A “WORM”WELCOME TO ALL!!!

Nanette Hope N. Sumaya

GROUP OF NEMATODES!!!

THE GOOD THE BAD THE UGLY

Entomopathogenic nematodes

Entomopathogenic nematodes

ubiquitoustransparent bodyconserved heat shock proteinsrelatively simple organizationregulates the rate of decomposition and

nutrient mineralizationmost diverse and numerically dominant

metazoans in aquatic and terrestrial habitats

Why nematodes???

Nematodes with GFPphoto by: NAMO group

Ecological indicators/Pollution studies

Species Interaction studies

Biological Control Agents

Genetics studies

Molecular studies

recent applications:

Why BIOLOGICAL CONTROL Agents?

NO TO EXTENSIVE SYNTHETHIC CHEMICAL

APPLICATION

Problems with residues?HIGH IN PESTICIDES

Analysis of Chemical Residue to Fruits and Vegetables sold in the German Market

Market contract with farmers

Comparison of data on performance ofchemical and biological control

IOBC / wprsOILB / sropFrom IOBC Internet book of Biological Control, Oct. 2006http://www.iobc-global.org

Lenteren, J.C. van, 1997. From Homo economicus to Homo ecologicus: towardsenvironmentally safe pest control. In: Modern Agriculture and the Environment,D. Rosen, E. Tel-Or, Y. Hadar, Y. Chen, eds., Kluwer Acadamic Publishers,Dordrecht: 17-31

Entomopathogenic Nematodes (EPNs) in the genera Heterorhabditis and Steinernema are used as biological control agent (BCA) for diverse insect pests.

Family : Steinernematidae with 45 known Steinernema sp.

Family : Heterorhabditidae with 11 known Heterorhabditis sp.

The enemy of my enemy is my friend

THE AMBUSHERS THE CRUISERS

EPN pest

Bacteria can be found in the vesicles (Steinernema spp.) and anterior or middle part of the intestine (Heterorhabditis spp.) Ca. 200-2000 bacterial cells inside the

EPNs.

Killing of insect host larvae after 24-48 hrs by releasing exoenzymes, toxins or secondary metabolites

Symbiotic relationship with the bacteria in the genera Photorhabdus and Xenorhabdus

1. Phoretic phase -bacteria in the Dauer Juveniles 2. Pathogenesis phase -synergistic interaction

3. Nematode reproduction - food supply

Different stages of the life cycle:1. Phoretic Phase

2. Path

og

enesis P

hase

3. Nematode reproduction

1.Phoretic Phase: Bacteria well protected in theintestine of the dauer juvenile (DL)

2.Pathogenic Phase: Synergistic effects toovercome defence mechanisms of the hostinsect for establishment.

3.Saprophytic Phase: Bacteria supply essentialgrowth factors during nematode developmentand reproduction

Penetration via mouth, anus, trachea or the cuticule of the host insect

EPNs will recover from the arrested dauer stageRelease of the bacteria (Photorhabdus/ Xenorhabdus)

3 h after penetration via the mouth of the nematode into the insect haemocoel

Killing of the insect by the bacteria after 24-72hNematode functions like a syringe,

vectoring the bacterium into a sterile environment

THE POWER OF TEAMWORK!

How are EPN attracted by insects?

EPN are attracted by CO2 and vibrations

CO2 and vibrations triggers not penetration behaviour but

Penetration behaviour is triggered by substances on the insect cuticle

EPN Smart Enough to recognize their symbionts

Heterorhabditis spp.

EPN Smart Enough to recognize their symbionts

Steinernema spp.

Infection of Plutella xylostella via the Anus

DBM- Cabbage Moth

Symbiosis: Nematode inhibits humoral defense against its symbiont

• Insects produce small polypeptides (e.g. Cecropine, Attacine, Diptericin), which kill bacteria invading the haemolymph by lysis of their cell wall

• DJs of S. carpocapsae produce a metallo-protease, that inhibits the production of the anti-bacterial peptides Cecropin

• As a result the LD50 for Xenorhabdus nematophilus is much reduced

• This is an active support by the nematode toprotect its symbiont from the insect´s defense

Life-cycle of EPNs in vivo and in vitro

Reproduction

Life Cycle of Heterorhabditis spp.

Endotokia matricida

Steinernematide DJs are determined in the sex – male and female

Life cycle of Steinernema spp.

The use of EPNs: Steinernema spp. & Heterorhabditis spp. Sciarid Fly (Bradysia sp., Lycoriella sp.)

Different Grubs

Flower Thrips ( Frankliniella occidentalis)

Sciarid Fly (Lycoriella sp., Bradysia sp.)

SEVERAL STUDIES CONDUCTED!

Becker Underwood , UK

e-nema GmbH, Germany

Bionema, Sweden

Andermatt, Switzerland Koppert, Holland

☼ Being produced commercially in large scale bioreactors and used as biological control agents

In the PHILIPPINES?

BUT RECENTLY...

Entomopathogenic nematodes were successfully isolated by the graduate research group of MSU-IIT.

Currently, undergraduate students are now on the verge of finding nematodes with the propensity to infect agricultural pests.

Pathogenecity tests will ensue after their preliminary experiments.

Artificial media preparation Rearing of the insect host, lesser wax moth

Soil collection and nematode baitingWhite trap method

THANK YOU FOR YOUR ATTENTION