Pest Control Methods Research Articles

Age and Infectious Dose Significantly Affect Disease Progression after RHDV2 Infection in Naïve Domestic Rabbits.

Rabbit haemorrhagic disease virus 2 (RHDV2 or GI.2, referring to any virus with lagovirus GI.2 structural genes) is a recently emerged calicivirus that causes generalised hepatic necrosis and disseminated intravascular coagulation leading to death in susceptible lagomorphs (rabbits and hares). Previous studies investigating the virulence of RHDV2 have reported conflicting results, with case fatality rates ranging from 0% to 100% even within a single study. Lagoviruses are of particular importance in Australia and New Zealand where they are used as biocontrol agents to manage wild rabbit populations, which threaten over 300 native species and result in economic impacts in excess of $200 million AUD annually to Australian agricultural industries. It is critically important that any pest control method is both highly effective (i.e., virulent, in the context of viral biocontrols) and has minimal animal welfare impacts. To determine whether RHDV2 might be a suitable candidate biocontrol agent, we investigated the virulence and disease progression of a naturally occurring Australian recombinant RHDV2 in both 5-week-old and 11-week-old New Zealand White laboratory rabbits after either high or low dose oral infection. Objective measures of disease progression were recorded through continuous body temperature monitoring collars, continuous activity monitors, and twice daily observations. We observed a 100% case fatality rate in both infected kittens and adult rabbits after either high dose or low dose infection. Clinical signs of disease, such as pyrexia, weight loss, and reduced activity, were evident in the late stages of infection. Clinical disease, i.e., welfare impacts, were limited to the period after the onset of pyrexia, lasting on average 12 h and increasing in severity as disease progressed. These findings confirm the high virulence of this RHDV2 variant in naïve rabbits. While age and infectious dose significantly affected disease progression, the case fatality rate was consistently 100% under all conditions tested.

Soil, senescence and exudate utilisation: characterisation of the\xa0Paragon var. spring bread wheat root microbiome

BackgroundConventional methods of agricultural pest control and crop fertilisation are unsustainable. To meet growing demand, we must find ecologically responsible means to control disease and promote crop yields. The root-associated microbiome can aid plants with disease suppression, abiotic stress relief, and nutrient bioavailability. The aim of the present work was to profile the community of bacteria, fungi, and archaea associated with the wheat rhizosphere and root endosphere in different conditions. We also aimed to use 13CO2 stable isotope probing (SIP) to identify microbes within the root compartments that were capable of utilising host-derived carbon.ResultsMetabarcoding revealed that community composition shifted significantly for bacteria, fungi, and archaea across compartments. This shift was most pronounced for bacteria and fungi, while we observed weaker selection on the ammonia oxidising archaea-dominated archaeal community. Across multiple soil types we found that soil inoculum was a significant driver of endosphere community composition, however, several bacterial families were identified as core enriched taxa in all soil conditions. The most abundant of these were Streptomycetaceae and Burkholderiaceae. Moreover, as the plants senesce, both families were reduced in abundance, indicating that input from the living plant was required to maintain their abundance in the endosphere. Stable isotope probing showed that bacterial taxa within the Burkholderiaceae family, among other core enriched taxa such as Pseudomonadaceae, were able to use root exudates, but Streptomycetaceae were not.ConclusionsThe consistent enrichment of Streptomycetaceae and Burkholderiaceae within the endosphere, and their reduced abundance after developmental senescence, indicated a significant role for these families within the wheat root microbiome. While Streptomycetaceae did not utilise root exudates in the rhizosphere, we provide evidence that Pseudomonadaceae and Burkholderiaceae family taxa are recruited to the wheat root community via root exudates. This deeper understanding crop microbiome formation will enable researchers to characterise these interactions further, and possibly contribute to ecologically responsible methods for yield improvement and biocontrol in the future.

Identification of putative abdominal vibration-related genes through transcriptome analyses in the brown planthopper (Nilaparvata lugens)

The sexually mature female brown planthoppers (BPHs) send out abdominal vibration (AV) signals through the rice so that the males can obtain intraspecific, gender, and localization information to prepare for mating. Destroying vibration signals is an alternative biological method for pest control. However, the regulatory mechanism of AV in female BPHs remains elusive, which presents an obstacle to pest control. We observed that before mating female BHPs emitted abdominal vibration signals that disappeared immediately after mating and reappeared after 6 days. Therefore, ovarian and brain samples of female BPHs from Unmated-6h+ (with AV), Mated-6h− (without AV) and Mated-6d+ (with AV) individuals were collected for transcript analyses. By transcriptional sequencing analyses, 33 candidate genes that might involve in the regulation of female AV were obtained. After selecting 4 candidate genes of them for verification by RNA interference (RNAi), it was found that interference of juvenile hormone binding protein (JHBP) could greatly reduce the probability and frequency of AV for female BPHs. In general, this study identified AV-related candidate genes in female BPHs through transcriptome analyses and provided an important basis for future research on pest control in BPHs.

Copulatory Signaling and Polygamy of Glassy-Winged Sharpshooters (Hemiptera: Cicadellidae)

AbstractFinding a partner to mate with may be only part of ensuring successful siring of offspring. Females often exhibit cryptic female choice (CFC) during or after copulation, which can influence whose sperm from her multiple partners is chosen for egg fertilization. Known behavioral mechanisms for CFC include assessment of males by their nuptial gifts, duration of copulation, and seminal fluid contents. In this study, the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), behaviors during the course of copulation were investigated. Glassy-winged sharpshooter (GWSS) use vibrational communication before copulation occurs. However, little is known about behaviors that occur during and after copulation. Results from this study determined that vibrational signaling also occurs during copulation. Vibrational signals similar to those emitted during precopulatory communication were identified during copulation alongside a new, ‘hum-like’ signal that typically occurred within 10 s after the pair joined in copulation. In addition, results determined the duration of copulation was on average of 15 h, though with a 10-h range (8.5–18.5 h) among observed male–female pairs. Finally, both males and females mated more than once. Collectively, results identified key reproductive parameters required for CFC to occur in GWSS. The study expands on the known animals that use CFC and emphasizes the role that copulatory vibrational communication may play setting the foundations for future more in-depth studies. Understanding of insect behaviors necessary for successful production of offspring is important from an ecological perspective and for development of pest control methods.

Development of novel green pesticide system by using cold plasma to control Plodia interpunctella in pistachio

Iran is the most important exporter of pistachios in the world. One of pistachio export challenges is the damage of pistachio by warehouse pests. Many efforts have been made to discover alternative methods of nontoxic pest control. To study the effect of the cold plasma jet on Plodia interpunctella of pistachio nut, three treatment variables were used by argon/air ratio, the plasma exposure time, and the power supply voltage. The results showed that increasing the power supply voltage has the greatest effect on the increased mortality of P. interpunctella compared to other variables. Also, the effect of the equal combination of air and argon gases was much higher than the effect of each alone. According to the optimal points obtained in mortality of P. interpunctella, plasma exposure time of 14.04 min, the voltage of 19.99 kV, and argon/air ratio of 51.65% cause the greatest increased mortality of P. interpunctella. Novelty impact statement Cold plasma can remove and control Plodia interpunctella. This method can be used as an alternative method to replace Conventional methods of pest control. Plasma exposure time of 14.04 min, the voltage of 19.99 kV, and argon/air ratio of 51.65% cause the greatest increased mortality of Plodia interpunctella.

Alternative Methods of Ant (Hymenoptera: Formicidae) Control with Emphasis on the Argentine Ant, Linepithema humile.

Simple SummaryAnts can be major pests to homeowners and other property owners. In the U.S., ants often rank as one of the most common and difficult-to-control pests around and in homes, businesses, and other facilities. Typically, ant control practices are conducted by licensed pest management professionals with sprays, baits, and granular products, containing various types of insecticides, applied to the outside perimeter of infested structures. Many of the insecticides used to control pest ants are harmful to non-target organisms, especially those in aquatic environments. To address these negative environmental impacts, research on alternative, generally low-impact and least toxic, ant control strategies has received a fair amount of attention. The underlying goal of this research is a reduction in human exposure to traditional insecticides. Examples of alternative approaches included in this review article include the use of essential oils and other chemicals as deterrents to ant nesting and foraging; ant trail pheromones as disruptants to foraging; mass trapping of ants; new gel baits containing extremely low concentrations of insecticide; and altering the behavior and distribution of ants by altering their access to food.Ants (Hymenoptera: Formicidae), especially the Argentine ant, Linepithema humile (Mayr), can be significant nuisance pests in urban and suburban environments. Conventional interventions have primarily relied on the use of chemical insecticides, namely fipronil and bifenthrin, applied as residual, contact treatments around the outside perimeter of infested structures. Despite tightening regulation limiting the scope of insecticide applications in urban settings, dependence on these products to manage ants continues, resulting in significant water contamination. The U.S. EPA, in response, has further restricted the use patterns of many insecticides used for ant control in professional and over-the-counter markets. The purpose of this review is to summarize the relevant literature associated with controlling nuisance pest ants, with emphasis on L. humile, without the use of liquid broadcast applications of EPA-registered insecticides while focusing on low-impact, alternative (to broadcast applications) pest control methods. Specific subsections include Trail Pheromone; Use of Behavior-Modifying Chemicals; Mass Trapping; Hydrogels, “Virtual” Baiting, and Exceedingly-Low Bait Concentrations; Food Source Reduction; Deterrents; and RNA Interference (RNAi).

Effect of RNAi targeting CYP6CY3 on the growth, development and insecticide susceptibility of Aphis gossypii by using nanocarrier-based transdermal dsRNA delivery system

RNA interference (RNAi) has been proved to be a viable method for agricultural pest control. Due to the limited uptake of dsRNA in hemiptera insects, this study used nanocarrier SPc (star polycation) transdermal delivery systems to deliver two truncated fragments (P1/P2) dsRNA of the CYP6CY3 for silencing this target gene in Aphis gossypii. After the cotton aphid was sprayed with the SPc + dsP1/P2 mixture, the expression level of target gene in SPc + dsP1 treatment group was not different from that in dsP1 group at 24 h, 48 h, and significantly lower than that in dsP1 group at 60 h, 72 h, respectively; and the expression level of target gene in SPc + dsP2 treatment group was not different from that in dsP2 group at 24 h, and significantly lower than that in dsP2 group from 48 h, 60 h, 72 h, respectively. In addition, the expression level was continuously silenced after spraying the SPc + dsP1/P2 mixture and significant reduced by 79.7% and 84.3% at 48 h compared with the H2O control group, the mortality rate reached 48.09% and 43.18% at 84 h, respectively. And the cumulative reproduction number of cotton aphids also decreased, but the cumulative death number of newborn nymphs had an increase trend, compared with the control groups. Bioassays after RNAi showed that the silencing of CYP6CY3 increased the susceptibility of the 4th instar aphid to imidacloprid, and increased mortality by 67.21% and 58.69% at 96 h, respectively. The life table parameters of the offspring from the 4th instar cotton aphids from the SPc + dsP1/P2 treatment groups showed that the offspring had a longer pre-reproductive period and post-reproductive period. The intrinsic growth rate was 0.231 ± 0.005, 0.210 ± 0.013 and the finite growth rate was 1.260 ± 0.007 and 1.234 ± 0.016 in the SPc + dsP1/P2 treatment group, these two parameters of the two groups were lower than that of the corresponding control，the population doubling time of the two groups was prolonged and the developmental duration was delayed. These results indicate that CYP6CY3 plays a key role in the growth, development, reproduction and detoxification ability in cotton aphids, and may be as a potential RNAi target for controlling aphids, laying the foundation for the development of new environmentally-friendly RNA pesticides in this field.

Farmer evaluation of pesticide seed-coating to control fall armyworm in maize

The arrival of fall armyworm (FAW) in Africa could cause large losses in maize production and affect food security. A new and promising technology to control the pest in the early stages of the maize plant's development is a seed-coating with the insecticide Fortenza Duo, developed by Syngenta and demonstrated in trials and demonstrations during the 2018/19 season in Zambia. Given the urgency of countering the invasion, this study was designed as a rapid and low-cost participatory evaluation of the technology, taking advantage of existing trials and demonstrations while adjusting the standard methodology to fit their lay-out and the timing of the study. The study was organized around an existing trial at the Zambia Agricultural Research Institute, where 44 farmers were invited at mid- and end-seasons, and six on-farm demonstrations organized by Syngenta, where 202 farmers were invited at the end of the regular production season. These evaluations were supplemented with a survey of 153 randomly selected farmers who hosted the demonstrations, and another 162 farmers from the same villages as control. The results showed that farmers scored seed-coated maize plots higher than other non-treated plots during the mid-season evaluation of the trial, but not higher than plots treated with other pesticides. At the end-season, seed-coated maize received slightly higher scores in the overall evaluation but did not score differently for FAW resistance. During the evaluation of on-farm demonstrations, farmers scored the seed-coated maize higher than average for several criteria, in particular for germination/crop stand and resistance to FAW and stalk borer, but the demonstrations did not include a control of untreated maize for comparison purposes. During the survey, however, farmers observed that only 50% of fields with seed-coated maize got infested with FAW vs. 80% in the control. Further, in fields with seed-coated maize FAW infestations occurred about two weeks later than in untreated maize plots. When choosing maize varieties, farmers indicated that yield, grain weight and germination were very important attributes, followed by drought resistance, number of cobs and grain size and, in seventh place, resistance to FAW. When choosing pesticides, farmers listed four criteria as important: convenience, low health risk, low cost, and labor requirements, and listed one criterion, odor, as of minor importance. We concluded that farmers generally evaluated the technology positively. The technology is likely to decrease infestation and damage by FAW, and fit the criteria of farmers in selecting maize seed and pest control methods. However, the results were not conclusive as the demonstrations did not include a proper control.

Efficacy of Diatomaceous Earth and Vitellaria paradoxa Seed Oil in Storage of Cowpea under Ventilated and Non-ventilated Conditions

Storage of cowpea is highly constrained by insect pest infestation and losses caused by the cowpea weevil (Callosobruchus maculatus, F.) are high. Several methods have been used over the years to protect cowpea grains in storage, but the use of synthetic insecticides is very dominant and this has led to problems, such as the killing of non-target species, user hazards, harmful food residues, and evolution of resistance to chemicals. A search for alternative insect pest control methods which are relatively less harmful to the user and cheaper has become essential. The effectiveness of Diatomaceous earth (DE) and Vitellaria paradoxa seed oil (VPSO) for cowpea storage in polypropylene and jute bags under ventilated and non-ventilated storeroom conditions were investigated over three months period. Crude DE was applied at a dose rate of 1 g/kg of cowpea and a diluted concentration (10% v/v) of VPSO of 400 mL was mixed with 8 kg of cowpea. Live insect count, dead insect count, and germination percentage were assessed weekly while proximate analysis was carried out before and after storage. Mean live insect count increased in the ventilated store-room from 0.67±0.34 to 36.13±19.51insects/kg after 1 month and 3 months of storage respectively for untreated cowpea. Insect population in treated samples increased from 0.38±0.26to 24.78±23.33, and from 0.17±0.30 to 10.75±5.27 for DE and VPSO treated samples, respectively. In the non-ventilated storeroom, insect population increased from 0.33±0.26 to 36.96±19.09 for untreated cowpea, 0.17±0.20 to 33.08±30.07 for DE and 0.21±5.63 to 8.17±11.30 for VPSO treated cowpea. Based on insect count, both treatments were very effective in controlling cowpea weevil in the first two months of storage, however their potency reduced by the third month. The potency of DE deteriorated faster compared to VPSO however, DE treated cowpea was most effective for retaining seed germination in both ventilated and non-ventilated storerooms. Proximate analysis showed that cowpea treated with both treatments had similar nutrient composition after storage. Diatomaceous earth and Vitellaria paradoxa seed oil have potentials in their raw form for short term insect pest control in the storage of cowpea.

Disruption of insect immunity using analogs of the pleiotropic insect peptide hormone Neb-colloostatin: a nanotech approach for pest control II

This work continues our studies on the pleiotropic activity of the insect peptide Neb-colloostatin in insects. In vivo immunological bioassays demonstrated that hemocytotoxic analogs of Neb-colloostatin injected into Tenebrio molitor significantly reduced the number of hemocytes in the hemolymph and impaired phagocytosis, nodulation and phenoloxidase activities in the insects. Among the analogs tested, [Ala1]-,[Val1]-, [Hyp4]- and [Ach4]-colloostatin were particularly potent in disrupting cellular immunity in larvae, pupae and adult insects. This result suggests that the most effective analogs showed increases in the bioactivity period in the hemolymph of insects when compared to Neb-colloostatin. Recently, we demonstrated that it is possible to introduce Neb-colloostatin through the cuticle of an insect into the hemolymph when the peptide is coupled with nanodiamonds. In this study, we showed that [Ala1]-, [Val1]-, [Hyp4]- and [Ach4]-colloostatin, when complexed with nanodiamonds, may also pass through the cuticle into the hemolymph and induce long-term impairments of immunity in T. molitor at all developmental stages. Studies on the tissue selectivity and effectiveness of Neb-colloostatin analogs and efficient methods for their introduction into insects may contribute to the development of eco-friendly pest control methods based on bioactive peptidomimetics.

Survival, development and reproduction of Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) under effects of insecticides used in tomato plants.

Agriculture depends on the correct use of different methods for pest control, however the cultivation methods adopted for Solanaceae demands numerous pesticide applications. These products can be either harmful or selective to beneficial organisms, such as Coccinellidae predators. The aim of this study was to assess the physiological selectivity of insecticides, registered for tomato pest control, on Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae). The maximum recommended field dosage of the insecticides spinetoram, spiromesifen, methoxyfenozide, metaflumizone, tebufenozide and methomyl was used. They were sprayed on eggs, third instar larvae, pupae and adults of H. axyridis using Potter´s tower; control treatment consisted of water. Methoxyfenozide didn't reduce any biological feature of the predator. Spiromesifen only reduced survival over time when sprayed on third instar larvae. Spinetoram shortened larval period and reduced survival of adults. When sprayed on larvae, metaflumizone reduced larval survival. Tebufenozide reduced egg viability, pupal period and larval survival over time. It is concluded that methoxyfenozide, spiromesifen and spinetoram are the least toxic to H. axyridis, and their usage should be prioritized in integrated pest management (IPM) programs; both tebufenozide and metaflumizone are harmful to some important biological features of the predator. Methomyl is highly toxic in controlled conditions, so its toxicity to H. axyridis should be confirmed in field and greenhouse tests, we also suggest further studies with the other compounds in different concentration and route of exposure.

Linking mango infestation by fruit flies to fruit maturity and fly pressure: A prerequisite to improve fruit fly damage management via harvest timing optimization

Fruit flies (Diptera: Tephritidae) are considered to be major pests of mango (Mangifera indica) worldwide. Their management, with an increasing focus on replacing synthetic pesticides with alternative pest control methods, is a challenging issue. A study was carried out from 2015 to 2017 in Reunion Island under field conditions in order to characterize the incidence of fruit flies on mango production and to link fruit fly infestation with fruit maturity and fly pressure. Mango fruits were mainly infested by Bactrocera zonata. Few fruits were infested by Ceratitis quilicii, and even fewer by Ceratitis capitata. Infestation increased as fruits ripened. Less than 4% of the fruits were infested at the green, green-mature and early yellow-point stages. Infestation increased to 10–11% at later yellow-point stages, and reached 14–16% at ripe and overripe stages. Fruit infestation was closely related to changes in the peel texture (firmness, in particular) and chlorophyll fluorescence of the fruit as it ripened. Whereas variability in fruit fly abundance in traps was observed between orchards and years, it did not clearly explain variability in fruit infestations, which was mostly explained by variability in fruit maturity. The study suggests that fruit fly trapping is not adequate to assess infestation risk or to guide management decisions, but instead provides evidence that fruit fly damage could be reduced by adjusting harvest timing, especially by harvesting fruits at the green-mature stage or at the yellow-point onset.

Resistance to Bemisia tabaci in tomato species and hybrids and its association with leaf trichomes

Chemical insecticides comprise the most widely used method of tomato pest control. Genotypes resistant to pests such as the silver leaf whitefly Bemisia tabaci may contribute towards the decreased use of insecticides to protect the environment. Leaf trichomes play a role in imparting resistance to pests, and exploiting intraspecific and interspecific variability for leaf trichomes in the tomato gene pool is an alternative to speed up introgression of resistance into improved lines or cultivars. We assessed the levels of whitefly resistance and trichome morphology/density in an array of accessions of the tomato gene pool and their hybrids with a tomato cultivar. A commercial cultivar (S. lycopersicum cv. Redencao), six wild species accessions, two S. lycopersicum var. cerasiforme genotypes, and eight intra and interspecific F1 hybrids were tested. The accessions LA 1401 (S. galapagense), AF 19684 (S. peruvianum), PI 127826 (S. habrochaites var. hirsutum), PI 134417 (S. habrochaites var. glabratum), LA 716 (S. pennellii), and RVTC 03 (S. lycopersicum var. cerasiforme) genotypes showed a higher density of glandular trichomes and carried the highest levels of whitefly resistance than the commercial cultivar. Segregating generations from their crosses with the cultivar may be promising sources to select plants with both higher density of glandular trichomes and resistance to whiteflies. Populations derived from S. lycopersicum var. cerasiforme’ RVTC 03’, which is part of intraspecific S. lycopersicum variability, maybe a more convenient source of pest resistance than those derived from interspecific crosses to obtain pest-resistant tomato cultivars.

Antimicrobial activity of essential plant oils and their major components

Development of bactericides and fungicides in terms of isolation and identification of substances is an important area of research. Presently, under the concept of integrated pest management, all possible plant pest and disease control methods are integrated to minimize the excessive use of synthetic chemicals and also the incidence of disease.The potential of various essential oils against Gram-positive and Gram-negative bacteria and fungi is being actively investigated in various laboratories across the world. Rice the most important crop, suffers from huge yield losses due to blast and blight diseases. Most of the labs have focussed to use transgenic approaches, the use of environmentally friendly natural products, as disease control strategies. In this context, we propose to evaluate the antimicrobial properties of essential oils and their ability to control diseases of rice. Seven Essential oils from seven different plants were selected for the study. The antimicrobial activity was assessed in terms of their antibacterial activity towards non-pathogenic bacteria and pathogenic drug resistant bacteria by means of their ability to sensitize the drug resistant bacteria in plasmid curing and, ß-lactamase inhibition and as antifungal agents. In conclusion, out of the seven essential oils used, lemongrass, palm rosa and eucalyptus were found to be good antimicrobial agents.

Potato protection against potato ladybird Henosepilachna vigintioctomaculata Motsch. (Coleoptera, Coccinellidae)

The results of the application of environmentally friendly methods of potato pest control are presented. Comparative field trials of insectoacaricides and microbiological preparations were carried out on potatoes of the recognized variety Yantar in the Primorsky Territory in 2018 and 2019. The object of research was the larvae and beetles of the potato ladybird Henosepilachna vigintioctomaculata. The tubers were planted at the optimal time for the region, late April – early May. The study used Fitoverm preparations based on aversectin C (50 g/l), Akarin based on avertin N (2 g/l), Batsikol based on the strain of Bacillus thuringiensis var. darmstadiensis (BtH10), Bitoxybacillin based on the strain of Bacillus thuringiensis var. thuringiensis (BtH1). The preparations were studied independently and with Corado insecticide. Potato plants were sprayed with the preparations once. Pest counts were carried out before treatment and after treatment on the 5th, 10th, 15th day on 10 potato plants in three replications in accordance with the approved methods. Bioinsecticide Fitoverm showed a high efficiency of 90.5–94.0% at the application rate of 0.16 l/ha. A single application of bioinsecticides for 15 days restrained the intensity of the pest development below the threshold level. The combined use of bioinsecticides and an insecticide against the potato ladybird provided a decrease in the phytophage population by 90.8–99.8% compared to the control variant (without the use of plant protection products). The inclusion of preparations of biological origin Fitoverm, Akarin, Batsikol, Bitoxybacillin in potato cultivation technology will allow to limit the number of potato ladybird and solve the problem of plant protection in an environmentallyfriendly way in the south of the Far East.

Evaluation of indigenous the nucleopolyhedrovirus (NPV) of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) in combination with chlorantraniliprole against Spodoptera species

BackgroundThe armyworms, Spodoptera exigua (Hübner), and S. litura (Fabricius) (Lepidoptera: Noctuidae) are polyphagous pests of many cash crops. Heavy crop losses have been reported for the fruit and vegetable crops each year owing to the diverse impact on global economies. The present study was aimed to sort out a novel method of pest control using the insect’s own nucleopolyhedrosis virus (NPV) alone and in combination with a new chemistry insecticide chlorantraniliprole.ResultsIn the study, the effect of indigenous isolated nucleopolyhedrovirus (NPV) and the chemical insecticide (chlorantraniliprole) formulations against the 2nd and 4th larval instars of S. litura and S. exigua, collected from the different geographical region of Punjab (Pakistan) province, was evaluated. Three concentrations of the NPV isolate, sub-lethal (1 × 104, 6 × 104 POB ml−1), lethal (3 × 105 POB ml−1), and chlorantraniliprole 0.01 μl l−1, were applied alone and in combination against the 2nd and 4th larval instars of both pest species. The lethal concentration of NPV + chlorantraniliprole exhibited synergistic interaction and caused high larval mortality against both instars, while in all other combinations, additive effect was observed. Moreover, NPV + chlorantraniliprole at lethal concentration exhibited decreased pupation, adult emergence, and egg eclosion.ConclusionThe implications of using NPV alone and in combination with an insecticide are discussed briefly in this study.

A documentation of plants used by rural small-scale farmers to control maize pests in the eastern cape province of South Africa

Maize(Zea mays L.)small-scale farmers in the rural areas of the Eastern Cape Province of South Africa are generally under-resourced, and as a result, their crops are vulnerable to pest attacks. The farmers often cannot afford farming implements and inputs, and tend to improvise with what is freely available in their surroundings. Regarding pests, farmers tend not to follow the conventional use of chemical insecticides and rather use alternative methods of control such as plant-based methods. Plant-based methods that are founded on formulations and plant combinations have been found to be eroding due to lack of documentation. This study sought to document the names of plants used in combinations and formulations and their preparation methods so that they can be further used to set a research agenda specific to affordable pest control methods for the Province. Surveys using the convenience and stratified purposive sampling techniques were conducted in selected rural areas of the Eastern Cape Province in order to investigate the plants, their combinations and formulations used by these farmers to control insect pests of maize. A total of 217 farmers were interviewed. Study protocols adhered to ethical standards set by the EasternCape Department of Rural Development and Agrarian Reform. Data were analysed using descriptive statistics, whereas percentages were calculated using Microsoft Excel (2010). Findings revealed that most of the plants used were from familiesSolanaceaeandAsteraceae. The most preferred plant was Chenopodiumambrosioides, a perennial herb from the family Chenopodiceae. Although, several arthropods were mentioned by farmers as pests of maize in their cultivation areas, the predominant targets of formulations and combinations were maize stalk borers. These insects were also cited as most troublesome. The common plant part used in combinations and formulations was the leaves. Thefindingsraisedtheneed for continuous scientific validation and documentation of indigenous pest control methods to bridge the generational gap and increase the range of their use.

Practices and constraints of tomato production among smallholder farmers in Uganda

Tomato(Solanum esculentum)is one of the most promising vegetables whose production is being intensified in Uganda. However, tomato yields remain low due to several constraints. The study aimed at identifying production and marketing practices, and constraints affecting tomato productivity in major tomato growing areas of Uganda. A survey was conducted in eight major tomato producing districts using a questionnaire to guide interviews for 240 farmers and 16 key informants. The data were analyzed using SPSS software. Results revealed that tomato production in Uganda is dominated by males who grow them on 0.68 acres of land on average. Mosttomatofarmers (78.4%) use mono cropping system with varietiesAsilla F1 (35.3%), Tengeru97(21.1%), Rambo (18.1%), NovelaF1(17.7%) and Riogrande (10.3%) dominating. The choice of tomato varieties used by farmers mainly depend on yield potential, pest and disease tolerance and market preference attributes such as long shelf life. In the study area, tomato is mainly fertilized using foliar fertilizers, followed by Diammonium phosphate and cattle manure. The key pests affecting tomato include caterpillars, thrips, worms and whitefly, while bacterial wilt, blight, leaf spots and viral infections are the major diseases. Majority (95.7%) of farmers use chemical sprays(pesticides and fungicides)and 4.3% of farmers used other control methods. The other methods of pest and disease control included rogueing, hand picking, ash, organic extracts, urine and frequent weeding. Average tomato yield was 4,846.3 kg/acre lower than the potential yield of 6000kg/acre. Thirty five percent of farmers market their tomato individually on-farm, 32.8% sell in rural markets, while 32.2% send to the nearest urban markets. The study revealed intensive chemical use accounting for 20% of the production costs, high seed costs (11%) and drought (10%) as the major production constraints impeding tomato production; and price fluctuations, low prices, high transport costs, post-harvest loss on farm, and poor market access as the major marketing constraints. The research findings will aid in the development of new market-oriented, highly productive tomato varieties with improved access to seed and designing initiatives to address production and marketing constraints, which will eventually enhance tomato production.

Toxic effect of chlorantraniliprole on new‐born larvae of the potato tuber moth Tecia solanivora (Lepidoptera: Gelechiidae)

AbstractThe potato tuber moth Tecia solanivora is an invasive species threatening potato crops and stored tubers. Previous studies have shown that South American populations of this species have evolved insecticide resistance to major classes of insecticides (i.e., pyrethroids, carbamates and organophosphates). Therefore, testing for other methods of pest control is of increasing importance. In this study, we evaluated the toxic effect of chlorantraniliprole against early immature stages of T. solanivora. We carried out a concentration–mortality bioassay using eggs. Subsequently, we subjected eggs to several insecticide application scenarios and evaluated hatching success, larvae activity and overall mortality of immature stages. Additionally, we analysed the hatching behaviour of larvae when the eggs were treated with chlorantraniliprole. After the concentration–mortality bioassay, we calculated an LC50 of 298.6 ppm, yet the mortality did not occur during the egg‐phase, but rather the neonate larvae experienced the toxic effects of chlorantraniliprole. In the subsequent exposure‐mode bioassay, the hatching success was overall high in all treatments, and larvae mortality reached 100% regardless of exposure mode. Consequently, larvae activity was severely reduced when in contact with the insecticide. Furthermore, when eggs are subjected to such LC50 dose, larvae manage to break through the chorion, but after releasing the legs, each hatching stages takes longer than the previous. Our results highlight the potential use of chlorantraniliprole for the control of T. solanivora in stored potato tubers. Additionally, chlorantraniliprole appears to be a promising alternative for the control of T. solanivora populations resistant to neurotoxic insecticides.

Assessment of pesticide residues level in watermelon fruits [Citrullus lanatus (Thunberg) Matsumura and Nakai] in Lower, Central and Upper Badibou Districts in North Bank Region, of the Gambia

Field and laboratory studies were conducted late 2019 in three districts of the Gambia’s North Bank Region; namely, Central Badibou, Lower Badibou and Upper Badibou to ascertain the pesticide residue level in watermelon fruit, determine the insect pest control methods, types of pesticide, frequency of application, and pre-harvest interval observed. Multistage sampling technique was used in selecting the research respondents. Eighty-five (85) farmers were identified; forty-five (45) were randomly selected as research respondents. Data was collected using structured questionnaires. SPSS Software was used to analyse the questionnaires and Gas Chromatograph to determine the pesticide residue level. Data obtained were analysed and compared with the European Union Maximum Residue Limit (MRL). The results of the analysis revealed that the farmers used chemical control method in watermelon production, and applied at frequency of once in every two weeks. Furthermore, the results indicated that the chemical applied at flowering stage and the pre-harvest interval (17-21 days) ranked the highest. The pesticides residues found in the watermelon samples were Dimethoate, Profenophos, Dicofol, Cypermethrin, Lambda-cyhalothrin, Permethrin and Deltamethrin and most were above the MRL. The presence of pesticides residues in the watermelon samples calls for strict regulation on the use of pesticides on watermelon. Further study is recommended in other fruits and vegetables grown in the country especially in the studied region.