Function of Migration in the Seasonal Synchronization of Insects

Abstract

Seasonal migrations of insects can be roughly divided into those within the temperate zone, those within the tropics, and those between the tropics and temperate areas. Temperate migrations often involve movements to and form diapause sites with correlated seasonal cycles in reproductive physiology. Many temperate migrants have apterous or brachypterous generations whose adaptive significance is not always clear, diapause may also be involved in tropical migrations, but the cue is likely to be food or moisture limitation rather than photoperiod. Interestingly, the capacity to diapause may be a prerequisite for migration into the temperate zone by tropical species: the two behaviours occur together in several migrants. An interesting subclass of tropical‐temperate migrants are “pied‐piper” species which apparently have no return movement: the action of natural selection in these cases is unclear. In all cases migration and diapause are intimately involved with other aspects of life histories because they allow choices of where and when to breed. The elucidation of the contributions of genetic and environmental variance to insect migration strategies is an important problem for entomologists. RÉSUMÉ Rôle de la migrations dans la synchronisation saisonnière des insectes. Les migrations saisonnières des insectes peuvent être globalement divisées en celles à l'intérieur de la zone tempérée, celles à l'intérieur des tropiques et celles entre les tropiques et les zones tempérées. Les migrations tempérées impliquent souvent des mouvements vers et à partir des sites de diapause en relation avec les cycles saisonniers de la physiologie de la reproduction. De nonbreux migrateurs des régions tempérées ont des générations aptères ou brachyptères, dont la signification adaptative n'est pas toujours claire. La diapause peut aussi être impliquée dans les migrations tropicales, mais la cause doit vraisemblablement être l'insuffisance d'aliment ou d'humidité plutôt que la photopériode. Il est intéressant de noter que l'aptitude à la diapause peut être une condition pour les migrations des espèces tropicales vers la zone tempérée; les deux comportements ont lieu ensemble chez plusieurs migrateurs. Une sous‐classe intéressante de migrateurs des tropiques vers les région tempérées est constituée par les espèces “pied piper” qui ont apparemment un mouvement sans retour; dans ce cas, l'action de la sélection naturelle est peu claire. Dans tous les cas la migration et la diapause sont intimement imbriquées avec tous les autres aspects de la biologie, parce qu'elles entraînent des choix sur où et quand se reproduire. La compréhension des contributions des variances génétique et environnementale dans les stratégies migratrices des insectes est un problème important pour les entomologistes.

Phenotypic plasticity, seasonal climate and the population biology of Bicyclus butterflies (Satyridae) in Malawi

“…Many insects migrate in space or time (diapause) to escape the dry season environment (e.g. Dingle, 1982;Wolda, 1988;Gatehouse, 1989). An alternative is found in some herbivorous insects, including species of satyrine butterflies, which show phenotypic plasticity and have different forms in each season (Shapiro, 1976;Brakefield & Larsen, 1984).…”

DIFFERENCES IN SURVIVORSHIP, DEVELOPMENT RATE AND FERTILITY BETWEEN THE LONGWINGED AND WINGLESS MORPHS OF THE WATERSTRIDER, LIMNOPORUS CANALICULATUS

“…One of the major questions in the study of the evolutionary forces which infl uence wing polymorphism concerns fi tness differences among the morphs. In many non-gerrids, dramatic differences between the fully-winged and the short-winged or functionally equivalent (Anderson, 1973) wingless morph have been documented in a variety of fi tness-associated traits (for reviews, see Harrison, 1980;Dingle, 1982). These include differences in such traits as survivorship under stress, duration of larval or nymphal development, age of fi rst reproduction, and fecundity.…”

A discrete dispersal model with constant and periodic environments

“…For the remainder of this section, we assume 12 and m 21 (t) = m 21 are positive constant, for i = 1, 2. Thus, system (1) can be written as…”

“…Not only has the migration and dispersal of animals, such as birds, insects, and fish, been a popular topic to study, but also the migration and dispersal of plants (seed dispersal) and tissue, blood, and cancer cells are being studied [7,[10][11][12]15,20,24]. In the last few decades, ecologists and mathematicians have been interested in the dispersal of amphibian populations ( [4,5,13,[16][17][18]22,23] just to name a few).…”