Location: Biological Control of Pests Research2021 Annual Report
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.
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microalgae (Chlorella vulgaris Beijerink), and fatty acids, stearic acid (18:0) or myristic acid (14:0) (Riddick, unpublished data).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.
Experiments started and are currently ongoing to determine if that powder derived from black soldier fly larvae combined with or without plant-based supplements is a cost-effective, healthy alternative food to support the development and reproduction (oviposition) of the pink spotted lady beetle Coleomegilla maculata in lieu of natural prey. Discovery of diet-based natural products to improve mass-rearing techniques for augmentative releases of coccinellids against herbivores, such as aphid species, on small fruits and vegetables is the aim of this research. Although augmentative releases of lady beetles have not been conducted, to date, preliminary observations in the laboratory indicate that mass-reared individuals readily recognize live natural prey and readily consume them in Petri dish and small cage trials. Strawberries were successfully planted in the high tunnels in early March. Currently, strawberry plants are under cultivation in four experimental high tunnels to ensure that augmentative release experiments can be conducted in late winter 2022 and Spring 2022. Studies on characterization analysis of high plasticity mealworm characters, development time and pupal weight, were initiated. Cohorts consisting of mealworms hatching within one day were obtained from the stock colony. Cohorts 1 and 2 were fully characterized by dividing the larvae in classes according to their development time and pupal weight. The second generation from cohort 2 resulting from the separated weight and development time classes was characterized by determining the frequency of pupal weight and development time values within each class. These data were analyzed using linear regression. This study was completed and provided evidence that despite of their high plasticity, the characters of development time and body size have a strong genetic basis. Eight diet formulations using agricultural by-products were evaluated for their effectiveness to grow the yellow mealworm. Diets were compared on their impact on larval growth, biomass production, development time, larval survival, and conversion efficiency. This work was completed and yielded three diet formulations composed of 80% or more by agricultural by-products.
1. Diets for mealworms and crickets composed of agricultural by-products. Currently there is not a consistent commercial source of feed specifically designed to grow crickets and mealworms. Mealworms are currently grown using wheat bran and some fresh vegetables and crickets are mostly produced using modifications of chicken feeds. ARS researchers in Stoneville, Mississippi, developed diets for mealworms and crickets composed of 80% or more by agricultural by-products, such as rice bran (whole and defatted), spent brewery grain, corn distilled grain, canola meal, and brewer’s yeast. These new diets are specifically formulated to enhance growth and reproduction in mealworms and crickets, making them superior to the existing diets used by commercial producers. These diet formulations, if commercialized, could provide with a much better feed to rise mealworms and crickets for animal feed.
2. Genetic determination of mealworm characters with high plasticity. Production of insect protein could be of great benefit for providing an alternative to fish meal in animal feed formulations. The productivity of insect colonies could be improved by genetically enhancing insect colonies to grow faster and larger. However, development time and body size have a high degree in mealworms and are affected by many environmental factors such as temperature, humidity, density, and diet quality. This high plasticity makes it difficult to apply effective methods of selection with the aim to produce improved mealworm lines. In fact, it is unknown to what degree these characters are influenced by environment and how much by genetics. ARS researchers in in Stoneville, Mississippi, conducted studies to provided strong evidence that characters of high plasticity in the yellow mealworm, such as development time and body size have a strong genetic basis and are susceptible to selection using the right methods. This information provides the basis for future research on breeding the yellow mealworm to grow faster and larger and to produce biomass more efficiently.
Grodowitz, M.J., Elliott, R.B., Evans, R.M., Rojas, M.G., Morales Ramos, J.A. 2020. Development of a physiological age-grading system for Nezara viridula (L.) (Hemiptera: Pentatomidae). Journal of Insect Science. 20(5):1-8. https://doi.org/10.1093/jisesa/ieaa092.
Morales Ramos, J.A., Rojas, M.G., Kelstrup, H., Emery, V. 2020. Self-selection of agricultural by-products and food ingredients by tenebrio molitor (coleoptera: tenebrionidae) and impact on food utilization and nutrient intake. Insects. 11:827. https://doi.org/10.3390/insects11120827.
Ebrahimifar, J., Parviz, S., Rasekh, A., Hemmati, S.A., Riddick, E.W. 2021. Evaluation of Artemia franciscana cysts to improve diets for mass rearing Stethorus gilvifrons, a predator of Tetranychus turkestani. Insects. 12:632. https://doi.org/10.3390/insects12070632.
Atashi, N., Shishehbor, P., Seraj, A.A., Rasekh, A., Hemmati, S.A., Riddick, E.W. 2021. Effects of Helicoverpa armigera egg age on development, reproduction, and life table parameters of Trichogramma euproctidis. Insects. 12:569. https://doi.org/10.3390/insects12070569.
Riddick, E.W. 2021. Potential of quercetin to reduce herbivory without disrupting natural enemies and pollinators. Agriculture. 11:476. https://doi.org/10.3390/agriculture11060476.
Riddick, E.W. 2020. Volatile and non-volatile organic compounds stimulate oviposition by aphidophagous predators. Insects. 11:1-11. https://doi.org/10.3390/insects11100683.