نوع مقاله : مقاله پژوهشی
نویسندگان
1 بخش تحقیقات گیاهپزشکی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی جنوب کرمان، سازمان تحقیقات، آموزش و ترویج کشاورزی، جیرفت، ایران
2 بخش تحقیقات گیاهپزشکی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی جنوب کرمان، سازمان تحقیقات، آموزش و ترویج کشاورزی، جیرفت، ایران.
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Aonidiella orientalis is one of the most important citrus pests in the south of Kerman. Population fluctuations and spatial distribution of A. orientalis were studied in the south of Kerman Sampling was done from stages of nymphs (1st instar) and adults on leaves, fruits, and brunches during 2020-2022. The parameters of Taylor’s, Iwao, Morista, and Id power law, RV, and number of optimum samples (at two precision levels of 0.1 and 0.25) were calculated. Results showed that the pest activity started in mid-March and increased gradually, depending on weather conditions. The peak of population happened in mid-April, mid-May, and late September. The spatial distribution of 1st instar nymphs on leaves and fruits was random based on the Taylor and Iwao index, (b= 0.918 and 0.989 respectively) and it was Aggregative for adults (b= 1.8, 1.5 respectively). Moreover, both nymphs (1st instar) and adults had uniform and random distribution in the sampling of branches (b= 0.56-0.71) respectively according to the Taylor and Iwao index. As R2 values of the Iwao index were higher than Taylor, 's therefore, Iwao index was used for estimating the spatial distribution and appropriate samples. The number of optimum samples for nymphs (1st instar) on leaf, fruit, and branch sampling methods were estimated as 24.61, 24.29, and 19.2, respectively with 0.25 accuracy. In three sampling methods, RV was close to 25 and 10 for nymphs (1st instar) and adults respectively. Overall, in pest management programs sampling can be done on nymphs and for ecological studies on adults.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Aonidiella orientalis is one of the most important citrus pests in the south of Kerman, which causes damage to different citrus cultivars. This pest feeds on the sap of leaves and fruits. Its most active is in September and October. The proper control of this pest depends on the determination of the peak time of 1st nymph appearance and the use of insecticides at that time. Determining the optimum time requires regular sampling of the pest population. Knowing the peak periods of the pest population and determining the most appropriate unit and size of sample provides its population density. This research was carried out with the objectives of 1) investigating the periods of population fluctuations of A. orientalis 2) determination of its spatial distribution and the optimal number of samples.
Materials and Methods
This study was conducted in a citrus orchard of grapefruit variety. Sampling was done from two growth stages, 1st nymph and adult of A. orientalis Sampling methods were fruit, leaves, and branches. Spatial distribution of 1st nymph and adult stages of A. orientalis was determined using Morista's, Taylor's, and Iwao distribution indices in the 2020-2022 years. The optimal number of samples was determined by the relevant equations using two precision values 0.25% and 0.1%.
Results and Discussion
Based on the results the pest activity started in mid-March and increased gradually, depending on weather conditions. The peak of A. orientalis population happened in mid-April, mid-May, and late September. The spatial distribution of 1st nymphs on leaves and fruits was random based on the Taylor and Iwao index and it was Aggregative for adults. Both nymphs (1st instar) and adult stages had a uniform and random distribution in the sampling of branches respectively according to the Taylor and Iwao index. The r2 value obtained from the Iwao index was greater than Taylor's, therefore, the Iwao statistics were used to determine the spatial distribution. The number of optimum samples for 1st nymphs on leaf, fruit, and branch sampling method was calculated at 24.61, 24.29, and 19.2, respectively with 0.25 accuracy. In three sampling methods, RV was close to 25 for nymphs (1st instar) which is favorable for pest management programs, and 10 for adults which is proper for ecological studies.
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