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Mating elicits dramatic changes in behaviour and physiology related to reproduction in female Drosophila melanogaster, but little is known about how mating affects nutrient intake and preferences in this model organism. Postmating switches in reproductive activity and feeding are likely to alter life span because both reproduction and nutrition are closely linked to survival. To explore these possibilities, we compared the intake patterns of protein (P) and carbohydrate (C) preferred by male, mated female and virgin female adults of D. melanogaster and their life span responses under varying dietary P:C balances (0:1, 1:1 and 4:1). Despite sex differences, the patterns of both macronutrient intake and life span were remarkably similar between males and virgin females. Compared to unmated virgins, mated females consumed ca. 2.7 times more nutrients and preferred a diet that was significantly more protein-rich (mated versus virgin females: P:C 1:1.5 versus 1:4). Surprisingly, females that had experienced mating in early adulthood lived longer than those that remained virgin, and this life span-extending effect of mating in females was most profound on a diet that was equally balanced (P:C 1:1). Our results indicate that mating is an important modulator that regulates sex-specific nutrient preference, which in turn alters longevity in D. melanogaster. [ABSTRACT FROM AUTHOR]

Nutritional conditions experienced during early growth have important implications for the lifetime fitness of herbivores in nutritionally heterogeneous environments. We investigated the early life effects of imbalanced nutrient intake on key fitness components and how such effects can be overcome in a generalist leaf-feeding lepidopteran caterpillar, Spodoptera litura. Over the fifth larval instar, caterpillars were pretreated on one of three diets that varied in protein and carbohydrate content (p35:c7, p21:c21 or p7:c35; % dry mass). After moulting to the sixth instar, they were transferred to one of three no-choice diets (p35:c7, p21:c21 or p7:c35) or a food choice where they received two nutritionally complementary diets (p35:c7 versus p7:c35). Approximately 80% of caterpillars that had been protein-deprived (p7:c35) during the fifth instar moulted to the seventh instar and developed into heavier pupae than those pupating after the sixth instar. The threshold body mass for pupal metamorphosis was 144mg at the start of the sixth instar. Ingesting a diet low in protein or carbohydrate during the early instar led to a deficit in body protein or lipid content, respectively. When given a choice, caterpillars pretreated on the low-protein diet (p7:c35) selected significantly more protein and thus had a higher intake ratio of protein to carbohydrate than those from other diets (p35:c7, p21:c21). Our results suggest that caterpillars are not only capable of switching their developmental program to reduce the deleterious effects of an early deficiency of protein, but also flexible at adjusting nutrient preferences to redress specific nutritional imbalances experienced early in life. [ABSTRACT FROM AUTHOR]

There is growing evidence that, rather than maximizing energy intake subject to constraints, many animals attempt to regulate intake of multiple nutrients independently. In the complex diets of animals such as herbivores, the consumption of nutritionally imbalanced foods is sometimes inevitable, forcing trade-offs between eating too much of nutrients present in the foods in relative excess against too little of those in deficit. Such situations are not adequately represented in existing formulations of foraging theory. Here we provide the necessary theory to fit this case, using an approach that combines state-space models of nutrition with Tilman''s models of resource exploitation (Tilman 1982, Resource Competition and Community Structure, Princeton: Princeton University Press). Our approach was to construct a smooth fitness landscape over nutrient space, centred on a ‘target’ intake at which no fitness cost is incurred, and this leads to a natural classification of the simple possible fitness landscapes based on Taylor series approximations of landscape shape. We next examined how needs for multiple nutrients can be assessed experimentally using direct measures of animal performance as the common currency, so that the nutritional strategies of animals can be mapped on to the performance surface, including the position of regulated points of intake and points of nutrient balance when fed suboptimal foods. We surveyed published data and conducted an experiment to map out the performance landscape of a generalist leaf-feeding caterpillar, Spodoptera littoralis. [Copyright &y& Elsevier]

Pyrethroids are primarily used for mosquito control in Korea. However, high frequencies of mutations conferring resistance to not only pyrethroids but also to other insecticides have been found in mosquito populations. This study aimed to examine the hypothesis that insecticides used outside of public health may play a role in selection. Briefly, the resistance mutation frequencies to three insecticide groups (pyrethroids, organophosphates, and cyclodienes) were estimated in two representative groups of mosquito species (Anopheles Hyrcanus Group and Culex pipiens complex). The relationship between these frequencies and the land-use status of the collection sites was investigated through multiple regression analysis. In the Anopheles Hyrcanus Group, the frequencies of both ace1 (organophosphate resistance) and rdl (cyclodiene resistance) mutations were positively correlated with 'proximity to golf course', possibly be due to the insecticides used for turf maintenance. They also showed positive correlations with field area and rice paddy area, respectively, suggesting the role of agricultural insecticides in the selection of these resistance traits. For the Cx. pipiens complex, the kdr (pyrethroid resistance), ace1, and rdl mutations were positively correlated with the residential area, field, and rice paddy, respectively. Therefore, pyrethroids used for public health could serve as a direct source of resistance selection pressure against kdr , whereas non-public health insecticides may pose primary selection pressure against the ace1 and rdl traits. The current findings suggest that the insecticides used in agriculture and the golf industry play a significant role in mosquito selection, despite variations in the extent of indirect selection pressure according to the mosquito groups and insecticide classes. [Display omitted] • The relationship between the resistance mutation frequencies (kdr, ace1, and rdl) and the land-use status of collection sites was analyzed to find out the indirect selection pressure that led to resistance development in mosquitoes. • In Anopheles Hyrcanus Group, the selection pressure was given by insecticides used in field (ace1), rice paddy (rdl) and golf courses (ace1 and rdl). • In Cx. pipiens complex, public health insecticides appear to be the main selection pressure on the kdr trait, whereas agricultural insecticides used in field and rice paddy play a role in the selection of ace1 and rdl mutations. • For the proper resistance management, it is necessary to consider the selection pressure by agricultural and industrial insecticides as well as that by public health insecticides. [ABSTRACT FROM AUTHOR]