Location: Biological Control of Pests Research
2022 Annual Report
Objectives
1. Expand studies on discovery, culturing, production and evaluation of natural enemies for biological control and insects as animal feed.
1.a. Behavior and evaluation of black soldier fly as feed and fertilizer.
1.b. Characterization of traits for high efficiency of food conversion and development of Tenebrio molitor for mass production as animal feed.
2. Develop improved rearing methods and artificial diets to reduce costs of insect mass production.
2.a. Test of prey recognition and consumption rate of lady beetles reared on artificial diet or factitious food for multiple generations.
2.b. Determine the effect of diet on the nutritional value of Tenebrio molitor produced for animal feed.
Approach
The invertebrate predator Coleomegilla maculata De Geer (Coleoptera: Coccinellidae) will be used as a model invertebrate in this test. It is an omnivorous predator that has the capacity to utilize microalgae and synthetic pollen as food to obtain essential nutrients not present in unsuitable prey (Riddick and Wu, 2015). This colony has been in continuous culture without any addition of wild type individuals for more than 50 generations in a climate-controlled room (24°C, 50%–60% RH, 16 h photophase). Individuals originating from the colony and used in this experiment have been mass-reared for more than 10 consecutive generations on a proprietary mixture of freeze-dried, powdered brine shrimp eggs Artemia franciscana Kellogg, freshwater microalgae (Chlorella vulgaris Beijerink), and fatty acids, stearic acid (18:0) or myristic acid (14:0) (Riddick, unpublished data). Larvae and adults have no prior exposure to H. illucens. Yet, published work using larvae and adults from this colony, indicated that the eggs of the common housefly Musca domestica L. (Diptera: Muscidae) were suitable prey in experimental trials (Riddick et al. 2014). All life stages have been maintained in separate cages in the same climate-controlled room (24 °C, 50%–60% RH, 16 h photophase) for more than 10 years at the National Biological Control Laboratory (NBCL), USDA, ARS, in Stoneville, Mississippi.
Cultivated strawberry (Fragaria × ananessa Duch. cv. Chandler) will serve as model plants to test the effects of H. illucens larval frass, as a fertilizer, on plant health. Approximately 1,000 bare root individuals will be purchased from a commercial nursery in Redding, CA, as mentioned in previous research (Riddick et al. 2019). All individuals will be removed from cold storage in NBCL, then transplanted into “flats” over the course of several consecutive days. Excess dead roots will be trimmed away, using stainless steel scissors. Once in flats at a spacing of approximately 6 cm between individual plants, a light covering of peat soilless media will be applied over the roots; then watered using tap water. All plants will be setup on metal benches in a temperature-controlled greenhouse (20-22°C, natural lighting) in Stoneville, Mississippi, USA. One month later, the healthiest plants will be transferred to plastic (1.3 L) pots, one plant per pot, containing the same quantity of soilless media in each pot.
Progress Report
Laboratory experiments have shown that powdered black soldier fly (BSF) larva supports both development and reproduction of pink spotted lady beetle (Coleomegilla maculata). However, the standard factitious diet (brine shrimp formulation) outperforms the BSF based diet. Developing an H. illucens-supplemented diet could be an ideal method to incorporate H. illucens protein into the standard factitious diet or an artificial diet. Publication of this research will be forthcoming.
ARS researchers in Stoneville, Mississippi, discovered that adults of the pink spotted lady beetle recognize and readily consume aphid prey after making physical contact with aphids regardless of the rearing diet (factitious diet, artificial diet, or plant pollen). Ongoing research will compare lady beetle recognition of two aphid species, tentatively identified as oleander aphid (Aphis nerii) and foxglove aphid (Aulacorthum solani). Note that the aphid species (Aphis ruborum) continuously on strawberry for several years, has been maintained at undetectable levels of abundance in three high tunnels, since monthly adult releases of pink spotted lady beetles began. Publication of this research is forthcoming.
The third cohort of yellow mealworm was obtained and its characterization for development time and pupal weight was completed. Three classes were selected for continued selection for three generations from cohort 3. The classes included 16:180, 18:200, 20:220, and 22:240; where the first number represents larval development time in weeks and the second number represents pupal weight in mg. Preliminary analyses show that classes are responding to selection showing significant differences in development time and pupal weight among them after full cohort characterization.
The colony of the pink spotted lady beetle that has been maintained in artificial diet for over 50 generations started showing signs of nutritional disbalance, showing reduced egg viability and reduced larval survival. Modifications were done to the current diet formulation by replacing the mealworm powder by house fly pupa powder. This substitution was sufficient to impact the colony positively. Egg hatching and larval survival levels are back to normal. These findings support the hypothesis that addition of black soldier fly powder to the artificial diet may provide benefits.
Work supporting the grand challenge included blanching, drying, and powdering of adult house crickets and yellow mealworm larvae to produce 50 kg of powder from each species. It took three months to complete this work. These powder ingredients were shipped to our collaborators at the USDA-ARS PPPSRU (Poultry Production and Product Safety Research Unit), Fayetteville, Arkansas, to formulate diets to be evaluated for broiler production. In addition, 50 Kg of mealworm frass were produced in the NBCL (National Biological Control Laboratory), Stoneville, Mississippi, and shipped to our cooperator from USDA-ARS PPPSRU in Fayetteville, Arkansas, for studies on its potential as plant fertilizer.
Also, as part of the grand challenge, mealworm larvae from selected lines were grown in the NBCL at Stoneville, Mississippi, fixed in a solution and shipped to our cooperators at USDA-ARS Center for Grain and Animal Science Research, Manhattan, Kansas, for genetic analysis. This is part of a study for genetic characterization of multiple populations of the yellow mealworm from diverse origins.
Accomplishments
1. Determination of heritability of two high plasticity characters associated with biomass productivity in the yellow mealworm. The yellow mealworm is one of the most important industrialized insects with potential to substitute unsustainable sources of animal protein for animal feed formulations. Methods for improving mealworm’s biomass productivity are critical for its commercial application. ARS researchers in Stoneville, Mississippi, three-year continuing research culminated in the determination of heritability of two characters of high plasticity (developmental speed and body size) in the yellow mealworm associated with biomass productivity. Larval development time showed a heritability of 63.37%, which is higher than expected given the level of impact that environmental factors exert on this character. Pupal weight had a heritability of 37.69%. These findings show that both characters are susceptible to change via selection providing a potential path for genetic improvement of mealworm lines. Ongoing three-generational selection studies show preliminary results that strongly support this assumption. These results show great potential for the development of improved mealworm lines with high biomass productivity. Such lines would benefit the existing industry and could significantly reduce the cost of insect biomass for animal feed.
Review Publications
Tabebordbar, F., Shishehbor, P., Ebrahimi, E., Polaszek, A., Riddick, E.W. 2022. Parasitoid age and host age interact to improve life history parameters and rearing of Trichogramma euproctidis. Biocontrol Science and Technology. 32(3):267-280. https://doi.org/10.1080/09583157.2021.1990858.
Gravandian, M., Fathipour, Y., Hajiqanbar, H., Riahi, E., Riddick, E.W. 2022. Long-term effects of cattail Typha latifolia pollen on development, reproduction, and predation capacity of Neoseiulus cucumeris, a predator of Tetranychus urticae. Biocontrol. 67:149-160. https://doi.org/10.1007/s10526-021-10116-4.
Rahmani Piyani, A., Shishehbor, P., Kocheili, F., Riddick, E.W. 2021. Comparison of natural prey Tetranychus turkestani, date palm pollen, and bee pollen diets on development, reproduction, and life table parameters of the predator Amblyseius swirskii. Acarologia. 61(4):890-900. https://doi.org/10.24349/G9ed-QB9h.
Rahmani Piyani, A., Shishehbor, P., Kocheili, F., Riddick, E.W. 2021. Functional and numerical responses of the predator Amblyseius swirskii to its prey Tetranychus turkestani in the laboratory. Acarologia. 61(4):901-909. https://doi.org/10.24349/r82w-YLJ1.
Riddick, E.W. 2022. Topical collection: natural enemies and biological control of plant pests. Insects. 13(5):421. https://doi.org/10.3390/insects13050421.
Rivers, A.R., Grodowitz, M.J., Miles, G.P., Allen, M.L., Elliott, B., Weaver, M.A., Bon, M., Rojas, M.G., Morales Ramos, J.A. 2022. Gross morphology of diseased tissues in Nezara viridula (Hemiptera: Pentatomidae) and molecular characterization of an associated microsporidian. Journal of Insect Science. 22(2):4. https://doi.org/10.1093/jisesa/ieac013.
