Spatio-temporal temperature variations in MarkSim multimodel data and their impact on voltinism of fruit fly, Bactrocera species on mango

Abstract

Fruit flies are the most serious economic insect pests of mango in India and other parts of the world. Under future climate change, shifts in temperature will be a key driver of ecosystem function especially in terms of insect pest dynamics. In this study, we predicted the voltinism of the three economically important fruit fly species viz., Bactrocera dorsalis (Hendel), Bactrocera correcta (Bezzi) and Bactrocera zonata (Saunders) of mango from 10 geographical locations in India using well established degree day approaches. Daily minimum and maximum temperature data were generated by using seven General Circulation Models (GCMs) along with their ensemble, in conjunction with the four representative concentration pathways (RCPs) scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) and three time periods (2020, 2050 and 2080) generated from MarkSim® DSSAT weather file generator. Historical data from 1969-2005 of these 10 locations were considered as baseline period. Under future predicted climates, model outputs indicates that all three fruit fly species will produce higher number of generations (1-2 additional generations) with 15-24% reduced generation time over the baseline period. The increased voltinism of fruit fly species due to increased temperature may lead to ≃5% higher infestation of mango fruits in India by the year 2050. Analysis of variance revealed that 'geographical locations' explained 77% of the total variation in voltinism followed by 'time periods' (11%). Such increase in the voltinism of fruit flies and the consequent increases in the infestation of mango fruits are likely to have significant negative impacts on mango protection and production.

Figure 1

Major mango growing locations of India selected for prediction of number of generations of Bactrocera sp. during future climate change scenarios. The map was created in ArcGIS 10.2 software (ESRI Inc.). *Period (Standard Meteorological Weeks, SMW) considered for prediction of voltinism and generation time of Bactrocera sp.

Figure 2

Inter model variation in number of generations of fruit flies (A = B. correcta; B = B. dorsalis; C = B. zonata) during future climate change periods across ten mango growing locations of India.

Figure 3

Inter-model and scenario variation in generation time of three major fruit flies species infesting mango fruits in India.

Figure 4

The relative degree of various sources of uncertainty in the predicted voltinism of three Bactrocera species. In bars others represents all remaining interactions except time × scenario interaction.