Trophic Egg Laying

Trophic egg laying is the behavior of producing unfertilised, non-hatching and non-developing eggs for the purpose of nutrition to other offspring or to consume by mother itself. The purpose is not for reproduction rather it serves as food(nutrition). This behaviour of Trophic Egg Laying is an evolutionary ecological concept which can be observed in diverse range of species with wide variety of parental care system. This can be observed in both vertebrates(Amphibians, Fish) and invertibrates (Snails, Insects, Spiders) and few species of frogs Leptodactylus Dallas and Oophaga and catfish Bagrus meridional. Trophic eggs are related to diverse system of parental care, parent-offspring conflict, inclusive fitness, and sibling rivalry.

Some Examples:

• A large proportion of ladybird beetle (Coleoptera: Coccinellidae) eggs are apparently infertile-they do not develop an embryo and are consumed by larvae hatching within the egg batch. 
  
• Trophic egg-laying is found common in sub-social insects, one of the most commonly studied bug Adomerus triguttulus ( Heteroptera: Cydinidae). Oviposition is asynchronous and the mother lays additional eggs immediately prior to hatching of the core brood that rapidly consume the additional eggs. In the absence of maternal defense egg masses were more heavily parasitized, suffered ant predation and an increased prevalence of sibling cannibalism. Maternal provisioning in the form of addition eggs significantly reduced the prevalence of sibling cannibalism of core brood eggs. 
• Worker bees in especially stingless bee species, Patrigona subnuda, have ovarian development and can lay trophic eggs within the brood combs that are later eaten by the queen bee and her progeny, including workers and future queen larvae.
• Many ant species produce trophic eggs, Pachycondyla apicalis (Formicidae: Ponerinae), the trophic eggs are laid by workers and offered to the queen rather than to developing offspring. However this depends on transmission of pheromone from the queen, since workers lacking contact with the queen may instead start to lay reproductive.
  

Hyphothesis

1. The provisioning hypothesis: Maternal provisioning of nutritional resources may reduce offspring mortality through starvation.Offspring consume infertile or damaged eggs, produced because egg development and oviposition are imperfect processes. The offspring behaviour of eating these structures may be an adaptation.

2. Cannibalism (Parents offspring conflict) reduction hypothesis:  To reduce the prevalence of sibling cannibalism. Trophic eggs are an adaptive maternal behaviour: in some systems, parents may use some offspring as food for others, not as a provisioning tactic per se but to reduce the cannibalism of viable siblings when it is against a mother's interests.

The Advantage:

1. Offspring survival may be improved by parental provisioning of food items

2. In many cases the survival of offspring cannot be predicted when food resources vary greatly over time and space. In such cases parents may opt to produce a core brood of high quality individuals and a group of marginal offspring that can be sacrificed if necessary to improve the survival of their siblings.

3. Safeguard from offspring cannibalism.

4. The mother require instant energy after laying huge number of eggs.