Transgenerational effects from single larval exposure to azadirachtin on life history and behavior traits of Drosophila melanogaster

Effect of nanoformulation Azadirachta indica on some factors associated with the vectorial capacity and competence of Anopheles aquasalis experimentally infected with Plasmodium vivax

Malaria remains a highly prevalent infectious disease worldwide, particularly in tropical and subtropical regions. Effectively controlling of mosquitoes transmitting of Plasmodium spp. is crucial in to control this disease. A promising strategy involves utilizing plant-derived products, such as the Neem tree (Azadirachta indica), known for its secondary metabolites with biological activity against various insect groups of agricultural and public health importance. This study investigated the effects of a nanoformulation prototype Neem on factors linked to the vector competence of Anopheles aquasalis, a malaria vector in Latin America. Different concentrations of the nanoformulation were supplied through sugar solution and blood feeding, assessing impacts on longevity, fecundity, fertility, and transgenerational survival from larvae to adults. Additionally, the effects of the Neem nanoformulation and NeemAZAL® formulation on the sporogonic cycle of P. vivax were evaluated. Overall, significant impacts were observed at 100 ppm and 1,000 ppm concentrations on adult survival patterns and on survival of the F1 generation. A trend of reduced oviposition and hatching rates was also noted in nanoformulation-consuming groups, with fertility and fecundity declining proportionally to the concentration. Additionally, a significant decrease in the infection rate and intensity of P. vivax was observed in the 1,000 ppm group, with a mean of 3 oocysts per female compared to the control's 27 oocysts per female. In the commercial formulation, the highest tested concentration of 3 ppm yielded 5.36 oocysts per female. Concerning sporozoite numbers, there was a reduction of 52 % and 87 % at the highest concentrations compared to the control group. In conclusion, these findings suggest that the A. indica nanoformulation is a potential as a tool for malaria control through reduction in the vector longevity and reproductive capacity, possibly leading to decreased vector population densities. Moreover, the nanoformulation interfered with the sporogonic development of P. vivax. However, further basic research on Neem formulations, their effects, and mechanisms of action is imperative to gain a more specific perspective for safe field implementation.

Callosobruchus maculatus males and females respond differently to grandparental effects

In this study, we used the cowpea weevil Callosobruchus maculatus (Coleoptera: Chrysomelidae) and two essential oils (mint and rosemary) to investigate the effect of the parents (F0) exposure to a sublethal dose of essential oil on grand offspring (F2) encountering the same essential oil. Then we evaluated biological parameters, including immature development time, sex ratio, adult emergence, egg number, egg hatch, longevity, and mating behaviors in three generations (F0, F1, and F2). Results showed when F0 experienced essential oil in the embryonic stage, parental and grandparental effects were more severe than adulthood experiences. Also, grandparental effects increased or decreased reactions of F2 generation when faced with a similar essential oil, depending on grand offspring sex. For example, when grandparents experienced rosemary essential oil in the embryonic stage, they produced more tolerant female grand offspring with a better ability to cope with the same essential oil (increased adult longevity and egg number). However, male grandoffspring were more sensitive (had a higher mortality percentage and less copulation success). Grandparental effects of exposure to mint essential oil diminished female grand offspring longevity and improved male copulation behavior parameters such as increased copulation duration and decreased rejection by females. In all, grandparental effects were different in male and female grand offspring based on the essential oil type experienced by F0.

Potential demographic impact of the insecticide mixture between thiacloprid and deltamethrin on the cotton aphid and two of its natural enemies

The use of pesticides impairs biological control in the agroecosystems and thus compromises the effectiveness of natural enemies against populations of pest species. The concerns over pesticides should expand beyond mortality and encompass their sublethal effects and their consequences to the target insect species and natural enemies to aid in our understanding of the potential and consequential use of these compounds. The present study aimed to determine the effects of an insecticide mixture on life-history and demographic parameters of the cotton aphid Aphis gossypii Glover (Hemiptera: Aphididae) and two of its main parasitoids - Aphidius flaviventris Kurdjumov (Hymenoptera: Aphelinidae) and Aphidius colemani Viereck (Hymenoptera: Braconidae). Based on the obtained results, thiacloprid + deltamethrin in its lethal concentration dose 20% of the pest population (LC₂₀) significantly affected the cotton aphid for two generations, increasing developmental time and demographic parameters. The LC₂₀ manifested changes in many demographic parameters of the parasitoid A. flaviventris. This concentration also increased preadult and female longevity, total pre-ovipositional period, and mean generation time (T) of A. colemani, but no other demographic parameters were affected. Nonetheless, the insecticide mixture did not affect the parasitism rate of A. colemani. Thus, the thiacloprid + deltamethrin mixture significantly impaired the cotton aphid population and its parasitoid A. flaviventris. Therefore, the use of thiacloprid + deltamethrin is not encouraged for controlling the parasitoid A. flaviventris, but it is a relatively safe compound for A. colemani.

Neem: A Novel Biocide for Pest and Disease Control of Plants

Plant extracts have recently captivated scientists’ attention as a potential source of biocide for plant protection. This is due to the health and environmental risks associated with the widespread use of synthetic chemicals with adverse effects on humans, nontarget organisms, and the agroecosystem. As a result, more environmentally friendly and safe alternative approaches to synthetic compounds are desirable. Neem (Azadirachta indica) has been identified as a promising biocontrol agent with low toxicity and high efficacy among several plant products for potential chemotherapeutic elements in plant pest and disease management systems. The biocidal potency of neem is attributed to its azadirachtin active ingredient, which impacts some metabolic processes in insects such as protein synthesis, changes in biological fitness, impaired sexual communication, and chitin synthesis. This systematic review intends to gather all the available scientific data regarding the application of neem and its formulations in pest and disease control of plants. The PRISMA (preferred reporting items for systematic reviews and meta-analysis) framework was employed in collecting data for the study. Findings from this review study have demonstrated the use of neem as an effective biocontrol agent for plants’ pests and diseases and have provided a solid foundation for future studies on the plant.

The insecticidal capacity of ethanol extract from Cascabela peruviana (L.) Lippold against fruit fly

Cascabela peruviana (L.) Lippold (C. peruviana) has been extensively used for its antifungal and antibacterial properties. However, its role in anti-insect is still under investigation. To investigate the ability of the ethanol extract of C. peruviana against insects, we used the fruit fly (Drosophila melanogaster) as a model to gain more insight into the toxic effects of this extract. We found that the ethanol extract from the stem and leaves of C. peruviana was effective against insects and contained polyphenol and flavonoid compounds. C. peruviana could induce mortality of 2^nd-instar larvae and reduce growth and reproduction of fruit flies. Interestingly, the toxicity of C. peruviana extract has been remained to affect the development of the next generation of fruit flies. The locomotor activity and feeding ability of the F1 generation of this insect were significantly reduced by C. peruviana. In addition, flavonoids and polyphenols, as well as saponins and tannins were detected in the ethanol extract of C. peruviana. We assume that the ability of the extract of C. peruviana to control insects may be related to the presence of high levels of these compounds. The findings highlighted that the extract from the leaves of Cascabela peruviana has the potential to be used as an insecticide.

In Silico Studies of Lamiaceae Diterpenes with Bioinsecticide Potential against Aphis gossypii and Drosophila melanogaster

Background: The growing demand for agricultural products has led to the misuse/overuse of insecticides; resulting in the use of higher concentrations and the need for ever more toxic products. Ecologically, bioinsecticides are considered better and safer than synthetic insecticides; they must be toxic to the target organism, yet with low or no toxicity to non-target organisms. Many plant extracts have seen their high insecticide potential confirmed under laboratory conditions, and in the search for plant compounds with bioinsecticidal activity, the Lamiaceae family has yielded satisfactory results. Objective: The aim of our study was to develop computer-assisted predictions for compounds with known insecticidal activity against Aphis gossypii and Drosophila melanogaster. Results and conclusion: Structure analysis revealed ent-kaurane, kaurene, and clerodane diterpenes as the most active, showing excellent results. We also found that the interactions formed by these compounds were more stable, or presented similar stability to the commercialized insecticides tested. Overall, we concluded that the compounds bistenuifolin L (1836) and bistenuifolin K (1931), were potentially active against A. gossypii enzymes; and salvisplendin C (1086) and salvixalapadiene (1195), are potentially active against D. melanogaster. We observed and highlight that the diterpenes bistenuifolin L (1836), bistenuifolin K (1931), salvisplendin C (1086), and salvixalapadiene (1195), present a high probability of activity and low toxicity against the species studied.

Identification of azadirachtin responsive genes in Spodoptera frugiperda larvae based on RNA-seq

The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous pest with 353 plant species as its hosts, including maize, sorghum, cotton, and rice. Azadirachtin is one of the most effective botanical insecticides. The effect of azadirachtin against S. frugiperda remains to be determined. Here we report strong growth inhibition of azadirachtin on S. frugiperda larvae under either 1.0 or 5.0 μg/g azadirachtin. To explore the relevant mechanisms, the larvae fed with normal artificial diet and with 1.0 μg/g azadirachtin exposure for 3 days were collected as samples for RNA-Seq. RNA-Seq on S. frugiperda larvae under different treatments identified a total of 24,153 unigenes, including 3494 novel genes, were identified. Among them, 1282 genes were affected by 1.0 μg/g azadirachtin exposure, with 672 up-regulated and 610 down-regulated. The impacted genes include 61 coding for detoxification enzymes (31 P450s, 7 GSTs, 11 CarEs, 7 UGTs and 5 ABC transporters), 31 for cuticle proteins, and several proteins involved in insect chitin and hormone biosynthesis. Our results indicated that azadirachtin could regulate the growth of S. frugiperda by affecting insect chitin and hormone biosynthesis pathway. The enhanced expression of detoxification enzymes might be related to detoxifying azadirachtin. These findings provided a foundation for further delineating the molecular mechanism of growth regulation induced by azadirachtin in S. frugiperda larvae.

Transient Administration of Dopaminergic Precursor Causes Inheritable Overfeeding Behavior in Young Drosophila melanogaster Adults

Imbalances in dopaminergic signaling during development have been indicated as part of the underlying neurobiology of several psychiatric illnesses, including schizophrenia, major depression, bipolar disorder, and food addiction. Yet, how transient manipulation of dopaminergic signaling influences long-lasting behavioral consequences, or if these modifications can induce inheritable traits, it is still not understood. In this study, we used the Drosophila melanogaster model to test if transient pharmacological activation of the dopaminergic system leads to modulations of feeding and locomotion in adult flies. We observed that transient administration of a dopaminergic precursor, levodopa, at 6 h, 3 days or 5 days post-eclosion, induced overfeeding behavior, while we did not find significant effects on locomotion. Moreover, this phenotype was inherited by the offspring of flies treated 6 h or 3 days post-eclosion, but not the offspring of those treated 5 days post-eclosion. These results indicate that transient alterations in dopaminergic signaling can produce behavioral alterations in adults, which can then be carried to descendants. These findings provide novel insights into the conditions in which environmental factors can produce transgenerational eating disorders.