Cotton yield decrease in Côte d’Ivoire are important because of the climate change and pest infestations. The target of this survey is to analyze the spatio-temporal dynamics of Intra-Seasonal Descriptors (ISD) of rainfall and the annual mean infestation levels (MILs) of two pests, Helicoverpa armigera and Jacobiella facialis, as well as their interactions. The analysis datas are mainly constituted of annual rainfall and entomological data of H. armigera and J. facialis covering the period 1971-2016. The spatio-temporal distributions of rainfall ISDs and pest MILs were statistically analyzed, mapped, and their interactions determined using Instat+ and Surfer 11 software. Outcomes showed an interannual variability in rainfall ISDs, with coefficients of variation exceeding 30%. For H. armigera, MIL peaks shifted from the South and Center (1995–2000) to the Center-East and North-East (2011–2016), with an overall declining trend in MILs, attributable to the adoption of the Insecticide Resistance Management Program (IRMP) in 1999. However, a recent increase in peak levels suggests that climatic conditions particularly reduced cumulative rainfall and fewer rainy days favor its development. Regarding J. facialis, MILs increased from 3 to 16 infested plants per 30 plants, due to the IRMP’s limited focus on this pest, with the infestation hotspot shifting from the North (1995-2000) to the North-East and Center-East (2011-2016). These results demonstrated the relevance of integrating climatic conditions into pest management strategies.

In order to update knowledge on the spatio-temporal evolution of Helicoverpa armigera, the geographical areas and the seasons of predilection of adult and larval populations have been studied in the last six years from 2012 to 2017. Monitoring of natural adult populations in different locations has established that populations are more abundant in South cotton production areas compared to the north. The most important outbreaks occurred in two phases (August and Mid-October to Mid-November. The monitoring of larval populations carried out on farm scale showed that infestations started on cotton early August and increased in September and October, reflecting a strong relationship between the evolutions of adult populations, larval infestations and cotton phenology. Late sowings D5 and D6 exhibited higher levels of infestation (0.213 to 0.762 larvae/30 plants) as compared to early sowing (0.21-0.31 larvae/30 plants). Annual variations of pest infestation levels increased from years to years, fluctuating from 0.008 to 0.024 larvae/30 plants over the study period. Mapping of the geographic distribution of infestation showed more severe pest pressure in the North East and South East cotton areas particulary in mostly in surrounding areas of Niakara, Ouangolo, Niellé and Bouaké (1.02 ; 0.86 ; 0.83 and 0.74 larvae/30 plants). With regard to the emerging status of H. armigera over recent years, the current pyrethroid resistance management strategy deserves to be improved on the basis of the pest geographic and seasonal profiles.