Mean Larval Weight Research Articles

Performance of Hermetia illucens reared on pure, mixed, and sequentially mixed organic wastes regionally available in central Argentina

Abstract Black soldier fly larvae (Hermetia illucens L.) are proficient decomposers of organic matter. We compared experiments with local substrates containing: domestic residues (DR), and brewery wastes (BW) in pure form, or mixed with in two different proportions (BW70 or BW30), and two sequential diets in which larvae were fed first DR and then BW (DR/BW) or vice versa (BW/DR). The effects of the diets on life cycle parameters for mass production of H. illucens larvae were evaluated using general linear mixed models, ANOVA and Kruskal-Wallis. The pure DR diet significantly prolonged the developmental period (47.8 days), although the pupal stage was shorter in larvae fed on this diet (13.8 days). Larval survival was similar between treatments (over 85%), but pupal survival tended to be higher in the mixed diets (over 96%). Larval weights differed significantly between treatments, with mixed diets promoting greater weight gains than pure and sequential diets. Larvae fed a DR/BW diet gained more weight than those fed a BW/DR diet. The highest mean larval weights (0.23 g) were observed in the mixed diet BW70, followed by the sequential diet DR/BW (0.22 g). Mixed diet BW70 also resulted in larger wings and bodies in both sexes. Sequential diet BW/DR and pure diet DR resulted in the smallest adult sizes. Sex ratios varied, favouring male emergence (1.8 M:0.2 F) in pure diet DR and in both sequential mixed diets (1.7 M:0.3 F and 1.3 M:0.7 F, respectively). This study highlights the importance of higher total protein plus carbohydrate concentrations in diets for optimal larval rearing, favouring mixed diets BW70. Carbohydrate-rich substrates should be provided earlier in the cycle to benefit larval and adult performance. Locally available waste vegetable or fruit peels, brewery waste, and spent yerba mate proved to be viable substrates for larval rearing, providing economic and environmental benefits for H. illucens rearing.

Impact of chick mash, rice bran, and wheat bran as starter feeds on the performance of black soldier fly larvae in food waste treatment

ABSTRACT Inadequate management of food waste (FW) has contributed to environmental degradation. Bioconversion of FW using black soldier fly larvae has proven to be a safe and cost-effective method for FW management. However, limited studies exist on the influence of starter feeds. The impact of rice bran, wheat bran, and chick mash as starter feeds was evaluated by investigating the optimal larval weight, substrate reduction, feed conversion ratio (FCR), and bioconversion rate (BCR) of the larvae after initial treatment in rice bran (T1), wheat bran (T2), chick mash (T3), and control (T4). The highest mean larval weight observed was 0.22 g in T3 followed by 0.18, 0.16, and 0.13 g in T2, T4, and T1, respectively. A similar trend was observed for substrate reduction and BCR. Nevertheless, the obtained substrate reduction range of 75.5–82.8% was comparable with the published ranges. The best performance in T3 may be attributed to high protein and nitrogen content in chick mash, while the lowest performance is attributed to high ash content in rice bran, which negatively affected the BCR. It can be concluded that the physico-chemical properties of the starter feeds strongly determine the growth and development of larvae.

Cultivation of black soldier fly larvae in substrates containing antibiotics

The use of antibiotics in agriculture to treat and prevent infectious diseases and to stimulate growth results in antibiotics accumulating in animal tissues and wastes. Further utilization of such animal waste causes an increase in antibiotic-resistant bacteria. One of the promising ways of manure processing leading to reduction of antibiotic concentrations and obtaining useful biomass from organic waste may be bioconversion with the help of insects, particularly black soldier flies (Hermetia illucens) ( Diptera: Stratiomyldae). It is important to know how the presence of antibiotics in the feeding substrate affects the insects and their characteristics for further utilization. The effect of adding the antibiotics ceftriaxone, coliflox, levofloxacin and their mixtures to feed substrates on the growth of black soldier fly larvae was studied. When ceftriaxone, coliflox and levofloxacin were given at a concentration of 1–100 mg/kg feed, an increase in mean larval weight was observed compared to the control group after 5 days of culturing. At antibiotic concentrations of 500–1000 mg/kg, this effect was compensated, presumably by the negative effect of the antibiotic on the microbiota of the insect digestive system. At antibiotic concentrations of 2000 mg/kg feed, growth of Hermetia illucens larvae was retarded. No effect of antibiotics on fatty acid composition, moisture and ash content of insects was found. The results indicate that the use of black soldier fly for the treatment of animal waste is feasible, but the likely negative effect on insect growth at high antibiotic concentrations should be considered.

Studies on biology and preference of Helicoverpa armigera (Hubner) on different host plants and evaluation of botanicals for its management

The biology and fitness of Helicoverpa armigera (Hubner) was studied on bottle gourd, lady’s finger, chilli and tomato. The total larval duration was found to be 20, 22.5, 20.3 and 18.3 days on tomato, chilli, lady’s finger and bottle gourd respectively. The total life cycle was of 35.25, 40.7, 34.2 and 31.3 days on tomato, chilli, lady finger and bottle gourd respectively. Shortest life cycle was observed on bottle gourd and longest on chilli. Feeding preference and fitness of H. armigera revealed that it preferred bottle gourd over other host plants. On bottle gourd, the pest recorded highest mean larval weight gain (0.112g/ day), while the lowest was on chilli (0.090g/ day). The feeding period was 8.073 days on bottle gourd and 8.266 days on chilli. Average food ingested on bottle gourd, lady finger, chilli and tomato were 3.083, 2.347, 2.076 and 1.988g respectively. Bioefficacy of botanicals (5 % aqueous extracts of periwinkle, giloy, tulsi and lantana) against H. armigera by leaf dip bioassay using leaves of tomato showed that the average food ingested in periwinkle, giloy, tulsi, lantana and control was 0.644, 0.944, 1.038, 0.985 and 2.297g respectively. This is the first report evidencing the insecticidal properties of aqueous extracts of giloy against H. armigera.

Influence of host larval weight of Anastrepha ludens on production parameters and quality attributes in the mass rearing of the parasitoid Diachasmimorpha longicaudata

AbstractLarvae of Anastrepha ludens (Loew) (Diptera: Tephritidae) are non‐native hosts of the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). These hosts appear to be a very good resource for the development of D. longicaudata in a wide range of larval weights. Therefore, the present study aimed to evaluate whether the larval weight of A. ludens influences the emergence and mass‐rearing parameters of D. longicaudata, including the parasitoid's adult attributes and host selection capacity. Three mean larval weights of 29, 25, and 21 mg were considered as high, medium, and low categories for the analysis. The tests included the effect of management of host larvae in the mass rearing of the parasitoids. In addition, evaluations of flight ability, survival, fecundity, and size were carried out in the adults that emerged from the larvae of the various weight categories. There was a direct relationship between host larval weight and parasitoid pupal weight, but there was no relationship with the emergence of adult parasitoids. However, a high percentage of females emerged from heavier larvae. Similarly, although adults that developed in the heaviest larval category were larger, adult quality parameters were not affected. In the evaluations of host selection, the parasitoids oviposited randomly in the larvae from the various weight categories; there was only selection if larvae of different weights were mixed. In addition, superparasitism did not differ between larval weight categories. In the evaluation of competition for hosts in cages under field conditions, larger female parasitoids that developed in the heaviest host larvae landed more frequently on infested fruit, but oviposition was similar between females of different sizes. In conclusion, the larval weight of A. ludens influenced the size of the host puparia and of adults of D. longicaudata, but the emergence and attributes of the developed adults were similar. Therefore, it can be concluded that the low larval weights of A. ludens evaluated in this study are within the range for proper development of D. longicaudata in mass rearing. This allows several options to produce hosts at a lower cost without negatively affecting the quality of parasitoid production.

Basic Developmental Characteristics of the Fall Armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), Reared under Laboratory Conditions

The life cycle of the invasive alien insect pest, fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), was studied using a colony established from field-collected larvae. Eggs, neonate larvae, and newly emerged adult moths were used in experiments to investigate the basic biology of the FAW. Adult females laid up to 1184 eggs with a mean of 469 ± 22 eggs per female. The incubation period of eggs and percentage hatchability were 2-3 days and 80–87%, respectively. The mean larval lengths from the first to the sixth instar were 4.63, 6.60, 9.76, 15.86, 25.13, and 27.81 mm, respectively. The mean larval weights were 0.003, 0.019, 0.045, 0.050, 0.060, and 0.067 g, respectively, for the six instars. The mean width of the head capsule of the sixth instar larva was 2.76 mm. The total larval duration throughout the six instar stages was 16–18 days, while the mean pupal weight was 0.25 ± 0.001 g and 0.35 ± 0.011 g for males and females, respectively. The mean pupal length was 14.3 ± 0.16 mm for males and 17.2 ± 0.14 mm for females. Pupal duration ranged from 8 to 14 days, with a mean of 10.35 ± 0.26 days, while the pupal emergence rate ranged from 60 to 94%, with a mean of 80.25 ± 1.28%. The life cycle of males lasted 33–44 days and that of females lasted 36–49 days under laboratory conditions. Adult copulation occurred between 8 and 11 pm, with the peak occurring at 9 pm. This study provides baseline information about the biology of the FAW. Apart from being an important reference point for future research on the FAW, the data provided would aid FAW management decision-making.

In vivo developmental studies of Helicoverpa armigera and in silico molecular interactions with trypsin reveal the bio-insecticidal potential of trypsin inhibitor (SSTI) isolated from Solanum surattense

We report the impact of gut protease inhibition on the development of Helicoverpa armigera by trypsin inhibitor and the use of molecular modeling to understand the mechanism of trypsin inhibition. Larvae of H. armigera fed on an artificial diet containing 150 and 300 μg/ml SSTI showed a negative impact on the insects' development in terms of mean larval weight, larval fatality, survival rate, and nutritional indices. Prominent physical abnormalities like curled wings, malformed appendages, and small body size were observed during the development. Gene expression studies revealed down regulation in trypsin (HaTry 1, 2, 3, 4, 6, 8) and chymotrypsin (HaChy 1, 2, 3, 4) genes of the larval gut upon treatment of SSTI. Homology modeling has been used to build the three-dimensional structure of SSTI, which showed β-sheets having a stable canonical inhibitory loop (CIL) with conserved lysine residue. Molecular docking studies showed the strong binding of SSTI at the active site of trypsin. Molecular dynamic (MD) simulation revealed the stable interactions of the rigid CIL of SSTI at the active site of trypsin, leading to its destabilization. Conserved lysine63 of the P1 site in SSTI forms a strong hydrogen bonding network with residues Asp189 and Ser190 of trypsin.

Biology and biometric characteristics of Spodoptera frugiperda (Lepidoptera: Noctuidae) reared on different host plants with regard to diet.

The fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith), native to the Americas, is a new invasive pest that was reported in India for the first time in May 2018. Being polyphagous, FAW can infest several different hosts and increase its population all year round. In this context, the present study was conducted under laboratory conditions to evaluate the biological parameters of FAW on four different hosts, Zea mays (maize), Gossypium hirsutum (cotton), Ricinus communis (castor) and Brassica oleracea var. botrytis (cauliflower), and a semi-synthetic diet. The shortest life cycle of 32.8 ± 0.52 days in males and 34.1 ± 0.43 days in females was observed on maize. Semi-synthetic diet was superior in terms of higher mean fecundity (1324.6 ± 61.21 eggs), larval weight (503 ± 0.02 mg), pupal weight (263 ± 0.01 mg) and adult female weight (128 ± 0.0mg) compared with natural hosts. Cotton was the least preferred host with a longer life cycle of 49.5 ± 0.50 days. Head capsule width and length were measured and the growth rate was validated using Dyar's rule. The mean width and length of the head capsule of first-instar larvae of FAW on different hosts was 0.35 ± 0.00 mm. The maximum width (2.76 ± 0.03 mm) and length (2.31 ± 0.03 mm) were observed in sixth-instar larvae grown on diet. The results of this study will be instrumental in understanding and formulating management strategies for FAW.

Impact of Biochar on Douglas-Fir Tussock Moth (Orgyia pseudotsugata Lepidoptera: Erebidae) Larvae Reared on Synthetic Diet.

Simple SummaryThe novel use of carbon-rich biochar as a soil amendment in forest systems may be beneficial in the restoration of disturbed sites due to its ability to increase soil water holding capacity, potentially reduce drought stress in surrounding vegetation and aid in long-term carbon sequestration. As biochar is utilized in forest management, it is necessary to establish the potential effects that it may have on insects and other invertebrate assemblages. The results of recent laboratory studies demonstrate a potential for negative impacts on insects. Examining direct exposure of insects to biochar in a laboratory experiment may help us understand what effects biochar may have on insects that come into direct contact with the material. Along with direct exposure, biochar applications in the field would result in the surface and possible contamination of insect nutrient sources. To determine the impacts of ingesting biochar, we reared Douglas-fir tussock moth, Orgyia pseudotsugata, on synthetic diet to examine the insect’s survival and longevity.The use of biochar as a soil amendment in forest ecosystems can be beneficial in the restoration of degraded soils. Forest insects such as the Douglas-fir tussock moth, Orgyia pseudotsugata (McDonnough) (Lepidoptera: Erebidae), may be exposed to biochar when the material is applied. Two experiments were conducted using biochar either (1) applied to the surface of the diet at three rates (0, 5, and 10 mg) or (2) incorporated into synthetic diet at four rates (0, 10, 20, and 40% volume/volume). The objective of both experiments was to determine if biochar on the surface or incorporated into a synthetic diet affected development and survival of O. pseudotsugata larvae. In both experiments, there was a significant decrease in estimated time to larval mortality in all biochar treatments compared to untreated controls. In the surface-applied biochar experiment, there was a significant difference in larval weight gain at day 12 between the control and 10 mg biochar treatments. In the experiment with biochar incorporated into the diet, mean larval weight at day 12 was highest in the low (10%) biochar treatment compared to all other treatments, although weight gain was only significantly different between the low- and high-concentration (40%) biochar treatments. Our results suggest that larvae, feeding on a low amount of biochar in the synthetic diet, may respond by engaging in compensatory feeding behavior. Fewer surviving larvae in the biochar treatment groups may contribute to the lack of significance found in the comparison of weight gain at day 24 in each experiment.

Growth of Black Soldier Fly Larvae Reared on Organic Side-Streams

Black soldier fly (BSF) larvae may play a role in a circular economy by upcycling low-value organic streams into high value biomass. In this paper, the capacity of BSF larvae to process 12 organic side-streams (mono-streams) and two standard substrates (chicken start mash and Gainesville diet) was investigated. Survival, larval mass, feed conversion ratio, and waste reduction were evaluated in relation to the proximate composition of the side-streams used. Survival rates larger than 80% were observed for 10 of the organic mono-streams and the two standard substrates. Maximum mean larval weight ranged from 38.3 mg up to 176.4 mg regardless of high survival and was highly correlated with substrate crude protein content. Feed conversion ratio (range 1.58–8.90) and waste reduction (range 17.0–58.9%) were similar to values reported in other studies in the literature. On low protein substrates (e.g., apple pulp), survival rates remained high, however, possibly due to protein deficiency, limited larval growth was observed. It is concluded that several low value organic side-streams can successfully be processed by BSF larvae, thereby opening the possibility of lowering the costs of BSF farming. Potentially mixing nutritionally distinct mono-streams into a mixed substrate might improve BSF performance. However, more research is needed for optimizing diets to guarantee production of BSF larvae of constant yield and quality.

Characterizing the Relationship Between Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Survival on Cry3Bb1-Expressing Corn and Larval Development Metrics.

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a significant pest of field corn, Zea mays L. (Poales: Poaceae), across the United States Corn Belt. Widespread adoption and continuous use of corn hybrids expressing the Cry3Bb1 protein to manage the western corn rootworm has resulted in greater than expected injury to Cry3Bb1-expressing hybrids in multiple areas of Nebraska. Single-plant bioassays were conducted on larval western corn rootworm populations to determine the level of resistance present in various Nebraska counties. The results confirmed a mosaic of susceptibility to Cry3Bb1 across Nebraska. Larval development metrics, including head capsule width and fresh weight, were measured to quantify the relationship between the level of resistance to Cry3Bb1 and larval developmental rate. Regression and correlation analyses indicate a significant positive relationship between Cry3Bb1 corrected survival and both larval development metrics. Results indicate that as the level of resistance to Cry3Bb1 within field populations increases, mean head capsule width and larval fresh weight also increase. This increases our understanding of western corn rootworm population dynamics and age structure variability present in the transgenic landscape that is part of the complex interaction of factors that drives resistance evolution. This collective variability and complexity within the landscape reinforces the importance of making corn rootworm management decisions based on information collected at the local level.

Productivity and larval growth ofTenebrio molitor reared on differently composed diets of similar nutritional composition

The artificial diet ofTenebrio molitor has been a focal point of many studies that aimed to design the best diet combination. Recently, studies are focusing on the use of by-products and their efficiency as diets for rearingT. molitor. The rearing was successful on a wide range of by-products-based diets. The feed has a profound impact on the lifespan, growth, productivity and nutritional composition ofT. molitor. Productivity is one of the traits highly influenced by the diet’s composition, especially macronutrients. This work aims to study the effect of eight different diets on the weight and productivity of females and their progeny weight: larval weight. Wheat bran, brewer’s yeast, spent grain and bread remains were used to compose the diets, based on different inclusion percentages of each by-product. The nutritional composition, mainly the macronutrients, of the diets had a narrow range of differences. The diets were designed in a way to avoid the effect of different nutritional compositions and study the effect of the by-products type only. Results showed that the female’s weight-change during the egg-laying period was not significant under different rearing diets. Moreover, the female’s productivity measured by the larval number showed no significant difference between the different diets. However, the total larval biomass (452.4 mg) was significantly higher for larvae reared on diet A composed of wheat bran and brewer’s yeast. Also, the total mean larval weight was significantly higher for larvae reared on diets A (3.1 mg) and G (3.2 mg) composed of wheat bran, brewer’s yeast and spent grain. The mentioned diets although composed of different by-products have similar amounts of protein and carbohydrates. These results prove that the type of by-products included in the experimental diets does not affect the reproductive performance ofT. molitor, while it can affect larval growth.

Concentration–Mortality Response of Mexican Populations Fall Armyworm (Lepidoptera: Noctuidae) to Commercial Formulations of Bacillus Thuringiensis

Abstract The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is the most economically important pest of maize (Zea mays L.) grown in Mexico. In order to identify biologically based management tactics for this pest, we determined the concentration–mortality response of 16 S. frugiperda populations collected in Mexico to two commercial formulations of Bacillus thuringiensis Berliner (Bt) (XenTari® [Bt subsp. aizawai] and DiPel® [Bt subsp. kurstaki]; Valent de México SA De CV, Jalisco, México). Laboratory bioassays established median lethal concentrations (LC50s) for each Bt formulation × population combination. We also determined mean larval weight 7 d after exposure and the number of larvae that reached the third instar of development. The populations were susceptible to both Bt formulations but they were, overall, more susceptible to Bt subsp. aizawai (XenTari) than to Bt subsp. kurstaki (DiPel). These results can serve as a reference to detect changes in S. frugiperda response to these Bt commercial products over time.

Comparing Selected Life-History Traits of Black Soldier Fly (Diptera: Stratiomyidae) Larvae Produced in Industrial and Bench-Top-Sized Containers

As global food demand is increasing along with human population growth, there is a greater need for alternative protein sources. Insect protein, especially the larvae of the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), has become a key approach for solving this issue in part due to its ability to convert organic waste into insect biomass with minimal resource (e.g., land, water) requirements. However, most information utilized to develop industrial production of this species is reliant on data generated from laboratory-scaled studies. Unfortunately, scaling these data to an industrial level potentially is not linear resulting in over, or under, estimating production. In this study, we compared selected life-history traits of larval black soldier fly produced at benchtop (e.g., 1 liter container with 614 larvae) and industrial scales (e.g., 29.5 liter container inoculated with 10,000 larvae). Larvae were provided a single feeding (2 g/larva) in each treatment. Significant differences in the mean larval weight (24.7%), survivorship (−28.2%), and biomass conversion (−2.7%) were determined between benchtop and industrial treatments. These results indicate larval number and the associated container size are important factors to consider when designing a black soldier fly factory. Furthermore, caution should be taken when applying data from laboratory studies to industrial scale production systems as the values potentially are not linear.

Effects of class-specific, synthetic, and natural proteinase inhibitors on life-history traits of the cotton bollworm Helicoverpa armigera.

Herbivorous insects have more difficulty obtaining proteins from their food than do predators and parasites. The scarcity of proteins in their diet requires herbivores to feed voraciously, thus heavily damaging their host plants. Plants respond to herbivory by producing defense compounds, which reduce insect growth, retard development, and increase mortality. Herbivores use both pre- and postdigestive response mechanisms to detect and avoid plant defense compounds. Proteinase inhibitors (PIs) are one example of plant compounds produced as a direct defense against herbivory. Many insects can adapt to PIs when these are incorporated into artificial diets. However, little is known about the effect of PIs on diet choice and feeding behavior. We monitored the diet choice, life-history traits, and gut proteinase activity of Helicoverpa armigera larvae using diets supplemented with synthetic and natural PIs. In choice experiments, both neonates and fourth-instar larvae preferred the control diet over PI-supplemented diets, to varying degrees. Larvae that fed on PI-supplemented diets weighed less than those that fed on the control diet and produced smaller pupae. Trypsin-specific PIs had a stronger effect on mean larval weight than did other PIs. A reduction of trypsin activity but not of chymotrypsin activity was observed in larvae fed on PI-supplemented diets. Therefore, behavioral avoidance of feeding on plant parts high in PIs could be an adaptation to minimize the impact of this plant's defensive strategy.

Effects of hexaflumuron, lufenuron and chlorfluazuron on certain biological and physiological parameters of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is one of the most economically devastating pests of agricultural crops around the world. In this study, the effects of hexaflumuron, lufenuron and chlorfluazuron were evaluated on some biological and physiological parameters of H. armigera larvae. Effects of the insecticides were assessed by adding different concentrations into the larval artificial diet. Dose-response bioassay showed LC50 values of 6.16, 61.31 and 31.75 mg ai/l for hexaflumuron, lufenuron and chlorfluazuron, respectively. Subsequently, sublethal effects of hexaflumuron, lufenuron and chlorfluazuron were assessed using LC10 concentration to find their possible effects on the biological and physiological parameters of H. armigera larvae. The results showed significant changes in biological parameters, where the mean larval and pupal weights significantly decreased following treatment, while their developmental time significantly increased compared to the control. Meanwhile, the longevity of adult males and females, number of laid eggs per female, and rate of egg hatch were significantly reduced due to the insecticide treatments. The activities of alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, acid- and alkaline phosphatases, lactate dehydrogenase, glutathione S-transferase were increased following the treatments. Sublethal exposure of the insecticides on larvae led to lower amounts of glycogen, triglyceride and protein compared to the control.

TOXICOLOGICAL AND BIOLOGICAL EFFECTS OF SOME INSECTICIDES ON THE COTTON LEAFWORM, Spodoptra littorallis (Boisd.)

Toxicity of five insecticides belonging to different groups of chemicals, namely: chlorpyrifos, methomyl, emamectin benzoate, protecto and biovar to cotton leafworm were evaluated under the field and laboratory conditions. The effect of the tested chemicals on some biological aspects of 2nd and 4th instar larvae of the cotton leafworm, Spodoptra littoralis (Boisd.) were investigated. The lethal concentrate (LC50 and LC90) values were calculated after 24, 48, and 72 hr., post-treatment. The obtained results showed that there was a wide range of toxicity of the tested pesticides; however the insecticide bestban showed to be the highest toxic compound effect against 2nd and 4th instar larvae, with LC50 and LC90 values after 72 hr., post-treatment recording 0.05, 0.22 mg/l and 0.15, 1.10 mg/l for 2nd and 4th instar larvae, respectively. On the other hand, the biopesticide biovar exhibited the lowest toxicity to the tested larvae at both levels of toxicity (LC50; LC90 values after 72 hr., recording 414; 856 mg/l and 1100; 1740 mg/l) for 2nd and 4th instar larvae, respectively. The other tested insecticides occupied an intermediate position between the highest and the lowest toxic pesticides. Regarding the biological effects, results showed that, the tested insecticides induced a clear reduction in mean larval weight and mean pupal weight compared with the control. The tested insecticides affected the larval duration, pupal duration, pupation, adult emergence and adult longevity.

Biological Activity of Trichilia americana (Meliaceae) on Copitarsia decolora Guenée (Lepidoptera: Noctuidae)

Abstract The biological activity of extracts from Trichilia americana (Sesse and Mocino) T.D. Penn. (rind), Carica papaya L., Jatropha curcas L., Ricinus communis L., and Lupinus campestris Schldl. & Cham. (seeds), at 1% and 5%, were evaluated on neonates of Copitarsia decolora Guenée in ingestion bioassays. The plants that caused the highest percentage of larval mortality were T. americana at 1% and 5%, and Carica papaya at 5% with 98% and 100% and 100%, respectively. Trichilia americana was the plant with higher toxicological properties against C. decolora. Extracts in hexane, ethyl acetate, acetone, and methanol from T. americana were then evaluated at 10, 100, 300, and 1,000 ppm also in ingestion bioassays against C. decolora. Extracts of ethyl acetate and acetone at 1,000 ppm recorded the highest percentages of larval mortality of C. decolora (90% and 55%, respectively). In addition to larval mortality, feeding on T. americana extract also decreased mean larval weight, prolonged duration of the larval stage, resulted in malformed pupae and adults, and affected adult fertility and fecundity. Finally, these extracts were evaluated in a toxicity model, for which the crustacean Artemia salina Leach was used. The ethyl acetate, acetone, and hexane extracts showed no toxicity to A. salina, while the methanol extract caused 30% mortality, which is considered to be slightly toxic. Based on the results obtained, T. americana is a species with insecticidal and insectistatic activity against C. decolora and can be considered as a potential insecticide for the management of this or other insect pests.

The Effect of Burned Liver on the Length, Weight and Development of Megaselia scalaris (Loew) (Diptera: Phoridae) – A Preliminary Assessment and Implications in Forensic Entomology

Development of insects in laboratory for minimum post mortem interval estimation (mPMI) or time of colonisation (TOC) in forensic entomology can be affected by the type and quality of food consumed during larval period. Since mPMI estimation also involves analysis of larval specimens collected from burned human remains, it is important to study if burned tissues could affect growth of sarcosaprophagous larvae. This study investigated the effect of burned tissues on the size and developmental period of Megaselia scalaris (Loew) (Diptera: Phoridae), a species of forensic importance. Development of M. scalaris on 75 g burned cow’s liver was compared with control liver in three study replicates. Mean larval length (2.87 ± 0.11 mm) and weight (0.81 ± 0.08 mg) of M. scalaris larvae in burned liver diets were significantly lower than larval length (5.03 ± 0.15 mm) and weight (2.85 ± 0.21 mg) of control liver diets (p < 0.001) whilst mean pupal length (2.53 ± 0.06 mm) and weight (0.92 ± 0.06 mg) in burned liver diets were significantly lower than pupal length (3.52 ± 0.06 mm) and weight (2.84 ± 0.16 mg) in control liver diets (p < 0.001). Development of larvae in burned liver was 5-9 hours slower than those feeding on control liver based on single observation. Although the assessment is preliminary, the findings indicate physical growth of larvae feeding on burned animal tissues was affected and entomological specimens recovered from burned remains should be evaluated carefully to avoid errors in mPMI/TOC estimation. Limitations and suggestions for further research are also presented herein. DOI : http://dx.doi.org./10.17576/JSKM-2018-1601-04

Life Cycle and Digestive Physiology ofTrogoderma granarium(Coleoptera: Dermestidae) on Various Wheat Cultivars

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is known as one of the world's most damaging pests of wheat and other stored products. The life cycle, nutritional indices, and digestive enzymatic activity of T. granarium in response to feeding on six wheat cultivars (Arg, Morvarid, Nai 60, Parsi, Pishtaz, and Shanghai) were evaluated under laboratory conditions (33 ± 1°C, 65 ± 5% relative humidity, and a photoperiod of 14:10 [L:D] h). In this research, delayed developmental time of T. granarium immature stages was detected on cultivars Parsi and Morvarid. The highest survival rate of immature stages was on cultivar Arg, and the lowest was on cultivars Morvarid and Parsi. Moreover, the highest mean larval weight and weight gain of larvae were on cultivar Arg, while the lowest ones were on cultivars Parsi and Morvarid. In addition, the lowest values of relative growth rate and proteolytic activity were detected when larvae were fed with cultivars Morvarid and Parsi. Based on the obtained results, it can be concluded that cultivars Parsi and Morvarid were the most unsuitable cultivars for the development and feeding of T. granarium . The resistant cultivars can be recommended to be grown in areas where the damage of T. granarium is high for protecting or at least delaying wheat infestation by this pest.