ROLE OF METEOROLOGICAL FACTOR IN LONG-TERM POPULATION DYNAMICS OF THE EUROPEAN CORN BORER, <i>Ostrinia nubilalis </i>Hbn., IN KRASNODAR AREA: THE ANALYSIS OF LIFE TABLES
The European corn borer, Ostrinia nubilalis Hbn. is one of the most dangerous pests of maize. Though weather, mostly air temperature and humidity, demonstrate their important influence on distribution, population level and development terms of the European corn borer, the accuracy of forecasting models remains rather low to predict pest population dynamics. The aim of our work consists in the comparison of meteorological data with the demographic indicators characterizing long-term population fluctuations in the European corn borer to identify the most significant meteorological criteria for the forecast of pest population dynamics. Observations of insect population dynamics conducted during 1994-2018 on maize fields in vicinity of village Botanika (Gulkevichi District, Krasnodar Area; 45°12′51″ N and 40°47′41″ E) during 1994-2018, and data obtained in 2018 were only used for verification of the dependence established on data array for 1994-2017. We estimated density of insect population at all stages of life cycle from egg to adult. The meteorological information was obtained from the Otrado-Kuban meteorological station located in the center of the territory of the test field location. Mortality for the different periods of insect development (eggs, I-II and III-V instar larvae, pupae, adults) was estimated as K = log N1 - log N2, where N1 and N2 are density of insects for the corresponding periods. Mortality for generation was calculates as K = log No - log Nf, where No and Nf is density of eggs and egg-laying females of the current generation. The breeding index per generation was calculated as I = Nt+1/Nt, where Nt and Nt+1 is density of eggs for the current (t) and the following (t + 1) generation, respectively. Two generations of the European corn borer annually develop in Krasnodar area, and size of population during the first generation usually grows, while those in second generation decreases. The demographic characteristics of insect statistically significant correlate with meteorological factors only during time interval from the third decade of May to the first decade of June when the peak of egg oviposition and mass hatching of I instar larvae of the first pest generation usually occur. Egg mortality shows the closest negative correlation with air temperatures and positive correlation with moisture (water drops and vapor). No association of demographic indicators with meteorological factors during oviposition and hatching of second-generation larvae was found probably due to formation of high and dense maize crops with a microclimate favorable for insect development. Thus, the data obtained demonstrate that the last decade of May - the first decade of June is the only critical period during the European corn borer development in the region. Based on the findings, we drown a 3D linear contour diagram of the European corn borer first generation egg mortality as dependent on mean daily air temperature and relative atmospheric humidity during the last decade of May. This dependence is of interest in terms of an improved model for short-term forecast of pest population dynamics in Krasnodar Area.