Effects of interaction of ration and temperature on growth and bioenergetics of Achaea janata Linnaeus (Lepidoptera: Noctuidae)

Summary Growth and bioenergetics of the last instar larvae of Achaea janata fed on a wide range of rations of leaves of Ricinus communis (ad libitum to 50 or 100 mg leaf per larva per day) at 22, 27, 32 and 35° C were studied. Increase in larval mortality, extension of larval duration and decrease in final body weight were some of the adverse effects of restricted rations. Whereas larval duration was influenced by ration level, pupal period was dependent on temperature. The larvae partially compensated for restricted rations by enhancing feeding rate over the limit expected in proportion to the ration offered. The level of compensation was higher at 27° C. Influence of temperature or its interaction with ration on assimilation efficiency was more significant than the independent influence of ration; the efficiency ranged from 57 to 67%. Restriction of ration below a critical level (300 mg/larva/day at 35° C and 200 mg/larva/day at other temperatures) significantly influenced the net conversion efficiency; the lowest efficiency of 1.3% was recorded for the larvae fed 100 mg leaf/day. Energy content of the terminal larva determined the percentage of energy transferred to the imago, which ranged from 37 to 55% of the terminal larval energy.     

Morphological variations in the pre-imaginal development of the ponerine ant Diacamma ceylonense

In the present paper, the larval development of the queenless ponerine ant Diacamma ceylonense is studied. Four instars were identified on the basis of cuticular processes – tubercles and spinules – which show discontinuous variation during growth and provide precise and reliable external morphological criteria for instar discrimination. In the first three instars, the larva possesses a striking proboscis, which disappears between the third and fourth instars. Larval weight increased around 50‐fold in the 21 days of larval life between eclosion and pupation (mean weight for first instar = 0.37 mg; for fourth instar = 20 mg). In addition, the morphology of the gemmae, structures resembling vestigial wings in workers, is described in nymphae.     

The influence of two endoparasitic wasps, <Emphasis Type="Italic">Hyposoter didymator</Emphasis> and <Emphasis Type="Italic">Chelonus inanitus</Emphasis>, on the growth and food consumption of their host larva <Emphasis Type="Italic">Spodoptera littoralis</Emphasis>

The influence of parasitism by Hyposoter didymator (Thunberg; Hymenoptera: Ichneumonidae) and Chelonus inanitus (Linnaeus) (Hymenoptera: Braconidae) on the growth and food consumption of their host Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) was studied in the laboratory. Parasitised larvae consumed significantly less artificial diet than unparasitised ones. Egg parasitisation by C. inanitus affected host larval consumption from the second day after emergence and it was significantly different from that of unparasitised ones. H. didymator, however, started to reduce larval consumption 4 days after parasitisation on the third instar host larvae. The overall reduction achieved by the larval endoparasitoid H. didymator is higher than that caused by the egg-larval endoparasitoid C. inanitus. The final body weight of a parasitised host larva by H. didymator and C. inanitus was only 6.7 and 13.0% of the maximum weight of an unparasitised sixth instar larva respectively. Moreover, parasitised larvae never reached the last instar. Results indicated that parasitised larvae might cause considerable less damage to the host plant than unparasitised ones.     

Temperature and food quality influences feeding behavior,assimilation efficiency and growth rate of arctic woolly-bear caterpillars

Summary The energy budget for feeding activity and growth of larval Gynaephora groenlandica was investigated on the tundra and in the laboratory. Larvae fed only in June when the buds and young leaves of Salix arctica, its principal host plant, contained the highest concentrations of macro-nutrients and total nonstructural carbohydrates (TNC). The mid-summer hiatus in larval feeding was coincident with an abrupt decline in the TNC content of leaves and a buildup of plant secondary metabolites in the leaves of S. arctica. Following cessation of feeding, the larvae remained concealed from the sun within crevices and vegetation mats. Growth rates of larvae incubated at 15 and 30°C were similar (4.7–5.0 mg/larva/day), but the assimilation efficiency at 15°C was four times greater (40%) than at 30°C. Growth rates were lowest at 5°C (0.22mg/larva/day) as was the assimilation efficiency (6.6%), because of the extended residence time of food in the gut. The high rate of ingestion and excretion at 30°C was caused by elevated maintenance metabolism. Changes in metabolic state influenced oxygen consumption, which was highest for feeding larvae (0.29 ml/g/h) and significantly lower for each, digesting, moving, starved larvae, and lowest for inactive larvae (0.06 ml/g/h). An influence of temperature and leaf quality on digestion rate and maintenance metabolism is the most likely cause of the feeding behavior pattern in G. groenlandica. The larvae may undergo voluntary hypothermia in order to avoid an energy, deficit resulting from high maintenance metabolism during mid-season when the energy content and food quality declines. The restriction of growth and development to a very short period prior to mid-summer may have contributed, to the extended 14-year life cycle of this species.     

Effect of parasitism byAscogaster reticulatus [Hym.: Braconidae] on growth of the host,Adoxophyes sp. [Lep.: Tortricidae]

The developmental interaction between the egg/larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae) and its host,Adoxophyes sp. (Lepidoptera: Tortricidae) was examined. Prior to the egress of a final-instar parasitoid larva from the 4^th-instar host larva, host weight decreased by 22% from the maximum weight. The final body weight of a host larva was 27% of the maximum weight of a healthy 5^th-instar host. Food consumption was significantly reduced in both 3^rd-and 4^th-instar parasitized larvae compared with healthy ones. In the 4^th instar, a parasitized larva consumed 28% less artificial diet and produced less frass than a healthy larva. The growth rate of the endoparasitoid larvae greatly increased after their host's molt to the 4^th instar. Parasitoid larval volume increased 40 fold in the 4^th-instar host.      

Temperature effects on egg and larval development and phenological forecasting of the smaller fruit tortrix,Grapholita lobarzewskii

The effects of temperature on egg and larval development of Grapholita lobarzewskii Nowicki (Lepidoptera: Tortricidae) were studied under controlled conditions to complement the basis for phenological forecasting and thus to optimize the timing of monitoring and control measures with respect to sustainable pest management. Egg development lasted on average 28.1 days at 12.7 °C and 5.5 days at 26.1 °C. Egg mortality was generally low, varying between 12 and 14% within a temperature range of 12.7–22.0 °C, but slightly increased to 20% at 26.1 °C. For egg development, a lower thermal threshold of 9.7 °C and a thermal constant of 90.6 degree days were established. Larval development took on average 76.0 days at 12.7 °C and 21.5 days at 26.1 °C. Larval mortality was 51% at 12.7 °C but only 6–12% at temperatures above 17 °C. The lower thermal threshold and the thermal constant for larval development were 7.6 °C and 389.2 degree days, respectively. Final larval weight increased with temperature from 18.6 mg at 12.7 °C to a maximum of 23.9 mg at 22.0 °C. Based on mortality rates, the optimal temperature range was between 12.7 and 22.0 °C for egg development and between 17.1 and 22.0 °C for larval development, which was confirmed based on the weight of fully grown larvae. These biological parameters of egg and larval development enabled us to parameterise a phenology model for G. lobarzewskii, which was incorporated into an existing decision support system for fruit pests. Precise forecasts of pest phenology facilitate the optimal timing of monitoring and control measures, improve their efficiency, and thereby contribute to sustainable crop protection.     

Développement endoparasitaire et croissance pondérale larvaire du parasitoïdeLixophaga diatraeae [Dip.: Tachinidae] dans un hôte de substitution:Galleria mellonella [Lep.: Pyralidae]

Résumé L'étude du développement endoparasitaire deLixophaga diatraeae (Towns.) dans un h?te de substitutionGalleria mellonella L. a été effectuée par dissections d'h?tes hébergeant des parasito?des d'age connu. Les résultats mentionnés sont obtenus avec en movenge 2.6 parasito?des par h?te. Les élevages ont lieu à 22.5±0.5°C et 85±5 % H.R. avec une photophase de 12 h pourL. diatraeae et à 28±1°C à l'obscurité pourG. mellonella. La croissance pondérale larvaire suit une loi exponentielle et correspond à un temps de doublement du poids de 0,65 j pour les stades 1 et 2 et environ 0,8 j pour le stade 3. Le développement larvaire complet requiert 7,5 j en moyenne. Les stades 1,2 et 3 durent en moyenne respectivement 2,9, 2,5 et 2,1 j. La mue larvaire L₁–L₂ intervient vers 0,23 mg et la mue L₂–L₃ vers 3,2 mg. La larve nouvelle née pèse 12,3 μg et la croissance larvaire représente un facteur multiplicatif maximum d'environ 2 500 fois. Le poids moyen des pupes obtenues est de 14,2 mg.

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Summary Endoparasitic development ofLixophaga diatraeae (Towns.) reared in a substitution hostGalleria mellonella L. was studied by dissections of hosts containing known aged parasitoids. The exposed results are obtained with an average of 2,6 parasitoids per host. Rearing ofL. diatraeae was performed at 22.5±0.5°C and 85±5% R.H. with 12 light hours and rearing ofG. mellonella at 28±1°C in darkness. The larval weight growth is exponential and exhibits a doubling time of 0.65 day for the 1st and 2nd stages and around 0.8 d. for the 3rd stage. Mean complete larval development time is 7.5 days. The 1, 2 and 3 stages last respectively 2.9, 2.5 and 2.1 days. Larval moulting 1–2 happens around 0.23 mg and moulting 2–3 around 3.2 mg. New hatched larva weights 12.3 μg and during larval growth multiplicates its weight by about 2,500. The mean pupal weight is 14.2 mg.

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Nous remercionsColette Ogier pour sa collaboration technique,P. Laviolette etG. Bonnot pour leur lecture critique du manuscrit.     

Life-cycle nitrogen budget for the gypsy moth, Lymantria dispar, reared on artificial diet

Lymantria dispar larvae were reared on a wheat germ-based artificial diet from egg eclosion until pupation. Utilization efficiency of dietary nitrogen underwent an age-specific decrease from 75% in the first instar to 54 and 43% for last-instar female and male larvae, respectively. Relative rates (mg/day/mg biomass) of nitrogen consumption and assimilation also decreased during larval development, but the excretion rate of nitrogen was constant for all instars and both sexes. Larval % nitrogen decreased as the larvae matured, while the percentage in the frass increased. These data suggest that need for nitrogen decreases as the larva matures. While L. dispar is comparatively inefficient at assimilating dietary nitrogen, over one-half of that assimilated by the female larva is transferred to egg production by the adult.     

Changes in biochemical composition and energy utilization during metamorphosis of leptocephalous larvae of the bonefish (Albula)

Synopsis Energy use and changes in whole-body content of lipid, protein, nitrogen, carbohydrate and ash were followed during metamorphosis of leptocephalous larvae of the bonefish (Albula). During metamorphosis, which requires about 8–12 days, larvae lost about 3–4 mg of lipid, or about 50% of the total lipid content. Lipid levels, calculated on a dry weight basis, showed no discernible trends, with values ranging from 138–185 mg (g dry wt)^–1. Protein content was 8.4 mg per larva and showed no significant change. However, protein levels increased from 147 to 329 mg (g dry wt)^–1. Nitrogen content decreased slightly from about 3.5 to 3.2 mg per larva. A comparison of protein and nitrogen values, expressed as % dry weight, showed that, in larvae which were just beginning to metamorphose, 70% of the total nitrogen was non-protein nitrogen (NPN). The NPN decreased to 58% of the total nitrogen towards the end of metamorphosis. Carbohydrate content fell from about 3.5 to 0.6 mg per larva, which represents an 83% loss. Carbohydrate levels also fell from about 81 to 32 mg (g dry wt)^–1. In addition, most of the carbohydrate appears to be bound to protein. Ash content decreased by 52%, from 4.6 to 2.2 mg per larva. Caloric content fell slightly from about 182 to 141 calories per larva whereas caloric density showed no discernible trends, with values ranging from 4.180 to 4.725 kcal (g dry wt)^–1. These results indicate that metamorphosing leptocephali, which apparently do not feed, probably derive most of their energy requirements from metabolizing endogenous lipid and carbohydrate stores formed during the premetamorphic interval.     

Nutritional levels of pregnant and postpartum tsetse Glossina pallidipes Austen captured in artificial warthog burrows in the Zambezi Valley of Zimbabwe

In Zimbabwe, female tsetse Glossina pallidipes Austen, collected from artificial warthog burrows and subjected to ovarian dissection and nutritional analysis, provide the first field estimates of resource allocation from mother to offspring across all of pregnancy. Approximately 45% of 1833 females captured are full‐term pregnant on entering the burrow. The remainder presumably use burrows as refuges at temperatures >32 °C. Maternal residual dry weight (RDW) increases by 1.5 mg after the first feed post‐larviposition but, thereafter, only by 1.4 mg by 90% of pregnancy completion. Uterine RDW changes little by 60% of pregnancy completion but increases by >6 mg by parturition. Between the times of 5% and 90% pregnancy completion, maternal RDW is approximately constant: it then declines 2.8 mg by parturition, balancing larval gains of 2.6 mg. Mothers accumulate 6.3 mg of fat in the first 80% of pregnancy, while uterine fat increases by only 0.8 mg. Thereafter, by parturition, larval fat increases by 4.1 mg, whereas maternal fat declines by 3.3 mg. The larva deposited is 5% heavier than its mother and has 52% more fat. RDW and fat levels, corrected for fly size and haematin, are 1 and 2 mg, respectively, lower in females from traps than those from burrows. Burrow catches provide an improved picture of tsetse pregnancy dynamics, highlighting a reproductive strategy involving resource commitment to the larva being delayed until late pregnancy when sufficient stores guarantee viable pupal production. Larval development in tsetse starts significantly later than the analogous changes during pregnancy in two mammals and two viviparous fish.     

Effects of temperature on the activity and kinetics of the granulovirus infecting the potato tuber moth Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae)

The granulovirus infecting the potato tuber moth (PoGV) is an important biocontrol agent, especially for managing the pest in rustic potato storerooms. For efficient propagation and use of baculoviruses in pest control strategies, information on the effects of temperature on virus multiplication and activity is crucial. The interaction between PoGV infection and incubation temperature on P. operculella was studied in laboratory bioassays by determining the survival, yield of virus-infected larvae, and the kinetics of virus in vivo increase. Bioassays for LC₅₀ determination by using the egg-dip method were repeated over a period of six years in controlled incubation chambers at six constant temperatures ranging from 16 to 28 °C. Additionally, at temperatures of 17 and 24 °C the kinetics of virus development and increase in larva were assessed in destructive time-series experiments. Three different virus concentrations were used for inoculation. Control mortality was significantly temperature-dependent and was well described by a second-order polynomial function, with lowest mortality at 25 °C (20%) and highest at 16 °C (>60%). LC₅₀ values and slopes of probit-mortality curves were not significantly different between temperatures. Numbers of virus-infected larvae increased exponentially with increasing log-concentration of virus inoculum; an effect of temperature was not evident. Virus granules per larva correlated highly with larval age and larval weight. Multiple regression revealed minor direct effects of temperature on virus numbers; however, with decreasing temperature, larval weight and hence virus numbers increased. As a result, temperature is an important factor to be considered in virus-production facilities. Rearing temperature in virus-production facilities should be maintained at temperatures around 24 °C.     

Effects of food quality,particularly nitrogen concentrations,of Eucalyptus blakelyi foliage on the growth of Paropsis atomaria larvae (Coleoptera: Chrysomelidae)

Five groups of E. blakelyi seedlings were differentially fertilized to obtain a range of N concentrations from 0.8–3.0% dry wt in the foliage. Groups of P. atomaria larvae were reared from eclosion to the prepupal stage on these seedlings. The effects on larval growth and development caused by foliar concentrations of N, moisture content, and tannins and leaf toughness were measured. Pupal dry weight and development time of P. atomaria did not differ between those reared on foliage with N levels of 1.7–3.0% but there was a significant decrease in pupal weight and increase in development time for individuals fed foliage with N below this level. Larvae fed foliage with an average of 0.8% N died before reaching instar III. Total dry matter consumption increased with a decrease in N concentration. Larval nitrogen utilization efficiency increased as foliar N level decreased until N reached a level somewhere between 1.7%–1.2% below which it decreased. There appeared to be an N concentration threshold above which P. atomaria larvae received adequate N by regulating consumption and nitrogen utilization efficiency but below which they could no longer accumulate enough N by compensation to maintain an optimum growth rate and development time. Effects of food quality variables on relative growth and consumption rates are presented and discussed.     

Peculiarities of ultrastructural organization of the metathoracic ganglion in the locustLocusta migratoria larva

In electron microscopic study of structural organization of the thoracic ganglion of the locust larva of the 1st age (1–2 days after hatching), the data on the structure of motoneurons of the 1st nerve, basal and motor neuropil of the larva were obtained. The effector elements of the larval locust CNS are formed rather early and have the structural plan similar to that in adult insects. However, in the larval motoneurons innervating the flight muscles (longitudinal dorsal muscles, wing depressors) the clearly seen features of immaturity of these nervous elements are revealed. Study of the larval ganglion neuropil has shown that the basal neuropil is morphologically formed sufficiently completely as early as in larvae of the first days after hatching. There are shown longitudinal contacts between axons of the ventral neuropil zone, the presence of axons forming theen-passant contacts as well as the synapses with a heterogeneous set of vesicles in the presynaptic area. The presence of the great number of granular vesicles in the basal neuropil of the locust larva may indicate an important role of catecholamines in the early development of the nervous system in the locust larva.     

Larval case and water balance in Tinea pellionella

In a very dry environment (0% r.h.) the case plays an important role in the physiology of the Tinea pellionella larva. Absence of the case leads to a reduction of oxygen consumption and a great loss of body water. At 0% r.h. the rate of water loss from a larva without its case, is twice that from a larva remaining within its case.In a very humid environment (r.h. higher than 95%) the case absorbs a very large quantity of water and becomes very heavy, but it does not interfere with larval physiology. With or without their cases the weight of the larvae stays stable, and their oxygen consumption does not change.When the humidity changes abruptly, the case acts as a buffer and assists in the regulation of the water balance of the larva. If the humidity decreases the case slows the rate of body water loss; if the humidity increases, it very quickly builds up a reserve of atmospheric water around the larva's body.     

Oxygen consumption of a Chaoborus species from a neotropical reservoir (socuy reservoir,Venezuela)

Oxygen consumption of all four larval instars of a Chaoborus species from Socuy Reservoir in western Venezuela was studied under laboratory conditions at 25°C. On a logarithmic basis, oxygen consumption per organism increased as a smooth, linear function of body weight (0.49 power of body weight). Observed rates were lower than other Chaoborus species with comparable body weight at the same temperature. Oxygen consumption per unit weight decreased from smaller to large instar larvae. With the exception of instar I, values of oxygen consumption per unit weight were lower than values reported for other Chaoborus species. The results suggest that our species have low energy demands for maintenance, and are consistent with suggestions about high efficiency in use of energy in genus Chaoborus.     

Preliminary studies on the respiratory energy loss of a spider,Lycosa pseudoannulata

To elucidate the basic food requirement of spiders, the important polyphagous predators of rice-plant insect pests, an attempt was made to measure the respiratory energy loss of fasting spiders, Lycosa pseudoannulata. Relationship between fresh (y) and dry (x) weights of spiders inhabiting the bottom layer of the rice-plant community was represented by the following allometric equation:y=0.428x^0.872. The carbon dioxide production by previously fed and unfed females under the dark at 29°C 100% R. H. was measured by a titration technique. The relationship between fresh body weight and CO₂ production by unfed animals could be represented by the equation M=aW^b, M being the CO₂ output per individual per day and W the fresh body weight. The constant b, which determines the slope of curve, was 0.808. Respiration of the adult female with 100 mg fresh weight was 1.155±0.250 mg CO₂/100 g fresh weight/day or 48.69 mg CO₂/g dry weight/day. This value corresponds to 35.81 cal/g fresh weight/day or 150.94 cal/g dry weight/day. Supposing the calorific content of spiders to be 5820 cal/g dry weight, rate of the respiratory energy loss to total energy of the body was estimated to be 2.60%. This rate did not strongly contradict with the loss of fresh body weight before and after the measurement. The metabolic rate showed remarkable fluctuation with changing food supply. The CO₂ production of starved individuals decreased to 83.63±16.34% as compared with individuals which were fed before the measurement.     

Energy budget for the larval development ofElminius modestus (Crustacea: Cirripedia)

Biomass (CHN), respiration rate and food uptake were estimated for the larval development ofElminius modestus at three temperatures (12, 18, 24°C). Mean values of dry weight, elemental composition and energy equivalents increased exponentially with the development from nauplius II to VI. Dry weight, elemental composition and energy content exhibited the highest values at 18°C. Respiration rates increased with the larval stages expressed by a power function, but increased logarithmically with the dry weight of the larvae. The cypris larvae showed a reduced respiration rate compared with nauplius VI. The ingestion rate was measured at a concentration of 100 cells ofSkeletonema costatum μl⁻¹. At 12 and 18°C ingestion rates increased exponentially and at 24°C by a logarithmic function. The fittings were used to estimate the energy budget ofE. modestus during larval development. The energy content of the larvae increased during the development from nauplius II to VI by a factor of 21 at 12°C, 25 at 24°C and 31 at 18°C. The estimated energy content of the freshly metamorphosed barnacle is 100 mJ (12°C), 130 mJ (24°C) and 150 mJ (18°C). The assimilation- (A/I) and gross growth efficiencies (K₁) increased strongly during the development from nauplius II to VI (A/I: 6–14% in nauplius II to 50–90% in nauplius VI; K₁: 4% in nauplius II to 75% in nauplius VI). The net growth efficiency (K₂) showed a relatively constant level ranging between 57 and 83%.     

Oxygen consumption and ammonia excretion of herbivorous chironomid larvae in Lake Balaton

The oxygen consumption and ammonia excretion of a herbivorous midge larva,Chironomus sp., inhabiting Lake Balaton was measured at two different temperatures. The loss of energy through respiration and that through ammonia excretion were calculated. The daily respiratory energy loss amounted to 655.5 ± 123.8 J g^–1 at 17 °C and to 1 160.0 ± 168.4 J g^–1 (dry weight) at 25 °C. Mean energy loss through ammonia excretion was about 40% less than through respiration.     

Lipid and fatty acid composition of striped bass (Morone saxatilis) larvae during development

Changes in lipid class, fatty acid composition, protein, and dry and wet weights of fertilized eggs and developing larvae of striped bass (Morone saxatilis) fed with the live food, Artemia, were investigated. A decrease of wet and dry weights and moisture was observed at the beginning of the larval stage. Larvae regained the original moisture level, and wet and dry weights increased steadily after feeding. Total lipids decreased from 190 μg/egg in fertilized eggs to 151 μg/egg during hatching and increased after feeding. When total lipid contents were expressed as a percentage of larval dry weight, a decline of lipid did not occur until after feeding. Total protein, on the other hand, increased right after feeding, but there was some variation between days. Polar lipids increased significantly from 20 μg/egg at the egg stage to 199 μg/larva at 26 days post-hatching (DPH), 2 days before the onset of metamorphosis, while neutral lipids declined from 175 μg/egg to 80 μg/larva during the same time period. Wax/steryl esters decreased from 150 μg/egg in fertilized eggs to 32 μg/larva at 26 DPH. Triacylglycerols dropped from 21 μg/egg to 15 μg/larva before feeding and increased gradually after feeding. In contrast, the level of cholesterol increased 2–3-fold. There was a significant increase of phospholipids, particularly phosphatidylcholine in larvae after feeding. The fatty acid composition of fish larvae was significantly influenced by the diet, Artemia. There was an indication of catabolism of endogenous eicosapentaenoic and docosahexaenoic acids during metamorphosis.