SEASONAL FLUCTUATION OF ASIAN CITRUS PSYLLA POPULATIONS IN THE CITRUS ORCHARDS INFECTED WITH HUANGLONGBING IN SARGODHA, PAKISTAN

A study on seasonal fluctuation in Citrus psylla (Diaphorina citri) (CP) population in citrus orchards infected with Huanglongbing was carried out in relation to environmental factors in six tehsils of Sargodha district. The population of citrus psylla was reached to the peak twice in a year. Young flushes favored the build-up in psylla population. Minimum temperature and rainfall had highly significant correlation with build-up in population of citrus psylla in all the six tehsils of Sargodha. Although, high temperature also favored the high population of citrus psylla in two tehsils. August and mid-March to April were the two times when population of citrus psylla reached to the peak. Therefore, an integrated management strategy can be formulated with this study that will not only help in reducing the HLB incidence but also increase in citrus production.

Efficacy of Insecticides Against Citrus Psylla (Diaphorina Citri Kuwayama) in Field and Laboratory Conditions

The experiments were conducted in a citrus orchard to check the efficacy of insecticides against citrus psylla, and mortality was observed after three days, seven days and then after one month. Four insecticides, Polytrin-C, Talstar, Bifenthrin and Imidacloprid applied, had an almost equal effect on the population reduction of citrus psylla on all citrus plants. The trial was laid out in randomized complete block design (RCBD) having five treatments with three replications in a citrus orchard, after three days of spray showed percentage control as 96.91%, 94.33%, 93.83% and 93.06% of following insecticides Polytrin- C, Imidacloprid, Bifenthrin and Actara, respectively, calculated by Minitab 15. Psylla adults were exposed to different concentrations (500, 400, 300, 200 and 100 ppm) of Imidacloprid and Bifenthrin, and two controlled conditions (with leaves and without leaves). Both Imidacloprid and Bifenthrin insecticides proved to be the most effective against D. citri with lethal times (LT50s) of 4 and 5 hours, respectively, at a concentration of 500 ppm, calculated from probability test with Minitab-15

Impact of abiotic factors on build-up of citrus psylla, Diaphorina citri Kuwayama population in Punjab, India

Seasonal abundance of citrus psylla (Diaphorina citri) Kuwayama was studied on Kinnow mandarin under Punjab conditions during 2012 and 2013. Population of D. citri was present throughout the year but only adults found surviving during December and February. There was no nymphal population when maximum temperature was > 39°C or < 7°C. Two population peaks of nymphs wer e observed, first in April-May and second in August- September. Thereafter, there was abrupt decline in nymphal population during June and July during both the years when the weather conditions i.e. maximum, minimum temperature (°C), relative humidity (%), rainfall (m m) and sunshine (hrs) ranged from 24.4-44, 22.4-31.8, 25.5-100, 0-108.0 and 0-13.5, respectively. Highest peaks of adult were found during May followed by June. With the decrease in temperature from the end of September, the population of D. citri started to decrease and reached its lowest during winter season. Correlation analysis for both the years indicated that maximum and minimum temperature, sunshine and rainfall were positively correlated with nymphal, adult and mixed population but the effect of rainfall on adult population was non-significant, while relative humidity was negatively correlated. The study is useful to find out the weak links of psyllid populations in relation to abiotic factors and that could be exploited to curb its infestation and disease transmission.