Protein storage and reproduction increase in grasshoppers on a diet matched to the amino acids of egg yolk protein.

The diets of animals are essential to support development, and protein is key. Accumulation of stored nutrients can support developmental events such as molting and initiation of reproduction. Agricultural studies have addressed how dietary protein quality affects growth, but few studies have addressed the effects of dietary protein quality on developmental transitions.

Protein Stores Regulate When Reproductive Displays Begin in the Male Caribbean Fruit Fly.

Many animals exhibit reproductive behavior that requires expenditure of valuable nutrients. In males of many species, competitive energetically demanding displays and the development of sexual ornaments require prior accumulation of nutrient stores. Males must coordinate nutrient stores with ornament development and reproductive displays or they risk depleting their resources mid-development or mid-display, reducing their chance of mating.

Life-extending dietary restriction and ovariectomy each increase leucine oxidation and alter leucine allocation in grasshoppers.

Reduced reproduction and dietary restriction each extend lifespan in many animal models, but possible contributions of nutrient oxidation and allocation are largely unknown. Ovariectomy and eating 70% of ad libitum-feeding each extend lifespan in lubber grasshoppers. When feeding levels between the two groups are matched, ovariectomy increases fat and protein storage while dietary restriction reduces fat storage.

Life-extending Dietary Restriction Reduces Oxidative Damage of Proteins in Grasshoppers but Does Not Alter Allocation of Ingested Nitrogen to Somatic Tissues.

Dietary restriction (DR) extends life span and reduces reproduction in most animals. The disposable soma hypothesis suggests that this longevity is the result of reduced investment in reproduction and increased nutrient allocation to the soma, permitting an increase in cellular maintenance. To investigate the role of nutrient allocation upon life-extending DR, tissue-specific nitrogen allocation was tracked in grasshoppers (Romalea microptera) upon a full or restricted (60% of full) diet.

Vitellogenin-RNAi and ovariectomy each increase lifespan, increase protein storage, and decrease feeding, but are not additive in grasshoppers.

Reduced reproduction has been shown to increase lifespan in many animals, yet the mechanisms behind this trade-off are unclear. We addressed this question by combining two distinct, direct means of life-extension via reduced reproduction, to test whether they were additive. In the lubber grasshopper, Romalea microptera, ovariectomized (OVX) individuals had a ~20% increase in lifespan and a doubling of storage relative to controls (Sham operated).

Vitellogenin RNAi halts ovarian growth and diverts reproductive proteins and lipids in young grasshoppers.

Reduced reproduction extends lifespan of females in many animals. To test the effects of reproduction on storage of macronutrients, we block reproductive output in the lubber grasshopper by injecting RNAi against the precursor to egg-yolk protein, vitellogenin, in early adulthood. Controls were injected with either buffer or RNAi against the major storage protein in the hemolymph, hexamerin-90.

Life-extending ovariectomy in grasshoppers increases somatic storage, but dietary restriction with an equivalent feeding rate does not.

Reduced diet or reduced reproduction each extends lifespan in many animals. It is often thought that reduced reproduction and reduced diet may act through the same mechanisms. In grasshoppers, ovariectomy extends lifespan and reduces feeding to a level similar to that used for life extension by dietary restriction, further suggesting mechanistic overlap.

Divergent egg physiologies in two closely related grasshopper species: Taeniopoda eques versus Romalea microptera (Orthoptera: Romaleidae).

We compared egg survivorship and egg development time at different soil moistures for two closely related grasshopper species from divergent habitats: marsh-inhabiting Romalea microptera (Beauvois) versus desert-inhabiting Taeniopoda eques (Burmeister). These two species can interbreed and produce viable offspring. In nature, both species have a similar 8-9 mo subterranean egg stage, but their soil environments differ dramatically in water content.

Ovariectomy in grasshoppers increases somatic storage, but proportional allocation of ingested nutrients to somatic tissues is unchanged.

Reduced reproduction increases storage and extends lifespan in several animal species. The disposable soma hypothesis suggests this life extension occurs by shifting allocation of ingested nutrients from reproduction to the soma. A great deal of circumstantial evidence supports this hypothesis, but no direct tracking of nutrients has been performed in animals that are long-lived because of direct reduction in reproduction.

Allocation of nutrients to somatic tissues in young ovariectomized grasshoppers.

The disposable soma hypothesis predicts that when reproduction is reduced, life span is increased because more nutrients are invested in the soma, increasing somatic repair. Rigorously testing the hypothesis requires tracking nutrients from ingestion to allocation to the soma or to reproduction. Fruit flies on life-extending dietary restriction increase allocation to the soma "relative" to reproduction, suggesting that allocation of nutrients can be associated with extension of life span.

Does it pay to delay? Flesh flies show adaptive plasticity in reproductive timing.

Life-history plasticity is widespread among organisms. However, an important question is whether it is adaptive. Most models for plasticity in life-history timing predict that animals, once they have reached the minimal nutritional threshold under poor conditions, will accelerate development or time to reproduction.

Thermal constraints for range expansion of the invasive green mussel, Perna viridis, in the southeastern United States.

Cold temperatures are thought to be among the most important determining factors of geographic distribution for tropical and sub-tropical marine invertebrates. The Asian green mussel, Perna viridis, has been introduced into coastal waters of Florida where its current distribution is hypothesized to be limited by low temperatures during winter. Lethal and sub-lethal effects (heat shock protein/Hsp70 expression) of cold water and air temperatures were analyzed in two size classes of P.

Life history plasticity after attaining a dietary threshold for reproduction is associated with protein storage in flesh flies.

Body condition affects the timing and magnitude of life history transitions. Therefore, identifying proximate mechanisms involved in assessing condition is critical to understanding how these mechanisms affect the expression of life history plasticity. Nutrient storage is an important body condition parameter, likely playing roles in both attaining minimum body-condition thresholds for life history transitions and expression of life history traits.

Protein accumulation underlying lifespan extension via ovariectomy in grasshoppers is consistent with the disposable soma hypothesis but is not due to dietary restriction.

Reduced reproduction extends lifespan in many experimental animals, but the mechanism by which this occurs is unclear. The disposable soma hypothesis suggests that when reproduction is reduced, more nutrients are allocated to the soma and lifespan is extended. Alternatively, the reproductive tissues or the process of reproduction may have a direct (i.

Calorie restriction and late-onset calorie restriction extend lifespan but do not alter protein storage in female grasshoppers.

Calorie restriction (CR) and late-onset CR enhance longevity in many organisms. Resource allocation theory suggests that longevity is enhanced by increasing somatic storage, at the expense of current reproduction. Phytophagous insects accumulate amino acids as hemolymph storage proteins for major developmental events.

Plasticity of grasshopper vitellogenin production in response to diet is primarily a result of changes in fat body mass.

Life history plasticity is the developmental production of different phenotypes by similar genotypes in response to different environments. Plasticity is common in early post-embryonic or adult development. Later in the developmental stage, the transition from developmentally plastic to canalized (i.

Starvation affects vitellogenin production but not vitellogenin mRNA levels in the lubber grasshopper, Romalea microptera.

The interaction of juvenile hormone (JH) and nutrition was studied during the oviposition cycle of the Eastern Lubber grasshopper (Romalea microptera). Starvation of females early or in the middle of the cycle inhibited oocyte growth. Starvation for 4 days also reduced hemolymph levels of JH III and vitellogenesis (Vg) to 25% and 15%, respectively, of the levels in fed animals.

Interpopulation variation in developmental titers of vitellogenin, but not storage proteins, in lubber grasshoppers.

We examined simultaneous plastic and latitudinal interpopulation variation in the time course of hemolymph protein titers during egg production in the lubber grasshopper. Our goal was to gain insight into possible evolutionary changes in the physiology underlying reproductive plasticity. We used lubbers from three locations in the United States (Florida [FL], Louisiana [LA], and Georgia [GA]), each offered three daily food rations.

Plasticity and canalization in the control of reproduction in the lubber grasshopper.

The ability to change reproductive tactics during adult development in response to environmental variation is predicted to enhance fitness. Many organisms show phenotypic plasticity early in non-embryonic development, but later exhibit phases of developmental inflexibility (=canalization). Therefore, we studied reproduction-related hormones and proteins and their relationships to plasticity in the Eastern lubber grasshopper.

Hemolymph ecdysteroids do not affect vitellogenesis in the lubber grasshopper.

The role of hemolymph ecdysteroids in the reproduction of non-dipteran insects is unclear. We examine the role(s) of hemolymph ecdysteroids during egg production in the lubber grasshopper, Romalea microptera. In all individuals, hemolymph ecdysteroids rose to a sharp peak with similar maxima and then fell to undetectable levels.

Geographic variation of reproductive tactics in lubber grasshoppers.

We investigate plastic and interpopulation variation of trade-offs among reproductive tactics. There is a potential three-way trade-off among timing of reproduction, somatic storage, and investment in reproduction. We tested whether this trade-off shows latitudinal interpopulation variation.

Slow movement increases the survivorship of a chemically defended grasshopper in predatory encounters.

Studies on insect defenses have investigated the benefits of noxious chemicals, aposematic coloration, and even gregariousness, but little information exists on the role of slow movement (as opposed to rapid escape movement and the absence of movement). Using the chemically defended, slow-moving lubber grasshopper (Romalea guttata) and the northern leopard frog (Rana pipiens), we investigated the role of slow movement in insect defense. In a five-day experiment, frogs did not learn an aversion to lettuce-fed lubbers; we infer that endogenous deterrent chemicals are not important in lubber defense from frogs.