Pest Populations Research Articles

On the impact of re-mating and residual fertility on the Sterile Insect Technique efficacy: Case study with the medfly, Ceratitis capitata.

The sterile insect technique (SIT) can be an efficient solution for reducing or eliminating certain insect pest populations. It is widely used in agriculture against fruit flies, including the Mediterranean fruit fly (medfly), Ceratitis capitata. The re-mating tendency of medfly females and the fact that the released sterile males may have some residual fertility could be a challenge for the successful implementation of the SIT. Obtaining the right balance between sterility level and sterile male quality (competitiveness, longevity, etc) is the key to a cost-efficient program. Since field experimental approaches can be impacted by many environmental variables, it is difficult to get a clear understanding on how specific parameters, alone or in combination, may affect the SIT efficiency. The use of models not only helps to gather knowledge, but it allows the simulation of a wide range of scenarios and can be easily adapted to local populations and sterile male production. In this study, we consider single- and double-mated females. We first show that SIT can be successful only if the residual fertility is less than a threshold value that depends on the basic offspring number of the targeted pest population, the re-mating rates, and the parameters of double-mated females. Then, we show how the sterile male release rate is affected by the parameters of double-mated females and the male residual fertility. Different scenarios are explored with continuous and periodic sterile male releases, with and without ginger aromatherapy, which is known to enhance sterile male competitiveness, and also taking into account some biological parameters related to females that have been mated twice, either first by a wild (sterile) male and then a sterile (wild) male, or by two wild males only. Parameter values were chosen for peach as host fruit to reflect what could be expected in the Corsican context, where SIT against the medfly is under consideration. Our results suggest that ginger aromatherapy can be a decisive factor determining the success of SIT against medfly. We also emphasize the importance of estimating the duration of the refractory period between matings depending on whether a wild female has mated with a wild or sterile male. Further, we show the importance of parameters, like the (hatched) eggs deposit rate and the death-rate related to all fertile double-mated females. In general, re-mating is considered to be detrimental to SIT programs. However, our results show that, depending on the parameter values of double-mated females, re-mating may also be beneficial for SIT. Our model can be easily adapted to different contexts and species, for a broader understanding of release strategies and management options.

Deleterious effects of the endosymbiont Rickettsiella viridis in Myzus persicae are environmentally dependent

AbstractEndosymbionts living within insect cells can modify host fitness and could provide new tools for pest control. The endosymbiont Rickettsiella viridis has been transferred experimentally into the green peach aphid, Myzus persicae, a globally important agricultural pest. This Rickettsiella spreads via vertical and horizontal transmission and induces host fitness costs which could potentially suppress pest populations. Endosymbiont prevalence can fluctuate in natural populations, and it is important to identify factors that contribute to their spread or loss. Here, we explore the effects of Rickettsiella infection when aphids are reared on eight different host plants or exposed to thermal, starvation and desiccation stresses. Rickettsiella infection reduced M. persicae fecundity and longevity across all host plants, but the magnitude of costs varied among host plants and generations. Rickettsiella was horizontally transmitted and spread in caged populations at initial ratios of 1:2 Rickettsiella (+): Rickettsiella (−) on all host plants, but with limited long-term persistence under cycling 20–30 °C. We also identified temperature-dependent costs of Rickettsiella infection on heat knockdown time, chill coma recovery, and starvation tolerance. Finally, we present evidence that Rickettsiella infection reduces host activity levels under heat stress. Our results suggest that Rickettsiella infections induce a variety of deleterious effects but with complex environment-dependent interactions. This work helps understand ecological conditions that enhance or limit the spread of these endosymbionts in aphid populations.

Influence of abiotic factors on diapause termination and temperature requirements for postdiapause development in the European red mite, Panonychus ulmi (Acari: Tetranychidae).

The European red mite Panonychus ulmi (Koch) is widely distributed and it can severely affect pome fruit crops, particularly apple. Pest outbreaks are related to an overuse of non-selective pesticide treatments that lead to the development of resistance and the absence of natural enemies in the orchard. A key aspect to optimize the use of pesticide treatments in the context of IPM is to increase the knowledge on the biology and ecology of the pest to better predict population dynamics and outbreaks. For the European red mite, knowledge on the conditions that lead to diapause breaking by winter eggs is essential to model population dynamics. To increase this knowledge, winter eggs were collected during field surveys in northen Spain during three years and egg hatching was monitored under controlled temperature and photoperiod conditions in the laboratory. The "number of days exposed to cold temperatures" was the most significant factor that positively affected hatching of overwintering eggs. The time required for 50% of the egg population to hatch (T50%) was also negatively modulated by the duration of exposure to cold temperature. The temperature threshold for postdiapause eggs development collected from the field was estimated between 5 and 6 ºC in 2005 and 2007, respectively. Moreover, the degree-days required for post diapause development were estimated between 263.2 and 270.3, depending on the year of collection. Collectively, we provide additional information on the diapause termination and postdiapause development of the European red mite that may effectively contribute to optimize pest population models.

Lethal and sublethal effects of Citrus aurantium and Citrus sinensis essential oils and their major component limonene on Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an insect pest with great socio-economic importance in different agricultural regions worldwide. This species is highly adaptive and polyphagous, feeding on wild and cultivated host plants. Successive pesticide applications, which negatively affect the environment, are mainly used for managing H. armigera. Studies have investigated alternative methods with low environmental and socioeconomic impacts, including using essential oils. Essential oils are secondary plant-derived metabolites with insecticidal activity in different insect pest populations. Thus, the objective of this study was to evaluate the insecticidal activity of essential oils of Citrus aurantium (Linnaeus) (Rutaceae) and Citrus sinensis (Linnaeus) (Rutaceae) as well as their major component limonene on the biology and reproduction of H. armigera. The essential oils were characterized using gas chromatography-mass spectrometry. Further, their toxicity and the effects of their lethal and sublethal concentrations in larvae and on biological and reproductive parameters in adults were evaluated. All treatments exhibited insecticidal activity and lethal and sub-lethal effects on the biology and reproduction of H. armigera. Therefore, these essential oils could be used to control H. armigera.

Involvement of Chemosensory Protein CrufCSP3 in Perception of the Host Location in a Parasitic Wasp Cotesia ruficrus.

Chemosensory proteins (CSPs) constitute a class of olfactory proteins localized in insect sensory organs that serve a crucial function in decoding external chemical stimuli. This study aims to elucidate the involvement of CrufCSP3 in olfactory perception within the context of Cotesia ruficrus, an indigenous endoparasitoid targeting the invasive pest Spodoptera frugiperda. Through fluorescence-competitive binding assays and site-directed mutagenesis, we pinpointed four amino acids as pivotal residues involved in the interaction between CrufCSP3 and five host-related compounds. Subsequent RNA interference experiments targeting CrufCSP3 unveiled a reduced sensitivity to specific host-related compounds and a decline in the parasitism rate of the FAW larvae. These findings unequivocally indicate the essential role of CrufCSP3 in the chemoreception process of C. ruficrus. Consequently, our study not only sheds light on the functional importance of CSPs in parasitic wasp behavior but also contributes to the development of eco-friendly and efficacious wasp behavior modifiers for effectively mitigating pest population surges.

Modeling insect growth regulators for pest management.

Insect growth regulators (IGRs) have been developed as effective control measures against harmful insect pests to disrupt their normal development. This study is to propose a mathematical model to evaluate the cost-effectiveness of IGRs for pest management. The key features of the model include the temperature-dependent growth of insects and realistic impulsive IGRs releasing strategies. The impulsive releases are carefully modeled by counting the number of implements during an insect's temperature-dependent development duration, which introduces a surviving probability determined by a product of terms corresponding to each release. Dynamical behavior of the model is illustrated through dynamical system analysis and a threshold-type result is established in terms of the net reproduction number. Further numerical simulations are performed to quantitatively evaluate the effectiveness of IGRs to control populations of harmful insect pests. It is interesting to observe that the time-changing environment plays an important role in determining an optimal pest control scheme with appropriate release frequencies and time instants.

MODELING AND ANALYSIS OF OPTIMAL IMPLEMENTATION OF STERILE INSECT TECHNIQUE TO SUPPRESS MOSQUITO POPULATION

Sterile Insect Technique (SIT) is a biological insect (or pest) control tool aiming to reduce or eliminate wild insect (or pest) populations by releasing sterile insects (or pests). In this paper, we propose and study a stage- and sex-structured entomological model describing the dynamics of wild-type mosquito population and observed that the extinction equilibrium of the model is globally asymptotically stable when the basic offspring number is less than unity. However, when the basic offspring number is greater than unity, the extinction equilibrium becomes unstable, followed by the emergence of the stable interior equilibrium. We extend the model by introducing sterile male mosquitoes as a biological control agent against wild-type mosquito species. We have considered the Allee effect in the fertile female mosquito population due to the presence of non-egg-laying females in the mosquito population. While the wild mosquito-free equilibrium of the SIT model is always locally asymptotically stable, there exists either no interior equilibrium or a pair of interior equilibria, among which one is always unstable, and the other is always locally asymptotically stable. We observed that the wild mosquito population of the SIT system goes to extinction, followed by a saddle-node bifurcation when the supply rate of sterile males increases through some critical threshold value. As an alternative to the eradication policy, we formulated an optimal control problem to suppress the wild mosquito population, which suggests increasing the investment in awareness campaigns to suppress the mosquito population.

Crop Diversity in Agroecosystems for Pest Management and Food Production.

During the past 30 years, there has been a growing belief in and promotion of agroecosystem diversity for pest management and future food production as an agroecological or nature-based approach. Monoculture agriculture, which produces most of our food, is considered to be highly vulnerable to pests in contrast to plant species-diverse agroecosystems which may possess a greater abundance of natural enemies, keeping pest populations under control. In this paper, we question the role of crop diversity for pest management and explore the relationship between crop and associated diversity and pests through the following processes: environmental stresses that favor monodominance; evolutionary adaptations that resist insect herbivores (genetic resistance response); mechanisms of spatial escape from insect herbivores (escape response); and the role of crop-associated biodiversity. We present strong evidence that not only questions the high vulnerability of monocultures to pest damage but also supports why monocultures continue to produce most of the world's food. Reference is made to the importance of targeted plant breeding and the role of trans-continental crop introduction supported by efficient quarantine for pest management. We conclude that-with the exception of irrigated rice-much more research is needed to better understand the role of crop diversity in agroecosystems for pest management and food production.

Volatile chemical cues emitted by an agricultural companion plant (Cnidium monnieri) attract predatory lacewings (Chrysoperla sinica)

Plant volatiles play an important role in the recruitment of arthropod natural enemies and are widely used in foraging by many species. Therefore, identification of plants that release useful volatile organic compounds (VOCs) for influencing natural enemies and for the control of pests can be helpful in conservation biological control. Cnidium monnieri (L.) can convene many predatory enemies (lady beetles, hoverflies, lacewings) as a functional plant. The Chrysoperla sinica (Tjeder) is a dominant generalist predator, and can control the population of various pests in agricultural fields. However, how C. monnier recruits C. sinica and the chemical association between them is unknown. In this study, we tested the attractiveness of odor released by flowers and leaves of C. monnieri to C. sinica in Y-tube olfactometer. Next, we conducted solid phase microextraction (SPME), gas chromatography-mass spectrometry (GC–MS), and electrophysiological studies (EAG) to analyze the compounds and identified the volatile components which have effects on C. sinica. We also used a Y-tube olfactometer to verify the effectiveness of the volatile components on C. sinica under laboratory conditions. In olfactometer trials, C. sinica adults preferred flowers compared with leaves and fresh air. In GC–MS and electroantennography trials, seventy-six volatiles extracted from C. monnieri, twelve antenna-active components in three different concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL) were detected for electroantennography. In the last behavioral identification assays, four synthetic compounds (10 μg/mL) had significant attractiveness of adult C. sinica antenna (i.e., γ-terpinene, trans-β-Ocimene, nerolidol, (Z)-3-Hexen-1-ol). These studies suggest that there is a chemical association between natural enemies C. sinica and the functional plant C. monnieri. This study provides a basis that can facilitate the production and application of attracting natural enemy and development and application of enhancing attractants.

Within-tree distribution and seasonal dynamics of Eutetranychus banksi and Euseius stipulatus (Acari: Tetranychidae, Phytoseiidae) on citrus: Implications for the biological control of the pest

The Texas citrus mite, Eutetranychus banksi (McGregor) (Acari: Tetranychidae), is a citrus pest widely distributed throughout the Americas and recently introduced in Spain. In this study we studied the within-tree distribution of E. banksi and the predatory phytoseiid mites, identify the phytoseiid species associated with the pest, and describe the seasonal trends to analyse the predator’s behaviour in response to the increase in pest density, allowing evaluation of biological control possibilities. The Texas citrus mite was mainly found on the adaxial (upper) side of leaves from the current year's shoots located at the periphery of the tree canopy, whereas phytoseiids prefer the abaxial (lower) side of leaves inside the tree canopy. The spider mite preferred to feed on leaves rather than fruits, whereas phytoseiids use both substrates equally. Eutetranychus banksi showed a single population peak in late summer-early autumn, while phytoseiids showed two peaks, a main spring peak and a second less abundant in autumn. The seasonal dynamics of E. banksi and phytoseiids on fruits occurred in parallel to those recorded on leaves. Euseius stipulatus (Athias-Henriot) was the most frequent and abundant phytoseiid species, apparently displacing other predatory mites. In autumn, when E. banksi reached high densities, phytoseiids moved from the leaf abaxial sides inside the tree canopy to the adaxial sides on the periphery and to the fruits, to feed on E. banksi. In addition, a change in phytoseiid colouration from white to reddish-brown was observed. Both, the number of red phytoseiids and their leaf occupation increased significantly in response to the prey population growth, which was indirect evidence of their contribution to the biological pest control. However, the low predator:prey ratios observed cannot avoid the pest population growth.

An assessment of Organic and Conventional Farming Practices for Yield, Pest Management and Soil Health

This study contrasts and compares conventional and organic farming. The purpose of the study is to assess the effectiveness and impact of each practice before deciding on the best crop-growing approach. Despite their agricultural systems can be categorized as conventional or sustainable depending on the techniques employed. Organic farming which cultivates a range of crops without the use of synthetic manures, the agricultural method that is most sustainable. While producing enough food, organic farming improves soil composition and supports biodiversity by relying on ecosystem services. The review compares the long-term effects of conventional and alternative organic farming practices on yield in which in short term organic yields were found to be 19.2% lower than conventional yield while in long term yields were lower in conventional systems by 31% and 50%, respectively, due to the long-term improvement in soil health. In soil health point of view long term practices of organic farming improves physical, chemical and biological properties of soil by increase soil carbon stock by 12 %, more nutrient release and microbial activity. Pest management is effectively controlled by crop rotation, increase beneficial population of pest in organic farming which reduce the dependency on chemical pesticides and maintain the sustainability of soil health and ecology. As a result, organic farming methods are being evaluated in a large number of research worldwide as an alternative due to their better physical, chemical and biological qualities than conventional farming methods.

Role of integrated pest management in agriculture

Agriculture in India has a pivotal role in promoting food security, livelihoods and sustainable development, especially for the rural poor. However, it is increasingly affected by issues such as degradation of natural resources, increased frequency of extreme weather events and change in rainfall patterns that are linked to climate change. The population is also growing fast, affecting the demand for food and other agricultural products. Due to these factors and given the limited availability of agricultural land, the burden on the farming sector has increased manifold. The various crop plants are greatly affected by multifarious types of pests which not only result in reduced productivity figures but also distress the farmers as they get less revenue due to crop losses to these pests. Pest attack coupled with disease breakout sometimes results in suicidal situations as has been witnessed in our country. As such strong measures have to be taken up for bringing the pest attack to halt forthwith and reduce the incidence of pests. According to estimates by the Food and Agriculture Organization of the United Nations (FAO), East Asia (including China) and South Asia together account for more than half of pesticide use in developing countries in the world. Moreover, farmers often apply large quantities of highly toxic pesticide or even use banned or spurious ones, instead of less toxic alternatives. In order to overcome these negative effects Integrated Pest Management (IPM) offers an alternative that is safer for human and environmental health. Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates practices for economic control of pests. IPM is the best combination of cultural, biological and chemical measures to manage diseases, insects, weeds and other pests. As the global population is on the rise the demand of growing world population for food and fiber require farmers to produce more crops on existing farm land. IPM is a big part of the solution. Increasingly it is being adopted in both developed and developing countries for long-term, sustainable agriculture that achieves adequate, safe and quality food production. IPM does not, however, consist of any absolute or rigid criteria. As it is a flexible system that makes good use of local resources and the latest research, technology, knowledge and experience. The main of the IPM aims to suppress pest populations below the economic injury level (EIL).

Climate Change Impact on Insect Population in Vegetable Crops: A Review

One of the world's largest nations, India is known for its distinctive landscape, which distinguishes it as a distinct geographical entity and a global center of mega diversity. Pest populations in vegetable crops may be significantly impacted by climate change. Additionally, warmer temperatures can lead to faster insect development and increased reproductive rates. Farmers and researchers need to monitor these changes and develop strategies to mitigate the potential negative effects on vegetable crops. In response to climate change, whiteflies may exhibit shifts in their distribution patterns, population sizes, and behavior. They may also evolve certain traits that help them better survive in warmer or more variable climates.

A chromosome-level genome assembly of the soybean pod borer: insights into larval transcriptional response to transgenic soybean expressing the pesticidal Cry1Ac protein

BackgroundGenetically modified (GM) crop plants with transgenic expression of Bacillus thuringiensis (Bt) pesticidal proteins are used to manage feeding damage by pest insects. The durability of this technology is threatened by the selection for resistance in pest populations. The molecular mechanism(s) involved in insect physiological response or evolution of resistance to Bt is not fully understood.ResultsTo investigate the response of a susceptible target insect to Bt, the soybean pod borer, Leguminivora glycinivorella (Lepidoptera: Tortricidae), was exposed to soybean, Glycine max, expressing Cry1Ac pesticidal protein or the non-transgenic parental cultivar. Assessment of larval changes in gene expression was facilitated by a third-generation sequenced and scaffolded chromosome-level assembly of the L. glycinivorella genome (657.4 Mb; 27 autosomes + Z chromosome), and subsequent structural annotation of 18,197 RefSeq gene models encoding 23,735 putative mRNA transcripts. Exposure of L. glycinivorella larvae to transgenic Cry1Ac G. max resulted in prediction of significant differential gene expression for 204 gene models (64 up- and 140 down-regulated) and differential splicing among isoforms for 10 genes compared to unexposed cohorts. Differentially expressed genes (DEGs) included putative peritrophic membrane constituents, orthologs of Bt receptor-encoding genes previously linked or associated with Bt resistance, and those involved in stress responses. Putative functional Gene Ontology (GO) annotations assigned to DEGs were significantly enriched for 36 categories at GO level 2, respectively. Most significantly enriched cellular component (CC), biological process (BP), and molecular function (MF) categories corresponded to vacuolar and microbody, transport and metabolic processes, and binding and reductase activities. The DEGs in enriched GO categories were biased for those that were down-regulated (≥ 0.783), with only MF categories GTPase and iron binding activities were bias for up-regulation genes.ConclusionsThis study provides insights into pathways and processes involved larval response to Bt intoxication, which may inform future unbiased investigations into mechanisms of resistance that show no evidence of alteration in midgut receptors.

COMPARATIVE EFFICACY OF NEEM OIL DERIVATIVES WITH IMIDACLOPRID AGAINST OKRA JASSID, AMRASCA BIGUTTULA (ISHIDA)

The present research study was conducted at the experimental field condition of Pakistan Agricultural Research Council, Southern Zone Agricultural Research Centre, University of Karachi, to compare the field performance of different neem oil derivatives doses with Imidacloprid, sprayed on okra crop against the jassid population. The experiments were carried out RCBD with the application of four treatments, including three different concentrations of neem oils at (2%, 1.5%, and 1%) with the comparison of Imidacloprid pesticide and control. Neem oil was selected as a natural pesticide against jassid population reduction on okra crop. All the treatments were sprayed twice and data were recorded before 24h of pre-treatment and post-treatment at 48h, 72h, and 144h, respectively. The overall maximum reduction % after the application of Imidacloprid against the jassid population was calculated (61.51%) in 1st spray and (58.25%) 2nd spray, followed by (43.01%), (39.75%) at 2%, consequent to (32.50%), (29.75%), at 1.5% and (25.55%), (24.52%) at 1%, respectively. The maximum efficacy in neem oil concentration was recorded at 2% followed by 1.5%, and 1% but all neem oil concentrations including Imidacloprid observed effective from the 1st day up to the 6th post-spray days. All neem oil concentrations after 24h, 48h, 72h, and 144h of post-spray found significantly different at (P< 0.05). The application of neem oil, 2% caused the phytotoxicity reduction in okra plants. Thus, it is recommended that the bio-pesticide should be applied at 1.5% neem oil concentration against the jassid pest population.

Impact of Climate Change on Pest Biology, Behaviour and Their Distributions

Increased temperatures, rising CO2 levels, and changing precipitation patterns are influencing agricultural production. These changes can lead to the expansion of insect pests geographic distribution, increased survival during overwintering, more generations per year, altered synchrony with plants, changed interspecific interactions, higher risk of invasion by migratory pests, increased incidence of insect-transmitted plant diseases, and reduced effectiveness of biological control. There is a serious risk of economic losses in crop production. Human food security is challenged due to potential disruptions in agricultural systems. Climate change necessitates adaptive management strategies to address evolving pest dynamics. Future research should focus on developing modified integrated pest management tactics to cope with changing pest statuses. Monitoring climate and pest populations is crucial for understanding and predicting the impact of climate change on insect pests. This review examines the climate change effect on insect pest biology and behavior and explores the potential use of modern pest monitoring technologies, modeling prediction tools can aid in forecasting and planning for potential pest outbreaks. Integrated pest management (IPM) approaches should be adapted to incorporate the changing dynamics influenced by climate change. This may involve a combination of chemical, biological, cultural, and mechanical control methods.

A whole ecosystem approach to pear psyllid (Cacopsylla pyri) management in a changing climate

AbstractWhole ecosystem-based approaches are becoming increasingly common in pest management within agricultural systems. These strategies consider all trophic levels and abiotic processes within an ecosystem, including interactions between different factors. This review outlines a whole ecosystem approach to the integrated pest management of pear psyllid (Cacopsylla pyri Linnaeus) within pear (Pyrus communis L.) orchards, focusing on potential disruptions as a result of climate change. Pear psyllid is estimated to cost the UK pear industry £5 million per annum and has a significant economic impact on pear production globally. Pesticide resistance is well documented in psyllids, leading to many growers to rely on biological control using natural enemies during the summer months. In addition, multiple insecticides commonly used in pear psyllid control have been withdrawn from the UK and Europe, emphasising the need for alternative control methods. There is growing concern that climate change could alter trophic interactions and phenological events within agroecosystems. For example, warmer temperatures could lead to earlier pear flowering and pest emergence, as well as faster insect development rates and altered activity levels. If climate change impacts pear psyllid differently to natural enemies, then trophic mismatches could occur, impacting pest populations. This review aims to evaluate current strategies used in C. pyri management, discuss trophic interactions within this agroecosystem and highlight potential changes in the top-down and bottom-up control of C. pyri as a result of climate change. This review provides a recommended approach to pear psyllid management, identifies evidence gaps and outlines areas of future research.

Response of Whitefly Population to Rabbit Urine Foliar Spray on Tomato (Solanum lycopersicum L.)

Whiteflies greatly contribute to low yields and quality in tomato production. Continuous use of synthetic pesticides leads to whiteflies developing resistance to these pesticides. This research aimed at promoting the use of rabbit urine as a biopesticide against whiteflies in tomato production. Although rabbit urine is been used as a biopesticide against different pests, the best concentration to control whiteflies in tomato production is unknown. Six treatments compared in the two experiments of this study included: 2 L rabbit urine : 9 L water; 2 L rabbit urine : 6 L water; 2 L rabbit urine : 3 L water; 2 L rabbit urine : 0 L water; 0 L rabbit urine : 2 L water, and 20 mL Duduthrin 1.75EC : 20 L water. The first experiment was conducted in a randomized complete block design with six treatments and four blocks to investigate the effects of rabbit urine on the control of whitefly eggs, nymphs, and adults. The second experiment was conducted in a completely randomized design to determine the effect of rabbit urine on the bioactivity of adult whiteflies. Results indicated that plots treated with rabbit urine foliar spray registered reduced populations of whitefly eggs, nymphs, and adults, and lower LT50 values of repelling and killing compared to the negative control (0 L rabbit urine : 2 L water). However, a high ratio of rabbit urine caused significant scorching to tomato leaves. A solution of 2 L rabbit urine : 6 L water optimally controls whiteflies without scorching the plant foliage. Rabbit urine has both repelling and killing effects on whiteflies. In the future, further research can be conducted to investigate the effect of rabbit urine on populations of other important insect pests of tomato.

Dynamic Analysis of a Delayed Differential Equation for Ips subelongatus Motschulsky-Larix spp.

The protection of forests and the mitigation of pest damage to trees play a crucial role in mitigating the greenhouse effect. In this paper, we first establish a delayed differential equation model for Ips subelongatus Motschulsky-Larix spp., where the delay parameter represents the time required for trees to undergo curing. Second, we analyze the stability of the equilibrium of the model and derive the normal form of Hopf bifurcation using a multiple-time-scales method. Then, we analyze the stability and direction of Hopf bifurcating periodic solutions. Finally, we conduct simulations to analyze the changing trends in pest and tree populations. Additionally, we investigate the impact of altering the rate of artificial planting on the system and provide corresponding biological explanations.

Annotated checklist of ladybugs (Coleoptera: Coccinellidae) with nine new country records from Cambodia

Ladybugs (Coccinellidae) are commonly known for their beneficial roles in insect pest population suppression. Despite their importance and the limited scientific research conducted in Cambodia, the ladybug fauna needs to be documented in the country. Therefore, this study aims to establish the first checklist of Cambodian ladybug fauna including a brief taxonomic description and distribution for each species. We identified a total of 13 species based on the specimens deposited in the collection of Cambodian Entomology Initiatives. 9 of all species are newly recorded for Cambodia. Within this addition and six previously recorded species, ladybugs reached 15 species recorded from Cambodia. However, many new species are under-discovered in the country. The study provided a valuable baseline checklist for the taxonomy, diversity and ecology of ladybugs in Cambodia.