Molecular characterisation, biology, behaviour and feeding potential of a novelpredator of the mango ecosystem: Sycanus bifidus (Fabricius, 1787)

The bagworm (Metisa plana) is a recurrent indigenous invasive defoliator in oil palm plantations. Moderate foliar injury can cost up to 40% yield loss and more for years. The main objective of this review is to disseminate published research demonstrating the versatile services that would benefit farmers by adopting the Asian weaver ant into their pest management agenda. Oecophylla smaragdina is a natural indigenous enemy applied as a successful biological control agent (BCA) and strong component of integrated pest management (IPM) against important damaging pest infestations of commercial crops in the Asia-Pacific region. Farmers facing invasion could benefit by introducing Oecophylla ants as a treatment. The foraging behavior and population dynamics of this species are poorly documented, and hence need further evaluation. Ants of the Oecophylla genus, while exhibiting an intrinsic obligate arboreal pattern, demonstrate additional lengthy diurnal ground activity. The absolute territorial characteristic via continuous surveillance is significantly valuable to maintain pest balance. The exploratory scheme of major workers over large territories is derived from their inner predation instinct. The insufficient understanding of the population dynamics of this weaver ant species diverges from the knowledge of underground species. However, population density estimations of weaver ants by direct nest visual recordings are practicable and viable. The abundance assessment of individual underground ant species colonies by excavation ends with their extinction, which is not a sustainable model for O. smaragdina. Mathematical model estimation by simulation could not resolve this issue, adding inaccuracy to the deficiency of experimental proof. Thus, long-term monitoring of the population dynamics in real time in the field is compulsory to obtain a valid dataset. Oecophylla colonies, with the criteria of population stability, individual profusion, and permanent daily patrol services, are eligible as a BCA and alternative IPM treatment. The last decades have witnessed the closing of the scientific applied research gap between Asian and African species in favor of O. longinoda with comprehensive novel findings. By introducing Oecophylla ants, two main goals are reached: easing the burden of management costs for injurious insects and ending the practice of applying highly toxic pesticides that are harmful to non-target taxa, thus promoting environmental restoration.

The escalating demand for sustainable and eco-friendly pest management strategies has raised interest in harnessing the pathogenic potential of microorganisms. Serratia marcescens, a Gram-negative bacterium, has emerged as a potential biological control agent for sustainable pest management. This review critically examines the history, biology, identification, and pathogenicity of S. marcescens strain with their potential application in pest management. The diverse mechanisms employed by the strain to exert control over pests, including the production of metabolites and the induction of systemic resistance in plants, are examined. The review also summarizes the ecological significance and global distribution of S. marcescens associated with the use of S. marcescens in biological control strategies. Furthermore, the usage efficacy of S. marcescens over other conventional chemicals is discussed. A comprehensive understanding of the pathogenic potential of S. marcescens strains as biological control agents is crucial for developing effective and sustainable pest management strategies. This review consolidates current research advances on S. marcescens, and provides insights into the prospects and challenges of using S. marcescens for integrated pest management.

Climate exerts powerful effects on the distribution and abundance of the earth's insect species, and we should expect climate warming to generate changes for many insect populations and the ecosystems they inhabit. A substantial scientific literature provides a foundation for describing how insect species are responding to recent climatic trends on the basis of insect physiology, and predicting generalised species distributions and population dynamics for the future. Warmer temperatures generally lead to more rapid development and survival in insects in mid‐ to high latitudes, which can account for detectable and unambiguous shifts in a range of insect species over the past half century. Increased warmth also advances the onset of insect life cycles for the many species that use thermal cues to match the timing of life history events with the changing seasons. Owing to their relatively short life cycles, high reproductive capacity and high degree of mobility, insects’ physiological responses to warming temperatures can also generate particularly large and rapid effects on species population dynamics. Key Concepts: Warmer temperatures associated with climate changes will tend to influence (and frequently amplify) insect species’ population dynamics directly through effects on survival, generation time, fecundity and dispersal. Individual insect species’ responses to climate change, however, will depend on their geographic range, trophic level and natural history. Insect populations in mid‐ to high latitudes are expected to benefit most from climate change through more rapid development and increased survival. Much less is known about the effects of increased warming on tropical insect species. Insect species’ mortality may decrease with warmer winter temperatures, thereby leading to poleward range expansions. The physiological effects of climatic warming on insects species can also act indirectly through trophic interactions (i.e. host plants and natural enemies). Insects feature prominently among the documented range expansions that illustrate biological responses to recent climate change. Because insect species in general have relatively short life cycles, high reproductive capacity and high degree of mobility, the physiological responses to warming temperatures can produce large and rapid effects on species population dynamics.

Insects are among the most diverse and abundant organisms on Earth, and their population dynamics are strongly influenced by entomopathogenic fungi. This study examines the role of carbon and nitrogen metabolism in the virulence of the entomopathogenic fungus Metarhizium rileyi against the migratory locust, Locusta migratoria. The findings demonstrate that the capacity of M. rileyi to utilize different carbon and nitrogen sources is a key factor in its virulence. Specifically, two strains of M. rileyi (PPDB201006 and SZCY201010) exhibited distinct metabolic abilities, with PPDB201006 displaying superior growth and enzyme activities on various carbon and nitrogen sources compared to SZCY201010. These metabolic differences were associated with significant variations in virulence, as PPDB201006 induced higher mortality rates in L. migratoria than SZCY201010. Metabolomics analysis revealed that infection by M. rileyi led to substantial alterations in the hemolymph metabolites of L. migratoria, particularly in organic acids, amino acids, sugars, and lipids. These results emphasize the significance of carbon and nitrogen metabolism in the pathogenicity of entomopathogenic fungi and offer new perspectives for optimizing their application as biological control agents. This study not only improves our understanding of fungal virulence mechanisms but also contributes to the development of more effective and sustainable pest management strategies.

Consequent Effects of Parasitism on Population Dynamics, Food Webs, and Human Health Under Climate Change

Seed production and seedling recruitment are thought to be of minor importance in determining population dynamics and long-term viability in long-lived perennial plants. Seed addition experiments, on the other hand, have amply shown that supplemental addition of seeds almost always, irrespective of longevity, results in increased seedling recruitment. Any change in the environment that affects fruit and seed production can thus be expected to affect seedling recruitment, but the extent to which increased fruit and seed production affect overall population dynamics remains relatively unknown. In this paper, we present demographic data of six populations of the long-lived woodland orchid Orchis purpurea that were monitored for seven consecutive years (2002-2008) occurring in two contrasting light environments. We use a nested life table response experiment (LTRE) at the vital rate level to disentangle the relative contributions of each of six annual transitions, six sites, and two light environments on the population dynamics of this species and to determine vital rate variations that contributed most to variation in population growth rate. Population growth rates (lamda) were significantly higher in the light environment than in the shaded environment (average lamda = 0.9930 and 1.0492 in the shaded and light environment, respectively). The LTRE analysis showed that variation in fecundity and, to a lesser extent, variation in growth made the largest total contributions to variation in lamda, whereas the contributions of variation in survival were almost negligible. Fruit production was two times larger and the net reproductive rate (R0) was approximately six times higher in the light environment than in shaded areas, suggesting that variables related to reproduction are the key drivers of population dynamics of this long-lived orchid species in different light environments. Our results indicate that light is an important factor affecting population dynamics of Orchis purpurea and illustrate that, even in long-lived species, flower and seed production can have important effects on the population dynamics.

The human colonization of Madagascar is associated with the extinction of numerous lemur species. However, the degree to which humans have negatively influenced the historical population dynamics of extant lemur species is not well understood. This study employs genetic and demographic analyses to estimate demographic parameters relating to the historical population dynamics of a wild lemur population, Verreaux's sifaka (Propithecus verreauxi). The genetic analyses are used to determine whether this population experienced a historically recent (i.e., within the last 2000 years) population bottleneck, as well as to estimate the historical population growth rate and the timing of any changes in population size in the past. In addition, a retrospective demographic analysis is used to determine sources of variation and covariation in the sifaka life cycle and how variation in life‐cycle transitions contributes to variation in population growth rate. The genetic analyses indicate that the sifaka population did not experience a recent population bottleneck; however, the historical population growth rate was negative, indicating that the ancestral population size was much larger than the current size. The timing of the ancestral population decline has a point estimate of 2300 years ago, but with large credible intervals: 3611–1736 years ago. This point estimate corresponds with the first evidence for human arrival to Madagascar. Climatic variation has also likely influenced past (and current) population dynamics due to stochastic annual rainfall patterns and climatic desiccation, the latter of which began in southwestern Madagascar around 4000 years ago. Variation in the survival of 2‐year‐old animals as well as large adult females makes the largest contribution to variation in population growth rate. In the absence of more explicit models pertaining to historical population dynamics, it is difficult to attribute the negative population growth rate of this species solely to a single factor (e.g., hunting, habitat destruction).

Reducing agricultural production inputs while maintaining a lucrative yield of high-quality goods is becoming more and more necessary as a result of the global sustainability agenda. Plant diseases pose a significant threat to productivity and product quality, yet many times there are no adequate measures available to control them. Consequently, research on substitute methods of crop protection has been mandated and has garnered significant interest from scholars around. A number of biological control agents (BCAs), including Bacillus, Pantoea, Streptomyces, Trichoderma, Clonostachys, Pseudomonas, Burkholderia, and specific yeasts, have been screened. Of these alternatives, biological controls through beneficial microorganisms have gained significant importance. BCAs, at the very least, support other sustainable disease management strategies like disease resistance and offer chances to control illnesses for whom alternative strategies are unfeasible or unobtainable. It is reasonable to anticipate that BCAs will be used more often to manage agricultural diseases in environmentally friendly ways.

Plant resistance against insect herbivory has greatly focused on antibiosis, whereby the plant has a deleterious effect on the herbivore, and antixenosis, whereby the plant is able to direct the herbivore away from it. Although these two types of resistance may reduce injury and yield loss, they can produce selection pressures on insect herbivores that lead to resistance. Tolerance, on the other hand, is a more sustainable pest management strategy because it involves only a plant response and therefore does not cause evolution of resistance in target pest populations. Despite its attractive attributes, tolerance has been poorly studied and understood. In this critical, interpretive review, we discuss tolerance to insect herbivory and the biological and socioeconomic factors that have limited its use in plant resistance and integrated pest management. First, tolerance is difficult to identify, and the mechanisms conferring it are poorly understood. Second, the genetics of tolerance are mostly unknown. Third, several obstacles hinder the establishment of high-throughput phenotyping methods for large-scale screening of tolerance. Fourth, tolerance has received little attention from entomologists because, for most, their primary interest, research training, and funding opportunities are in mechanisms which affect pest biology, not plant biology. Fifth, the efforts of plant resistance are directed at controlling pest populations rather than managing plant stress. We conclude this paper by discussing future research and development activities.

Plant resistance against insect herbivory has greatly focused on antibiosis, whereby the plant has a deleterious effect on the herbivore, and antixenosis, whereby the plant is able to direct the herbivore away from it. Although these two types of resistance may reduce injury and yield loss, they can produce selection pressures on insect herbivores that lead to pest resistance. Tolerance, on the other hand, is a more sustainable pest management strategy because it involves only a plant response and therefore does not cause evolution of resistance in target pest populations. Despite its attractive attributes, tolerance has been poorly studied and understood. In this critical, interpretive review, we discuss tolerance to insect herbivory and the biological and socioeconomic factors that have limited its use in plant resistance and integrated pest management. First, tolerance is difficult to identify, and the mechanisms conferring it are poorly understood. Second, the genetics of tolerance are mostly unknown. Third, several obstacles hinder the establishment of high-throughput phenotyping methods for large-scale screening of tolerance. Fourth, tolerance has received little attention from entomologists because, for most, their primary interest, research training, and funding opportunities are in mechanisms which affect pest biology, not plant biology. Fifth, the efforts of plant resistance are directed at controlling pest populations rather than managing plant stress. We conclude this paper by discussing future research and development activities.

The risk of extinction of populations has not previously been empirically related to parameters characterizing their population dynamics. To analyze this relationship, we simulated how the distribution of population dynamical characters changed as a function of time, in both the remaining and the extinct populations. We found for a set of 38 bird populations that environmental stochasticity had the most immediate effect on the risk of extinction, whereas the long-term persistence of the population was most strongly affected by the specific population growth rate. This illustrates the importance of including information on temporal trends in population size when assessing the viability of a population. We used these relationships to examine whether time to extinction can be predicted from interspecific life history variation. Two alternative hypotheses were examined. (1) Time to extinction should decrease with increasing clutch size or decreasing survival rate because of the larger stochastic components in the population dynamics of such species. (2) Time to extinction should increase with decreasing clutch size or longer life expectancy if extinction rates are most strongly influenced by variation in the specific population growth rate. In the present data set, time to extinction increased with decreasing clutch size because of larger stochastic influences on the population dynamics of species with large clutch sizes located toward the fast end of the “slow–fast continuum” of life history variation. This demonstrates that interspecific variation in extinction risk can be predicted from knowledge of general life history characteristics. Such information can therefore be useful for assessing minimum sizes of viable populations of birds.

Simple SummaryBiological control can be used as an alternative control measure to reduce pesticide resistance. Unfortunately, many biological control agents, such as natural enemies of pests, are susceptible to a broad spectrum of pesticides. This creates a potential problem when these two components are utilized together. Therefore, it is necessary to find alternatives that are not harmful to natural enemies but also have the potential to replace synthetic pesticides. Essential oils (EOs) are widely used in crop protection and organic agriculture. The EO formulations evaluated in this study are new botanical pesticides that play an important role in agriculture. EOs are available as an alternative to synthetic pesticides. Two blends (Fungatol and Gamma-T-ol) are mostly composed of Alpha Tops, and Gamma Tops were assessed for their effects on the aphid parasitoid Aphidius colemani in laboratory and glasshouse trials. According to the International Organization for Biological Control (IOBC) classification, they were found to be safe or only slightly toxic, making them potential candidates for introduction into an integrated pest control program for aphids.Beneficial insects play a major role in controlling pest populations. In sustainable agricultural production systems, control methods compatible with integrated pest management (IPM) are preferred over broad-spectrum pesticides. EOs from aromatic plants may provide a new and safe alternative to synthetic chemicals. In this research, the efficacy of Fungatol, Gamma-T-ol, Fungatol plus neem, and Gamma-T-ol plus neem was evaluated against Aphidius colemani Viereck (Hymenoptera: Braconidae; Aphidiidae), the parasitoid of the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae). Under laboratory and greenhouse conditions, five different concentrations of each formulation were applied to parasitized mummies and adult parasitoids. Results for parasitoid emergence from aphid mummies sprayed with different concentrations of Fungatol, Gamma-T-ol, Fungatol plus neem, and Gamma-T-ol plus neem in the laboratory and glasshouse showed that the formulations did not adversely affect adult emergence as rates above 60% were observed. For residual toxicity tests done by exposing adult parasitoids to a fresh, dry biopesticide film sprayed on glass plates, less than 20% mortality was observed after 48 h of exposure. Adult longevity tests revealed that the highest concentrations of some of the formulations evaluated were slightly toxic to A. colemani. According to the IOBC rating, our results indicated that most of the tested concentrations for each formulation were harmless to A. colemani. Based on the above results, it may be proposed that the formulations evaluated in this study are potential botanical pesticide candidates for incorporation into an IPM program.

Chapter 4 - Host-specific and generalist biopesticides

Predators of apple and pear pests in northern and central Europe and their use as biological control agents are reviewed. Many natural enemy species are specialized feeders and are able to respond to the population dynamics of particular pest species. The most oustandingly successful example of this is the use of phytoseiid mites, particularly Typhlodromus pyri , against phytophagous pest mites in apple. This mite management strategy is now widespread throughout European apple growing regions. Another example is the use of Anthocoris nemoralis against pear psyllids, Cacopsylla pyricola and C. pyri . Several groups of naturally occurring polyphagous predators, such as chrysopids, coccinellids, syrphids and spiders, also prey on a number of pest species in orchards, contributing generally to the reduction in pest populations. However, they are unlikely alone to prevent pest damage fully and reliably. In seeking biological control opportunities for a particular pest, these polyphagous natural enemies are unlikely to be a high priority. An exception, due to its abundance in orchards, is the common earwig, Forficula auricularia , although this predator may also cause some fruit injury. Another option to consider when reviewing possibilities for biological control in orchards is the introduction of biological control agents. The success rate of this approach, using arthropod predators to control pests of field crops, has been generally poor. Furthermore, mass production methods for predators are likely to be difficult and very costly. The biological supplies industry is constantly seeking culture techniques, largely for arthropod biological control agents of pests of protected crops. It is possible that some future advance may be relevant to orchards, though currently available predators do not appear promising. A careful economic appraisal of the feasibility of use of any potential biological control agent would be prudent before embarking on research.

In recent decades, the egg parasitoid Hadronotus pennsylvanicus (Ashmead) has gained substantial attention as an important natural enemy of pestiferous leaffooted bug species in the genera Anasa Amyot and Serville and Leptoglossus Guérin-Méneville. Throughout its native range of North America, H. pennsylvanicus parasitizes Anasa and Leptoglossus eggs in various vegetable and orchard systems. The overreliance on broad-spectrum insecticides in these systems and the demand for effective and sustainable coreid pest management strategies have motivated researchers to consider H. pennsylvanicus as an augmentative biological control agent. The potential use of H. pennsylvanicus as a classical biological control agent has also been studied in Europe in response to the rapid spread of Leptoglossus occidentalis Heidemann, an invasive pest causing significant economic losses to the European pine nut industry. Improved understanding of H. pennsylvanicus taxonomy, life history, host range, parasitoid–host ecology, laboratory rearing, and field deployment techniques have created a robust scaffold on which to build future biological control programs. This natural enemy profile reviews the current advances in the aforementioned areas of H. pennsylvanicus research and outlines the parasitoid’s prospects as a biological control agent.