Larval Body Size Research Articles

Pengaruh pemberian sampah organik terhadap pertumbuhan dan kandungan astaxanthin pada pupa black soldier fly (Hermetia illucens (Linnaeus))

Black soldier fly (Hermetia illucens (Linnaeus)) atau BSF merupakan serangga pengolah sampah organik yang fase larvanya memiliki kandungan nutrisi tinggi sehingga berpotensi sebagai sumber protein alternatif pakan dan pangan. Astaxanthin merupakan senyawa antioksidan yang lazim diperoleh dari tumbuhan, alga, dan Crustacea. Deteksi astaxanthin pada Bombyx mori (Linnaeus) menjadi titik tolak dugaan bahwa astaxanthin potensial ditemukan pada serangga lain termasuk BSF. Penelitian bertujuan untuk mempelajari pengaruh pemberian jenis pakan sampah organik terhadap pertumbuhan larva BSF dan kandungan astaxanthin pada pupa BSF. Desain penelitian menggunakan rancangan acak lengkap dengan 4 perlakuan jenis pakan sampah organik berupa sisa buah dan sayur (BS), ampas tahu (AT), sisa nasi (N), campuran sisa buah dan sayur, ampas tahu dan sisa nasi (C). Pakan ternak T51 digunakan sebagai kontrol. Setiap perlakuan pakan diulang 3 kali. Parameter penelitian terukur meliputi parameter pertumbuhan larva berupa berat, panjang, dan karakteristik larva; dan parameter kandungan senyawa kimia termasuk astaxanthin pada pupa BSF. Ekstraksi pupa dilakukan dengan metode maserasi triphasic menggunakan kombinasi 5 pelarut berupa n-heptane, etil asetat, acetonitrile, butanol-l, dan akuades, sedangkan identifikasi senyawa dilakukan menggunakan uji kualitatif terpenoid, uji thin layer chromatography (TLC), dan liquid chromatography-mass spectrometry (LC-MS). Hasil penelitian menunjukkan bahwa buah dan sayur (BS) paling berpengaruh meningkatkan pertambahan ukuran tubuh larva dengan berat 0,09 ± 0,04 gram/larva dan panjang 1,49 ± 0,31 cm/larva. Analisis LC-MS mendeteksi senyawa dereplikasi lutein, anisodamine, derivat resveratrol, dehydroarginine, dan senyawa dereplikasi astaxanthin dengan massa molekuler sebesar 597,23 m/z pada larva BSF yang diberi pakan buah dan sayur.

Riparian invader: A secondary metabolite of Impatiens glandulifera impairs the development of the freshwater invertebrate key species Chironomus riparius

Invasive species represent a significant threat to native biodiversity. The Himalayan Balsam Impatiens glandulifera is an annual plant, which is invasive in Europe and often inhabits the riparian zone. It produces several secondary metabolites causing, for example, growth inhibition of terrestrial plants and invertebrates. One of these metabolites is the quinone 2-methoxy-1,4-naphthoquinone (2-MNQ). The compound gets washed out from the above-ground parts of the plant during precipitation and may then leach into nearby waterbodies. Despite some evidence for the allelopathic effect of plant secondary metabolites on terrestrial invertebrates, little is known about how 2-MNQ affects the survival or development of aquatic dipteran larvae, despite the importance of this functional group in European freshwaters. Here, we investigated the effects of 2-MNQ on larvae of the river keystone species Chironomus riparius in acute and chronic scenarios. The toxicity of 2-MNQ towards the first and the fourth larval stage was determined in a 48-hour acute exposure assay. We show that 2-MNQ has a negative impact on the development, growth and survival of C. riparius. The LC50 of 2-MNQ was 3.19 mg/l for the first instar and 2.09 mg/l for the fourth instar. A ten-day chronic exposure experiment, where the water was spiked with 2-MNQ, revealed that 2-MNQ had a significantly negative impact on larval body size, head capsule size, body weight, development and survival. These results demonstrate the negative impact of the secondary metabolite 2-MNQ from the terrestrial plant I. glandulifera on a crucial macroinvertebrate inhabiting the adjacent stream ecosystem in riverine ecosystems. This may lead to a decline in population size, resulting in cascading effects on the food web.

Domestication Gene Mlx and Its Partner Mondo Are Involved in Controlling the Larval Body Size and Cocoon Shell Weight of Bombyx mori.

Bombyx mori was domesticated from Bombyx mandarina. The long-term domestication of the silkworm has brought about many remarkable changes to its body size and cocoon shell weight. However, the molecular mechanism underlying the improvement in the economic characteristics of this species during domestication remains unclear. In this study, we found that a transposable element (TE)-Bm1-was present in the upstream regulatory region of the Mlx (Max-like protein X) gene in wild silkworms but not in all domesticated silkworms. The absence of Bm1 caused an increase in the promoter activity and mRNA content of Mlx. Mlx and its partner Mondo belong to the bHLHZ transcription factors family and regulate nutrient metabolism. RNAi of Mlx and Mondo decreased the expression and promoter activity of glucose metabolism-related genes (trehalose transport (Tret), phosphofructokinase (PFK), and pyruvate kinase (PK)), lipogenic genes (Acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS)), and glutamine synthesis gene (Glutamine synthase 2, (GS2)). Furthermore, the transgenic overexpression of Mlx and Mondo in the fat body of silkworms increased the larval body size, cocoon shell weight, and egg number, but the silencing of the two genes resulted in the opposite phenotypes. Our results reveal the molecular mechanism of Mlx selection during domestication and its successful use in the molecular breeding of Bombyx mori.

Grinding as a slaughter method for farmed black soldier fly (Hermetia illucens) larvae: Empirical recommendations to achieve instantaneous killing.

At least 200 billion black soldier fly (Hermetia illucens) larvae (BSFL) are reared each year as food and feed, and the insect farming industry is projected to grow rapidly. Despite interest by consumers, producers, and legislators, no empirical evidence exists to guide producers in practicing humane - or instantaneous - slaughter for these novel mini-livestock. BSFL may be slaughtered via freezing, boiling, grinding, or other methods; however standard operating procedures (SOPs) and equipment design may affect the likelihood of instantaneous death using these methods. We tested how larval body size and particle size plate hole diameter affect the likelihood of instantaneous death for black soldier fly larvae that are slaughtered using a standard meat grinder. Larval body size did not affect the likelihood of instantaneous death for larvae that are 106-175 mg in mass. However, particle size plate hole diameter had a significant effect on the likelihood of instantaneous death, with only 54% of larvae experiencing an instant death when using the largest particle size plate (12-mm hole diameter) compared to 84% using the smallest particle size plate (2.55 mm). However, a higher percentage of instantaneous death (up to 99%) could be achieved by reducing the proportion of larvae that become stuck in the machine. We conclude by outlining specific recommendations to support producers in achieving a 99% instantaneous death rate through specific SOPs to be used with similarly designed machines. We also develop a protocol for producers that wish to test their own grinding SOPs.

Mitochondrial metabolism in Drosophila macrophage-like cells regulates body growth via modulation of cytokine and insulin signaling.

Macrophages play critical roles in regulating and maintaining tissue and whole-body metabolism in normal and disease states. While the cell-cell signaling pathways that underlie these functions are becoming clear, less is known about how alterations in macrophage metabolism influence their roles as regulators of systemic physiology. Here, we investigate this by examining Drosophila macrophage-like cells called hemocytes. We used knockdown of TFAM, a mitochondrial genome transcription factor, to reduce mitochondrial OxPhos activity specifically in larval hemocytes. We find that this reduction in hemocyte OxPhos leads to a decrease in larval growth and body size. These effects are associated with a suppression of systemic insulin, the main endocrine stimulator of body growth. We also find that TFAM knockdown leads to decreased hemocyte JNK signaling and decreased expression of the TNF alpha homolog, Eiger in hemocytes. Furthermore, we show that genetic knockdown of hemocyte JNK signaling or Eiger expression mimics the effects of TFAM knockdown and leads to a non-autonomous suppression of body size without altering hemocyte numbers. Our data suggest that modulation of hemocyte mitochondrial metabolism can determine their non-autonomous effects on organismal growth by altering cytokine and systemic insulin signaling. Given that nutrient availability can control mitochondrial metabolism, our findings may explain how macrophages function as nutrient-responsive regulators of tissue and whole-body physiology and homeostasis.

A Drosophila model of gestational antimony exposure uncovers growth and developmental disorders caused by disrupting oxidative stress homeostasis

The toxic heavy metal antimony (Sb) is ubiquitous in our daily lives. Various models have shown that Sb induces neuronal and reproductive toxicity. However, little is known about the developmental toxicity of Sb exposure during gestation and the underlying mechanisms. To study its effects on growth and development, Drosophila stages from eggs to pupae were exposed to different Sb concentrations (0, 0.3, 0.6 and 1.2 mg/mL Sb); RNA sequencing was used to identify the underlying mechanism. The model revealed that prenatal Sb exposure significantly reduced larval body size and weight, the pupation and eclosion rates, and the number of flies at all stages. With 1.2 mg/mL Sb exposure in 3rd instar larvae, 484 genes were upregulated and 694 downregulated compared to controls. Biological analysis showed that the disrupted transcripts were related to the oxidative stress pathway, as verified by reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) and glutathione (GSH) intervention experiments. Sb exposure induced oxidative stress imbalance could be rectified by chelation and antioxidant effects of NAC/GSH. The Drosophila Schneider 2 (S2) model further demonstrated that NAC and GSH greatly ameliorated cell death induced by Sb exposure. In conclusion, gestational Sb exposure disrupted oxidative stress homeostasis, thereby impairing growth and development.

Larval feeding types shape the predation aggression of predatory mites in both intraspecific and interspecific encounters

Cannibalism (intraspecific predation) and intraguild (interspecific) predation are widely observed phenomena in the animal kingdom, including amongst predatory mites of the Phytoseiidae family. While the larval stage of phytoseiids is a vulnerable and important life stage, it has received less attention than the adult stage. The larvae of phytoseiid species can be categorised into three types based on their feeding behaviour: non-feeding, facultative feeding, and obligatory feeding. This study aimed to investigate the occurrence of cannibalism and intraguild predation among the larval stages of three generalist predatory phytoseiids: Amblydromalus limonicus (Garman & McGregor), Amblyseius herbicolus (Chant), and Neoseiulus cucumeris (Oudemans). We hypothesised that the larval feeding type could influence the aggressiveness of the predators in intraspecific and interspecific encounters, with obligatory-feeding larvae being the most aggressive and non-feeding larvae being the least aggressive. To test this hypothesis, we conducted a no-choice experiment under laboratory conditions using larvae to observe the prevalence of predation among conspecifics and heterospecifics in these three predatory mite species. In addition to observing predation outcomes, we measured larval body size, cheliceral size, and cheliceral morphology to investigate these parameters’ correlation with predation success. Our study revealed significant differences in the prevalence of cannibalism and intraguild predation among the three predatory species in agreement with our hypothesis: N. cucumeris larvae did not engage in predatory behaviours, while A. herbicolus displayed the highest predation success. Our findings suggest that cheliceral morphology may be a better indicator than body size of the aggressiveness of larval predation against conspecifics and heterospecifics. Our results provide valuable insights into the importance of larval behaviour in population dynamics and the development of effective pest management strategies. The study also highlights the need for further research on the larval stage of phytoseiids and emphasises the significance of considering larval behaviour when studying and managing these important predatory mites.

The effect of temperature and invasive alien predator on genetic and phenotypic variation in the damselfly Ischnura elegans: cross-latitude comparison

BackgroundUnderstanding and predicting how organisms respond to human-caused environmental changes has become a major concern in conservation biology. Here, we linked gene expression and phenotypic data to identify candidate genes underlying existing phenotypic trait differentiation under individual and combined environmental variables. For this purpose, we used the damselfly Ischnura elegans. Egg clutches from replicated high- (southern Sweden) and central-latitude (southern Poland) populations facing different degrees of seasonal time constraints were collected. Damselfly larvae were exposed to experimental treatments: current and mild warming temperatures crossed with the presence or absence of an invasive alien predator cue released by the spiny-cheek crayfish, Faxonius limosus, which is only present in Poland to date. We measured the following traits: larval development time, body size, mass and growth rate, and used the larvae for gene expression analysis by RNA-seq. Data were analysed using a multivariate approach.ResultsWe showed latitudinal differences in coping with mild warming and predator cues. When exposed to an increased temperature and a predator cue, central-latitude individuals had the shortest development and the fastest growth compared to high-latitude individuals. There was a general effect of predator cues regarding mass and growth rate reduction independent of latitude. Transcriptome analysis revealed that metabolic pathways related to larval anatomy and development tended to be upregulated in response to mild warming but only in fast-growing central-latitude individuals. Metabolic pathways linked to oxidative stress tended to be downregulated in response to a predator cue, especially in central-latitude individuals.ConclusionDifferent phenotypic and transcriptomic responses to environmental factors might be attributed to the variability in I. elegans life history strategies between the two latitudes caused by seasonal time constraints and to its coexistence with the invasive alien predator in nature. By providing insights into how organisms may respond to future anthropogenic changes, our results may be of particular interest in conservation biology.

Limited population and community effects of hatching asynchrony in a pond‐breeding salamander

AbstractUnderstanding attributes of phenology beyond the mean date of a life history event, such as variability among individuals within a population, is critical to predict how climate‐induced phenological shifts may alter population dynamics. Identifying how phenological variability impacts organisms is especially needed to better understand how phenological shifts affect trophic dynamics (e.g., shifts in variability of top predators affecting primary production). To better understand the effects of phenological variability on both populations and communities, we examined how variation in egg hatching synchrony of predatory marbled salamanders (Ambystoma opacum) impacted intraspecific interactions at the larval stage, ultimately affecting demographic traits and survival through metamorphosis. We also examined how hatching synchrony affected overall trophic dynamics (e.g., primary consumers and producers) in pond food webs. We experimentally manipulated the degree of hatching synchrony of embryonicA. opacumand subsequently reared larvae in outdoor mesocosms. We monitored demographic traits such as larval growth, size at and time to metamorphosis, and survival. To assess trophic dynamics, we monitored zooplankton abundance and phytoplankton biomass during the experiment. Larvae exhibited greater variability in body size in medium and low hatching synchrony treatments compared to high synchrony treatments. Larval body size variation diminished over time to ultimately result in no differences in most life history traits at metamorphosis or survival among hatching synchrony treatments. We also found no differences among treatments in zooplankton abundance or phytoplankton biomass, likely because of minimal variation inA. opacumsurvival among treatments that would induce top‐down changes. Overall, we found that phenological variation may be context dependent in its influence on demography and overall community structure. Because of concerns for how phenological shifts will affect species interactions, greater scrutiny into conditions that would promote changes in population and community dynamics is needed.

Diet Induced Variation in Gut Microbiota Is Linked to the Growth Performance of an Agricultural Pest Chilo suppressalis

Chilo suppressalis is a major global host-specific pest of rice and water oat crops, having caused severe yield damage and great economic loss. The pest occasionally feeds on other plants, preventing them from completing a full life cycle. Dietary differences may shape the gut microbiota of the pest and may further influence its performance. In order to test this hypothesis, an assembly of the gut bacterial community of C. suppressalis larvae reared on rice, water oat, corn, and an artificial diet were investigated using an amplicon-based next-generation sequencing approach. The larval body size and feeding rate on each diet type were analyzed in parallel. We found that the size and feeding rate of C. suppressalis varied among the different dietary regimes, as a low feeding rate was found for rice and corn diets, whereas rice-fed larvae had the biggest body size and corn-fed larvae had the lowest body size. Further high-throughput sequencing results showed that the artificial-diet-fed larvae had the lowest bacterial diversity among all the samples, and the corn-fed larvae presented the most diversified microbial community. Further analysis revealed that the bacterial genera Enterococcus, Sphingobacterium, Klebsiella, Gluconobacter, Serratia, and Lactococcus possessed high abundance in C. suppressalis larvae, and the varied abundances contributed to the differences in community structure. The microbial function classification suggested that metabolic function categories significantly increased while the larvae were feeding on their preferred diet (rice and water oat) and decreased when on an artificial diet. This study expands our understanding of the microbe–insect interaction of C. suppressalis larvae in response to changes in diet, and is an essential step towards the future development of potential microbial-based pest management strategies.

SYNERGISTIC EFFECT OF HONEY AND LEMONJUICE-ENRICHED MULBERRY DIETS ON THE DIGESTIVE METABOLISM OF THE SILKWORM, BOMBYX MOR

Synergistic impact of honey and lemon juice-enriched mulberry diets has been studied on the digestive metabolism of fth instar larval Bombyx mori. The study focused on the digestibility of proteins, carbohydrates, sucrose and cellulose by their digestive enzymes in the larval midgut wall and midgut lumen compartments and biomass accumulation in the gut wall. The honey and lemon juice-enriched diets showed positive impact on protease activity and protein digestion, but did not show discernable effect on the activity levels of α-amylase, sucrase and cellulase and the digestibility of carbohydrates, sucrose and cellulose. Nevertheless, they signicantly reinforced the digestive mass accumulation in gut wall cells in accordance with the Hutchinson's investment principle. Further, as evidenced by higher growth rates in the digestive parameters during rst ve days of the fth instar regime, the rate of biomass accumulation is ne-tuned by the timing of acquisition of critical larval body size determinants.

Heritability of dispersal-related larval traits in the clown anemonefish Amphiprion percula.

A major goal of marine ecology is to identify the drivers of variation in larval dispersal. Larval traits are emerging as an important potential source of variation in dispersal outcomes, but little is known about how the evolution of these traits might shape dispersal patterns. Here, we consider the potential for adaptive evolution in two possibly dispersal-related traits by quantifying the heritability of larval size and swimming speed in the clown anemonefish (Amphiprion percula). Using a laboratory population of wild-caught A. percula, we measured the size and swimming speed of larvae from 24 half-sibling families. Phenotypic variance was partitioned into genetic and environmental components using a linear mixed-effects model. Importantly, by including half-siblings in the breeding design, we ensured that our estimates of genetic variance do not include nonheritable effects shared by clutches of full-siblings, which could lead to significant overestimates of heritability. We find unequivocal evidence for the heritability of larval body size (estimated between 0.21 and 0.34) and equivocal evidence for the heritability of swimming speed (between 0.05 and 0.19 depending on the choice of prior). From a methodological perspective, this work demonstrates the importance of evaluating sensitivity to prior distribution in Bayesian analysis. From a biological perspective, it advances our understanding of potential dispersal-related larval traits by quantifying the extent to which they can be inherited and thus have the potential for adaptive evolution.

SYNERGISTIC EFFECT OF HONEY AND LEMON JUICE-ENRICHED MULBERRY DIETS ON THE GROWTH OF SILKWORM, BOMBYX MORI DURING METAMORPHOSIS

Synergistic impact of honey and lemon juice-enriched mulberry diets on the growth of Bombyx mori was studied. The body size progressively increased during larval stage, but declined during pupal and adult stages. The nutrient diets promoted larval growth and positively modulated pupal and adult growth. The larval growth curves are typical Gompertz trajectories that reected the growth promoting nature of honey and lemon juice. The log-based growth curves were used to derive critical larval body size determinants that control molting and metamorphosis. The nutrient diets improved critical body size determinants without affecting their time schedules. The compound periodical growth rates showed instar-specic and stage-specic variations. The size specic growth rates in body mass, length and perimeter dimensions indicated the prevalence of an effective mass management mechanism as dened in the Hutchinson's investment principle. The silkworm recorded either higher or lower growth ratios indicating deviation from the Dyar's constancy rule.

Genetic variation underlies plastic responses to global change drivers in the purple sea urchin, Strongylocentrotus purpuratus.

Phenotypic plasticity and adaptive evolution enable population persistence in response to global change. However, there are few experiments that test how these processes interact within and across generations, especially in marine species with broad distributions experiencing spatially and temporally variable temperature and pCO2. We employed a quantitative genetics experiment with the purple sea urchin, Strongylocentrotus purpuratus, to decompose family-level variation in transgenerational and developmental plastic responses to ecologically relevant temperature and pCO2. Adults were conditioned to controlled non-upwelling (high temperature, low pCO2) or upwelling (low temperature, high pCO2) conditions. Embryos were reared in either the same conditions as their parents or the crossed environment, and morphological aspects of larval body size were quantified. We find evidence of family-level phenotypic plasticity in response to different developmental environments. Among developmental environments, there was substantial additive genetic variance for one body size metric when larvae developed under upwelling conditions, although this differed based on parental environment. Furthermore, cross-environment correlations indicate significant variance for genotype-by-environment interactive effects. Therefore, genetic variation for plasticity is evident in early stages of S. purpuratus, emphasizing the importance of adaptive evolution and phenotypic plasticity in organismal responses to global change.

Requirement of Myoglianin for metamorphosis in the beetle Henosepilachna vigintioctopunctata.

Henosepilachna vigintioctopunctata is a serious defoliating beetle attacking Solanaceae and Cucurbitaceae plants in many Asian countries. In the present paper, we identified a putative myoglianin (myo) gene. Hvmyo was actively transcribed throughout development, from embryo to adult. RNA interference (RNAi)-aided knockdown of Hvmyo delayed larval development by more than 2 days, reduced larval body size, inhibited the growth of antennae, wings and legs and disturbed gut purge. Knockdown of Hvmyo impaired the larval-pupal transition. All the Hvmyo RNAi larvae arrested at the larval stage or formed misshapen pupae or adults. The deformed pupae and adults were partially wrapped with exuviae, bearing separated wings. Moreover, the expression levels of five ecdysteroidogenesis genes (Hvspo, Hvphm, Hvdib, Hvsad and Hvshd), a prothocicotropic hormone (PTTH)/Torso pathway gene (Hvtorso), two 20E receptor genes (HvEcR and HvUSP), and two 20E signalling genes (HvE93 and HvFTZ-F1) were as a result of HvMyo RNAi significantly lowered. Conversely, the expression of a JH biosynthesis gene (Hvjhamt), a JH receptor gene HvMet and a JH signalling gene HvKr-h1 was greatly enhanced. Although ingestion of 20E and Hal rescued the 20E signal, it could not alleviate larval performance and defective phenotypes. Our results suggest that Myo exerts four distinctive roles in ecdysteroidogenesis, JH production, organ growth and larva-pupa-adult transformation in H. vigintioctopunctata.

Strong decrease in egg mass on subsequent days of oviposition generates little variation in offspring performance in the pine‐tree lappet moth, Dendrolimus pini

AbstractThe pine‐tree lappet moth, Dendrolimus pini (L.) (Lepidoptera: Lasiocampidae), is a pest whose natural range mostly follows that of its host, Scots pine, Pinus sylvestris L. (Pinaceae). Under natural conditions, we observed differences in larval body size, pointing to different rates of their growth and development. This study aimed to check whether differences in egg mass can differentiate the growth and development rate of D. pini larvae. We assumed that decrease in egg mass on subsequent days of oviposition can have a large impact. Our results indicate that there is an unusually strong fecundity advantage of large female mass in D. pini, but with each day of laying, the mean mass of the eggs decreases. However, offspring phenotype and development in D. pini is not clearly correlated with egg mass. We also confirmed a strong decrease in the number and mass of eggs on subsequent days of oviposition. However, egg mass decline did not correspond with the performance of the offspring in a laboratory rearing because the specimens formed from ‘medium‐mass’ eggs were characterized by the highest fitness. Although we noted a significant impact of the day of oviposition on some offspring's fitness parameters (e.g., development stage duration, pupal mass, adult mass), the variation was not large. The offspring hatched from eggs on the 3rd day of oviposition were characterized by increased values of some parameters (e.g., higher mass, heavier cocoons, faster development). Variation in the development of the larvae could be a strategy to help offspring survive under short‐term unfavorable conditions, and also reduces intra‐species competition which is generally beneficial.

A PRELIMINARY EVALUATION ON BIVARIATE ALLOMETRY IN ACTIVE-FEEDING Chrysomya megacephala (FABRICIUS, 1794) (DIPTERA: CALLIPHORIDAE) LARVAE

The potential use of larval cephalopharyngeal skeleton as an alternative growth indicator in forensic entomology practice was assessed based on its developmental pattern, growth performance and allometric relationship with larval body. Chrysomya megacephala (Fabricius, 1794), was used as an experimental species and larval development were studied at ambient temperatures and relative humidity. Larval body size was measured from furthest part of the head to the last abdominal segment. Cephalopharyngeal skeleton was extracted from the body and measured from the tip of dorsal bridge to the left face of dorsal cornu. Daily progression of larval body length and cephalopharyngeal skeleton length showed the latter significantly had slower growth rates. The allometry of larval body and cephalopharyngeal skeleton showed they were correlated only because both variables increased across the three larval instars, which suggesting a spurious correlation. Separate bivariate correlations between the two variables showed only the first instar larvae had a significant (p<0.01) but weak correlation, r=0.33. However, removing the effect of larval instars still produced statistically significant correlation (p<0.001) albeit with moderate strength, r=0.57. From this study, there was not enough evidence to support cephalopharyngeal skeleton as an equal or a better alternative to larval body as growth indicator.

Density-dependent selection in Drosophila: evolution of egg size and hatching time

Many different laboratory studies of adaptation to larval crowding in Drosophila spp. have all yielded the evolution of preadult competitive ability, even though the ecological context in which crowding was experienced varied across studies. However, the evolution of competitive ability was achieved through different suites of traits in studies wherein crowding was imposed in slightly different ways. Earlier studies showed the evolution of increased competitive ability via increased larval feeding rate and tolerance to nitrogenous waste, at the cost of food to biomass conversion efficiency. However, more recent studies, with crowding imposed at relatively low food levels, showed the evolution of competitive ability via decreased larval development time and body size, and an increase in the time efficiency of conversion of food to biomass, with no change in larval feeding rate or waste tolerance. Taken together, these studies have led to a more nuanced understanding of how the specific details of larval numbers, food amounts etc. can affect which traits evolve to confer increased competitive ability. Here, we report results from a study in which egg size and hatching time were assayed on three sets of populations adapted to larval crowding experienced in slightly different ways, as well as their low density ancestral control populations. Egg size and hatching time are traits that may provide larvae with initial advantages under crowding through increased starting larval size and a temporal head-start, respectively. In each set of populations adapted to some form of larval crowding, the evolution of longer and wider eggs was seen, compared to controls, thus making egg size the first consistent correlate of the evolution of increased larval competitive ability across Drosophila populations experiencing crowding in slightly different ways. Among the crowding-adapted populations, those crowded at the lowest overall eggs/food density, but the highest density of larvae in the feeding band, showed the largest eggs, on an average. All three sets of crowding-adapted populations showed shorter average egg hatching time than controls, but the difference was significant only in the case of populations experiencing the highest feeding band density. Our results underscore the importance of considering factors other than just eggs/food density when studying the evolution of competitive ability, as also the advantages of having multiple selection regimes within one experimental set up, allowing for a more nuanced understanding of the subtlety with which adaptive evolutionary trajectories can vary across even fairly similar selection regimes.

Optimasi Budidaya dan Pemasaran Maggot Black Soldier Fly di Kelompok Peternak Labung Raya untuk Bahan Pakan Sumber Protein

The main problem of livestock farming is still providing qualified feed at lower costs. Commercial feed prices are not suitable for traditional farming, thus increasing production costs more. The Labung Raya farmer's group understood that the provision of maggot larvae of Black Soldier Fly (BSF) could meet the protein needs of the livestock, such as poultry and catfish. The problems raised so far were that the growth of maggot produced was not maximized, such as few eggs, small larval body size, maggot coming out of the bucket, and not optimal fermentation of maggot feed. The activity began with a brainstorming event about the negative impact of the Covid-19 pandemic on the community. The implementation of the activities was continued with the method of counselling, training, and continuous mentoring. This community engagement was welcomed by the general community and the Labung Raya breeder group's partners. The practice of cultivating Maggot BSF is straightforward for anyone to do. The cultivation process only requires simple technology and low cost but requires breeding skills for optimal results. Maggot as a product is expected to be used as an alternative protein-rich animal feed ingredient in soaring prices for conventional feed, especially for poultry.

Host Range and Pathogenicity Potential of Helicoverpa armigera Nucleopolyhedrovirus (HaNPV) to Lepidopterous Pests of Cotton

Farmers rely on chemical control for managing insect pests which cause various human and environmental health hazards. So, biopesticides like Nucleopolyhedrovirus (NPVs) can be a suitable alternative due to their less toxic effects on non-target organisms and environment. As a matter of fact, NPVs have been proven very effective against lepidopteran larvae. However, defining the host range of NPV was required according to the ecological conditions of Pakistan. So, this study was planned in which NPV isolated from Helicoverpa armigera, HaNPV, was used to infect H. armigera, Spodoptera litura, S. exigua, Pectinophora gossypiella and Trichoplusia ni under controlled conditions (temperature = 25 ± 2 °C; RH = 60 ± 5%). Higher mortality was observed in H. armigera among all the tested hosts. Additionally, mortality of all the other tested species showed no significant difference as compared to their untreated control. Similarly, a higher peak was achieved in H. armigera after two days of infection. Due to the multiplication of virions inside the host body, host tissues are destroyed. Many factors like larval body size, temperature and environmental conditions affect the rate of response and pathogenicity. Thus the pathogenicity varies with time of infection. Decrease in infection and mortality can be attributed to resistance and increase in the size of larvae with the passage of time. Non significant mortality in non-hosts species by HaNPV suggests its highly specific nature. Thus, it can be successful highly specific ecofriendly management tool for H. armigera. However, in extreme environmental conditions, NPV should be used with sunblock.