Current Research Projects in our Insect Rearing Education and Research Program

Several current projects are being conducted, the first one being completed in cooperation with the USDA, APHIS.  They are 1) understanding the feeding biology of the invasive pest, the emerald ash borer (EAB).  2) The biology and metabolism of greater wax moths, with special attention to diet-induced thermogenesis and metabolic responses to different diet components. 3) The physicochemical characteristics of gelled diets for insects to elucidate the role of various diet components in improving insect diets. 

EAB larva in artificial diet

EAB larva in artificial diet


EAB in ash tree

Figure 1. Emerald Ash Borer under bark of ash tree in North Carolina



Approaches: Here are the diet/rearing system development algorithms:

  1. Emerald Ash Borer: use existing diet from the literature as starting point, and build on that using a) analysis of feeding biology, b) analysis of food eaten (phloem wood and leaves from fresh ash trees), c) using SAS, JMP Mixture Design, d) use bioassays to get feedback about the acceptability of diets, e) use texture analysis (rheology) to develop a model of the standard, f) use a continuous improvement “iteration” technique to continue to introduce new or improved components to the rearing system, g) use various presentation techniques (such as diet sandwiches made with either Parafilm or Plexiglass), and test environmental conditions to try to simulate conditions in the natural feeding system, especially with regard to EAB  inside trees, where they feed under bark (please note larva that was revealed after bark was peeled away: also note the trail of frass that characterizes successful feeding dynamics). One of the most noteworthy aspects of these studies is the discovery that both adults and larvae of the EAB use extra-oral digestion to consume and fully utilise the nutrients in the ash phloem and ash leaf feeding targets.
  2. The greater wax moth (Galleria mellonella L. Pyralidae) produces large amounts of heat as they grow and develop on their diets.

Briefly, we show here the heat production of a group of about 300 waxworm larvae with a silk “chimney” allowing the insect to circulate to the screen at the top of the container and back to the diet where the larvae form a mass that communally raises the temperature to 5-20 degrees C above ambient.

3. Physicochemical Characteristics of Gelled Diets: the influences of various diet components on the physics and chemistry of diets. Starting with the standard tobacco hornworm (Manduca sexta) diet designed by Yamamoto 1969 and modified by Bell and Joachim 1976, we are testing the effects of all the diet components on several physical and chemical responses of the diets (please see the series of illustrations of the response surface design experiments that we conducted):

This is a table of the Yamamoto diet ingredients (it’s often called a wheat germ-based diet), with two larvae feeding on the diet (left) and a picture of Professor R. T. Yamamoto circa 1965 when he was a faculty member of the Department of Entomology here at NCSU.
These three images (above) show the partial results of a surface response design (from JMP design of experiments). The factors in the experiment include wheat germ, casein, sucrose, torula yeast, and Wesson salt mixture (shown in the middle image in the proportions they were used in 28 unique diets. The top table shows the response in terms of gel firmness or hardness (determined with a texture analyser), and the responses (results) are shown to include cohesiveness, pH, water activity, diffusion rate, syneresis, firmness, and antioxidant capacity. Protein concentration and antioxidant activity were determined but are not shown. The bottom image shows the surfaces in a 3D format for the hardness response to different concentrations of casein and wheat germ.