performance and rivalry in a sub-social bug. Á/ Oikos 107: 28 Á/35.Trophic eggs, which are inviable and usually function as a food supply for offspring, have been regarded as extended parental investment or the outcome of parent Á/ offspring conflict in sibling oophagy. Adomerus triguttulus (Heteroptera: Cydnidae) is a sub-social bug showing a complex pattern of maternal care, including progressive provisioning of host seeds and trophic-egg production. To investigate the functions of trophic eggs, we removed trophic eggs from clutches under different resource conditions. The longevity of nymphs was greatly extended by feeding upon trophic eggs when seeds were excluded. When seeds were provided, trophic-egg feeding by nymphs enhanced their development, but there were no significant effects on brood survival. Some viable eggs were also fed upon by sibling nymphs. However, there was no difference in the proportion of viable eggs consumed between clutches with and without trophic eggs. Females lay viable eggs within the first oviposition day. The synchronous hatching resulting from this oviposition mode seems to prevent sibcannibalism. The body size of females affected their relative investment in trophic eggs; larger females produced more viable eggs with relatively fewer trophic eggs. The functions and adaptive allocation of trophic eggs are discussed in light of the two hypotheses mentioned above.

In the subsocial burrower bug, Adomerus triguttulus (Motschulsky, 1886), females produce trophic eggs, which are inviable and serve as a food supply for hatched nymphs, and add them onto egg masses during maternal care. Trophic eggs are expected to be less costly for females to produce and for offspring to consume than viable eggs. Such specialization may be reflected in the size, structure, and developmental process of the eggs. Inviable trophic eggs were smaller than viable eggs, and the intraclutch size variation of the former was larger than that of the latter. The viable eggs always had approximately five micropylar processes at a pole, whereas the trophic eggs mostly lacked them. Active oogenesis was maintained during the maternal egg care period; oocyte development continued after the deposition of viable eggs and declined close to the hatching time of the clutches. Mature chorionated eggs were consistently observed in ovaries. It is strongly suggested that at least some trophic eggs contained in clutches at hatching are those that have matured and been deposited during the maternal care of eggs. We discuss possible selective factors leading to the specialization of these unusual heteropteran trophic eggs and the ecological significance of their ovarian dynamics.Résumé : Chez la punaise mineuse subsociale Adomerus triguttulus (Motschulsky, 1886) (Heteroptera : Cydnidae), les femelles produisent des oeufs trophiques non viables qui servent de ressource alimentaire aux larves nouvellement écloses; les femelles les ajoutent aux masses d'oeufs lors des soins maternels. Les oeufs trophiques sont reconnus comme moins coûteux à produire par les femelles et à consommer par les rejetons que des oeufs viables. Cette spécialisation peut se refléter dans la taille, la structure et le processus de développement des oeufs. La taille des oeufs trophiques non viables est plus petite et leur variation de taille dans une même masse d'oeufs plus grande que celle des oeufs viables. Les oeufs viables possèdent toujours à l'un des pôles environ cinq structures en micropyle, alors que la plupart des oeufs trophiques n'en ont pas. L'ovogenèse active se continue durant la période de soins maternels des oeufs; le développement des oocytes se poursuit après la ponte des oeufs viables et diminue près de la période de l'éclosion des oeufs. Il y a constamment des oeufs chorionés matures dans les ovaires. Nous sommes fermement convaincus qu'au moins certains des oeufs trophiques présents dans les masses d'oeufs au moment de l'éclosion sont ceux qui se sont développés et qui ont été pondus durant la période de soins maternels des oeufs. Nous discutons des facteurs possibles de sélection qui mènent à la spécialisation de ces oeufs trophiques inhabituels chez les hétéroptères et de la signification écologique d'une telle dynamique ovarienne.[Traduit par la Rédaction]

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.

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