NEW DEVELOPMENTS IN THE MASS PRODUCTION OF PREDATORY BUGS

1. NEW DEVELOPMENTS IN THE MASS PRODUCTION OF PREDATORY BUGS Patrick DE CLERCQ, Eric RIDDICK & Tom COUDRON Dept. Crop Protection, Ghent University, Ghent, Belgium National Biological Control Laboratory, USDA-ARS, Stoneville, MS, USA Biological Control of Insects Research Laboratory, USDA-ARS, Columbia, MO, USA

2. PREDATORY BUGS IN AUGMENTATIVE BIOLOGICAL CONTROL • Several species of predatory bugs (Heteroptera) are economically important biological control agents • Most are polyphagous, feeding on a wide array of arthropod prey; many species can also exploit plant resources (omnivory) • Important heteropteran predators used in augmentative biological control include: • Anthocoridae: Oriusspp. (thrips, aphids…) • Miridae: Macrolophuspygmaeus, Nesidiocoristenuis(whiteflies, leaf miners, spider mites…) • Geocoridae: Geocorisspp. (whiteflies, thrips, mites…) • Pentatomidae: Podisus, Perillus, Armaspp. (lepidopteran and coleopteran larvae…) • Reduviidae: Rhynocoris, Zelus spp. (lepidopteran larvae…)

3. PREDATORY BUGS IN AUGMENTATIVE BIOLOGICAL CONTROL Nesidiocoristenuis Arma chinensis Oriuslaevigatus Zelussp. Geocorissp. Macrolophussp.

4. REARING OF PREDATORY BUGS FOR BIOLOGICAL CONTROL • The main challenge for augmentative biological control is a wide availability of cheap and effective natural enemies for the growers cost-effective and reliable mass production of high-qualitynaturalenemiesisessential • The presentpaperwillreviewdevelopments in the rearing of predatory bugs as related to: • Foods: natural, factitious, artificial • Plant materials and alternatives • Rearing techniques and colony maintenance??? • Quality assurance

5. REARING SYSTEMS FOR PREDATORY BUGS BASED ON FOOD TYPES • Natural rearingsystems: use the natural or targetpreyfor production of thepredator, usually on a host plant • Systems usingfactitiousprey:organism that is unlikely to be attacked by a natural enemy in its natural habitat, but that supports itsdevelopment and/or reproduction; usuallya speciesthatiseasier and lessexpensive to rear; with or without plant materials • Artificialrearingssystems:use inanimateartificialfoods and preferably no plant materials

6. NATURAL REARING SYSTEMS • In naturalrearingsystems the beneficialisreared on itstargetprey or host, whichitselfismaintained on its host plant (or on plant parts) "tritrophic" system • Thesesystemscanbeeconomically viable: Encarsiaformosa, Phytoseiuluspersimilis • Possible drawbacks are: • tritrophicrearingsystems are expensive due to space and labour needed for plant production • theremaybediscontinuityproblemsat one or more of the trophiclevels to bemaintained (e.g. diseases or otherpestsattacking host plants) • plant materialsshouldbe free of pesticide residues! • there are risks of contamination associatedwith the release of beneficialsreared on naturalsubstrates

7. FACTITIOUS, UNNATURAL OR ALTERNATIVE FOODS • The use of factitiousfoodsmayallowsomerationalization or automation of production or release • Factitious host or prey: organism that is unlikely to be attacked by a natural enemy in its natural habitat, but that supports itsdevelopment and/or reproduction • Usually a speciesthatiseasier and lessexpensive to rear • Examples: • Storage mites forpredatorymites (Phytoseiidae, Laelapidae) • Eggs of lepidopterans for insectpredators • Brineshrimpcysts for predatoryinsects and mites

8. Eggs of lepidopterans • Eggs of severaleasilyrearedlepidopteranspeciescanbeused as a factitiousfood for arthropodpredators and Trichogrammaeggparasitoids: Ephestiakuehniella, Sitotrogacerealella, Corcyracephalonica… • Eggs are frozen or (UV, gamma) irradiated for use • Eggs of E. kuehniellaare a nutritionallyadequatefood for > 10 spp. of predators and severalTrichogrammaspp. 72% water; dry matter: 46% protein, 34% fat (>50% is 18:1), 8.5% carbohydrates • High price of E. kuehniellaeggs(ca. 500 EUR/kg) due to investments for climatization and mechanization, and foods • Production poses possible healthhazards for workers (allergy to scales)

9. Eggs of the MediterraneanflourmothEphestiakuehniellaare the basis for rearingOrius, Macrolophus, Adalia, Chrysoperla… and Trichogrammaeggparasitoids

10. Looking beyond the borders: the Artemiastory • Cysts (= diapausingeggs) of brineshrimps, Artemiasp. (Crustacea), are a feedused in aquaculture for shellfish and fish production • The cystsweredeveloped as a factitiousfood for predatoryinsectsat Ghent University • The cystscanbeoffered to the predators in encapsulated or decapsulatedform (= rigidoutershellremovedwith hypochlorite), and in hydrated or dry form Artemiacysts versus Ephestiaeggs Decapsulated Non-decapsulated

11. Looking beyond the borders: the Artemia story • Artemiacystsproved acceptable for predatorswithbothchewing and piercing-suckingmouthparts • Artemiacysts have nowreplacedEphestiaeggs in the commercial production process of predatorybugs; theyalsohold promise for the rearing of predatory mites • Cystscanbeoffered in part of the life cycle (e.g. nymphal stage) or in a mixture withEphestiaeggs • Cost of cystsis 1/10th or less of that of Ephestiaeggs; cystscanbeeasilystored in dry form

12. ARTIFICIAL DIETS • The availability of an artificialdietmayofferfurtherpossibilities to automate the rearingprocess • Types of diets: • Dietswith and withoutinsect components (e.g., wholeinsect bodies, hemolymph...) • Oligidic, meridic and holidicdiets: • Holidic: chemicallydefineddiets (aminoacids, fattyacids, sugars, vitamins, minerals...) • Meridic: holidic base with one or more unrefined or chemicallyunknown substances (e.g., yeast, liverextract...) • Oligidic: containingonlycrudeorganicmaterials (e.g., meatdiets)

13. HOLISTIC METHOD FOR DEVELOPING AN ARTIFICIAL DIET ARTIFICIAL DIET Mix of proteins Biochemical analyses of preferred food (amino acids, fatty acids, sugars, …) Biochemical composition of the artificial diet (amino acids, fatty acids, sugars,…) Copy Copy Computing Mix of fats and oils Digestive enzymes of the predator Growth factors (vitamins, minerals, proteins…) Water content Physical properties (gelling or filling agents, encapsulation…) Preservation Biochemical analyses of natural enemy fed on artificial diet The right components, in the right proportions and takingaccount of possible interactions among the components

14. Oriuslaevigatusfeedingon a meat and liver diet wrapped by hand in Parafilm

15. Egg yolk based artificial diet for Macrolophuspygmaeusin machine-made Parafilm domes

16. PLANTLESS REARING SYSTEMS • Manyarthropodnaturalenemiesrequire plants for successfuldevelopment and reproduction: • Source of water and supplementarynutrients (omnivory!) • Living substrate and refuge • Ovipositionsubstrate (e.g. Macrolophus, Orius) • If plant materials could be omitted from the rearing systems, there would no longer be a need to maintain large surfaces of greenhouses or to purchase (often pesticide contaminated) plant materials on the market

17. PLANTLESS REARING SYSTEMS • Omission of plant materials from the rearing system of beneficials would require the development of artificial moisture sources, living and oviposition substrates • Such substrates are now being used for mass production of certain predatory bugs Nesidiocoristenuis

18. Hydrocapsules filled with water as an artificial moisture source Nesidiocoristenuis

19. QUALITY OF NATURAL ENEMIES REARED UNDER UNNATURAL CONDITIONS • Whenrearing a naturalenemyon a factitious host or artificialdiet, loss of fitness mayoccurbecause of genetic or non-genetic changes in biological, biochemical, physiological and behavioural traits, whichmay affect itsquality as a biocontrol agent => need for quality assurance! • Nutritionaldeficienciesmayonlybecomeclearafterseveralgenerations, leading to lowerviability and/or reproduction (e.g. Orius bugs on Artemiacysts)markers • Geneticadaptation and associative learningmay affect host/preyacceptance or parasitization/predationcapacityof a parasitoid/predatorreared on an unnaturalfood (e.g. loweracceptance of target host Ostrinianubilalisin Trichogrammaparasitoidsafter long termrearing on E. kuehniellaeggs)

20. Age specificfecundity of Oriuslaevigatus in the first and thirdgeneration on Artemiacysts

21. QUALITY OF NATURAL ENEMIES REARED UNDER UNNATURAL CONDITIONS • Assessingdevelopmental and reproductive fitness of naturalenemiesisoftentedious and time consuming • Rapid tools to assess reproductive potential include: • Correlating easily measured parameters (e.g. size) with fecundity • Dissection tests to count oocytes in ovaria • ELISA-based detection of yolk proteins dissection of Orius dorsalplate of phytoseiidmite

22. PRODUCTION OF NATURAL ENEMIES: RESEARCH CHALLENGES • The development of artificial diets is not about nutrition alone. The complexity of designing these media requires expertise from different disciplines • We need to improve our understanding of the nutritional physiology and ecology of arthropod natural enemies, including interactions with their hosts and micro-organisms • Food processing technology may greatly advance the development of insect diets. Equipment needs to be further developed for large-scale diet preparation and packaging (e.g., extruder applications) • More attention needs to go to the development of effective artificial living and oviposition substrates • Quality control and quality assurance are important considerations for the mass production of natural enemies: “Will they work in the field?”