Plant Insecticides Research Articles

Population Dynamic of Brown Plant Hopper, Predators and Neutral Insects in Irrigated Rice of Yogyakarta after Insecticides Application

Brown Plant Hopper (BPH) infestation in irrigated rice agroecosystem resulted yield loss. The application of insecticides by farmers are usually excessive, reducing pest population and negatively affecting the predators. This research aimed to define the impact of insecticides on the population dynamic of BPH, predator and neutral insects which influenced rice yield. Research was conducted at Yogyakarta, Indonesia, during May to September 2021. Randomized Block using four replications was applied. Rice varieties Inpari 32 HDB and Inpari 42 GSR were planted. Insecticide with active ingredient spinetoram 120 g/l and triflumezopyrim 106 g/l were applied to the rice plant on day 40th then pimetrozin 50% was applied at day 50th. Results showed that BPH population was reduced from 30-50 nymph per 30 plants to 10 nymph at day 12th after pimetrozin 50% application or at the day 2nd after spinetoram and triflumezopyrim insecticides application until day 50th. In contrast, BPH population in all insecticide plants was significantly lower than in all control and did not increase until harvest. On the other side, predators such as Paederus sp and Coccinelids were not affected by all insecticides, except Ophionea sp, Spiders and Cythorinus sp. However, their population recovered at day 30th after first insecticides application. Within the fluctuated population of BPH, rice productivity of Inpari 32 HDB and Inpari 42 GSR applied with insecticides were 9.52 ton ha-1 and 10.60 ton ha-1, while Inpari 32 HDB control and Inpari 42 GSR control 9.44 ton ha-1 and 10.72 ton ha-1

Field Application of Ethanolic and Aqueous Chili Extracts to Control Diamondback Moth (Plutella Xylostella L.) in Cabbage (Brassica Oleracea Var. Capitata L.)

The Diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) is an economic oligophagous pest that feeds on the members of the Brassicaceae family. Cabbage as one of the brassicas is mostly targeted by the larvae of P. xylostella in tropical countries including Papua New Guinea (PNG). Attempts to control this pest continue to be a challenge for farmers since it is now resistant to commonly used synthetic insecticides. Chili (Capsicum frutescens L.) in particular is an insecticidal plant that has been proven to reduce the impact of pests including P. xylostella. Previous studies have focused on the extraction of chili phytochemicals with ethanol as an extraction solvent (tincture). The current study experimentally tested the potential of hot water chili extract. Tincture chili extract was relatively more effective than hot water extract against P. xylostella. The current study further confirms that the absence of chili extracts in dry conditions enhances the recruitment of the pest, P. xylostella. Furthermore, the tincture extract was also capable of withstanding rainy days due to its adhesive phytochemicals. Keywords: Plutella xylostella, tincture, hotwater, rainfall, relative humidity

Toxicity of insecticidal plant oils on the larval and adult stages of a major malaria vector (Anopheles gambiae Giles 1920)

Despite increasing reports and concerns about the development of resistance to public-health insecticides in malaria vectors, significant progress has been made in the search for alternative strategies to disrupt the disease transmission cycle by targeting insect vectors and thus sustaining vector management. The use of insecticidal plants is a strategy that can be employed and this study investigates the toxicity potential of insecticidal plant oils shortlisted in an ethnobotanical survey on Anopheles gambiae larvae and adult stages. The shortlisted plants parts, the leaves of Hyptis suaveolens, Ocimum gratissimum, Nicotiana tabacum, Ageratum conyzoides, and Citrus sinensis fruit-peel were collected and extracted using a Clevenger apparatus. Larvae and female adults of deltamethrin-susceptible Anopheles gambiae were obtained from an already-established colony at the University of Ilorin's Entomological Research Laboratory. In five replicates, twenty-five third instar stage larvae were used for larvicidal assays and twenty 2-5days old adults were used for adulticidal assays. After 24h, An. gambiae exposed to Hy. suaveolens and Ci. sinensis exhibited significantly higher larval toxicity (94.7-100%). The mortality induced by the oils of the four plants peaked at 100% after 48h. Ni. tabacum (0.50mg/ml) induced the highest percentage of adult mortality on An. gambiae (100%) when compared to the positive control Deltamethrin (0.05%). The lowest KdT50 was observed with 0.25mg/ml of Ni. tabacum (20.3min), and the lowest KdT95 was observed with 0.10mg/ml of Ag. conyzoides (35.97min) against adult An. gambiae. The evaluated plant oils demonstrated significant larval and adult mortality rates, lower lethal concentrations, and knockdown times, indicating promising results that can be further developed for malaria vector management.

Systematic and Toxicological Study with Synergy of the Mosquitoes in EL Kantara Region (Biskra, Southern Algeria)

Abstract Recent years have seen the re-emergence of vector-borne diseases, representing more than 17% of infectious diseases globally. Most of these diseases can be prevented by vector control measures. Series of difficulties which are linked to the fight. Plant insecticides can present interesting alternatives to the chemical insecticides currently used in the fight against these pests. In the first part, we have inventoried the vector species in the region of El Kantara, Biskra, by conducting surveys of three sites. The second part focuses on the biological control of the larvae of the most abundant species in the region, that is, Culiseta longiareolata. The faunal inventory of the species of Culicidae in the three sites of El Kantara showed seven species belonging to three genera. The genus Culiseta was the best represented, particularly with the species C. longiareolata (89.91%). The toxicological activity of the ethanoic extracts of the seeds of Peganum harmala and Citrullus colocynthis was studied in synergy against the larvae of Culiseta longiareolata at different concentrations. The mortality rate increased over time to reach more than 70% after 5 days.

Insecticidal plants as trade opportunities and use by small vegetable producers: an example using essential oils to control Diaphania hyalinata (Lepidoptera: Crambidae).

Production and sale of botanical insecticides depend on knowing the potential opportunities for these products. Essential oils from plants secondary metabolism can control pests, especially in agricultural systems where synthetic insecticides are limited, as in organic agriculture. The objective of this study was to evaluate the toxicity of essential oils to Diaphania hyalinata (Lepidoptera: Crambidae) and to show regions with the potential to use Cinnamomum zeylanicum, Citrus sinensis, and Syzygium aromaticum in the formulation and commercialization of insecticides to control this insect. The C. zeylanicum oil was more toxic to larvae and pupae and the S. aromaticum to eggs of D. hyalinata. Essential oils are an alternative for the management of D. hyalinata. The production of pesticides from essential oils of C. zeylanicum, C. sinensis, and S. aromaticum to control D. hyalinata has high potential in America. Also, Asia, Africa, Europe, the Middle East, and Asia can extract these plants to formulate insecticide molecules for the America countries.

EFEKTIVITAS INSEKTISIDA NABATI DALAM MENGENDALIKAN HAMA KUTU PUTIH (Paracoccus marginatus) PADA TANAMAN PEPAYA (Carica papaya L.)

Papaya (Carica papaya L.) cultivation gets a lot of disturbances such as pests or diseases that can reduce the quality and quantity of papaya fruit. The use of vegetable insecticides is effective in controlling pests and has potential as a plant insecticide such as citronella, neem and cloves. This study aims to determine daily mortality and obtain the most effective botanical insecticides in controlling mealybug pests on papaya plants. The study consisted of two stages: (1) assessing the percentage of daily mortality, (2) the effectiveness of citronella oil, neem extract and clove oil vegetable insecticides on papaya seedlings. Daily mortality data were calculated using the daily mortality formula and data on the effectiveness of vegetable insecticides were analyzed using analysis of variance. The results showed that the highest percentage of mortality by giving citronella oil had a 24-hour daily mortality percentage and clove oil at a 48-hour daily mortality percentage. Botanical insecticides had an effect on all observation parameters, plant height, number of leaves and stem diameter, while the most effective treatment in controlling the mealybug P. marginatus treatment N1 was citronella oil with a concentration of 1 cc/500 mL.

Transgenic plants — a threat to local flora?

The paper covers major threats associated with wide-range introduction and cultivation of transgenic plants due to germplasm mixing with that of indigenous species of natural plant communities and risks of transgenic plants adverse impact on the environment. Among them are: influencing non-target species, invasive power, possibility of GMPs escaping into the environment by horizontal gene transfer as well as harmful effect on the soil biota.
 Currently, herbicide- and pest-resistant genetically modified plants (GMP) became an integral part of contemporary agrotechnologies in many economies [1]. However, most countries lack national strategy providing science-based substantiated procedure of creating, distribution and safe production of GMP. Rapid development of agricultural biotechnology and GMP production offered many economical benefits but also caused concern due to their potential environmental impact. To date, truly negative effects of GMP production, revealed in the course of growing, are known: harmful effect of entomocide Cry-proteins (Bt endotoxins) on non-target biota, target phytophage resistance to insecticidal plants, phytophage species succession to replace the species eliminated in the agrocoenosis. Vertical transfer of GMP transgenes (repollination between transgenic plants and wild species or isogenic varieties), as well as slow decomposition of transgenic plants remains all these factors can have remote environmental consequences [2, 3]. Wind-dispersed pollen of insecticidal GMP contaminates soil and open water reservoirs by toxins, thus posing potential hazards for aquatic organisms and geobionts (including rhizospheric organisms).
 Thus, uncontrolled GMP production and introduction, creates a real threat of losing biodiversity and genetic diversity of indigenous plants due to biological contamination. Therefore, GMP cultivation and monitoring in the fields is of exceptional importance and must be regulated by a science-based national strategy. This strategy would allow to exclude agroecological and environmental genetic risks, to keep the genetic diversity of natural plant communities.

Effects of phytocompound Precocene 1 on the expression and functionality of the P450 gene in λ-cyhalothrin-resistant Spodoptera litura (Fab.).

Spodoptera litura (Fabricius) is an agriculturally significant polyphagous insect pest that has evolved a high level of resistance to conventional insecticides. A dietary assay was used in this work to assess the resilience of field populations of S. litura to λ-cyhalothrin. Analysis of the function and expression of the cytochrome P450 gene was used to test the sensitivity of S. litura larvae to sub-lethal concentrations of the insecticidal plant chemical Precocene 1, both by itself and in combination with λ-cyhalothrin. The activity of esterase enzymes (α and β) was found to decrease 48h post treatment with Precocene 1. The activity of GST enzyme and cytochrome P450 increased with Precocene 1 treatment post 48h, however. Expression studies revealed the modulation by Precocene 1 of cytochrome P450 genes, CYP4M16, CYP4M15, CYP4S8V4, CYP4G31, and CYP4L10. While CYP4M16 expression was stimulated the most by the synergistic Precocene 1 + λ-cyhalothrin treatment, expression of CYP4G31 was the most down-regulated by Precocene 1 exposure. Hence, it is evident that λ-cyhalothrin-resistant pest populations are still sensitive to Precocene 1 at a sublethal concentration that is nevertheless capable of hindering their development. Precocene 1 can therefore be considered a potent candidate for the effective management of insecticide-resilient S. litura.

COMBINATION OF ANNONA MURICATA LINN SEED AND CLOVE (SYZYGIUM AROMTICUM) SEED EXTRACT AS A BIOINECTICIDE AGAINST HOUSEHOLD COCKHOUSES (PERIPLANETA AMERICANA)

Plants that are potential sources of plant insecticides, one of which is soursop. The active component of soursop seeds is acetogenin, which is considered to be larvicidal, and the azitogenin it contains is also an insecticide, acaricide, antiparasitic, and bactericidal agent. Another alternative to plants that can be used as herbal insecticides, besides soursop fruit seeds, is the clove leaf, which contains essential oil chemicals such as eugenol and other ingredients traditionally used to control cockroaches. The aim of the study was to determine the effect of soursop seed and clove leaf extract as a bioinsecticide in the control of vector cockroaches. This type of study is a real experiment with a research sample of 288 cockroaches. The results of this study showed that the extract of soursop seeds and clove leaves at a concentration of 80% caused the death of 14 cockroaches. The effectiveness level of soursop seed extract and clove leaves in the fight against domestic cockroaches is 80% concentration.

Thiamethoxam in soybean seed treatment: Plant bioactivation and hormesis, besides whitefly control?

Amid concerns on the myriad of existing chemical stressors in agroecosystems, pesticides and particularly neonicotinoid insecticides are in the forefront. Despite that, these neurotoxic compounds remain the dominant group of insecticides in worldwide use with the added versatility of use in seed coatings. Such use sparks environmental concerns counterbalanced by their reported insecticidal efficacy and potential plant bioactivation. Nonetheless, this alleged double benefit and interconnection expected with neonicotinoids has been little explored particularly when the whole plant phenology is considered. Regardless of the expected efficacy against targeted insect pest species, like whiteflies, neonicotinoids may spark dual effect on plants – negative at higher concentrations, positive at low concentrations, which is consistent with the hormesis phenomenon that may be expressed as a plant bioactivation. This effect may also cascade to the targeted insect species, what deserves attention. Therefore, soybean seeds treated with increasing concentrations of the neonicotinoid thiamethoxam were followed throughout their development in greenhouse, recording the plant response and yield, besides their effect in whiteflies (Bemisia tabaci MEAM1). Thiamethoxam application was correlated to leaf contents of thiamethoxam and its metabolite clothianidin. Plant hormesis was found for leaf area and root growth, but not for other plant morphological or physiological parameters, nor plant yield. The insecticide concentration-dependency compromised whitefly population growth without evidence of cascading any plant-mediated hormesis to the insects. Thus, although plant hormesis was recognized with thiamethoxam in treated soybean seeds in relevant parameters, no evidence of plant bioactivation was observed to justify its use with such a secondary objective, nor did this hormesis impair whitefly control.

Biological Profiling of Essential Oils and Hydrolates of Ocimum basilicum var. Genovese and var. Minimum Originated from Serbia

The genus Ocimum has many species that are used to treat diverse kinds of illnesses and sicknesses from ancient times. One of them, Ocimum basilicum L., commonly known as basil, has a vital role due to its various medicinal goods. It is best known as a plant with pharmacological activities, but also as an antioxidant, antimicrobial, and larvicidal agent. Although it has been traditionally used in Serbia in traditional medicine for centuries as an insecticidal, antibacterial, and antifungal plant as well as a traditional culinary plant, none of the O. basilicum varieties have been commercialised until today. There are significant numbers of information across the world that oils and by-products are part of the global market, but no references to the essential oil composition of Serbian plants were found. Therefore, the objective of this work was to evaluate the antioxidant and antimicrobial potentials of essential oil and hydrolate of two different varieties: O. basilicum var. genovese and Ocimum. basilicum var. minimum originating from Serbia for further industrial production of antimicrobial- and/or antioxidant-valued products. The results of this study confirm that essential oils of O. basilicum var. genovese and var. minimum represent a significant source of bioactive compounds, especially linalool, with a high rate of biological activities. Similar behaviour is observed for hydrolates, which are the by-product of the essential oil distillation process and can be utilised as bioactive-rich waste in further investigation.

Mosquitoes' larvicidal activity of Phoenix dactylifera Linn extracts against Aedes aegypti

Aedes aegypti mosquitoes are inducers of viruses such as DENV and ZIKV when they bite a person, which could lead to clinical symptoms like fever, headache, and rashes. This contemporary study aspired to examine the insecticidal potency of different extracts of the seed of Phoenix dactylifera on larvae of Aedes aegypti. The cold maceration process was used for the extraction of an accurately weighed 100 g of the finely powdered seed of P. dactylifera plant using hexane, petroleum ether, and methanol with strong handshaking for 48 hours. Methanolic extract of P. dactylifera showed 52% mortality at 1000 ppm and 20% dead at 500 and 250 ppm, respectively, and showed no larvicidal potency at 125 ppm against the fourth instar larvae of Ae. aegypti. Whereas hexane and petroleum ether seed plant extracts were found to be equally less effective against the fourth instar larvae of Ae. aegypti species, both showed 20% and 12% at 1000 and 500 ppm, respectively. The various concentrations of P. dactylifera extracts of hexane, petroleum ether, and methanol induced the larvicidal potency (LC50) after 24 h against IV instar larvae of Ae. aegypti were 2049.229, 2049.229, and 984.488 ppm, respectively. It was concluded that the seed extracts of P. dactylifera are potential candidates to be utilized as novel plant insecticides in curbing the spread of DENV and ZIKV disease vectors.

Efficacy of binary combinations of powders from selected botanicals against Callosobruchus maculatus Fabricius damage in stored cowpea seeds

The efficacy of powder mixes of two different insecticidal plants against Callosobruchus maculatus Fabricius was determined at the Entomology Research Laboratory, Department of Crop, Soil and Pest Management of the Federal University of Technology, Akure, Ondo State, Nigeria, under ambient laboratory conditions of 26 ± 4° C and 65 ± 10% RH. The powder combinations were made from Azadirachta indica leaf Thaumatococcous daniellii rhizome Eugenia aromatica dry flower buds, seeds of Piper guineense and rhizome of Zingiber officinale in a 1:1 ratio. The binary combinations were assessed at the dosages of 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 g per 20 g of cowpea seeds in separate 250 ml plastic containers with lids, against five pairs of newly emerged C. maculatus adults. Insect mortality was recorded 24, 48 and 72 hours post treatment and the number of F1 adult emergence was recorded after up to 35 days post treatment. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale produced 60% and 53% mortality respectively, of adults of C. maculatus at the lowest tested dosage (0.2 g/20 g of grain), and 100% and 83% mortality respectively, at the highest tested dosage (2.0 g/20 g of grain). Oviposition and progeny production of C. maculatus were also significantly lower in treatments involving the use of these two combinations; significantly fewer seeds bore beetle eggs and adult exit holes. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale may be included in pest management strategies for mitigating C. maculatus damage to stored cowpea.

The UDP-Glycosyltransferase Gene Family in Achelura yunnanensis (Lepidoptera: Zygaenidae): Identification, Phylogeny, and Diverse Expression Patterns

The caterpillars of the Lepidoptera are important herbivores as most of them belong to serious agricultural and forestry pests. To adapt to their habitats and feeding host plants, the larvae utilize uridine diphosphate (UDP)-glycosyltransferases (UGTs) to metabolize plant defensive compounds and insecticides. However, information on the UGT gene family in Achelura yunnanensis remains scarce. Here, we characterized the UGT genes through gene identification, phylogenic analyses, and comprehensive expression profiles regarding sexes, tissues, and stages. Transcriptome analyses led to the yields of 50 transcripts encoding UGTs in A. yunnanensis, representing a comparable gene number compared to those in other lepidopteran species. Sequence and phylogenetic analyses revealed a low amino acid identity of 28.23% among 31 full-length AyunUGTs, but some members shared relatively high conservation (>50% identities) with a phylogenetically clustered distribution. In addition, the majority of AyunUGTs possessed conserved residues involved in the catalysis and sugar-donor binding. Combining RNA sequencing and PCR approaches, a number of AyunUGTs were found to have the expression in chemosensory or detoxification tissues, possibly associated with the sensing of odorant molecules and the metabolism of toxic chemicals. More importantly, at least 27 AyunUGTs displayed detectable expression in reproductive tissues of both sexes. This study identifies candidate A. yunnanensis UGTs responsible for detoxification, olfaction, and reproduction, allowing us to address putative roles of UGTs in the adaptation of larvae to the habitats and feeding hosts.

Micro-Scale Liquid Smoke Extraction as a By-Product from Coconut Shell Charcoal Production in Kotabatu Village

Liquid smoke is produced from the pyrolysis process and condensation from the coconut shell waste combustion process. This liquid smoke is known to have a high level of polyphenol content and is used as a rubber processing, deodorizing, and wood preservative to make it resistant to termites. In addition, it can also be used as an insecticide for plants. This community service is carried out to design and manufacture a micro-scale liquid smoke pyrolysis machine, which is expected to reduce the amount of smoke produced during the charcoal burning process, also to help partners create an additional type of product, namely liquid smoke. for plant insecticides so that it will increase partners' monthly income. The method that will be used in achieving this goal is to provide training and practice to partners on how to process cranium waste other than into charcoal, namely into liquid smoke as an insecticide in plants.

BIO-EFFICACY OF GROUNDED SESAMUM RADIATUM AND PSORALEA CORYLITOLIA ON EMERGENCE OF ANOPHELES GAMBIAE AND CULEX QUINQUEFASCIATUS

Mosquito larvae are highly distributed species in tropical regions where breeding sites are diverse and causing a number of public health diseases, when they emerge. This study tested the efficacy of two grounded insecticidal plant powders against the emergence of Anopheles and Culex species. Larvae of mosquitoes were collected using 350mL deep ladles and scooping spoon from Ethiope East LGA, Delta State, Nigeria. The mosquito larvae were exposed to 0.5, 1.0, and 1.5g of Psoralea corylitolia and Sesamum radiatum in 100mL of water. This corresponded to 0.005, 0.01, and 0.015g/mL concentration of experimental set up respectively. Mosquitoes were exposed to these treatments in 20 larvae per concentration in quadruplicates. Mean mortality and time of mortality were recorded. Probit model was used to determine LT50 and LT95. Mortality of larvae increased as concentration and time increased. Highest mortality was recorded in Culex mosquitoes exposed to 1.5g of Psoralea corylitolia and was closely followed by Anopheles mosquitoes exposed to same concentration of Sesamum radiatum. The differences between the mortalities were highly significant (P<0.00001). Emergence depreciated as the concentration increased with high mortality especially with 0.5g of Psoralea corylitolia exposed to Anopheles mosquito larvae. The insecticidal test plants did not determine the sex of mosquitoes and it was not significant (F sex ratio=1.127; P=0.357). Physicochemical parameters supported the mortality of both larvae exposed to Sesamum radiatum from 30 minutes till end of the post experimental exposure. Lethal time for 50% of mosquitoes ranged from 31 to 5858min whereas LT95 ranged from 1435 to 10218min for the two insecticidal test plants respectively. There is need for more study with the trial of oil of Sesamum radiatum and the determination of the gas chromatograph of this novel plant to ascertain the active components.

Insecticidal Triterpenes in Meliaceae: Plant Species, Molecules and Activities: Part Ⅰ (Aphanamixis-Chukrasia).

Plant-originated triterpenes are important insecticidal molecules. The research on insecticidal activity of molecules from Meliaceae plants has always received attention due to the molecules from this family showing a variety of insecticidal activities with diverse mechanisms of action. In this paper, we discuss 102 triterpenoid molecules with insecticidal activity of plants of eight genera (Aglaia, Aphanamixis, Azadirachta, Cabralea, Carapa, Cedrela, Chisocheton, and Chukrasia) in Meliaceae. In total, 19 insecticidal plant species are presented. Among these species, Azadirachta indica A. Juss is the most well-known insecticidal plant and azadirachtin is the active molecule most widely recognized and highly effective botanical insecticide. However, it is noteworthy that six species from Cedrela were reported to show insecticidal activity and deserve future study. In this paper, a total of 102 insecticidal molecules are summarized, including 96 nortriterpenes, 4 tetracyclic triterpenes, and 2 pentacyclic triterpenes. Results showed antifeedant activity, growth inhibition activity, poisonous activity, or other activities. Among them, 43 molecules from 15 plant species showed antifeedant activity against 16 insect species, 49 molecules from 14 plant species exhibited poisonous activity on 10 insect species, and 19 molecules from 11 plant species possessed growth regulatory activity on 12 insect species. Among these molecules, azadirachtins were found to be the most successful botanical insecticides. Still, other molecules possessed more than one type of obvious activity, including 7-deacetylgedunin, salannin, gedunin, azadirone, salannol, azadiradione, and methyl angolensate. Most of these molecules are only in the primary stage of study activity; their mechanism of action and structure–activity relationship warrant further study.

Natural Products: Are They Efficient Alternatives against the Stored Grain Pest Sitophilus zeamais?

Cereal crops strongly contribute with the world economy and because of this the reduction of their productivity may lead to irreparable economic consequences worldwide. The maize weevil Sitophilus zeamais is the main pest of maize in the field or during processing, storage and commercialization of grains, also attacking processed food. The population control of S. zeamais uses a restrict panel of synthetic insecticides which are associated with environmental contamination, selection of resistant individuals and toxicity to non-target organisms, including humans and other animals. This scenario has stimulated the search for new insecticides and plant metabolites stand out because of their high degree of biodegradability and more selective toxicity. This work provides a review of the effect of plant compounds on S. zeamais to encourage the use of these ingredients in more ecofriendly strategies for pest control. Plant insecticides can exert their toxicity by ingestion, contact and/or fumigation resulting in damage to the development, survival and reproductive potential of S. zeamais, or may present food deterrent activity, which protects the substrates from the attack by the insects. The data reviewed contribute to consolidate the use of natural products in control of S. zeamais.

Field assessment of a pulse width modulation\xa0(PWM) spray system applying different spray volumes: duty cycle and forward speed effects on vines spray coverage

The pulse width modulation (PWM) spray system is the most advanced technology to obtain variable rate spray application without varying the operative sprayer parameters (e.g. spray pressure, nozzle size). According to the precision agriculture principles, PWM is the prime technology that allows to spray the required amount where needed without varying the droplet size spectra which benefits both the uniformity of spray quality and the spray drift reduction. However, some concerns related to the effect of on–off solenoid valves and the alternating on/off action of adjacent nozzles on final uneven spray coverage (SC) have arisen. Further evaluations of PWM systems used for spraying 3D crops under field conditions are welcomed. A tower-shaped airblast sprayer equipped with a PWM was tested in a vineyard. Twelve configurations, combining duty cycles (DC: 30, 50, 70, 100%) and forward speeds (FS: 4, 6, 8 km h−1), were tested. Two methodologies, namely field-standardized and real field conditions, were adopted to evaluate the effect of DC and FS on (1) SC variability (CV%) along both the sprayer travel direction and the vertical spray profile using long water sensitive papers (WSP), and (2) SC uniformity (IU, index value) within the canopy at different depths and heights, respectively. Furthermore, the SC (%) and deposit density (Nst, no stains cm−2), determined using short WSP, were used to evaluate the spray application performances taking into account the spray volumes applied. Under field-controlled conditions, the pulsing of the PWM system affects both the SC variability measured along the sprayer travel direction and along the vertical spray profile. In contrast, under real field conditions, the PWM system does not affect the uniformity of SC measured within the canopy. The relationship between SC and Nst allowed identification of the ranges of 200–250 and 300–370 l ha−1 as the most suitable spray volumes to be applied for insecticide and fungicide plant protection products, respectively.

Plants with insecticidal potential used by ethnic groups in North-Central Nigeria for the management of hematophagous insects

Abstract. Adelaja OJ, Oduola AO, Abiodun OO, Adeneye AK, Obembe A. 2021. Plants with insecticidal potential used by ethnic groups in North-Central Nigeria for the management of hematophagous insects. Asian J Ethnobiol 4: 65-75. Studies on the traditional knowledge of insecticidal plants are vital in the discovery of bioactive components for the management of hematophagous insects. This study investigated the ethnobotany and traditional knowledge of insecticidal plants among nine ethnic groups in North-Central Nigeria. Information on identifying insecticidal plants and their traditional knowledge among community leaders, elders, herb sellers, and herbalists was collected between January and December 2017, using a semi-structured questionnaire. The mentioned plants were collected and identified. A total of 388 respondents were interviewed from nine ethnic groups. All the respondents had knowledge of medicinal and insecticidal plants in their communities. The respondents mentioned 17 insecticidal plants. The most frequently mentioned plants were Hyptis suaveolens (19.6%, 76/388), Ocimum gratissimum (18.7%, 73/388), and Citrus sinensis (10.8%, 42/388). Hanging of plants in homes was reported among 52.9% of the respondents and smoldering for personal protection among 47.1%. The respondents also acknowledged that these plants were available (88.4%), accessible (77%), and very effective (76.3%) in controlling hematophagous insects. There was a significant relationship (P<0.05) between the perceived efficacy of these plants and the gender, age, educational status, and ethnicity of respondents. This study documented the knowledge and evidence of insecticidal plants among ethnic groups in North-Central Nigeria.