Search Results (6)

Different life histories result in different strategies to allocate energy in biosynthesis, including growth and reproduction, and somatic maintenance. One of the most notable life history differences between Lepidoptera and Blattodea species is that the former grow much faster than the latter, and during metamorphosis, a large amount of tissue in Lepidoptera species disintegrates. In this review, using Lepidoptera caterpillars and cockroach nymphs as examples, we show that, due to these differences in growth processes, cockroach nymphs spend 20 times more energy on synthesizing one unit of biomass (indirect cost of growth) than butterfly caterpillars. Because of the low indirect cost of growth in caterpillars, the fraction of metabolic energy allocated to growth is six times lower, and that for maintenance is seven times higher in caterpillars, compared to cockroach nymphs, despite caterpillar’s higher growth rates. Moreover, due to the higher biosynthetic energy cost in cockroach nymphs, they have better cellular qualities, including higher proteasomal activity for protein quality control and higher resistance to oxidative stress. We also show that under food restriction conditions, the fraction of assimilated energy allocated to growth was reduced by 120% in cockroach nymphs, as they lost body weight under food restriction, while this reduction was only 14% in hornworms, and the body mass increased at a lower rate. Finaly, we discuss future research, especially the difference in adult lifespans associated with the energetic differences. Full article

Starvation is a complex physiological state that induces changes in protein expression to ensure survival. The insect midgut is sensitive to changes in dietary content as it is at the forefront of communicating information about incoming nutrients to the body via hormones. Therefore, a DIA proteomics approach was used to examine starvation physiology and, specifically, the role of midgut neuropeptide hormones in a representative lepidopteran, Manduca sexta. Proteomes were generated from midguts of M. sexta fourth-instar caterpillars, starved for 24 h and 48 h, and compared to fed controls. A total of 3047 proteins were identified, and 854 of these were significantly different in abundance. KEGG analysis revealed that metabolism pathways were less abundant in starved caterpillars, but oxidative phosphorylation proteins were more abundant. In addition, six neuropeptides or related signaling cascade proteins were detected. Particularly, neuropeptide F1 (NPF1) was significantly higher in abundance in starved larvae. A change in juvenile hormone-degrading enzymes was also detected during starvation. Overall, our results provide an exploration of the midgut response to starvation in M. sexta and validate DIA proteomics as a useful tool for quantifying insect midgut neuropeptide hormones. Full article

Animals with different life histories budget their intake energy differently when food availability is low. It has been shown previously that hornworm (larva of Manduca sexta), a holometabolous insect species with a short development stage, prioritizes growth at the price of metabolism under food restriction, but it is unclear how hemimetabolous insect species with a relatively long development period budget their intake energy under food scarcity. Here, we use orange head cockroaches (Eublaberus posticus) to investigate this question. We found that for both species under food restriction, rates of metabolism and growth were suppressed, but the degree of reduction was more severe in growth than that of metabolism for cockroaches. Under both free-feeding and food restriction conditions, hornworms allocated a larger fraction of assimilated energy to growth than to metabolism, and cockroaches were the opposite. More importantly, when food availability was low, the fraction of assimilated energy allocated to growth was reduced by 120% in cockroaches, and the energy from growth was channeled to compensate for the reduction in metabolism; but, the fraction of assimilated energy allocated to growth was only reduced by 14% in hornworms. These results suggest that, compared to hornworms, cockroaches prioritize metabolism over growth. Full article

One of the most interesting groups of fatty acid derivates is the group of conjugated fatty acids from which the most researched include: conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA), which are associated with countless health benefits. Sex pheromone mixtures of some insect species, including tobacco horn-worm (Manduca sexta), are typical for the production of uncommon C16 long conjugated fatty acids with two and three conjugated double bonds, as opposed to C18 long CLA and CLNA. In this study, M. sexta desaturases MsexD2 and MsexD3 were expressed in multiple strains of Y. lipolytica with different genotypes. Experiments with the supplementation of fatty acid methyl esters into the medium resulted in the production of novel fatty acids. Using GCxGC-MS, 20 new fatty acids with two or three double bonds were identified. Fatty acids with conjugated or isolated double bonds, or a combination of both, were produced in trace amounts. The results of this study prove that Y. lipolytica is capable of synthesizing C16-conjugated fatty acids. Further genetic optimization of the Y. lipolytica genome and optimization of the fermentation process could lead to increased production of novel fatty acid derivatives with biotechnologically interesting properties. Full article

Plants are under constant attack by a suite of insect herbivores. Over millions of years of coexistence, plants have evolved the ability to sense insect feeding via herbivore-associated elicitors in oral secretions, which can mobilize defense responses. However, herbivore-associated elicitors and the intrinsic downstream modulator of such interactions remain less understood. In this study, we show that tobacco hornworm caterpillar (Manduca sexta) oral secretion (OS) induces reactive oxygen species (ROS) in tomato (Solanum lycopersicum) protoplasts. By using a dye-based ROS imaging approach, our study shows that application of plant-fed (PF) M. sexta OS generates significantly higher ROS while artificial diet-fed (DF) caterpillar OS failed to induce ROS in isolated tomato protoplasts. Elevation in ROS generation was saturated after ~140 s of PF OS application. ROS production was also suppressed in the presence of an antioxidant NAC (N-acetyl-L-cysteine). Interestingly, PF OS-induced ROS increase was abolished in the presence of a Ca²⁺ chelator, BAPTA-AM (1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid). These results indicate a potential signaling cascade involving herbivore-associated elicitors, Ca²⁺, and ROS in plants during insect feeding. In summary, our results demonstrate that plants incorporate a variety of independent signals connected with their herbivores to regulate and mount their defense responses. Full article

Plant secondary metabolites such as terpenes, phenolics, glycosides, and alkaloids play various functional roles including pigmentation, foliar and floral volatile synthesis, hormonal regulation, and direct and indirect defenses. Among these, phenolic compounds are commonly found in plants, but vary in the distribution of their specific compounds among plant families. Polyphenols, including anthocyanins and tannins, are widely distributed and have been well documented for their roles- primarily in plant pigmentation and also in plant defenses. However, commercialization of such compounds for use in insect pest management is severely hampered by expensive, inefficient, and time-consuming extraction protocols. Using a recently developed inexpensive and easy extraction method using the byproducts of pigmented (purple) corn processing, we examined whether the crude pericarp extract rich in polyphenols can affect the growth and development of tobacco hornworm (Manduca sexta L.) caterpillars. Our findings show that purple corn pericarp extract negatively affected M. sexta egg hatching and larval mass gain and prolonged developmental time compared to regular yellow corn extract or an artificial control diet. We also found that these effects were more severe during the early stages of caterpillar development. These results conclusively demonstrate that purple corn pericarp, an inexpensive by-product of the corn milling industry, is a valuable product with excellent potential as an insect antifeedant. Full article