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2. Development of ovaries, allometry of reproductive traits and fecundity of Episyrphus balteatus (Diptera: Syrphidae)
- Creator:
- Branquart, Etienne and Hemptinne, Jean-Louis
- Type:
- article, model:article, and TEXT
- Subject:
- Syrphidae, Episyrphus balteatus, fecundity, egg production, ovaries, and allometry
- Language:
- English
- Description:
- Episyrphus balteatus only matures eggs after emergence. Ovaries develop in 4 stages. In the absence of oviposition sites, females refrain from ovipositing and their ovaries progressively fill the abdomen and then egg resorption occurs. The potential fecundity, which is expressed by the ovariole number, the reproductive biomass and the abdomen volume, scales isometrically with the size of females. Egg size is much less variable and does not rise proportionally to body size. In laboratory conditions, females of E. balteatus might lay between 2,000 and 4,500 eggs during their life-time at a rate of 1 to 2 eggs per ovariole per day. Both life-time fecundity and rate of egg production are directly related to the size of females. The potential and realized fecundities are likely to be limited by the availability of food resources during larval and adult life, respectively.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
3. Niche width and niche specialization in four species of ladybirds (Coleoptera: Coccinellidae) co-occurring in the same habitat
- Creator:
- Godeau, Jean-François, Ceryngier, Piotr , and Hemptinne, Jean-Louis
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- Coccinellidae, Calvia decemguttata, Calvia quatuordecimguttata, Calvia quindecimguttata, Sospita vigintiguttata, diet, frass analysis, food niche, and individual specialization
- Language:
- English
- Description:
- We investigated food niches, diet diversity and individual food specialization of the larvae and adults of four species of ladybirds, Sospita vigintiguttata (L.), Calvia quindecimguttata (F.), C. quatuordecimguttata (L.) and C. decemguttata (L.), co-occurring in European alder carr forests. The first two species are considered to be strict habitat specialists associated with alders (Alnus spp.) in marshy forests and the other two are less habitat-specialized, inhabiting various deciduous trees and shrubs. Our investigations were based on the analysis of food remains in frass produced by field-collected ladybirds. In each of the species studied, adults had more diversified diets than larvae based on Levins' D index of diversity. The most diverse diet recorded for adults was that for S. vigintiguttata followed by C. quatuordecimguttata, C. quindecimguttata and C. decemguttata. The diversity of larval diet was higher for the habitat specialists, C. quindecimguttata and S. vigintiguttata, than for the more habitat-generalists Calvia decemguttata and C. quatuordecimguttata. Although the main type of prey recorded for both adults and larvae of each of the species studied was aphids, other types of prey made up a relatively high part of the diet of different species/stage combinations. Psylla alni (L.), for example, was frequently recorded in the frass of adults and larvae of S. vigintiguttata and of adults of C. quatuordecimguttata and chrysomelid larvae commonly in the frass of adults and larvae of C. quindecimguttata. Quite a high proportion of the frass of all the species studied contained the remains of Psocodea. The niche width of adults was broader than that of larvae except in C. quindecimguttata in which it was the opposite. The larval niches of the strict habitat specialists, C. quindecimguttata and S. vigintiguttata, were broader than those of the less habitat-specialists C. decemguttata and C. quatuordecimguttata. Adults of all the species studied showed relatively higher levels of food specialization than larvae, except for C. quindecimguttata. The results of this study indicate that ecological specialization is a complex phenomenon and habitat specialization does not imply food specialization.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
4. Nutritive cost of interguild predation on eggs of Coccinella septempunctata and Adalia bipunctata (Coleoptera: Coccinellidae)
- Creator:
- Hemptinne, Jean-Louis, Dixon, Anthony F. G., and Gauthier, Catherine
- Type:
- article, model:article, and TEXT
- Subject:
- Adalia bipunctata, Coccinella septempunctata, Coccinellidae, ladybird beetles, intraguild predation on eggs, costs, larval development, survival, and alkaloids
- Language:
- English
- Description:
- Coccinella septempunctata was approximately 20% more reluctant to eat the eggs of Adalia bipunctata than the reverse. In addition, fourth instar larvae of C. septempunctata failed to complete their development on a diet of A. bipunctata eggs and only 30% of those of A. bipunctata completed their development on a diet of C. septempunctata eggs, and the survivors took nearly 2 times as long as those fed aphids. This is an indication that the costs of intraguild predation might outweigh the benefits.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public