Global Plant Protection News

Training Workshop on

Indigenous Biological Control Agents of the Fall Armyworm:

Techniques in field collection, mass rearing and release

 Organizers: icipe in collaboration with the Integrated Pest Management-Innovation Lab, Virginia Tech

Date: February 25 to March 1, 2019

Venue: icipe, Nairobi, Kenya

 OBJECTIVE

The purpose of this workshop is to assess and learn methods in field collection, mass rearing and release of indigenous biological control agents of the fall armyworm including egg and larval parasitoids.

BACKGROUND

Fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), is native to tropical and subtropical regions of the Americas and is the key insect pest of maize in tropical regions. The first occurrence of FAW was reported in West Africa in late 2016. Since then, it has rapidly spread to different parts of the continent and currently its occurrence has been confirmed in over 40 Sub-Saharan African countries. Given the importance of maize in Africa as a main stable food crop, the recent invasion of FAW threatens the food security of millions of people in the region. According to a recent estimate in SSA, in the next year FAW damage can cause damage on an estimated 13.5m tons of maize (valued at US$3,058.8m), which accounts for about 20% of the total production in the region. Currently, farmers in Africa are using high doses of insecticides to control FAW; nevertheless, relying on insecticides alone will come with several problems soon. The potential problems include pest resistance, pest resurgence, environmental pollution and destruction of natural enemies. Long-term and sustainable solutions for FAW control should follow a management approach integrated with IPM for maize. IPM includes regular pest monitoring and use of two or more control options in a compatible manner. Biological control is one of the components of the IPM approach. In 2018, five different species of larval parasitoids, four belonging to Hymenoptera and one to Diptera, were reported from FAW larvae in East Africa. These include: Cotesia icipe, Palexorista zonata, Charops ater, Chelonus curvimaculatus and Coccygidium luteum.  Recently, two egg parasitoids, Trichogramma and Telenomus, were identified. Information on the occurrence and rates of parasitism of indigenous natural enemies has a paramount importance in designing biological control of FAW either through conservation of native natural enemies or augmentative release. This training is technical and is designed for national researchers, development agents and technicians to gain practical hands-on experiences in field collection, mass rearing in the lab, and mass release of indigenous biological control agents of the fall armyworm including egg and larval parasitoids in the field.

Contact: ttefera@icipe.org

Program schedule:

Day 1: Monday, Feb 25, 2019

Day 1 covers status of the fall armyworm (FAW) in Africa and potential biological control agents and their use in controlling FAW. The objectives of Day 1 are to understand status of FAW in Africa and to assess potential biological control agents against FAW.

Day 2 (Tuesday) and Day 3 (Wednesday)

Day 2 (Tuesday) and Day 3 (Wednesday) cover various ranges of laboratory practices. Participants will be introduced to lab policy and safety precautions before they start doing anything in the lab. The laboratory hands-on practices include the following (detailed lab protocols and procedures will be provided during the lab sessions):

Mass rearing FAW using artificial diets

Mass rearing of FAW is required as some of its natural enemies depend on the host (FAW) number. The lab practice covers mass rearing of FAW using artificial diets and this includes: colony initiation, egg collection and sterilization, media preparation and dispensing, inoculation of diets with first instars neonates, pupae collection and harvesting, and pairing of adult moths (oviposition). It also includes rearing FAW using natural host maize.

Mass rearing the Mediterranean flour moth or mill moth (Ephestia kuehniella), a factitious host for Trichogramma

The purpose of multiplying mill moths is to multiply the egg parasitoid Trichogramma sp on factitious host E. kuehniella eggs. This includes rearing E. kuehniella in a lab for colony establishment as well as rearing E. kuehniella for Trichogramma mass production. This lab session includes selection of natural diets of mill moth (cereal bran), inoculation of diet with egg or larvae, organizing lab materials required, oviposition and egg harvesting, collection of newly emerged adult moths and sexing them.

Mass rearing the egg parasitoid Trichogramma on mill moth eggs for field release

This covers sexing Trichogramma wasps, exposing the eggs of mill moth to Trichogramma wasps, preparing glue cards, pouring the eggs to cards painted with glue, preparation of honey solution for the wasps, release of Trichogramma to the eggs glued to the card, removal of exposed cards, labelling and incubating the parasitized eggs.

Mass rearing the egg parasitoid Telenomus remus on FAW eggs

Field collection of FAW eggs from 5-6 weeks old maize into rearing jars, examining egg masses for parasitism using hand lens (compare both eggs with parasite and without parasite for better understanding of the differences; parasitized FAW eggs turn deep black compared to unparasitized FAW eggs),  keeping the egg masses at room temperature for 10 days to observe for T. remus adult emergence, allow mating for two days before exposing fresh FAW egg masses for parasitism, exposing fresh FAW egg masses to T. remus.

Mass rearing the larval parasitoid Cotesia icipe on FAW larvae

Collect 4-5-week-old maize leaf damaged by FAW, examine under leaf surface for Cotesia cocoons, collect the cocoons into jars/vials separately by cutting leaves, observe for adult C. icipe emergence, introduce honey solution into the jars or vials for adult feeding. Transfer 2^nd instar FAW larvae to the cage (second instars are preferred by this parasitoid), introduce fresh maize leaves inside the cage for larvae to feed, introduce about 10 pairs of Cotesia icipe into the cage using aspirator for about 200 FAW larvae, expose them for 24 hrs during which the larval parasitoid, Cotesia icipe, stings/oviposit into the FAW larvae. Collect the stung larval instars 24 hrs. after exposure and keep them in a lunchbox, provide them with fresh maize leaves and change the leaves every 2 days, observe for white fluffy cocoons 6-7 days after exposure, harvest the cocoons and keep them in adult emergence cage; the cycle of exposure continues until the required population is attained.

Participants will be assigned to the following groups for lab practical exercises. Those responsible are Tadele, Malusi and Faith.

Day 4: Thursday, Feb 28, 2019

Responsible: T Tefera, Malick Ba, P Malusi and the host farmer, Mr Kamathi

Field trip to Mwea, about 80 km from Nairobi. In Mwea, maize (4 weeks old) was planted under farmer’s management condition and not sprayed.

Purpose of the field trip and practice: To identify FAW eggs under field conditions, to understand FAW damages to plants, to collect FAW eggs and parasitoid cocoons for lab examination of emergence of natural enemies, and to exercise field release of Trichogramma and Cotesia icipe under field condition. The field practice, thus, includes:

• Collection of FAW eggs for egg parasitoids examination in lab
• Collection of larval parasitoids cocoons
• Exercise field release of Trichogramma and Cotesia icipe

Day 5: Friday, March 1, 2019

In the morning, participants will be arranged in four groups and will be given time to go to the lab to practice any of the procedures they think that they would like to repeat for better understanding. In the afternoon there will be a wrap-up session and conclusion of the training.