Forecasting the phenological development of harmful non-gregarious locusts in the agroclimatic zones of Kazakhstan based on spatial analysis

Abstract

Background and Aim. Forecasting phenology of damaging non-gregarious locusts allows timely organizing phytosanitary monitoring, optimizing survey periods. The goal of the research was to identify the spatial features and trends over time in the period of mass emergence of damaging non-gregarious locust nymphs within agro-climatic regions of Kazakhstan using data from phytosanitary surveillance conducted between 2003 – 2025.

Materials and methods. Data for a long period of time about dates of phenophases in harmful non-grasshopper species from regions of Kazakhstan are presented. The calendar date of massive nymph emergence was transformed to day-of-year (DOY). Space analyses carried out with consideration of agro-climate zoning according to thermal and water supply criteria. Differences between zones were assessed using the Friedman test, consistency of the spatial order was assessed using Kendall’s coefficient of concordance, long-term trends were assessed using the Mann–Kendall test and Sen’s slope estimator. The spatial stability of the phenological regime was assessed using Spearman’s rank correlation coefficient.

Results. Spatial variability of time of mass nymphs hatching for agro-climatic regions of Kazakhstan revealed. Difference between minimum and maximum dates – 23 days (April 21 in dry-hot region up to May 14 in very-wet moderately-warm region); differences between regions are significant (χ2=226.0; p<0.001), stability of spatial pattern is high (W=0.983). Statistically significant trend towards earlier nymph hatching was -0.20 days/year (p=0.010) with preserved spatial pattern (rho = 0.995); model with fixed effects of district and year accounted for 98.9 % variance in hatching dates; estimated time from mass hatching until reaching second instar was 13-16 days.

Conclusion. Agroclimatological zonation allows considering the space-time variability of phenology of damaging nongregarious locusts. The obtained results may find application in differential scheduling of phytosurveys and optimization of a phenological forecasting system based on current field and agro-meteorological observations.

Background and Aim. Forecasting phenology of damaging non-gregarious locusts allows timely organizing phytosanitary monitoring, optimizing survey periods. The goal of the research was to identify the spatial features and trends over time in the period of mass emergence of damaging non-gregarious locust nymphs within agro-climatic regions of Kazakhstan using data from phytosanitary surveillance conducted between 2003 – 2025.

Materials and methods. Data for a long period of time about dates of phenophases in harmful non-grasshopper species from regions of Kazakhstan are presented. The calendar date of massive nymph emergence was transformed to day-of-year (DOY). Space analyses carried out with consideration of agro-climate zoning according to thermal and water supply criteria. Differences between zones were assessed using the Friedman test, consistency of the spatial order was assessed using Kendall’s coefficient of concordance, long-term trends were assessed using the Mann–Kendall test and Sen’s slope estimator. The spatial stability of the phenological regime was assessed using Spearman’s rank correlation coefficient.

Results. Spatial variability of time of mass nymphs hatching for agro-climatic regions of Kazakhstan revealed. Difference between minimum and maximum dates – 23 days (April 21 in dry-hot region up to May 14 in very-wet moderately-warm region); differences between regions are significant (χ2=226.0; p<0.001), stability of spatial pattern is high (W=0.983). Statistically significant trend towards earlier nymph hatching was -0.20 days/year (p=0.010) with preserved spatial pattern (rho = 0.995); model with fixed effects of district and year accounted for 98.9 % variance in hatching dates; estimated time from mass hatching until reaching second instar was 13-16 days.

Conclusion. Agroclimatological zonation allows considering the space-time variability of phenology of damaging nongregarious locusts. The obtained results may find application in differential scheduling of phytosurveys and optimization of a phenological forecasting system based on current field and agro-meteorological observations.