Larvae Of Different Ages Research Articles

Potential effect of increasing the water content in the digestibility of microdiets for fish larvae

This study aimed to find a way for increasing the water content after rehydration of microdiet particles for fish larvae and to assess whether such increase contributes to a better disaggregation and digestion of particles within the gut of gilthead seabream larvae (4–15 days after hatching, dph). Four microdiets were prepared with increasing amounts of carboxymethylcellulose (CMC): 0, 20, 40 and 80 g kg−1. The inclusion of CMC resulted in an effective increase of the hydration capacity of particles. Water content after immersion ranged from 800 g kg−1 in the microdiet without CMC to 900 g kg−1 with 80 g kg−1 CMC. Larvae of different ages were fed during 10 h with these microdiets. The microparticles containing 80 g kg−1 CMC were more degraded in the gut of the younger larvae. No clear differences were observed from 10 dph onwards. Differences in enzymatic activities were not evident except for α-amylase in 6 dph larvae. Gene expression of the enzyme precursors did not show any relation to the water content of microdiets. Overall, the results indicate that increasing the water content up to 900 g kg−1 may enhance the disintegration of food particles within the gut of younger larvae and to a lesser extent affect the response of digestive enzyme activities.

Ingestion and digestion of live microalgae and microalgae concentrates by sandfish, Holothuria scabra, larvae

Information on the nutritional requirements and preferred diets of sea cucumber (Holothuriidae) larvae is extremely limited and this has hindered development of hatchery culture methods. This study assessed ingestion and digestion of two live (TISO and Chaetoceros muelleri) and six concentrated microalgae (Instant Algae®, Reed Mariculture Inc.) by sandfish (Holothuria scabra) auricularia larvae of different ages using epifluorescence microscopy. This is the first study to report the use of epifluorescence microscopy with larval echinoderms and experiments were conducted using 2, 6 and 10 day old auricularia larvae. Seven of the eight microalgae tested were ingested and digested by the larvae with digestion occurring more rapidly in older larvae. C. muelleri was rapidly digested by 6-day and 10-day old larvae but our results indicate that C. muelleri is unsuitable as a food for 2-day old sandfish larvae. TISO was well ingested by sandfish larvae in both live and concentrated forms and live TISO was the most suitable of the microalgae tested in terms of ingestion and digestibility. All commercially available microalgae concentrates tested were readily ingested and digested by H. scabra larvae with the exception of Thalassiosira pseudonana (3H 1800®) which was not ingested by larvae of any of the three ages tested. Our results show potential for using microalgae concentrates as alternatives to live microalgae in hatchery culture of sandfish. However, further research should be conducted to assess the relative nutritional values of digestible microalgae as a basis for optimising a diet for hatchery culture of sandfish, and to provide further information on the nutritional requirements of sandfish larvae.

Asynchronous hatching and brood reduction by filial cannibalism in the burying beetle Nicrophorus quadripunctatus

Despite decades of intensive research, there is still much debate about the adaptive significance of asynchronous hatching. A major obstacle in understanding the significance of this process is the difficulty involved in separating the hypotheses that explain asynchronous hatching as an adaptive trait from those that explain it as a by-product of physiological constraints on hatching or egg-laying patterns. We investigated the burying beetle Nicrophorus quadripunctatus, a species in which the parent can eliminate less-adaptive offspring (e.g., slower-growing offspring) by filial cannibalism and adjust the age structure of offspring to an adaptive pattern. The main aim of this study was to determine the age composition of offspring that survived and to determine the effect of larval growth on filial cannibalism. We investigated how the point in time at which each group of larvae hatched affects the timing of filial cannibalism by the female parent. We found that N. quadripunctatus exhibited asynchronous hatching, and reared larvae of different ages. We also found that later-hatching larvae had lower survival and growth rates; therefore, filial cannibalism plays a role in eliminating later-arriving, slower-growing, and hence less-adaptive offspring.

Parent–Offspring Conflict over the Transition to Independence in Nicrophorus vespilloides: Parental Chemical Cues and Offspring Begging

AbstractIn species where parents provide their offspring with food, the offspring must undergo a transition from nutritional dependency to independence. Parent–offspring conflict theory predicts that the optimal timing for this transition will differ between parents and offspring and that the realised timing depends on each party’s ability to control the transition. The burying beetle Nicrophorus vespilloides is an excellent species for studying conflict over the transition to independence; the larvae beg for pre‐digested carrion from their parents until they cease begging around 72 h after hatching. The cessation of begging is not associated with changes in parental behaviour, suggesting that the transition is mostly under offspring control. However, recent work has demonstrated that caring parents express distinct chemical cues that stimulate larval begging, the expression of which varies between breeding and non‐breeding beetles, suggesting that parents might exert control over the transition to independence by altering these cues throughout development. If so, we predict that begging larvae should behave differently towards parental chemical cues from different stages of development and that larvae of different ages should behave similarly towards parental chemical cues from the same stage of development. We found no evidence for either prediction: begging larvae did not behave differently towards parental chemical cues from different stages of development, and larvae of different ages still behaved differently towards parental chemical cues from the same stage of development. Our results provide no support for the hypothesis that parents can control the transition to nutritional independence by altering their chemical profiles.

Variation in rates of early development in Haliotis asinina generate competent larvae of different ages.

IntroductionInter-specific comparisons of metazoan developmental mechanisms have provided a wealth of data concerning the evolution of body form and the generation of morphological novelty. Conversely, studies of intra-specific variation in developmental programs are far fewer. Variation in the rate of development may be an advantage to the many marine invertebrates that posses a biphasic life cycle, where fitness commonly requires the recruitment of planktonically dispersing larvae to patchily distributed benthic environments.ResultsWe have characterised differences in the rate of development between individuals originating from a synchronised fertilisation event in the tropical abalone Haliotis asinina, a broadcast spawning lecithotrophic vetigastropod. We observed significant differences in the time taken to complete early developmental events (time taken to complete third cleavage and to hatch from the vitelline envelope), mid-larval events (variation in larval shell development) and late larval events (the acquisition of competence to respond to a metamorphosis inducing cue). We also provide estimates of the variation in maternally provided energy reserves that suggest maternal provisioning is unlikely to explain the majority of the variation in developmental rate we report here.ConclusionsSignificant differences in the rates of development exist both within and between cohorts of synchronously fertilised H. asinina gametes. These differences can be detected shortly after fertilisation and generate larvae of increasingly divergent development states. We discuss the significance of our results within an ecological context, the adaptive significance of mechanisms that might maintain this variation, and potential sources of this variation.

Bioenergetic strategy of a xylem-feeder

To understand the efficiency of energy flow through an organism living in a nutrient poor environment, the bioenergetics of a xylem-feeding beetle Aredolpona rubra was investigated. The larvae of different ages were kept at a constant high, constant low and seasonally variable temperature or in agar plates and agar + nitrogen plates. Bioenergetic parameters were measured during the course of 1 year. The results showed (i) a very strong influence of food moisture on the bioenergetic parameters of A. rubra, (ii) the influence of temperature depends on whether it is fluctuating or constant, (iii) opposite mechanisms regulate growth in a shortage of water and at a suboptimal temperature: in the former case, consumption does not change while the metabolic rate decreases, and at a suboptimal temperature the metabolic rate is dictated by temperature and the consumption rate is altered and (iv) a nitrogen-rich diet results in a decreased metabolic rate, suggesting the existence of energetically costly adaptations to low quality wood as a food source. The study results have broad implications for environmental influences on insect life histories.

Feeding essential oils and 2-heptanone in sugar syrup and liquid protein diets to honey bees (Apis mellifera L.) as potential Varroa mite (Varroa destructor) controls

SummaryEssential oils were fed to honey bees to determine whether the components were absorbed into bee larvae. The oils were added in either sucrose syrup (origanum and 2-heptanone) or in a liquid protein diet (origanum oil, cinnamon oil, thymol, and 2-heptanone), because sugar and protein sources are differentially utilized in food fed to larvae of different ages. The volatiles emitted by isolated larvae from oil-supplemented colonies were sampled at three different ages (Day 4, Day 6 and Day 9) by Solid Phase Micro-Extraction (SPME) and analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The only oil volatiles recovered in larvae were the origanum oil components carvacrol and thymol; neither 2-heptanone nor the cinnamon oil components were detected in any larvae. For larvae from colonies fed oil- supplemented sugar syrup, carvacrol volatiles were emitted at higher amounts in younger larvae (Day 4) than in older larvae (Day 9). In contrast, carvacrol and thymol volatiles were detected only in older larvae (Day 6 and Day 9) in colonies reared on oil-supplemented liquid protein diet. Carvacrol was also detected in the cocoons of Day 9 larvae from colonies fed oil-supplemented liquid protein diet, but not oil-supplemented sugar syrup diet. We believe that the age-related differences in oil incorporation by bee larvae reflect the relative importance of supplemental sugars and protein as food sources for bee larvae of these ages. Supplementation in a liquid protein diet represents a more efficacious route for the incorporation of origanum oils in fifth instar bee larvae targeted for invasion by Varroa destructor mites.

Antioxidant Properties of Royal Jelly Associated with Larval Age and Time of Harvest

This study aimed to evaluate the antioxidant properties of royal jelly (RJ) collected from larvae of different ages that were transferred in artificial bee queen cells for 24, 48, and 72 h. RJ harvested from the 1 day old larvae 24 h after the graft displayed predominant antioxidant properties, including scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, inhibition of linoleic acid peroxidation, and reducing power. Regardless of the initial larval age, lower antioxidant activities were observed in the RJ harvested later than 24 h except for the activity of superoxide dismutase. In addition, higher contents of proteins and polyphenolic compounds were determined in the RJ harvested 24 h than that harvested 48 or 72 h after the graft. It implied that the polyphenolic compounds may be the major component for giving the antioxidant activities in RJ. In summary, the time of harvest and the initial larval age did affect the antioxidant potencies in RJ, and RJ collected 24 h after the larval transfer showed the most substantial antioxidant activities.

Cytosolic glutathione S-transferases ofOesophagostomum dentatum

Oesophagostomum dentatum stages were investigated for glutathione S-transferase (GST) expression at the protein and mRNA levels. GST activity was detected in all stages (infectious and parasitic stages including third- and fourth-stage larvae of different ages as well as males and females) and could be dose-dependently inhibited with sulfobromophthalein (SBP). Addition of SBP to in vitro larval cultures reversibly inhibited development from third- to fourth-stage larvae. Two glutathione-affinity purified proteins (23 and 25 kDa) were detected in lysates of exsheathed third-stage larvae by SDS-PAGE. PCR-primers were designed based on peptide sequences and conserved GST sequences of other nematodes for complete cDNA sequences (621 and 624 nt) of 2 isoforms, Od-GST1 and Od-GST2, with 72% nucleotide similarity and 75% for the deduced proteins. Genomic sequences consisted of 7 exons and 6 introns spanning 1296 bp for Od-GST1 and 1579 and 1606 bp for Od-GST2. Quantitative real-time-PCR revealed considerably elevated levels of Od-GST1 in the early parasitic stages and slightly reduced levels of Od-GST2 in male worms. Both Od-GSTs were most similar to GST of Ancylostoma caninum (nucleotides: 73 and 70%; amino acids: 80 and 73%). The first three exons (75 amino acids) corresponded to a synthetic prostaglandin D2 synthase (53% similarity). O. dentatum GSTs might be involved in intrinsic metabolic pathways which could play a role both in nematode physiology and in host-parasite interactions.

Detection of <I>Anoplophora glabripennis</I> (Coleoptera: Cerambycidae) Larvae in Different Host Trees and Tissues by Automated Analyses of Sound-Impulse Frequency and Temporal Patterns

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), an invasive pest quarantined in the United States, is difficult to detect because the larvae feed unseen inside trees. Acoustic technology has potential for reducing costs and hazards of tree inspection, but development of practical methods for acoustic detection requires the solution of technical problems involving transmission of resonant frequencies in wood and high background noise levels in the urban environments where most infestations have occurred. A study was conducted to characterize sounds from larvae of different ages in cambium, sapwood, and heartwood of bolts from three host tree species. Larval sounds in all of the tested trees and tissues consisted primarily of trains of brief, 3-10-ms impulses. There were no major differences in the spectral or temporal pattern characteristics of signals produced by larvae of different ages in each tissue, but larval sounds in sapwood often had fewer spectral peaks than sounds in cambium and heartwood. A large fraction, but not all background sounds could be discriminated from larval sounds by automated spectral analyses. In 3-min recordings from infested bolts, trains containing impulses in patterns called bursts occurred frequently, featuring 7-49 impulses separated by small intervals. Bursts were rarely detected in uninfested bolts. The occurrence of bursts was found to predict infestations more accurately than previously used automated spectral analyses alone. Bursts and other features of sounds that are identifiable by automated techniques may ultimately lead to improved pest detection applications and new insight into pest behavior.

Detection of Anoplophora glabripennis (Coleoptera: Cerambycidae) Larvae in Different Host Trees and Tissues by Automated Analyses of Sound-Impulse Frequency and Temporal Patterns

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), an invasive pest quarantined in the United States, is difficult to detect because the larvae feed unseen inside trees. Acoustic technology has potential for reducing costs and hazards of tree inspection, but development of practical methods for acoustic detection requires the solution of technical problems involving transmission of resonant frequencies in wood and high background noise levels in the urban environments where most infestations have occurred. A study was conducted to characterize sounds from larvae of different ages in cambium, sapwood, and heartwood of bolts from three host tree species. Larval sounds in all of the tested trees and tissues consisted primarily of trains of brief, 3–10-ms impulses. There were no major differences in the spectral or temporal pattern characteristics of signals produced by larvae of different ages in each tissue, but larval sounds in sapwood often had fewer spectral peaks than sounds in cambium and heartwood. A large fraction, but not all background sounds could be discriminated from larval sounds by automated spectral analyses. In 3-min recordings from infested bolts, trains containing impulses in patterns called bursts occurred frequently, featuring 7–49 impulses separated by small intervals. Bursts were rarely detected in uninfested bolts. The occurrence of bursts was found to predict infestations more accurately than previously used automated spectral analyses alone. Bursts and other features of sounds that are identifiable by automated techniques may ultimately lead to improved pest detection applications and new insight into pest behavior.

Mitochondrial Transcription Factor B2 Is Essential for Metabolic Function in Drosophila melanogaster Development

Characterization of the basal transcription machinery of mitochondrial DNA (mtDNA) is critical to understand mitochondrial pathophysiology. In mammalian in vitro systems, mtDNA transcription requires mtRNA polymerase, transcription factor A (TFAM), and either transcription factor B1 (TFB1M) or B2 (TFB2M). We have silenced the expression of TFB2M by RNA interference in Drosophila melanogaster. RNA interference knockdown of TF2BM causes lethality by arrest of larval development. Molecular analysis demonstrates that TF2BM is essential for mtDNA transcription during Drosophila development and is not redundant with TFB1M. The impairment of mtDNA transcription causes a dramatic decrease in oxidative phosphorylation and mitochondrial ATP synthesis in the long-lived larvae, and a metabolic shift to glycolysis, which partially restores ATP levels and elicits a compensatory response at the nuclear level that increases mitochondrial mass. At the cellular level, the mitochondrial dysfunction induced by TFB2M knockdown causes a severe reduction in cell proliferation without affecting cell growth, and increases the level of apoptosis. In contrast, cell differentiation and morphogenesis are largely unaffected. Our data demonstrate the essential role of TFB2M in mtDNA transcription in a multicellular organism, and reveal the complex cellular, biochemical, and molecular responses induced by impairment of oxidative phosphorylation during Drosophila development.

Competition between larvae in a butterfly Pieris napi and maintenance of different life‐history strategies

1. In scramble competition all individuals suffer equally from competition, whereas in contest competition some individuals outperform the others. Generally, larger individuals gain asymmetric advantage in competition over smaller ones. Given the positive correlation between age and size, asynchronous birth may result in asymmetric competition among juveniles. 2. In Pieris napi (Lepidoptera: Pieridae), reproductive rate is determined by the females' intrinsic mating tactic. The early reproductive rate is high in females with a low mating frequency and low in females with a high mating frequency, whereas lifetime fecundity shows the opposite pattern. Thus, offspring of monandrous females start to develop in relatively low densities and they are relatively large when the offspring of highly polyandrous females start to hatch. 3. The purpose of this study was to explore if asymmetry in larval competition could outweigh the late-life benefits of polyandry. In a laboratory experiment, P. napi larvae of different ages were reared together in different densities. 4. Increasing density decreased both larval survival and reachable pupal mass, but had no effect on duration of larval period. Younger larvae suffered from high mortality and reduced size compared with the older larvae. Mortality decreased in the older cohort with increasing age difference between the cohorts, and the reverse occurred in the younger cohort. Increasing age difference between the cohorts was associated with increase in pupal mass in both cohorts. All the variables showed a lot of variation between broods of different females. 5. The results suggest that polyandrous females, or more generally females with a low early reproductive rate, may lose a great proportion of their late-life benefits, which may partly explain the maintenance of polymorphism in reproductive strategies within species.

Salinity tolerance in young Allis shad larvae (Alosa alosa L.)

Abstract – Estuarine migration in Allis shad (Alosa alosa) usually does not take place before mid‐summer, but exposure to salinity in brackish water may occur earlier as many spawning areas are of necessity located in upper estuarine zones due to the placement of dams. Therefore, Allis shad conservation programmes need to consider the risk of mortality due to the ability of young Allis shad to tolerate salinity. To evaluate larval mortality due to the inability of larvae to withstand salinity during early ontogeny, we exposed larvae of different ages (from few days old to 27 days old) to salinities ranging from 0 to 30 g·l−1. Results indicate that direct seawater exposure induces high mortality in young larvae whatever the ontogenetic stage. However, young larvae can easily deal with upper estuary salinity conditions.

The nutritional value of seven species of tropical microalgae for black-lip pearl oyster (Pinctada margaritifera, L.) larvae

Recent years have seen major developments in the culture and availability of tropical microalgae as a food source for tropical bivalve species. The nutritional value of seven small (<9 μm) tropical microalgae species: two diatoms (Chaetoceros muelleri and Chaetoceros sp.); three golden-brown flagellates (Isochrysis sp., Pavlova salina and Pavlova sp.) and two green-flagellates (Micromonas pusilla and an unidentified coccoid CS-126), were analysed for carbohydrate, lipid and protein contents as well as fatty acid composition. Each species of microalgae was fed singly to early (D-stage veliger) and later (umbo stage veliger) stage larvae of the black-lip pearl oyster, Pinctada margaritifera. Highest survival of D-stage larvae over the 10-day experiment was recorded for those fed Pavlova sp. (CS-50). Greatest shell growth was shown by D-stage larvae fed the golden-flagellates Pavlova sp. (CS-50) and Pav. salina. Based on growth of D-stage larvae, the microalgae could be divided into three groups: (1) larvae fed Pav. salina and Pavlova sp. showed significantly greater growth than those fed other microalgae; (2) those fed Isochrysis sp., C. muelleri and M. pusilla showed significantly greater growth than unfed larvae; and (3) larvae fed Chaetoceros sp. and CS-126 did not grow at a rate greater than unfed larvae. Growth of D-stage veliger larvae was significantly correlated with carbohydrate, lipid and protein content of microalgae and with levels of dietary polyunsaturated fatty acid, specifically DHA (r=0.829, P=0.021). In a second experiment survival of umbo-stage larvae (including the unfed control) did not differ significantly between treatments (P<0.05) after 8 days of culture. Larvae fed Pavlova sp. and Pav. salina showed the greatest incremental growth increases, but these were not significantly greater than those of larvae fed TISO and C. muelleri (P>0.05). Growth of umbo-stage larvae fed M. pusilla, Chaetoceros sp. and the Prasinophyta sp. (CS-126) did not differ significantly from that of unfed larvae (P<0.05). This study is the first comprehensive assessment of the nutritional value of tropical microalgae species for pearl oyster larvae. The results provide a basis for development of more effective larval culture techniques by identifying microalgae supporting good growth of P. margaritifera larvae of different ages.

Dynamic expression of the LIM-homeodomain gene Lhx15 through larval brain development of the sea lamprey ( Petromyzon marinus)

LIM-homeodomain genes encode a family of transcription factors with highly conserved roles in the patterning and regionalisation of the vertebrate brain. The expression of one of those genes, Lhx15, in the embryonic lamprey brain, characterises precise functional subdivisions. In order to analyse the non-embryonic development of the lamprey brain, we chose this gene to perform in situ hybridisations in Petromyzon marinus larvae of different ages. We demonstrate the usefulness of Lhx15 to follow the development and morphogenesis of brain structures and show the dynamical expression of this gene through time. Furthermore, we provide evidence for the evolutionary conservation of the expression of this gene in the spinal cord, notochord and urogenital system.

Effects of various concentrations ofBacillus thuringiensis-corn leaf material on food utilization byChilo partellus larvae of different ages

When herbivores feed on insect-resistant transgenic plants, food consumption and utilization are probably affected. Quantifying these parameters is of importance, because they may be associated with the performance of parasitoids, which are important antagonists of herbivorous pests. In this study, relative consumption rate (RCR), relative growth rate (RGR), approximate digestibility (AD), efficiency of conversion of digested food into body matter (ECD) and efficiency of conversion of ingested food into body matter (ECI) ofChilo partellus Swinhoe larvae (Lepidoptera: Crambidae) exposed to different concentrations of transgenic insect-resistantBacillus thuringiensis-corn (Bt-corn) tissue suspension, were investigated under laboratory conditions. For the control groups, different concentrations of control corn tissue suspension were used. In order to determine whether Bt effects were influenced by larval age, 4- and 17-day-old larvae were used. At all concentrations and for larvae of both ages, RGR, RCR, ECD and ECI values in the control were significantly higher than in the Bt group. Moreover, there was a gradual decrease in RCR, RGR and ECI values when Bt concentrations were increased. However, AD values at the lowest Bt concentration were significantly higher than in the control, whereas no significant differences between both groups could be detected at higher concentrations. In conclusion, the experiments showed that nutritional indices of herbivores exposed to transgenic insect-resistant plants could be quantified to determine the effects of these plants on target or non-target organisms. This could be one component in future evaluation of the effect of transgenic insect-resistant plants on the second and third trophic level.

Age‐specific bioassays and fecundity of Phthorimaea operculella (Lepidoptera: Gelechiidae) reared on cry1Ac ‐transgenic potato plants

SummaryVariation in the susceptibility of lepidopterous pest larvae of different ages to transgenic crops and the potential for survivors to reproduce could have important consequences for the development of resistance in such pests. Experiments were undertaken in the laboratory to determine if larvae of the potato tuber moth, Phthorimaea operculella, of different ages (0 (&lt; 1 day old), 3, 5, 7 days) varied in their susceptibility to cry1Ac9–transgenic potato (Solanum tuberosum) foliage grown in the glasshouse or field. The survival and fecundity of larvae reared on transgenic tubers was also determined in the laboratory. There were no apparent differences in susceptibility of larvae of different ages to transgenic foliage. Larvae fed glasshouse or field‐grown non‐transgenic foliage had significantly larger relative growth indices and more larvae pupated, than those fed transgenic foliage, regardless of larval age. Eggs from a laboratory colony were placed on transgenic or non‐transgenic tubers to measure survival and fecundity. Between 6% and 15% of eggs placed on transgenic tubers developed into pupae for three of the four transgenic potato lines tested. On one transgenic line, only six adults emerged from 1300 eggs. In contrast, between 71% and 97% of the eggs placed on non‐transgenic tubers developed into pupae. Male and female pupae from transgenic lines weighed less than those from non‐transgenic lines. The fecundity of females from two of four transgenic lines was lower than from the non‐transgenic parent cultivar. Although larvae of different ages did not exhibit any overall age‐dependent pattern of increasing or decreasing susceptibility to transgenic foliage of glasshouse or field‐grown plants, the ability of larvae to survive and reproduce on transgenic tubers suggests this pest has the ability to evolve resistance to the transgenic plants used in the present study.

Two monoclonal antibodies for the recognition of Mytilus spp. larvae: studies on cultured larvae and tests on plankton samples

Monoclonal antibodies (mAbs) were generated against 2-day-old mussel larvae in an attempt to develop a rapid and rigorous method for the identification of mussel larvae in field plankton samples. Previously, we have shown that two of these mAbs recognised Galician Mytilus galloprovincialis obtained from monospecific cultures, but did not recognise the larvae of other bivalve species present in that area. To assess the possibility of using these mAbs in routine assays for measuring the abundance of mussel larvae in plankton, studies on cultured mussel larvae, at different stages of development, and tests on bivalve larvae from plankton samples were carried out. Initially, to see whether the two mAbs also recognise other mussel larval stages, they were tested against mussel larvae of different ages obtained from monospecific cultures. The results indicate that both antibodies stain all the stages tested, even 1-month-old postlarvae. In addition, we also demonstrate that these mAbs also recognise other forms of Mytilus. Both antibodies bind to M. galloprovincialis larvae from the Mediterranean Sea and M. edulis larvae. Finally, and more significantly, studies on field plankton samples were performed to confirm if both mAbs are really mussel-specific, and do not cross-react with larvae of any other bivalve species existing in the plankton. The results presented here clearly indicate that our two monoclonal antibodies specifically recognise the mussel larvae in field plankton samples from different geographical regions, but not the larvae of any other bivalve species. Thus, these monoclonal antibodies could be used for routine monitoring of mussel larvae in plankton samples from different sources.

Susceptibility of potato tuber moth (Lepidoptera: Gelechiidae) to postharvest gamma irradiation.

Gamma irradiation doses applied to inhibit potato sprouting were tested against potato tuber moth larval and pupal stages. Young larvae and pupae were more susceptible to irradiation injuries than older ones. When larvae of different ages were exposed to doses > or = 100 Gy, only 13-35% pupated, but no adult emergence was obtained. The exposure of 1-1.5- or 3-3.5-d-old pupae to 150 Gy induced high level of sterility and remarkable reduction in female mating ability and fecundity, whereas the reduction was less noticeable for 5-5.5-d-old pupae. Postharvest gamma irradiation of potatoes could be considered as an efficient control approach against potato tuber moth larval and pupal infestations.