Biomorphometry of Automeris liberia Cramer (Lepidoptera: Saturniidae) in oil palm in the Amazon

Automeris liberia Cramer are found in South America, with documented sightings in Ecuador, Peru, some regions of Mexico and, more recently, the Brazilian Amazon. These moths cause damage to several plant species. We designed an experiment to study the biology and morphometry of A. liberia in the laboratory and provide information for the management of the pest in oil palm cultivation in the Brazilian Amazon. Caterpillars for rearing were collected from commercial areas of oil palm cultivation, where they cause defoliation of the plant. They were fed a natural diet of oil palm leaves of the Tenera variety and observed from second generation onwards. Sex, behavior, posture, mass, body length, wingspan, body diameter, sex ratio, average growth ratio, and antenna were quantified. The embryonic stage lasted 14 days, followed by seven larval instar stages over 36 days. The pupal stage lasted 21 days. Adults had a longevity of 4.5 and 6 days and a total biological cycle of 78.5 and 80 days, for males and females, respectively. The growth ratio was 1.49. The antennae showed sexual dimorphism, with bipectinate morphology in males and filiform in females. In the adult stage, morphological variables were evaluated (body length, thoracic diameter, wingspan, forewing length, forewing height, hindwing length, hindwing height, antenna length, number of antennomeres, and body mass), and they showed significant differences between males and females (Newman-Keuls test, P < 0.05).

Drosophila D-idua Reduction Mimics Mucopolysaccharidosis Type I Disease-Related Phenotypes

Deficit of the IDUA (α-L-iduronidase) enzyme causes the lysosomal storage disorder mucopolysaccharidosis type I (MPS I), a rare pediatric neurometabolic disease, due to pathological variants in the IDUA gene and is characterized by the accumulation of the undegraded mucopolysaccharides heparan sulfate and dermatan sulfate into lysosomes, with secondary cellular consequences that are still mostly unclarified. Here, we report a new fruit fly RNAi-mediated knockdown model of a IDUA homolog (D-idua) displaying a phenotype mimicking some typical molecular features of Lysosomal Storage Disorders (LSD). In this study, we showed that D-idua is a vital gene in Drosophila and that ubiquitous reduction of its expression leads to lethality during the pupal stage, when the precise degradation/synthesis of macromolecules, together with a functional autophagic pathway, are indispensable for the correct development to the adult stage. Tissue-specific analysis of the D-idua model showed an increase in the number and size of lysosomes in the brain and muscle. Moreover, the incorrect acidification of lysosomes led to dysfunctional lysosome-autophagosome fusion and the consequent block of autophagy flux. A concomitant metabolic drift of glycolysis and lipogenesis pathways was observed. After starvation, D-idua larvae showed a quite complete rescue of both autophagy/lysosome phenotypes and metabolic alterations. Metabolism and autophagy are strictly interconnected vital processes that contribute to maintain homeostatic control of energy balance, and little is known about this regulation in LSDs. Our results provide new starting points for future investigations on the disease’s pathogenic mechanisms and possible pharmacological manipulations.

First Evidence of Feeding-Induced RNAi in Banana Weevil via Exogenous Application of dsRNA

Banana weevil (Cosmopolites sordidus) is the most devastating pest of banana and plantain worldwide, yet current control measures are neither effective, sustainable, nor environmentally sound, and no resistant farmer-preferred cultivars are known to date. In this paper, we examined the ability to induce RNA interference (RNAi) in the banana weevil via feeding. We first developed an agar- and banana corm (rhizome) flour-based artificial diet in a multi-well plate setup that allowed the banana weevils to complete their life cycle from egg through the larval instars to the pupal stage in an average period of 53 days. Adults emerged about 20 days later. The artificial diet allowed the tunneling and burrowing habits of the larvae and successful metamorphosis up to adult eclosion. Adding dsRNA for laccase2 to the artificial diet resulted in albino phenotypes, confirming gene-silencing. Finally, C. sordidus was fed with dsRNA against a selection of essential target genes: snf7, rps13, mad1, vha-a, vha-d, and lgl for a period of 45 days. 100% mortality within 9–16 days was realized with dssnf7, dsrps13, and dsmad1 at 200 ng/mL artificial diet, and this corresponded to a strong reduction in gene expression. Feeding the dsRNA targeting the two vha genes resulted in 100% mortality after about 3–4 weeks, while treatment with dslgl resulted in no mortality above the dsgfp-control and the water-control. Our results have implications for the development of RNAi approaches for managing important crop pests, in that banana weevils can be controlled based on the silencing of essential target genes as snf7, rps13, and mad1. They also highlight the need for research into the development of RNAi for banana protection, eventually the engineering of host-induced gene-silencing (HIGS) cultivars, given the high RNAi efficacy and its species-specific mode of action, adding the RNAi approach to the armory of integrated pest management (IPM).

Lobesia botrana: A Biological Control Approach with a Biopesticide Based on Entomopathogenic Fungi in the Winter Season in Chile

Lobesia botrana (Denis and Shiffermüller) (Lepidoptera: Tortricidae) is one of the main pests that affect the production and export of table grapes in Chile. Because this pest has quarantine status, the fruit must be fumigated with methyl bromide, which reduces the fruit’s export competitiveness in the destination market. In the present study, to help resolve this issue, six native entomopathogenic fungi were identified through multilocus analysis, including three Beauveria pseudobassiana and three Metarhizium robertsii. These fungi were evaluated in the laboratory to control L. botrana in its pupal stage in a silk cocoon and compared against a biological control product. Formulations with additional carbon sources improved the performance of the fungi. The treatments with outstanding performance contained the fungal strains B. pseudobassiana RGM 2184 and M. robertsii RGM 678. These strains were evaluated in the field during the winter season in two different regions of the country; the strains reached maximum efficacies of 80% and 88%, respectively, at 21 days post first application. Therefore, entomopathogenic fungi can contribute to reducing pupal populations in winter, thereby decreasing the moth population in spring–summer.

Performance of a Native Butterfly and Introduced Moth on Native and Introduced Lineages of Phragmites australis

This study examined the performance of Poanes viator (Edwards) (Hesperiidae), a native North American skipper, and Rhizedra lutosa (Hübner) (Noctuidae), an introduced moth, reared on native and non-native, invasive lineages of Phragmites australis. Poanes viator is a generalist on monocots and larvae were also fed leaves of Zizania aquatica, a native macrophyte that the skipper commonly uses as a host plant. Larval survival and duration, pupal weight, and pupation time were compared for P. viator feeding on leaf tissue and R. lutosa feeding on rhizomes of either native or introduced plants. We also tested an artificial diet supplemented with P. australis rhizome powder as a potential food for rearing other stalk and rhizome boring Lepidoptera. In experiments using excised plant tissues, some individuals of both species fed and developed to the pupal stage on native and introduced plants, but overall, larval survival rates were low. Plant species/haplotype identity did not cause strong differences in larval survival for either species. However, P. viator larvae only pupated when feeding on native plants (Zizania aquatica and native P. australis haplotypes), whereas R. lutosa successfully pupated on both native and introduced P. australis. Although larval survival was low, 100% of P. viator and 95% of R. lutosa that reached the pupal stage emerged as adults. Rhizedra lutosa larvae fed an artificial diet supplemented with P. australis rhizome powder had significantly greater survival and pupal weights, and shorter pupation times than larvae fed rhizomes only. Several specialist Lepidopteran species are being considered for approval as biological control agents for the non-native P. australis haplotype, and the convenience and increased larval performance make this artificial diet a good alternative for rearing organisms.

Predation capacity and larval development of Ceraeochrysa claveri (Neuroptera: Chrysopidae) fed with Raoiella indica (Acari: Tenuipalpidae)

Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) is a predator found in several agricultural ecosystems and feeds on insects and phytophagous mites. Its high reproductive potential and forage capacity makes it a candidate for biological control of agricultural pests. Raoiella indica Hirst (Acari: Tenuipalpidae) is an important pest that can damage several species of palms, in particular, Cocos nucifera L. Given the scarcity of available knowledge about the biological aspects of Chrysopidae fed with phytophagous mites, the present work aimed to study the larval development of C. claveri fed mainly with R. indica, in order to obtain information that would be of help in the integrated management of this pest. The evaluation was performed in the F0 generation. Larva 3 is the instar that consumes the most mites (F value = 32.99; P > 0.0001) (L3: 46.80 ± 10.12 a; L2: 9.80 ± 1.23 b; L1: 9.40 ± 1.58 b). C. claveri did not complete larval development when fed only with R. indica. Larval instars L1, L2 and L3 lived 7.4 ± 2.2, 7.6 ± 1.9 and 9.0 ± 3.9 days, respectively. The larvae that reached the pupal stage failed to grow further. When adding Sitotroga cerealella Olivier (Lepidoptera: Gelechidae) eggs to the diet, the development lasted 7.9 ± 0.2, 7.4 ± 0.8, 6.5 ± 0.9 and 13.6 ± 0.9 days for L1, L2, L3 and pupae, respectively. The adults lived on average 6.7 ± 4.9 days. The sexual ratio was rt = 0.42. According to the conditions under which the experiment was carried out, it can be inferred is that C. claveri cannot complete its development by feeding only on R. indica, and that it thus consumes this mite as an occasional prey. Highlights: Ceraeochrysa claveri is a predator found in various agricultural ecosystems and feeds on insects and phytophagous mites. Raoiella indica is an important mite that can damage several species of palms, in particular Cocos nucifera Ceraeochrysa claveri does not complete its biological cycle by feeding only on indica. By adding another protein source to L3, it can reach the adult stage in 35.4±2.8 days. Ceraeochrysa claveri does not complete its cycle by feeding only on R. indica and consequently takes this mite as occasional prey.

The Effect of Pyrrolidinium Bromide Salt in The Life of The Southern Cowpea Beetle Callosobruchus Maculatus (Fab) (Coleoptera: Chrysomelidae)

The study aimed to evaluate the efficacy test of a chemical compound (pyrrolidinium bis - bromide salt) laboratory-prepared in the life of the southern cowpea beetle Callosobruchus maculatus, which is one of the most important pulses stored pest. The compound N1 was prepared and the structure was proved using1H NMR, IR technique. For treating the seeds out, three concentrations from N1, 500, 1500, 3000 ppm, were prepared. The results showed that the compound outperformed the percentage of repellent (prevention of laying eggs), with the concentration of 500 ppm registered the lowest number of eggs laid, with 96.67 eggs and an repellent rate of 53.97 %, compared to 210.00 eggs. While the results showed a significant effect when the concentration increased. This caused a 66.32 % drop in first-generation personnel from the highest rate of 95.00. The higher concentration also showed the lowest productivity compared with the rest of the concentrations, at 21.05 % compared to controlling sample 45.45%, and had no significant effect on increasing the duration of the pupal stage by 7.83 days compared to 7.50 days. Compared to 7.50 days of control, it affected the increase in the 7.50-day period of the larvae stage compared to the control of 5.50 days. The 1500 ppm concentration did not affect the vitality of the seeds after being treated as they were not significantly different from control. The results also showed that not all of the compound's concentrations had a repellent effect against the southern cowpea beetle.

Use of Microwave Heating Technology for Disinfestation of Stored Green Gram (Vigna radiata) against Cowpea Bruchid Callosobruchus maculatus (Fabricius)

Background: Pulses are an integral component of food in India which acts as major source of protein required for growth and maintenance of body. But during their storage they suffer heavy losses resulting in depletion of their quality and edibility. The present studies focused on disinfestation of green gram grains using microwaves as an alternative approach to chemical methods for controlling insects in grains and pulses. Methods: In this laboratory studies during 2017-18, the grains of green gram were infested with different life stages of the cowpea weevil and exposed to 200, 400, 600 and 800 W microwave power levels, each at an exposure period of 10, 20, 30 and 40 s. Result: Eggs were the most susceptible, while pupal and adults were the least susceptible life stages to microwave treatments. Complete mortality of eggs was achieved with microwave treatments (400, 600 and 800 W), each at an exposure period of 30 and 40 s. Complete inhibition of larval stage was attained with 400 and 600 W (30 and 40 s) and 800 W (20, 30 and 40 s exposure) while for pupal stage it was observed at the higher wattages of 600 (40 s exposure) and 800 (30 and 40 s exposure). Microwave wattage of 600 W for 40 sand 800 W for 30 and 40 s exposure caused 100% mortality of 2d old adults of cowpea bruchid.

Evaluation of linear and nonlinear models for temperature driven development of Spodoptera litura (Fabricius) on soybean crop

The tobacco caterpillar, Spodoptera litura, a major pest of soybean in India is under surveillance in all soybean growing areas in Maharashtra in order to issue alerts to farmers and prevent economic losses. In this context, two linear models were fitted to developmental data of S. litura life stages reared on soybean at five constant temperatures viz. 15, 20, 25, 30 and 35°C through laboratory experiments. Optimum temperature for development (Topt) and upper temperature threshold (Tmax) were estimated from three nonlinear models by additionally including developmental response at >35°C. Topt estimates for the total immature development were 34.5°C (Lactin-2), 33.7°C (Briere-1) and 33.2°C (Simplified Beta type function) while Tmax estimates were in the range of 38 to 40°C. Application of a thermodynamic non-linear model (Optim SSI) gave estimate ofintrinsic optimum temperature (Tφ) for development of egg (28.3°C), larva (27.5°C) and pupal stage (30.3°C). The phenology model of S. litura on soybean based on estimated developmental threshold temperatures and thermal constants was validated using available field surveillance data to facilitate informed pest management decisions.

Conditional knockdown of transformer in sheep blow fly suggests a role in repression of dosage compensation and potential for population suppression

The transformer (tra) gene is essential for female development in many insect species, including the Australian sheep blow fly, Lucilia cuprina. Sex-specific tra RNA splicing is controlled by Sex lethal (Sxl) in Drosophila melanogaster but is auto-regulated in L. cuprina. Sxl also represses X chromosome dosage compensation in female D. melanogaster. We have developed conditional Lctra RNAi knockdown strains using the tet-off system. Four strains did not produce females on diet without tetracycline and could potentially be used for genetic control of L. cuprina. In one strain, which showed both maternal and zygotic tTA expression, most XX transformed males died at the pupal stage. RNAseq and qRT-PCR analyses of mid-stage pupae showed increased expression of X-linked genes in XX individuals. These results suggest that Lctra promotes somatic sexual differentiation and inhibits X chromosome dosage compensation in female L. cuprina. However, XX flies homozygous for a loss-of-function Lctra knockin mutation were fully transformed and showed high pupal eclosion. Two of five X-linked genes examined showed a significant increase in mRNA levels in XX males. The stronger phenotype in the RNAi knockdown strain could indicate that maternal Lctra expression may be essential for initiation of dosage compensation suppression in female embryos.