Trophic ecology of Atlantic bluefin tuna Thunnus thynnus larvae

Feeding intensity, diet composition, selectivity, energy ingestion and dietary niche breadth of larval Atlantic bluefin tuna Thunnus thynnus were studied on the eastern (Mediterranean) spawning grounds of the species. Larval T. thynnus were collected in the Balearic Archipelago (north-west Mediterranean Sea) during 2004 and 2005 using surveys specific for larval scombrids. Larvae between 2·6 and 8·7 mm standard length (L(S) ) are diurnal feeders, and 94% of the guts collected during daylight hours were full. The mean ±s.d. number of prey per gut was 7·1 ± 5·7, with mean ±s.d. ranging from 3·0 ± 1·6 in the smallest T. thynnus larvae to 11·1 ± 5·8 in 5·0-6·0 mm L(S) larvae. Up to 21 prey were found in a single larval gut (5·0-6·0 mm L(S) ) at the end of the day. Larvae progressively selected larger prey and exhibited increased carbon content concurrent with preflexion development of feeding and locomotory structures. Larvae of 5·0-6·0 mm L(S) exhibited positive selection of cladocerans over other prey (Chesson's index), whereas copepod nauplii dominated the diets of earlier stages. The dietary niche breadth measured increased initially but decreased at c. 5·5 mm L(S) . Appendicularians were found in the diet of larger larval sizes, but no piscivory was observed. Results are discussed in light of the sparse existing data for larval T. thynnus and other larval tuna species.     

Impact of dietary allelochemicals on gypsy moth (Lymantria dispar) caterpillars: importance of midgut alkalinity

Midgut pH of gypsy moth larvae was depressed artificially with buffered diet to examine the impact of alkalinity on the caterpillars' ability to tolerate a dietary polyphenol and a quinone. A 2x3 factorial design was used, with 2 levels of succinate buffer and 3 dietary amendments (tannic acid, juglone, or control). Development was monitored during the third and fourth instars, with consumption, food passage rates, midgut pH, and midgut redox potential (Eh) measured in the fourth instar. Diet buffering successfully depressed midgut pH to hypothetically suboptimal acidic levels without reductions in survivorship, but it did reduce larval growth and impede development. Buffering dramatically reduced survivorship of fourth instar larvae eating diets containing tannic acid or juglone. Growth increased on unbuffered diet amended with tannic acid, but not with juglone. Caterpillars passed food through the gut more slowly when feeding on buffered tannic acid diet or on unbuffered juglone diet. These results indicate that maintenance of midgut alkalinity is critical to tolerance of dietary tannic acid and juglone, and that these allelochemicals have very different activities in the caterpillar gut.     

Growth and fatty acid composition of freshwater prawn, Macrobrachium rosenbergii, larvae fed diets containing various ratios of cod liver oil–corn oil mixture

A feeding trial was conducted to determine the effect of replacing costly cod liver oil with corn oil as a source of dietary lipid on the growth and fatty acid composition of the larval freshwater prawn, Macrobrachium rosenbergii de Man. Prawn larvae were weaned to artificial diets containing cod liver oil and corn oil either singly or in various combinations (2 : 1, 1 : 1, 1 : 2, w/w). Weaning to artificial diets from Artemia nauplii commenced at larval stage III with complete substitution by stage X. The reference group was reared solely on Artemia nauplii during the entire experiment. Incorporation of corn oil at 33–67% of dietary supplemental oil did not have significant effects on the post‐larval production. However, larvae fed with corn oil alone revealed a significantly lower post‐larval production compared to other experimental diets as well as to the reference group. No significant differences (P > 0.05) were observed in dry weight, protein and lipid concentration among larvae fed on various dietary treatments. Palmitic (16 : 0) and oleic/vaccenic (18 : 1) acids were the dominant saturated and monounsaturated fatty acids in larval tissues, respectively, whereas the polyunsaturated fraction was dominated by eicosapentaenoic (20 : 5n‐3) acid. The polyunsaturated fatty acid composition was dominated by n‐3 acids rather than n‐6 fatty acids. The fatty acid composition of the prawn in general reflected that of the diet. Larvae on diets containing higher concentrations of corn oil rich in linoleic (18 : 2n‐6) acid showed a higher concentration of this acid in their tissues. No evidence of de novo synthesis of linoleic (18 : 2n‐6) acid was found. Higher levels of stearic (18 : 0), arachidonic (20 : 4n‐6) and eicosapentaenoic (20 : 5n‐3) acids found in larvae as compared with those fed Artemia and artificial diets strongly indicated the larval ability in chain elongation and desaturation of palmitic (16 : 0), linoleic (18 : 2n‐6) or linolenic (18 : 3n‐3) acids, respectively. Despite a large variation of n‐3 to n‐6 ratios of the live and artificial diets, larval n‐3 to n‐6 ratios were relatively stable among different dietary treatments, possibly indicative of the importance of such a ratio in the larval fatty acid metabolism.     

Hostplant,larval age,and feeding behavior influence midgut pH in the gypsy moth (Lymantria dispar)

Summary The midgut pH of late instar gypsy moth (Lymantria dispar L.) larvae is strongly alkaline, and varies with diet, larval stadium, and time since feeding. Midgut pH rises with time since feeding, and does so more quickly, reaching greater maximum values, on some diets than others. Leaf tissues of 23 tree species resist increases in alkalinity differentially; this trait and differing initial leaf pH may explain the impact of diet on gut pH. Third instar larvae may have gut conditions favorable for tannin-protein binding shortly after ingesting certain foods, but with time midgut alkalinity becomes great enough to dissociate tannin-protein complexes. Older instars rarely exhibit gut pHs low enough to permit tannin activity. Alkaline gut conditions may explain the gypsy moth's ability to feed on many tanniniferous plant species, especially in later instars. Consequences for pathogen effectiveness are discussed.     

The Intestinal Bacterial Community in the Food Waste-Reducing Larvae of <Emphasis Type="Italic">Hermetia illucens</Emphasis>

As it is known that food waste can be reduced by the larvae of Hermetia illucens (Black soldier fly, BSF), the scientific and commercial value of BSF larvae has increased recently. We hypothesised that the ability of catabolic degradation by BSF larvae might be due to intestinal microorganisms. Herein, we analysed the bacterial communities in the gut of BSF larvae by pyrosequencing of extracting intestinal metagenomic DNA from larvae that had been fed three different diets. The 16S rRNA sequencing results produced 9737, 9723 and 5985 PCR products from larval samples fed food waste, cooked rice and calf forage, respectively. A BLAST search using the EzTaxon program showed that the bacterial community in the gut of larvae fed three different diets was mainly composed of the four phyla with dissimilar proportions. Although the composition of the bacterial communities depended on the different nutrient sources, the identified bacterial strains in the gut of BSF larvae represented unique bacterial species that were unlike the intestinal microflora of other insects. Thus, our study analysed the structure of the bacterial communities in the gut of BSF larvae after three different feedings and assessed the application of particular bacteria for the efficient degradation of organic compounds.     

Feeding ecology of the freshwater detritivore Ptychoptera paludosa (Diptera, Nematocera)

1. We examined selected aspects of the nutritional ecology of larval Ptychoptera paludosa and their role in nutrient cycling in the Breitenbach, a first-order stream in Hesse, Germany.
2. Food preference experiments demonstrated significant preference for sediments with a high organic matter content and live bacteria.
3. pH was circumneutral in all sections of the gut.
4. Enzymatic activity (β-glucosidase and amino-peptidase) in different parts of the gut was measured using 4-methylumbelliferyl-β- D -glucopyranoside (MUF-Glc) and leucine-4-methylcoumarinyl-7-amide (Leu-MCA). β-glucosidase activity was highest in the hindgut.
5. The mean larval gut passage time was between 7 and 8 h.
6. The egestion rate of last instar larvae was about 0.35 mg dry weight (DW) faeces per larva h^–1 and about 1.25 mg ash-free dry weight (AFDW) faeces per mg larval AFDW day^–1.
7. Larval faeces contained at least 4–18 times more organic matter than the average in the sediments in which they were feeding, that is, larvae fed selectively, extracting organic matter from sediments.
8. P. paludosa larvae are important in the dynamics of detritus in slow-flowing reaches of the Breitenbach. They gather organic material from the sediment to a depth of 3 cm, and release it as faeces onto the sediment surface. A total of 770 g DW faeces m^–2 yr^–1, comprising about 16% organic matter, was produced by the Ptychoptera population.     

Penicillin-induced oxidative stress: effects on antioxidative response of midgut tissues in instars of Galleria mellonella

Penicillin and other antibiotics are routinely incorporated in insect culture media. Although culturing insects in the presence of antibiotics is a decades-old practice, antibiotics can exert deleterious influences on insects. In this article, we test the hypothesis that one of the effects of dietary penicillin is to increase oxidative stress on insects. The effects of penicillin on midgut concentrations of the oxidative stress indicator malondialdehyde (MDA) and on midgut antioxidant enzyme (superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and glutathione peroxidase [GPx]) and transaminases (alanine aminotransferase and aspartate aminotransferase) activities in greater wax moth, Galleria mellonella (L.), were investigated. The insects were reared from first instars on artificial diets containing 0.001, 0.01, 0.1, or 1.0 g penicillin per 100 g of diets. MDA content was significantly increased in the midgut tissues of each larval instar reared in the presence of high penicillin concentrations. Activities of antioxidant and transaminase enzymes did not show a consistent pattern with respect to penicillin concentrations in diet or age of larvae. Despite the increased penicillin-induced oxidative stress in gut tissue, antioxidant and transaminase enzymes did not correlate with oxidative stress level or between each other in larvae of other age stages except for the seventh instar. We found a significant negative correlation of MDA content with SOD and GST activities in seventh instars. SOD activity was also negatively correlated with CAT activity in seventh instars. These results suggest that exposure to dietary penicillin resulted in impaired enzymatic antioxidant defense capacity and metabolic functions in wax moth larval midgut tissues and that the resulting oxidative stress impacts midgut digestive physiology.     

Coevolution of the checkerspot butterfly Euphydryas chalcedona and its larval food plant Diplacus aurantiacus: larval response to protein and leaf resin

Summary Prediapause larvae of the checkerspot butterfly Euphydryas chalcedona were raised from hatch until entrance into diapause on artificial diets. The proportions of protein and host plant leaf resin differed among the diets. Larval size growth rates and mortality were monitored and overall rates and efficiencies of food use were computed.Larval survivorship, growth rate and size of larvae at idapause were significantly enhanced by increasing dietary protein content, particularly over the range found in leaves of the host plant. In contrast, an increasing dietary content of Diplacus aurantiacus leaf resin significantly depressed larval surviviorship, growth rates and size of larvae at diapause. A simple dosedependent interaction was observed between the effects of dietary leaf resin and protein on larval success. Dietary content of leaf resin and protein significantly influenced some measures of food utilization efficiency (ECI and ECD), but not others (AD and NUE).The negative interaction between the effects of dietary leaf resin and protein content suggests the leaf resin phenolic compounds reduce the availability of protein to the larvae. The results for efficiency indices of larval food use are potentially in conflict with this interpretation.The influence of host plant leaf resin and protein on larval success, coupled with the relation between photosynthesis and leaf nitrogen content, are consistent with the hypothesis that productivity can be enhanced by herbivore deterrence resulting from leaf resin production.     

Effects of dietary variation on growth,composition, and maturation of Manduca sexta (Sphingidae: Lepidoptera)

Most studies linking dietary variation with insect fitness focus on a single dietary component and late larval growth. We examined the effects of variation in multiple dietary factors over most life stages of the sphingid moth, Manduca sexta. Larvae received artificial diets in which protein, sucrose, and water content were varied. The relationship between larval size, growth and consumption rates differed significantly across diets. Larvae on control and low-sucrose diets grew most rapidly and attained the largest pupal and adult sizes. Conversely, larvae on low-water and low-protein diets initially grew slowly, but accelerated in the fifth instar and became pupae and adults comparable to control animals in size. There were no fundamental differences in protein:carbohydrate consumption patterns or strategies among experimental diets and larval instars. However, inadequate dietary water appeared to be more important for early than late instar larvae. Larvae on all artificial diets showed increasing fat content throughout all stages, including wandering and metamorphosis. Compensatory feeding among low-water and low-protein larvae was correlated with significantly higher fat content in larvae, pupae and adults, whereas low-sucrose animals were substantially leaner than those on the control diet. These differences may have strong effects on adult physiology, reproduction, and foraging patterns.     

Parasitic copepods affect morphospace and diet of larvae of a temperate reef fish

The effects of ectoparasites on larvae of the clingfish Gobiesox marmoratus were evaluated at the dietary and morphometric levels. The larvae and ectoparasites were collected by nearshore plankton samplings during October, November and December 2013 off El Quisco Bay, central Chile. The standardized abundance of total larvae and those ectoparasitized larvae (PL) was positively related and high parasite prevalence was found throughout the sampling period (up to 38%). Geometric morphometrics analyses indicate main changes in the shape through early ontogeny and subtle but significant variations between PL and non‐parasitized larvae (NPL). Prey composition varied between PL and NPL; small size (<6 mm standard length, L_S) parasitized larval G. marmoratus ate mostly gastropod larvae, whereas small non‐parasitized specimens ate mainly cirripede nauplii. All larger (>8 mm L_S), pre‐settlement stages parasitized by Trifur and, or Caligus copepods had content in their gut, suggesting that ectoparasites did not diminish prey capture in host with larger size. Morphometric and dietary changes occurring during larval development were decoupled, both for PL and NPL. The maintenance of a slender, more hydrodynamic body through pelagic development and the ingestion of less‐mobile prey in PL suggests non‐lethal effects of ectoparasitism on rocky‐reef fish larvae.     

Worker honey bee ovary development: seasonal variation and the influence of larval and adult nutrition

We examined the effect of larval and adult nutrition on worker honey bee (Apis mellifera L.) ovary development. Workers were fed high or low-pollen diets as larvae, and high or low-protein diets as adults. Workers fed low-protein diets at both life stages had the lowest levels of ovary development, followed by those fed high-protein diets as larvae and low- quality diets as adults, and then those fed diets poor in protein as larvae but high as adults. Workers fed high-protein diets at both life stages had the highest levels of ovary development. The increases in ovary development due to improved dietary protein in the larval and adult life stages were additive. Adult diet also had an effect on body mass. The results demonstrate that both carry-over of larval reserves and nutrients acquired in the adult life stage are important to ovary development in worker honey bees. Carry-over from larval development, however, appears to be less important to adult fecundity than is adult nutrition. Seasonal trends in worker ovary development and mass were examined throughout the brood rearing season. Worker ovary development was lowest in spring, highest in mid-summer, and intermediate in fall.     

Influence of dietary aconitine and nicotine on the gut microbiota of two lepidopteran herbivores

The gut microbiota plays an important role in pheromone production, pesticide degradation, vitamin synthesis, and pathogen prevention in the host animal. Therefore, similar to gut morphology and digestive enzyme activity, the gut microbiota may also get altered under plant defensive compound-induced stress. To test this hypothesis, Dendrolimus superans larvae were fed either aconitine- or nicotine-treated fresh leaves of Larix gmelinii, and Lymantria dispar larvae were fed either aconitine- or nicotine-treated fresh leaves of Salix matsudana. Subsequently, the larvae were sampled 72hr after diet administration and DNA extracted from larval enteric canals were employed for gut microbial 16S ribosomal RNA gene sequencing (338 F and 806 R primers). The sequence analysis revealed that dietary nicotine and aconitine influenced the dominant bacteria in the larval gut and determined their abundance. Moreover, the effect of either aconitine or nicotine on D. superans and L. dispar larvae had a greater dependence on insect species than on secondary plant metabolites. These findings further our understanding of the interaction between herbivores and host plants and the coevolution of plants and insects.     

Algae as first food for cod larvae,Gadus morhuaL.: filter feeding or ingestion by accident?

Cod larvae. Gadus morhua L., 24 days posthatch, were fed different species of algae in order to evaluate both rates and mechanisms of ingestion. The results were compared with cod larvae feeding on a natural assemblage of algae in a lagoon. Small algae (Nannochloris atomus Butcher, 14 pm) were found to enter the larval gut in accordance with drinking rate. In contrast, the cod larvae concentrated larger algae [Dunaliella salina (Dunal) Teodor. 6 10 pm] in the gut at rates from 492 to 7251 times the drinking rate. D. salina was captured in the slits between the visceral arches, and increased activity when the algae was added indicate that the cod larvae are active filter feeders during early larval stages. In the gut of cod larvae from the lagoon the fraction of algal material with diameter larger than 8 pm was 39.2% in 7-day-old larvae while, in 12-day-old larvae it had decreased to 12.6%. The most conspicuous characteristics of gut content in the youngest larvae were green spheres (10 μn) and a naked dinoflagellate (20 μn). Short chains of the diatom Skeletonemu cosrarum (Greville) Cleve were also frequently found.     

Nutrient balance in medfly, Ceratitis capitata, larval diets affects the ability of the developing insect to incorporate lipid and protein reserves

The Mediterranean fruit fly [Ceratitis capitata Wiedemann (Diptera: Tephritidae)], or medfly, is mass produced in many facilities throughout the world to supply sterile flies for sterile insect technique programs. Production of sterile males requires large amounts of larval and adult diets. Larval diets comprise the largest economic burdens in the mass production of sterile flies, and are one of the main areas where production costs could be reduced without affecting quality and efficacy. The present study investigated the effect of manipulating diet constituents on larval development and performance. Medfly larvae were reared on diets differing in the proportions of brewer's yeast and sucrose. We studied the effect of such diets on the ability of pupating larvae to accumulate protein and lipids, and on other developmental indicators. Except for diets with a very low proportion of brewer's yeast (e.g., 4%), pupation and adult emergence rates were in general high and satisfactory. The ability of pupating larvae to accumulate lipid reserves and proteins was significantly affected by the sucrose and yeast in the diet, and by the proportion of protein to carbohydrates (P/C). In contrast to previous nutritional studies conducted with other insects, low P/C in medfly larval diets (with excess dietary carbohydrates) resulted in pupating medfly larvae having a relatively reduced load of lipids; medfly larvae protein contents in these diets were, as expected, relatively low. Similarly, high P/C ratios in the diet produced larvae with high protein and lipid contents. Differences with other insects may be due to differential post‐ingestion regulation where a high dietary carbohydrate diet reduces the lipogenic activity of the larvae, and induces a shift from lipid to glucose oxidation. Larvae reared on low P/C diets spent more time foraging in the diet than larvae maintained on a high P/C diet, suggesting a compensatory mechanism to complement nutrient intake. The results suggest that the content of brewer's yeast, the most expensive diet component, could be fine‐tuned without apparently affecting fly quality.     

Veligers of an introduced bivalve,Limnoperna fortunei,are a new food resource that enhances growth of larval fish in the Paraná River (South America)

1. Larvae of ‘sábalo’, Prochilodus lineatus, whose adults represent over 60% of overall fish biomass in the Río de la Plata Catchment, have been observed to feed intensively on veligers of the exotic bivalve Limnoperna fortunei. 2. To assess the effects of this dietary shift on the growth of P. lineatus, 28‐day laboratory experiments were carried out feeding newly hatched P. lineatus larvae with three diets: zooplankton artificially enriched with L. fortunei veligers; natural zooplankton; and zooplankton artificially enriched with cladocerans and copepods. The average length, weight and gut contents of the fish larvae were assessed weekly and metabolic rates of fish larvae were measured. 3. Proportions of veligers in gut contents were always higher than those in the experimental diet: 100, 76 and 21% for veliger‐enriched, natural and low‐veliger diets, respectively. Larvae fed a veliger‐enriched diet grew to a significantly larger size than larvae fed the other two diets. In energetic balance comparisons using metabolic rates and prey energy content, all three diets were sufficient to support metabolism and growth. The greatest values of excess energy at the end of each week were in the veliger‐enriched experiments. 4. Feeding on veligers of L. fortunei significantly enhances the growth of P. lineatus larvae and supports the idea that this new and abundant resource is selectively preyed upon by P. lineatus during its larval stage. Higher growth rates may stem from the higher energy contents of veligers compared to crustaceans and/or from the lower energy costs of capturing slower prey.     

Developmental responses to variable diet composition in a butterfly: the role of nitrogen,carbohydrates and genotype

Understanding the evolution of herbivore–plant interactions requires detailed information on proximate responses to relevant dietary variability and genetic variance, if any, associated with these responses. We measured the behavioral and developmental responses of Pieris rapae larvae to variation in the nitrogen (N) and carbohydrate (CARB) content of chemically‐defined diets, using differences in the average responses of sibling groups to estimate underlying genetic variance. Larval P. rapae responded to dietary reductions in both N and CARB with increased feeding, but these responses were inadequate to compensate for dietary N deficiencies within the range of N found in host plants. As a result, larvae on reduced N diets exhibited lower relative growth rates and longer development times, whereas larvae on reduced CARB diets maintained normal developmental trajectories. We also report evidence for genetic variation underlying (a) compensatory feeding responses to CARB and N availability, (b) N‐driven variation in growth rate and (c) CARB‐driven variation in larval duration. Our results highlight N availability as a key factor in the growth and development of this herbivorous butterfly, with CARB availability being less constraining and sufficiently addressed by changes to larval consumption rate. Furthermore, our study reveals standing genetic variance associated with larval responses to macronutrient availability, suggesting continued potential for herbivore–plant co‐evolution in this system despite a putative history of strong directional selection.     

Dynamic changes of gut bacterial communities present in larvae of Anoplophora glabripennies collected at different developmental stages

The Asian long-horned beetle, Anoplophora glabripennies (Motschulsky), is a destructive wood-boring pest that is capable of killing healthy trees. Gut bacteria in the larvae of the wood-boring pest is essential for the fitness of hosts. However, little is known about the structure of the intestinal microbiome of A. glabripennies during larval development. Here, we used Illumina MiSeq high-throughput sequencing technology to analyze the larval intestinal bacterial communities of A. glabripennies at the stages of newly hatched larvae, 1st instar larvae and 4th instar larvae. Significant differences were found in larval gut microbial community structure at different larvae developmental stages. Different dominant genus was detected during larval development. Acinetobacter were dominant in the newly hatched larvae, Enterobacter and Raoultella in the 1st instar larvae, and Enterococcus and Gibbsiella in the 4th instar larvae. The microbial richness in the newly hatched larvae was higher than those in the 1st and 4th instar larvae. Many important functions of the intestinal microbiome were predicted, for example, fermentation and chemoheterotrophy functions that may play an important role in insect growth and development was detected in the bacteria at all tested stages. However, some specific functions are found to be associated with different development stages. Our study provides a theoretical basis for investigating the function of the intestinal symbiosis bacteria of A. glabripennies.     

The effects of boric acid-induced oxidative stress on antioxidant enzymes and survivorship in Galleria mellonella

Larvae of the wax moth, Galleria mellonella (L.), were reared from first instar on a diet supplemented with 156, 620, 1,250, or 2,500 ppm boric acid (BA). The content of malondialdehyde (MDA, an oxidative stress indicator), and activities of the antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx)] were determined in the fat body and hemolymph in the 7th instar larvae and newly emerged pupae. Relative to control larvae, MDA was significantly increased in larval hemolymph, larval and pupal fat body, but decreased in the pupal hemolymph. Insects reared on diets with 156- and 620-ppm BA doses yielded increased SOD activity but 1,250- and 2,500-ppm doses resulted in decreased SOD activity in larval hemolymph. SOD activity was significantly increased but CAT was decreased in the larval fat body. High dietary BA treatments led to significantly decreased GST activity. However, they increased GPx activity in larval hemolymph. Dietary BA also affected larval survival. The 1,250- and 2,500-ppm concentrations led to significantly increased larval and pupal mortality and prolonged development. In contrast, the lowest BA concentration increased longevity and shortened development. We infer that BA toxicity is related, at least in part, to oxidative stress management.     

Characterization of the Mamestra configurata (Lepidoptera: Noctuidae) larval midgut protease complement and adaptation to feeding on artificial diet,Brassica species,and protease inhibitor

The midgut protease profiles from 5th instar Mamestra configurata larvae fed various diets (standard artificial diet, low protein diet, low protein diet with soybean trypsin inhibitor [SBTI], or Brassica napus) were characterized by one‐dimensional enzymography in gelatin gels. The gut protease profile of larvae fed B. napus possessed protease activities of molecular masses of approximately 33 and 55 kDa, which were not present in the guts of larvae fed artificial diet. Similarly, larvae fed artificial diet had protease activities of molecular masses of approximately 21, 30, and 100 kDa that were absent in larvae fed B. napus. Protease profiles changed within 12 to 24 h after switching larvae from artificial diet to plant diet and vice versa. The gut protease profiles from larvae fed various other brassicaceous species and lines having different secondary metabolite profiles did not differ despite significant differences in larval growth rates on the different host plants. Genes encoding putative digestive proteolytic enzymes, including four carboxypeptidases, five aminopeptidases, and 48 serine proteases, were identified in cDNA libraries from 4th instar M. configurata midgut tissue. Many of the protease‐encoding genes were expressed at similar levels on all diets; however, three chymoptrypsin‐like genes (McSP23, McSP27, and McSP37) were expressed at much higher levels on standard artificial diet and diet containing SBTI as was the trypsin‐like gene McSP34. The expression of the trypsin‐like gene McSP50 was highest on B. napus. The adaptation of M. configurata digestive biochemistry to different diets is discussed in the context of the flexibility of polyphagous insects to changing diet sources. Published 2010 Wiley Periodicals, Inc.     

Growth and survival of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed isocaloric diets with different protein levels during weaning

The growth of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed four isocaloric diets (4200 kcal kg^?1) with different protein levels during weaning was determined. Diets containing 45, 50, 55, and 60% protein were formulated by linear programming using amino acid profiles based on that of 2‐day‐old river catfish larvae. Artificial diets were fed to the larvae beginning at day 5 after being initially fed Artemia nauplii for 4 days. The larvae thrived solely on artificial diets from day 8 to day 16. On the other hand, the control larvae were fed Artemia nauplii from day 1 to day 16. Results of the feeding trial showed that growth and survival of M. nemurus larvae given the diet containing 60% protein were high and comparable to those of the larvae given only live food (control). Larvae fed the 55% protein diet had significantly lower growth and survival than the larvae on the control and 60% diets but significantly higher growth and survival rates than did larvae fed with 45 and 50% protein diets. Carcass moisture and total lipids after 16 days of feeding did not differ significantly (P > 0.05), but body protein increased with increasing dietary protein. Body protein of the control larvae was similar to that of larvae given the 60% protein diet.