Extinction and permanence of the predator-prey system with general functional response and impulsive control

Traditional approach for modelling the evolution of populations in the predator-prey ecosystem has commonly been undertaken using specific impulsive response function, and this kind of modelling is applicable only for a specific ecosystem under certain environ- mental situations only. This paper attempts to fill the gap by modelling the predator-prey ecosystem using a ‘generalized’ impulsive response function for the first time. Different from previous research, the present work develops the modelling for an integrated pest management (IPM) especially when the stocking of predator (natural enemy) and the har- vesting of prey (pest) occur impulsively and at different instances of time. The paper firstly establishes the sufficient conditions for the local and the global stabilities of prey eradica- tion periodic solution by applying the Floquet theorem of the Impulsive different equation and small amplitude perturbation under a ‘generalized’ impulsive response function. Sub- sequently the sufficient condition for the permanence of the system is given through the comparison techniques. The corollaries of the theorems that are established by using the ‘general impulsive response function’ under the locally asymptotically stable condition are found to be in excellent agreement with those reported previously. Theoretical results that are obtained in this work is then validated by using a typical impulsive response func- tion (Holling type-II) as an example, and the outcome is shown to be consistent with the previously reported results. Finally, the implication of the developed theories for practical pest management is illustrated through numerical simulation. It is shown that the elim- ination of either the preys or the pest can be effectively deployed by making use of the theoretical model established in this work. The developed model is capable to predict the population evolutions of the predator-prey ecosystem to accommodate requirements such as: the combinations of the biological control, chemical control, any functional response function, the moderate impulsive period, the harvest rate for the prey and predator pa- rameter and the incremental stocking of the predator paramete

Songbird-mediated Insect Pest Control in Low Intensity New England Agriculture

Global agricultural intensification has caused large-scale wildlife declines, but agricultural lands that maintain natural habitats can support healthy wildlife populations and receive significant ecosystem services from these natural communities. However, how on-farm biodiversity results in beneficial ecosystem services is highly variable and is reported to differ among taxa and guilds. One group that has attracted attention for their potential beneficial role in reducing pest abundance are birds. Understanding the role of bird communities and individual species in pest control could be important for managing farms under a low intensity agroecological framework. In New England, farmers are increasingly applying low intensity agricultural practices, and these low intensity farms have high conservation value for bird communities. The value of bird communities to on-farm productivity, however, remains poorly understood. Therefore, we quantified the amount of insect pest control provided by birds to three important crops to New England farmers: brassicas (e.g., kale, broccoli), cucurbits (e.g., squash, cucumber), and Solanaceae (e.g., eggplant, potato). We also examined the role of different songbird species in the provision of pest control in this system. To determine the amount of pest control services provided by birds in this system, we conducted an exclusion experiment at nine low intensity farms in Franklin and Hampshire counties of Massachusetts. Birds were excluded from crops, and pest abundance and leaf damage were compared between exclusion plots and immediately adjacent control plots. In brassica crops, the abundance of imported cabbageworm (Pieris rapae) and diamondback moth (Plutella xylostella) were significantly reduced, while cabbage looper (Trichoplusia ni) was not significantly affected. In cucurbit crops, all life stages of squash bugs (Anasa tristis) were significantly reduced, though striped cucumber beetle (Acalymma vittatum) populations were not significantly changed. In Solanaceous crops, bird presence caused significantly larger populations of Colorado potato beetle (Leptinotarsa decemlineata) larvae, while the other life stages of Colorado potato beetle and aphids (superfamily Aphidoidea) were not significantly affected. Leaf damage was reduced by bird presence in all three crop types, though this effect was only significant for cucurbits. The varied effects of bird predation in different crop types highlights the need for crop-specific knowledge in applying agroecological pest management in New England. To determine the roles of different bird species in insect pest control, bird diets were studied at 11 low intensity farms in western Massachusetts. DNA metabarcoding was used to determine the frequency of crop pests and pest natural enemies in fecal samples collected from birds on each farm. We found evidence of pest species being consumed in 12.6% of the 737 total fecal samples collected, while pest natural enemies were present in 2.0% of samples. Among bird species, Gray Catbirds and Common Yellowthroats were determined to feed on crop pests significantly more frequently than Song Sparrows, while no bird species effect was found for natural enemy frequency. The only crop pest surveyed in our exclosure experiment which was present in fecal samples was Colorado potato beetle. Though birds preyed on Colorado potato beetle, they also preyed on two known predators of Colorado potato beetle eggs and larvae: Chrysopa oculata and Chrysoperla rufilabris. This provides evidence that the increase in Colorado potato beetle larvae we observed when birds were present was due to ecological release. Combined, our results show that birds provide important, though variable, insect pest control services on low intensity New England farms. Bird predation had primarily beneficial impacts on crops, suppressing abundance of several pest species and decreasing or minimally affecting leaf damage. The effects of bird predation on pest abundance and damage can be integrated into farm management to control insect pests without reliance on expensive, and sometimes damaging, outside inputs like pesticides. Promotion of woody, non-crop habitats on farms can promote species like Gray Catbirds and Common Yellowthroats that feed more frequently on insect pests. Management of New England farmlands for bird pest control may support healthy bird communities and improve agricultural output

A study on the application technology of the sterile insect technique, with focus on false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus in South Africa

False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is considered the most important indigenous pest of citrus in southern Africa. Major concerns such as progressive insecticidal resistance, the negative impact of insecticides on the environment, as well as the influence of consumers opposed to chemical residues on fruit, created opportunities for biological control methods such as Sterile Insect Technology (SIT). This technology is now established in the Western and Eastern Cape provinces of South Africa as an effective, sustainable alternative to conventional FCM control methods. Due to the prevalence of the pest in all citrus producing areas of South Africa, potential for SIT to expand is enormous. Success of an SIT programme is highly dependent on efficient application of the technology to achieve its objectives in a timeous manner. The aim of this study was to advance the application of SIT for control of FCM on citrus in South Africa, by investigating the effect of certain critical stages in the process. The effect of long-distance transportation on fitness of irradiated FCM was determined, showing reduced performance with cold-immobilized transport. A significant decrease in flight ability and longevity of irradiated FCM was found, although critically, realized fecundity was not affected. The effect of two different insecticides in the pyrethroid and organophosphate chemical groups were investigated for their residual effect on mortality of released irradiated FCM, to determine if these pest control programmes could be integrated. Both chlorpyrifos and tau-fluvalinate were effective in killing irradiated FCM for a number of days after application, after which degradation of the active ingredient rendered it harmless. This effect was found to be similar for irradiated and non-irradiated males, consequently ratios of sterile : wild male FCM should be retained regardless of whether sprays are applied or not. The modes for release of sterile FCM in an SIT programme were investigated. Efficacy of ground and aerial release platforms were tested by evaluating the recovery of released irradiated male FCM in these orchards. More irradiated FCM were recovered in orchards released from the ground compared to air. However, an economic analysis of both methods shows application of irradiated insects over a large geographical area is more cost-effective by air. Depending on the terrain and size of the target area, a combination of both methods is ideal for application of SIT for control of FCM in citrus. Development of application technology for advance of the programme is discussed and recommendations for future research and development are offered

Proceedings of the 5th International Symposium on Biological Control of Arthropods

This proceedings contains papers dealing with issues affecting biological control, particularly pertaining to the use of parasitoids and predators as biological control agents. This includes all approaches to biological control: conservation, augmentation, and importation of natural enemy species for the control of arthropod targets, as well as other transversal issues related to its implementation. It has 14 sessions addressing the most relevant and current topics in the field of biological control of arthropods: (i) Accidental introductions of biocontrol agens: positive and negative aspects; (ii) The importance of pre and post release genetics in biological control; (iii) How well do we understand non-target impacts in arthropod biological control; (iv) Regulation and access and benefit sharing policies relevant for classical biological control approaches; (v) The role of native and alien natural enemy diversity in biological control; (vi) Frontiers in forest insect control; (vii) Biocontrol marketplace I; (viii) Weed and arthropod biological control: mutual benefits and challenges; (ix) Maximizing opportunities for biological control in Asia's rapidly changing agro-environments; (x) Biological control based integrated pest management: does it work?; (xi) Exploring the compatibility of arthropod biological control and pesticides: models and data; (xii) Successes and uptake of arthropod biological control in developing countries; (xiii) Socio-economic impacts of biological control; (xiv) Biocontrol marketplace II

The continuing persistence and biomagnification of DDT and metabolites in American robin (Turdus migratorius) fruit orchard food chains

DDT is an organochlorine insecticide that was widely used in fruit orchards in the South Okanagan Valley from the late 1940s and in the 1990s, this was documented to have caused extensive contamination of American robin (Turdus migratorius) food chains. Due to the environmental persistence of DDT and its metabolite, p,p’-DDE, the objective of this study was to re-sample previous orchards, as well as several new agricultural areas with the prediction that DDT and metabolite concentrations would significantly decline twenty-six years after a similar sample collection was conducted in 1993-1995. This was done by: 1) collecting soil, earthworms and American robin eggs from orchard and non-orchard areas in the South Okanagan Valley, 2) comparing previous and current contaminant burdens for DDE, DDT and DDD metabolites, and 3) calculating biomagnification factors for earthworms and robins on a lipid normalized basis. All robin eggs contained DDE, DDT and DDD, with the highest concentration being p,p’-DDE at 107 ug/g (wet weight), confirming that contamination is still present at similar and high levels relative to the 1990s. DDE and DDT levels in robins were significantly higher than Aporrectodea and Lumbricidae earthworms, and earthworm-robin regressions for DDE showed a significant positive relationship. Biomagnification factors were generally > 1 and were higher for DDE than DDT and DDD. Concentrations of p,p’-DDE in American robins in this study were comparable to and/or exceeded published levels in other migratory birds nesting in fruit orchards, including the eastern bluebird (Sialia sialis), where reproductive and immunostimulation effects were observed. The relatively high concentrations of DDE in the South Okanagan Valley may pose a health risk to local predators and birds of prey, such as Accipiter hawks and falcons, who often feed at higher trophic levels where DDE and other contaminants are biomagnified

Strategic irrigation against apple scab

Proceedings to the 15th International Conference on Organic Fruit Growing

Browntail Moth (Euproctis chrysorrhoea) Integrated Pest Management Program: Evaluation of Monitoring Traps and Biopesticides

Browntail Moth (BTM; Euproctis chrysorrhoea) is a non-native species currently outbreaking in Maine. BTM are polyphagous folivores and feed on a variety of woody plant species, including many economically and ecologically important ornamental and forest trees such as oaks and apples. Human health is also a concern as BTM larvae produce urticating hairs that can cause severe dermatitis in people. New monitoring and management programs are urgently needed, with the current population densities reaching a 100-year high. The Maine Forest Service monitors BTM populations by visually assessing winter nest densities and defoliation patterns, both time and labor intensive. This research investigated the optimization of BTM sex pheromone monitoring traps in field trials during the adult flight period in 2021 and 2022. Trials in 2021 tested lure purity and two trap types, bucket style and delta style sticky traps. Results indicate that male moths were more attracted to lures with \u3e 95% purity and bucket-style traps. Trials in 2022 tested additional trap styles and color variations. Results from 2022 indicate that white traps were significantly more attractive than green or multicolored traps. The Pherocon 1C trap caught the most male BTM; however, it was not significantly different from the other white traps, indicating that any white trap could be recommended for use in future long-term monitoring programs for BTM. In addition to monitoring evaluations, management strategies were tested for the control of BTM. Current control is the responsibility of municipalities and landowners, and broad-spectrum insecticides are commonly used due to the limitations of alternative control methods. Trials developing methods and testing the efficacy of more targeted biopesticide were conducted to determine if they were effective at reducing BTM populations. Initial trials observed BTM behavior in bioassay studies. Differences were found in the amount eaten and mass of larvae depending on the number of larvae present in bioassay cups (10, 25, 50 larvae, or the whole winter nest), which indicates that the amount of larvae present can impact lab experiment results. Treatment bioassay trials testing the efficacy of different commercially available Bacillus thuringiensis (Bt) products were conducted in 2021 and 2022 on pre-diapause larvae. Survival and defoliation rates were determined for the various Bt treatments, both alone and including the use of spider peptides, which have the potential to increase the longevity and compound efficacy of Bt treatments. Results indicate that Bt products significantly reduce the amount eaten by larvae from control (water) treatments. Deliver (Bt kurstaki) used with peptide products was not significantly different from the current industry standard biopesticide product, Entrust (spinosad), a broad-spectrum insecticide. Peptide treatments alone did not significantly reduce the amount eaten from control treatments, but there were inconsistencies in the results of Basin and further testing is needed. The results of this research provide evidence supporting the adoption of new monitoring approaches and the potential use of less broad-spectrum biopesticides to manage BTM

Managing biodiversity for ecosystem services in apple orchards

Conventional intensive agriculture is largely reliant on high agrochemical inputs and has resulted in damaging environmental impacts including large scale biodiversity loss. More environmentally sustainable agricultural production methods are required. Ecological intensification is an approach which aims to sustainably increase production by using biodiversity-derived ecosystem services and replacing agrochemical inputs where possible. This can be achieved through modifying agricultural management practices to support ecosystem service-providing beneficial species. This thesis investigates the ecological intensification of commercial apple orchards in the UK. Apples are one of the most economically and nutritionally important fruit crops globally and their production relies upon a number of ecosystem services including pollination, pest regulation, and soil fertility services. Alleyway cover crops were trialled as a novel management practice which has the potential to improve a number of orchard ecosystem services. Three different cover crop species mixtures, all based on perennial legumes but each with a different rationale, were compared to a standard mown-grass control. Growing cover crops in the alleyways was provided improved habitat quality for beneficial species, attracting greater numbers of natural enemy taxa including predatory beetles, parasitoids, and active-hunting spiders, without increasing the abundance of crop pests. Greater numbers of pollinators were also observed in alleyways sown with cover crops. Despite the greater numbers of beneficial species recorded in the cover crop treatments, no increases in pest regulation or pollination services were detected and no change in production was observed during the timescale of the study. A second potential benefit of alleyway cover crops is the production of mulch material. Traditionally, organic mulches were used in orchards to help supress weeds underneath the trees, increase soil nutrients, and retain soil moisture, however many of these functions have now been replaced by agrochemical inputs. The cuttings from alleyway cover crops can provide an in-situ source of mulching material. Alleyway cuttings were compared to two traditional mulch materials, compost and straw, and a standard no-mulch control. Alleyway cover crop cuttings boosted numbers of earthworms and enhanced leaf litter decomposition, whilst the traditional straw and compost mulches improved some soil fertility measures including soil organic matter and moisture when compared to the control. In the final study of the thesis, the importance of pollination is quantified and the methods used to assess pollinator dependence and pollination deficits are tested, with recommendations made about the scale at which these experiments should be carried out. Following pollinator exclusion apple yields were found to fall to 55% whilst supplementary hand pollination led yields to increase to 167% of current ‘open’ pollination rates, showing that pollination deficits existed in the study orchards. This study also highlights the importance of pollination for fruit quality, a key deciding factor of a crop’s economic value. Alleyway cover cropping was found to have positive effects on ecosystem service providers both above and below ground. Even relatively inexpensive cover crop mixtures, combined with a reduction in mowing frequency and increase in mowing height, were found to increase numbers of beneficial species. The findings demonstrate the potential benefits of this multi-purpose habitat management method