Fat stunts growth of tobacco hornworm caterpillars

Fat metabolism pathways are similar among vertebrates, including humans and invertebrates such as the tobacco hornworm caterpillar. According to the study's authors, understanding the role of fats in insects could help understand human metabolic diseases.

Fat is important for reproduction and development in insects. While insects with a high-carbohydrate intake have greater fat stores, little is known about what happens when insects eat fat. Researchers from North Dakota State University fed tobacco hornworm caterpillars of different ages low-, medium- or high-fat diets. They found that 80 percent of the young larvae raised on the high-fat diet died. The larvae's body mass was 43 percent lower than the body mass of larvae fed low- and medium-fat diets. Development was also slower: Caterpillars on the high-fat diet started wandering later than their peers fed low- and medium-fat diets. Older larvae on the high-fat diet fared better. They had similar mortality rates as their counterparts on low- and medium-fat diets, but they also grew more slowly.

The researchers found that fat-fed caterpillars had a smaller body size because they ate less overall. The researchers measured lower food consumption and fewer fecal pellets produced. "The results suggest that increased dietary fat results in cessation of feeding in these insects," according to the researchers.