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Published online: 25 June 2019 ; Monthly field surveys of diamondback moth (DBM), Plutella xylostella (L.) and its parasitoids were conducted to assess seasonal abundance and diversity under changing altitude. Twenty-four crucifer farms spread across three altitudinal zones of Mount Kilimanjaro and Taita hills were sampled for the insects at monthly interval from 2013 to 2014. Diamondback moth abundance differed significantly between seasons (F3, 21 = 3.883, p = 0.024) in the high zone of Taita hills. The abundance among altitudinal zones of the two transects was not significantly different (Mt. Kilimanjaro: F2, 98 = 0.415, p = 0.661; Taita hills: F2, 116 = 0.303, p = 0.739). Eight parasitoid species emerged in the laboratory from collected DBM larvae and pupae. Cotesia vestalis (Haliday) provided the most DBM parasitism in the low zone and Diadegma semiclausum (Hellen) in the medium and high zones. Parasitism by D. semiclausum increased by 32.5% between the low and medium zones (p = 0.001) of Taita hills. Diversity of parasitoid species declined considerably from the low to medium zones of Taita hills. The diversity of wild crucifer species increased with altitude but was twice as diverse in the high zone of Mt. Kilimanjaro than the high zone of Taita hills. Ecological complexity of the cropping system contributed greatly to a wider parasitoid diversity along Mt. Kilimanjaro. The introduced C. vestalis has successfully established in East Africa and adapted to the warmer areas in the low altitudes. ; Ministry of Foreign Affairs, Finland ; Department for International Development, United Kingdom ; Swedish International Development Cooperation Agency ; Swiss Agency for Development and Cooperation ; Federal Ministry for Economic Cooperation and Development, Germany ; Government of Kenya ; Peer Review

Crop modelling has the potential to contribute to global food and nutrition security. This paper briefly examines the history of crop modelling by international crop research centres of the CGIAR (formerly Consultative Group on International Agricultural Research but now known simply as CGIAR), whose primary focus is on less developed countries. Basic principles of crop modelling building up to a Genotype × Environment × Management × Socioeconomic (G × E × M × S) paradigm, are explained. Modelling has contributed to better understanding of crop performance and yield gaps, better prediction of pest and insect outbreaks, and improving the efficiency of crop management including irrigation systems and optimization of planting dates. New developments include, for example, use of remote sensed data and mobile phone technology linked to crop management decision support models, data sharing in the new era of big data, and the use of genomic selection and crop simulation models linked to environmental data to help make crop breeding decisions. Socio-economic applications include foresight analysis of agricultural systems under global change scenarios, and the consequences of potential food system shocks are also described. These approaches are discussed in this paper which also calls for closer collaboration among disciplines in order to better serve the crop research and development communities by providing model based recommendations ranging from policy development at the level of governmental agencies to direct crop management support for resource poor farmers. ; Peer Review