Vent holes of cartons used for export are covered with nets to prevent reinfestation.

Sanitation of packinghouses and storage rooms will likewise prevent reinfestation.

Limit the potential storage life and sale of fruits and vegetables to distant markets.

The largest single cause of postharvest loss.

Diseases could either be non-infectious or infectious.

Strictly Preharvest Disease – fruits and vegetables are infected at the early stages of growth and symptoms are already present at harvest.

Postharvest Diseases due to Latent Infection –the infected during growth with no symptoms at harvest.

Strictly Postharvest Diseases –microorganisms infect the commodity during or after harvest.

Direct contact

e.g. Durian that falls on the ground susceptible to disease due to soil-borne inoculum of Phytophthora palmivora.

Indirect contact

- spores or bacterial cells are transferred by an intermediate agents.

Entry through natural openings or wounds and mechanical injuries.

e.g. Pectobacterium carotovorum can enter only through wounds or natural openings.

Direct penetration

e.g. Colletotrichum gloeosporioides

pH

Water status

Physiological stage

Species

Cuts, wounds, abrasion and other forms of mechanical damage.

High temperature – this favors disease development that can be due to either enhancement of ripening process or enhanced growth of the pathogen.

High relative humidity – most fungi and bacteria require moist conditions for growth and disease spread.

Gas composition (O₂, CO₂, Ethylene)

Anthracnose

Stem-end Rot

Black Rot

Biology of the pathogen and the relationship to disease development

Environment during growth and after harvest

Production practices Postharvest handling

practices

Identification of the causal agent of the disease.

Thorough knowledge of the following:

Control of Preharvest Infection

e.g. Fungicide application, and bagging

Control of infection during and after harvest

e.g. Careful handling, Sanitation/cleanliness and Avoid favorable conditions for microbial development particularly warm moist conditions.

1. Sulfites e.g. Sulfur dioxide (grapes), Sodium metabisulfite (peeled young coconut).

2. GRAS chemical – Generally Regarded as Safe e.g. Lime and Alum (bacterial soft rot)

3. Edible coating – e.g. Chitosan

4. Growth Regulators e.g. Gibberelic acid (GA3)

5. Fungicides – through Dipping, Spraying, Chemical pads or Oil Wraps (usually Biphenyl).

Concerns with regards to Fungicide Usage:

1. Fungicide Residues

2. Resistance to fungicides

3. Fungicide disposal

1. Heat Treatments

e.g. Hot water treatment, Hot water rinse and brush method, and High-humidity hot air

2. Irradiation – the use of Gamma irradiation

3. Ultraviolet-C – has been mainly used for surface disinfection.

4. Low Temperature Storage

5. Atmosphere Modification

1. Antagonistic Microorganisms

Mode of Action

Production of

antibiotics

(e.g. B.

subtilis

controls C.

gloeosporioi

des)

Competition

for nutrient

and space

Direct

parasitism

(P.

guillermindi

VS B.

cinerea)

Induction of

Resistance

Method of Application

1. Incorporated in waxes

2. Fine sprays

3. Dips

Concentration of antagonist – a successful biocontrol program requires that the antagonist be applied at low concentration.

2. Natural Biocides – are plant-derived extracts and secondary metabolites that are biocidal.

3. Natural Defense Mechanisms – e.g. Structural Components and Defensive reactions that could be:

Systemic Acquired Resistance (SAR), Induced Systemic Resistance (ISR)