Trophic‐egg production in a subsocial bug: adaptive plasticity in response to resource conditions

Abstract

Adomerus triguttulus (Heteroptera: Cydnidae) females provision host Lamium spp. seeds to their nymphs. Females also produce trophic eggs, which are inviable and usually function as a food supply for hatched nymphs. Here we report experimental evidence of the potentially adaptive maternal effects of this unusual resource investment. To investigate the effects of food‐resource environments on trophic‐egg production, we reared females under different resource conditions prior to oviposition and then compared the subsequent allocations of trophic eggs. Females that had been supplied with less‐developed seeds produced fewer viable eggs than those supplied with well‐developed seeds. However, there was no difference in the number of trophic eggs produced between the two treatments, and thus the trophic‐egg ratio, i.e. the number of trophic eggs per viable egg, was higher in females supplied with less‐developed seeds. Trophic‐egg feeding by hatched nymphs enhances their growth or survival, and a higher trophic‐egg ratio would be adaptive particularly under limited resource conditions. In A. triguttulus, adults and offspring depend on the same food resource, i.e. host seeds, and the resource conditions experienced by females prior to oviposition should be well correlated with those experienced later by the offspring. This may enable females to adjust the trophic‐egg ratio in response to varying resource environments prior to oviposition.

Egg Cannibalism in a Facultative Polygynous Ant: Conflict for Reproduction or Strategy to Survive?

“…1998; Heteroptera: Nakahira 1994; Hironaka et al. 2005; Kudo & Nakahira 2005; Coleoptera: Perry & Roitberg 2005). In ants they are produced by workers or virgin queens and constitute an efficient transfer of resources within the colony (Elgar & Crespi 1992).…”

“…Trophic eggs are commonly used as a food supply in diverse insect taxa (e.g. Hymenoptera: Passera et al 1968;Gobin et al 1998;Heteroptera: Nakahira 1994;Hironaka et al 2005;Kudo & Nakahira 2005;Coleoptera: Perry & Roitberg 2005). In ants they are produced by workers or virgin queens and constitute an efficient transfer of resources within the colony (Elgar & Crespi 1992).…”

Adjustment of Parental Investment in the Dung Beetle Onthophagus atripennis (Col., Scarabaeidae)

“…However, manipulation of parental resource has often revealed the opposite tendency. Reduced resource availability for mothers resulted in the production of a fewer number of smaller progenies, and vice versa under conditions of enhanced resource availability (reviewed by Fox & Czesak 2000), with some exceptions in vertebrates (Reznick & Yang 1993;Reznick et al 1996) and in insects (Kudo & Nakahira 2005). These unexpected results have been accounted for by proximate constraints on females, such as nutritional conditions of mothers (Krist et al 2004), and for large variation of resource availability for females (van Noordwijk & de Jong 1984).…”

Mothers modify eggs into shields to protect offspring from parasitism

“…Their adaptive value seems apparent in systems in which, compared with viable eggs, they have a different morphology or colour [19][20][21], are underdeveloped [22] or are actively fed to offspring by the parents [23]. The two main hypotheses regarding the functions of trophic eggs include offspring feeding when starvation risk is high or resources are scarce and/or reducing sibling cannibalism [24,25]. The fact that at least some top eggs laid by M. amicus have been fertilized brings up an interesting question about the classification of eggs that contain DNA, but function solely to protect other eggs or satiate other offspring.…”