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Highlights • A mathematical model is proposed for pest control in Jatropha curcas using integrated pesticides. • Bio-pesticides are costly; require a long term process and expensive to impose. • Chemical pesticides can be introduced in the farming system along with bio-pesticide making the process faster and cost effective. • Optimal profile of both pesticides minimizes the negative effects in cost effective way. Abstract This paper presents the formulation and analysis of a mathematical model for Jatropha curcas plantation with a view to control its natural pests using application of integrated pesticides. Bio-pesticides are costly, require a long term process and expensive to impose. But if chemical pesticides are introduced in the farming system along with bio-pesticide, the process will be faster as well as cost effective. Here, we study the control of pests using integrated approach i.e. using combination of bio-pesticides and chemical pesticides. We identify the parameter for which stability switches may occur. Finally, optimal concentration profile of both pesticides have been determined using optimal control theory to minimize it negative effects and also to make the process cost effective. Numerical simulations justify the main results. [ABSTRACT FROM AUTHOR]

Abstract: The only constant in landscapes is change. Among other influences, such as climate change, these changes are driven by political decisions affecting ecosystem services. The overall research objective is to define how the European Union''s political strategies implemented through Rural Development Programmes and the Common Agricultural Policy might influence or change ecosystem goods and services in the future. This paper aims at outlining the research framework and especially focuses on spatially explicit modelling the distribution of subsidy cash flows on farm and parcel level. Experiments with changing political strategies and incentive payments were carried out in the Mondsee catchment (Austria) using Geographic Information Systems (GIS). The results were visualised and show the dominant (inter-)national and regional funding programmes of this area. They further display the likely effects of changing political strategies on the monetary value of certain parcels and the overall farm–parcel balance. The validation of an aggregated set of funding measures reveals 15% deviation between the model framework and real subsidy payments. This approach is suitable for both (a) estimating the impact of changed funding strategies at EU level and (b) supporting farmers in identifying the best economic income sources on parcel and farm level. Embedded in the overall research objective the results constitute the basis for opening a discussion on how ecosystem services might change with political intervention strategies in rural areas and resulting landscape changes in the future. [Copyright &y& Elsevier]

Abstract: The spruce terminal weevil Pissodes strobi (Peck) is a major pest in western spruces, attacking trees of all ages beyond the juvenile stage, killing the leader and causing tree distortion. This paper describes a computer simulation model of the joint population dynamics within this tree/pest system, over the lifetime of a plantation, and is combined with the Province of British Columbia''s Tree and Stand Simulator (TASS) to drive individual tree growth and stand establishment and development. The model differs from current models of this system, and of other similar systems, in two important ways: (1) it simulates the entire life of a stand, from planting until harvest, and (2) it is based on the underlying biological processes that govern behavior of individual weevils on and in each tree. Each model simulation begins by planting a stand using tree materials from seed or clonal hedge orchards, choosing trees either individually and independently or in groups represented as clones or families. Stand growth and mortality are advanced through a juvenile period, after which weevils appear in the stand. From this time until harvest, the model simulates daily changes in the weevil populations on each tree, tracking mortality, oviposition, and juvenile maturation and emergence, as well as weevil movement from tree to tree. Once a year, the code projects tree mortality and growth, taking into account within-stand competition and damage to leaders caused by weevil attacks. At harvest, the model computes an estimate of the merchantable timber produced by the stand. As illustrations of model output, we present (1) simulated average numbers of adult and juvenile weevils in stands generated using materials from seed orchards, both throughout a single season and also through the years from stand planting until harvest; and (2) the differential effect of weevil damage on two tree genotypes, one resistant and one susceptible, in a stand composed of adjacent clonal blocks. The results of model simulations are in agreement with some of the population dynamics statistics observed in plantations, suggesting that the model reflects biological realism and can be used as a research or management tool. [Copyright &y& Elsevier]

Abstract: There has been a recent resurgence of interest in fisheries recruitment as a dynamic and complex process that is integrated over several life stages, with a variety of factors acting across scales to initiate, modulate, and constrain population abundance and variability. In this paper, we review the theory of recruitment phase transitions using a marine fisheries perspective. We propose that transitions in recruitment are dependent upon the balance of activating and constraining processes of recruitment control, and we highlight fundamental differences in recruitment transitions precipitated by climate events, those related to community alterations, and those manifested by fishery practices (though each is not necessarily mutually exclusive). We maintain that the emergent properties of fisheries populations post-phase transition are contingent upon their histories, their differing initial states, the degree of food web complexity, interaction strengths among interspecifics, and contrasting external forcing, any or all of which may be dissimilar between one regime and another. We suggest that it may be challenging to forecast recruitment phase transitions, though we encourage efforts to determine whether there are unifying relationships that govern recruitment dynamics. [Copyright &y& Elsevier]

• Human participants exhibit a more resilient behaviour than myopic optimising agents. • Three types of resilient behaviour: successful survival, planned exits, path breaking. • Human participants tend to be better at avoiding losses than realising gains. • Some participants strongly outperform computer agents under challenging situations. • Loss avoidance through planned instead of forced farm exists and smarter adjustment. This paper aims to examine the extent to which human participants show higher resilience compared to computer agents in agent-based participatory experiments. We motivate and examine three types of resilient behaviour of farmers during a crisis or as response to competitive pressure: successful survival, loss-minimising farm exits, and path breaking respectively path creating growth strategies. Our experiments revealed that human decision makers recognised and exploited such resilient strategies in periods of crisis or under challenging circumstances in general better than myopic optimising agents, although they did not perform better on average. The reason can be seen in a substantial heterogeneity of human decision makers, for which we identified four categories: negligent gamblers, actors missing opportunities, solid farm managers and successful path breakers. Image, graphical abstract [ABSTRACT FROM AUTHOR]