Pomegranate Orchards Research Articles

A comparison of naturally growing vegetation vs. border-planted companion plants for sustaining parasitoids in pomegranate orchards

Abstract Diversification of vegetation within and around agricultural habitats is an effective strategy to support populations of natural enemies of crops’ pests. Such diversification can be achieved by conservation of natural vegetation that develops spontaneously around the plots, as well as by active introduction of companion plants to the crop. In this study we compared these two approaches in pomegranate orchards in Mediterranean climate. First, we evaluated ten candidate companion plant species for their potential to attract parasitoids of pomegranate pests. We then planted a combination of the two leading species − celery and Syrian oregano − along the perimeter of five orchards. In five additional, paired orchards, no plants were added. Arthropods were sampled from added and naturally growing companion plants throughout the pomegranate fruit growth season. Parasitoids were the most common natural enemies in our samples, and their overall abundance was similar in both treatments. Pest levels did not differ between treatments either. However, the distribution of some parasitoids ( Neochrysocharis and Telenomus ) and pests (leafhoppers and dipteran leafminers) within the orchards was affected by the margin vegetation type: these insects were more abundant in the margins than in the centers of the orchards with companion plants (suggesting a role as trap plants), whereas the opposite was observed in orchards with natural vegetation. We conclude that introduction of companion plants and conservation of local natural vegetation were equally effective in sustaining parasitoid numbers and diversity, but that planting attracted some parasitoids away from the orchards towards their margins. This possibly provides these natural enemies with a refuge from agricultural disturbances, but might reduce their contribution to pest control.

First record of Siphoninus phillyreae on pomegranate in Greece

On June 2012, the ash whitefly Siphoninus phillyreae (Haliday) (Hemiptera: Aleyrodidae) was recorded for the first time on pomegranate in Greece. Its occurrence was observed in a pomegranate orchard at Kato Tithorea, in Fthiotida. Information on its morphology, biology and distribution is presented.

Survey on pomegranate anthracnose caused by Colletotrichum Gloeosporioides (Penz.) In Marathwada region

Among fungal diseases anthracnose caused by Colleotrichum gloeosporioides is the most important disease. Survey of pomegranate (Punica granatum) orchards was conducted during 2013-14 in all the cropping seasons viz. mrig bahar, Hastabar and ambia bahar to assess the incidence and severity of anthracnose on pomegranate in Aurangabad, Jalna, Beed Osmanabad, Latur, Nanded, Hingoli and Parbhaani district of Marathwada region of Maharashtra state. The per cent disease incidence (PDI) and disease severity were recorded using 0-5 point scale. The maximum PDI on leaf was recorded in Hingoli (24.04%) followed by Nanded (22.62%) and Parbhani (22.22%) while least PDI recorded in Aurangabaad (15.09%). On fruit maximum PDI recorded in Parbhani (28.80%) which least in Beed district (19.02%). The 9.83 per cent disease variety on leaf was observed in Hingoli district and 10.70 per cent on fruit in Parbhani district. The maximum PDI (27.44%) on fruit and disease severity 12.45 per cent on fruit was recorded in Arakata. The maximum mean PDI 21.30 per cent on leaf and 25.85 per cent on fruit was recorded on trees aged above 5 years. The highest per cent disease incidence 25.34 per cent on leaf and 26.78 per cent on fruit was recorded on mrig bahar and the highest disease severity of leaf 10.05 per cent and fruit 11.22 per cent was reocrded in mrig bahar.

Changing soil hydraulic properties and water repellency in a pomegranate orchard irrigated with saline water by applying polyacrylamide

Soil wettability and water repellency are important physical properties which greatly affect soil-water relations. This study was conducted to investigate the effects of polyacrylamide (PAM) on soil water repellency and wettability in a pomegranate orchard drip irrigated with saline water in Isfahan Province, central Iran. The experiment was a randomized complete block design conducted within each “durations of drip irrigation” (considered as the environment) including control (uncultivated), and 8 and 15 years old trees under drip irrigation system (DIS). PAM concentrations were 0 (control), 10 and 20mgl−1 arranged in each block at three replications. The PAM (solubilized in saline water with electrical conductivity of 6.2dSm−1) with the mentioned concentrations was applied once during the irrigation time. A week after applying the PAM, soil samples were taken from 0 to 0.3, 0.3–0.6 and 0.6–0.9m depths under the emitters. Water repellency index (WRI) and soil-water contact angle (β) were determined using intrinsic sorptivity method by measuring the water and ethanol sorptivities in all soil samples. Increasing the duration of irrigation with saline water increased electrical conductivity (ECe), concentrations of (Ca2++Mg2+) and Na +, and sodium adsorption ratio (SAR) of the saturated extract in the 0–0.3m soil layer under the emitters. Increasing the duration of irrigation also increased WRI and β, and decreased water infiltration, especially in the 0–0.3m soil layer, presumably through enhancing effects of long-term use of saline water on surface tension of water, soil aggregate stability, physical protection of organic matter in soil and stability of hydrophobic coatings. PAM application significantly reduced soil water repellency and increased soil water sorptivity. In the 0–0.3m, 8 and 15 years of drip irrigation increased the WRI by 56 and 134 percent, respectively, compared with the control. PAM application at rates of 10 and 20mgl−1 decreased WRI by 27 and 40 percent, respectively, when compared with the control. Application of 20mgl−1 of PAM could completely ameliorate the degradative effects of drip irrigation with saline water for 8 years, whereas amelioration in the 15-year treatment remained incomplete.

Determining pomegranate water and nitrogen requirements with drip irrigation

Despite being an ancient crop there is limited knowledge on the water and nitrogen (N) requirements of pomegranate. We conducted research at the University of California, Kearney Agricultural Research and Extension Center (KARE) to determine the water and N requirements of a developing pomegranate orchard. Pomegranate trees (Punica granatum L. var. Wonderful) were planted in 2010. The irrigation treatments were surface drip irrigation (DI) and subsurface drip irrigation (SDI) with three N sub-treatments (N application rates of 50, 100, and 150% of current practice) and 5 replications in split-plot design. A weighing lysimeter located in the experimental field was used to automatically irrigate the orchard after 1.0mm of measured crop water use. The trees received uniform application of fertilizers and water during the first two years of growth to insure uniform stand establishment prior to beginning the experiment. The pH of the irrigation water was maintained at 6.5±0.5 by injection of N as urea sulfuric acid (US-10; 10% N). Differential N treatments were started in 2012 and continued through the end of the project. Phosphorus (PO4–P) was continuously injected during irrigation and potassium (K2T) was injected weekly. We report the results of the study from 2013 to 2015. From 2013 to 2015 the applied N ranged from 62 to 332kg/ha and the total yields ranged from 33,144 to 57,769kg/ha. There were no statistical differences in yield within any year related to total applied N. The yearly applied irrigation water increased as the plant size increased. The total water requirement is approximately 952mm and the maximum daily water use was 10.5mm. The DI irrigation application went from 645mm to 932mm and the SDI application increased from 584mm to 843mm from 2013 to 2015. A fifth order polynomial was fitted to the crop coefficient using the 2015 data. The use of SDI resulted in lower weed pressure in the SDI plots than in the DI irrigated plots in all three years. High frequency irrigation resulted in nitrate being managed within the soil profile to a depth of 1.5 m by minimizing deep percolation losses to the groundwater. While the yields were higher in the SDI than the DI system they were not statistically different. Although there were some differences in N content in tree leaves and fruit peels, there were no differences in fruit arils among N rates. The N requirement is in the range of 62–112kg/ha (109–198g/tree) for a mature pomegranate orchard and will ultimately depend on the planting density.

Planning of pomegranate (Punica granatum L.) orchards management for season December-July (Ambe bahar)

The study was carried out to evaluate the Ambe bahar of pomegranate for optimum production of pomegranate for Solapur district in the semi-arid zone of Maharashtra. Generally, for crop planning, rainfall analysis and water balance studies are required, to determine drought investigation, water requirement and water surplus/ deficit for better management of orchards. Rainfall is the major determinant of pomegranate production, especially in rain fed areas because the contribution of rain fed horticulture is almost half to the national production. Therefore, an attempt has been made to estimate the occurrence of drought. Data are classified into certain degrees of drought severity (Drought, normal and surplus) based on a number of truncation levels corresponding to specified mean values of the rainfall. Pomegranate evapotranspiration determined by the crop co-efficient (kc) approach where the effects of various weather conditions were incorporated into reference crop evapotranspiration and crop characteristics into crop co-efficient. The water to be applied through drip system at 90 per cent efficiency to pomegranate plantation spaced at 3 x 4.5 m.The water balance parameters and climatic shift in Ambe bahar of pomegranate for 14 stations of Solapur district were estimated.Thus, the study revealed that the average intensity of drought for all stations was higher in Ambe season (bahar) followed by Hasta and Mrig seasons (bahars) of pomegranate. For Ambe bahar, the total amounts of water to be applied is 1696 l/tree for the pomegranate tree of 5th year age at 70 per cent probability level for Solapur district. The average climate during season January-August (Ambe bahar) is arid with very poor moisture adequacy index but it is beneficial for quality and disease free production of pomegranate. The average moisture index was -78.31 per cent with highest and lowest moisture index were observed in Solapur (-72.77) and Mangalvedha (-81.96) stations, respectively. Thus, it concludes, good season for disease free, quality and more beneficial production of pomegranate when external source of water supply is available.

Standardization of organic manure application in pomegranate (Punica granatum) orchards grown in semi-arid regions

An experiment was conducted at ICAR - National Research Centre on Pomegranate during 2011-12 and 2012-13 on pomegranate (Punica granatum L) cv. Bhagwa plants. The experiment comprises of application of raw and well decomposed farmyard manure in the form of slurry (liquid form, manures mixed with water in 1:10 ratio and kept for 10 to 15 days with intermittent stirring) as a sole or in combination with micronutrients and/or various microbial inoculants. It was compared with normally practiced method of organic manure application in the soil. The results revealed that application of farmyard manure in slurry form decreased electrical conductivity (0.94 to 0.72 dS/m) and increased organic carbon content (0.55 to 1.45 %) in the soil. Combined application of FYM in the form of slurry along with micronutrients and microbial inoculants significantly increased available N (339.7 kg/ha) and P (34.8 kg/ha) and micronutrients content in the soil. Substantially increased plant height (20.8%), plant spread (22.8 %) and produced maximum number of fruits (39.0/ plant). Population of soil microbes, viz. Aspergillus niger, Pseudomonas fluorescence and potash solubilising organisms were significantly highest with the combined application of FYM in slurry form and microbial inoculants. While, Azotobacter population was more in raw FYM slurry along with microbial inoculants. It is recommended that on light textured soils, farmyard manures should be applied in the form of slurry. It reaches in the active root zone of the plants along with percolating water.

Study of Predatory Lady Beetles Fauna (Coleoptera, Coccinellidae) Associated with Pomegranate Orchards on <I>Aphis punicae</I> Passerini in the Najafabad Region (Isfahan Province), Iran

Lady beetles (Coleoptera: Coccinellidae) as a biological control agent are a group of beetles with a considerable diversity and adaptation in different habitats. Among aphids, Aphis punicae Passerini (Hemiptera: Aphididae) is one of the most important pests of pomegranate orchards in Iran. This pest reduces plant vigor, facilitate the growth of mold on leaves, and consequently influences crop quality and yield. Study on the fauna of predatory ladybugs associated with pomegranate orchards was conducted that were feeding on Aphis punicae in the Najafabad region (Isfahan province, Iran). Twelve species of 8 genera were collected Sampled specimens were identified according to their morphological, male and female genitalia characters using identification keys. The identified species were as follow: Adalia bipunctata (Linnaeus, 1758), Coccinella septempunctata Linnaeus, 1758, Coccinella undecimpunctata Linnaeus, 1758, Exochomus undulates Weise, 1878, Hippodamia variegate (Goeze, 1777), Hippodamia tredecimpunctata ( Linnaeus, 1758), Oenopia conglobata (Linnaeus, 1758), Oenopia oncina (Olivier, 1808), Propylea quatuordecimpuctata (Linnaeus, 1758), Psyllobora vigintiduopunctata (Linnaeus, 1758), Scymnus syriacus (Marseul, 1868), Scymnus mongolicus (Weise, 1890).

An economic analysis of production of pomegranate in middle Gujarat

The area and production of pomegranate in Gujarat is increasing noticeably from last decade.The economic viability of pomegranate cultivation has been studied in middle Gujarat. The study was based on the data collected from 90 Pomegranate grower spread over total 9 blocks of the Vadodara, Chhota udepur and Kheda district for the agricultural year 2013- 14. Pomegranate cultivation involves high initial investment, but same time annual net return was also high. The establishment cost of pomegranate orchard was found to be Rs. 81063. The average per ha net return was found Rs. 88686 and average production was found 5482 kg per hectare. The value of economic parameters, viz., NPV, BCR, IRR and PBP was found Rs. 993842, 3.07, 47.66 and 58 month, respectively at 10 per cent discount rate. In all the varying situations of cost and return in sensitivity analysis, values of all these economic parameters satisfied the acceptance rules for investment proposition. This indicates that in varying situations of cost and return, the economic viability of investment on the pomegranate cultivation was stable and certain.

Efficacy of mating disruption technique against carob moth, Apomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) in pomegranate orchards in Southeast Turkey (Şanlıurfa)

ABSTRACTCarob moth, Apomyelois (=Ectomyelois) ceratoniae Zeller (Lepidoptera: Pyralidae) is a key pest in pomegranate orchards in Southeast of Turkey. The pest causes significant damage and reduces marketability of fruits, and is difficult to control with insecticides. Therefore, it is imperative to develop environmentally sound effective alternative management approaches. In this study, we aimed to evaluate the mating disruption technique and determine the appropriate application dose for the management of the pest. The study was carried out in Central and Suruç districts of Şanlıurfa province (Turkey) in 2011 and 2012. SPLAT EC (Specialized Pheromone-Lure Application Technology) trade named dispenser containing 2% Z7, E9-11-dodecatrienyl formate pheromone mimic was applied at 500, 625 and 750 g/ha in three pomegranate orchards in each district. Results indicated that mating disruption technique significantly reduced the pest populations. But effectiveness of the method was less in terms of the damage rate on fruits. Pheromone applied at 500 g/ha was not effective. However, application at 625 g/ha reduced the pest populations to an acceptable level. Thus, the concentration could be considered an appropriate dose for the less abundant pest population within integrated pest management while higher population would require combining the mating disruption method with a bio-insecticide.

Predatory gall midges on mealybug pests – Diversity, life history, and feeding behavior in diverse agricultural settings

Predatory gall midges (Diptera: Cecidomyiidae) are some of the most common natural enemies associated with mealybugs. However, the generally poor knowledge on their life history and taxonomy has obscured their role in the biological-control of these pests. A comprehensive survey in vineyards and in banana, citrus, persimmon and pomegranate orchards throughout Israel, using more than 670 sentinel baits, revealed five species of gall midges. All species fed in the laboratory on Planococcus citri (Risso) and Phenacoccus solani Ferris, and in trials with Diadiplosis multifila (Felt) no preference for either of these mealybug species was found. Larvae fed on all stages of the mealybugs, and the gall midges completed their life cycle within 10–20days. Adult peak activity of the five studied species was in summer, with low numbers obtained from baits in winter and fall. No difference in overall numbers of gall midges was found among crops, and differences in species composition among sites are attributed to geographic and climatic conditions.

Soil and leaf nutritional constraints in major pomegranate growing states of India

Pomegranate orchards grown under hot, semi-arid to arid tropical climate were surveyed to diagnose nutrient constraints through soil and leaf analysis. A total 347 pomegranate orchards covering an area about 60,000 ha were surveyed in major pomegranate growing areas of Maharashtra, Karnataka and Andhra Pradesh states during 2007 to 2013. Physico-chemical analysis of the soil samples revealed that most of the pomegranate cultivation is on shallow and light textured soils having pH (< 8.9), EC (< 1.86dS/m) and CaCO<sub>3</sub> (< 10% in majority orchards) which is within tolerable limit for pomegranate cultivation. Soil as well as leaf nutrient status indicated that P was the most limiting nutrient, followed by N while K and Ca was in sufficient quantity. Micronutrient constraints through foliar analysis revealed that Fe content was in sufficiency range in almost all the orchards despite its low availability in the soils. Similarly, leaf Cu content was very low in majority orchards despite its availability in the soil in excess range. Zinc content in the leaves was in sufficient quantity in all the orchards located in all the states. The nutrients should be applied in a balance ratio ensuring periodical application of organics to maintain soil health.

Are Entomopathogenic Nematodes Effective Biological Control Agents Against the Carob Moth, Ectomyelois ceratoniae?

The carob moth (Ectomyelois ceratoniae) is the key pest of pomegranate, which causes a significant percentage of losses in pomegranate orchards and warehouses of Iran annually. The pest larvae are characterized by displaying a cryptic behavior within the fruit, which avoids most routine control techniques, especially chemical method. The low efficiency of traditional measurements and also the rich species diversity of natural enemies within the infested fruits highlight the necessity of exploring effective control methods, especially environmental friendly approaches. Entomopathogenic nematodes (EPNs) are a group of biological control agents that actively search for the host, including those in a cryptic habitat like the carob moth larvae within infested fruits. Here, we assumed that treatment of the infested and dropped fruits with EPNs may provide new insight into the management of the carob moth. Three species of EPNs, Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora were selected and used in a series of in vitro and in vivo experiments. In preliminary assays, the EPNs species were used with different concentrations of infective juveniles (IJs) (0, 1, 5, 10, 25, and 50 IJ/larvae) in 2-cm diam. plates. The mortality rates of the laboratory tests were 79.75% and 76.5% for S. feltiae and S. carpocapsae, corresponded to LC50 value of 2.02 IJ/larva for S. feltiae and 2.05 IJ/larva for S. carpocapsae. On the contrary, H. bacteriophora demonstrated low virulence on the pest larvae in petri tests with a LC50 = 426.92 IJ/larva. Hence, both Steinernema species were selected for subsequent experiments. The penetration rate for S. feltiae and S. carpocapsae into the hemocoel of the pest was 43% and 31%, respectively, and the corresponding reproduction rate was 15,452 IJ/larva for S. feltiae and 18,456 IJ/larva for S. carpocapsae. The gathered data from those in vitro tests were used for a field assay. Different concentrations (5, 10, 50, 100, and 160 IJ/cm2 of the arena) of S. feltiae and S. carpocapsae were applied in the field test. The mean mortality results from the last test were 10.89% and 26.65% for S. feltiae and S. carpocapsae, respectively. Finally, we found that these low virulence rates of the nematodes were attributed to inhibitory/repellency effects of saprophytic fungi within the infested pomegranates, a usual status of the infested fruits in autumn or winter seasons. Future work on additional EPN populations more adapted to the extreme conditions of the pomegranate production area in Iran may provide sufficient evidence to continue the further investigation on the best EPN species populations and advanced formulations with high durability.

First record of the grape cane borer, Amphicerus bimaculatus (Olivier, 1790)(Coleoptera: Bostrichidae), on pomegranate in Greece

Discoloration of the leaves of unhealthy pomegranate trees, caused by the Coleopteran species Amphicerus bimaculatus (Olivier, 1790), was found in a newly planted pomegranate orchard in April 2011 in northern Greece (Vrontou area). Identification of the species was based on morphological characteristics. This report is the first record of A. Bimaculatus in Greece infesting pomegranate trees.

Effect of some diets on biological parameters of Apomyelois ceratoniae in laboratory and efficiency of natural pheromone traps in pomegranate orchards

Pomegranate fruit moth (PFM), Apomyelois ceratoniae Zeller is a major pest of pomegranate in Iran. In this study, the effect of four diets including pistachio, pomegranate, semi-artificial and artificial diets were studied on biological parameters of PFM in a growth chamber under controlled conditions at 30 ± 2 °C, 65 ± 5% RH and 16:8 (L: D) h. The results demonstrated that the longest incubation period, larval developmental time and preimaginal development time was observed on artificial diet and the shortest was on the pomegranate. The highest and lowest body length of fifth instar larvae were observed on pistachio and artificial diet, respectively. The heaviest weight of third day pupae was recorded for the larvae that were reared on pistachio (0.0275 ± 0.0004 g) while the lightest was on artificial diet (0.0216 ± 0.0004 g). In the next experiment, the effect of four diets was considered to assess the efficiency of pheromone traps in a twenty year old pomegranate orchard cultivated with Malasse Yazdi cultivars. The effect of food on catch of traps showed a significant difference. The virgin PFM that were fed with pomegranate attracted more males. Also the traps caught the males mostly from 11:00 pm until 4:00 am, with the peak time between 23:00 and midnight. No significant difference was seen between diet and time of catch, indicating that starting or ending time and the maximum time of catch was not affected by the diets.

Overwintering biology of the carob moth Apomyelois ceratoniae (Lepidoptera: Pyralidae)

The pomegranate fruit moth, Apomyelois ceratoniae (Zeller), is the most important pest of pomegranate orchards in Iran, where infestations lead to 20%–80% fruit loss. A. ceratoniae overwinters as larvae in several instars. The success in overwintering determines the fruit loss in the following season, thus overwintering physiology of A. ceratoniae could provide insights into population prediction. To this end, overwintering strategy and some seasonal physiological and biochemical changes were investigated in the field-collected larvae of A. ceratoniae. The lowest supercooling point was recorded in November (−14.6 ± 0.9 °C) and the highest in both October and March (−10.2 ± 0.9 °C). The median lethal temperature (LT50) of larvae was higher than supercooling point, suggesting that A. ceratoniae is chill-susceptible. Overwintering larvae had slightly higher concentrations of glycerol and sorbitol compared to summer larvae. There were no significant seasonal changes in body water content or hemolymph osmolality. Current winter temperatures in Iranian orchards are higher than the cold tolerance thresholds of A. ceratoniae, suggesting that overwintering mortality is not a key factor in determining A. ceratoniae populations.

A field screening of pomegranate cultivars for resistance to the carob moth, Ectomyelois ceratoniae, and compatibility with its larval parasitoids

The use of resistant cultivars could be an efficient pest management strategy against the carob moth Ectomyelois ceratoniae in pomegranate orchards. To identify possible resistant pomegranate cultivars, fruit infestation with E. ceratoniae larvae as well as the incidence of their parasitoids were monitored on 19 pomegranate cultivars in Isfahan, Iran. There were significant differences between cultivars in terms of larval infestation of fruits and the parasitoid activity on them. The cultivars S-Sefid-Saveh and Malas-Esfahan were the most resistant cultivars with 10% ± 0.9% and 15% ± 2.4% infestations, respectively. The most susceptible cultivars were D-hamomi-Pishva, Shahpar-Pishva and G-shahpar-Varamin with 80% ± 2%, 80% ± 0.88% and 79% ± 0.7% infestation, respectively. Parasitism rate was significantly different between cultivars as well, but this was not related to the cultivars resistance. Three parasitoid species, Apanteles myeloenta, Venturia canescens and Bracon hebetor, were collected and identified from the pest larvae, and A. myeloenta was the most abundant species. The highest rate of parasitism (6.8% ± 0.4%) was observed on the G-Shahpar-Varamin, which was the only cultivar from which all the parasitoid species were collected.

EVALUATION POTENTIAL OF STERILE INSECT TECHNIQUE IN CONTROLLING (ECTOMYELOIS CERATONIAE ZELLER) IN THE GARDEN

Iran is the first producer and exporter of pomegranate in the world. The losses of pomegranate in our country because of Ectomyelois ceratoniae Zeller is too much. Ectomyelois ceratoniae Zeller is an important agent of decreasing quality and quantity of pomegranate in our country. According to annual thermal and humidity condition and cultivars the losses are different annually. This pest is very active in all pomegranate areas of Iran now. Due to biology of the pest application of pesticide is not practical and other methods like biological, mechanical, agronomical, etc. cannot be effective alone. Application of sterile insect technique is a method in the world that is used for a few insects with special condition. This research was done for primary evaluation control of Ectomyelois ceratoniae Zeller in the garden in a complete randomized blocks design as follows: pest larval stage are collected from pomegranate orchards and reared in lab conditions (28± 2°C, 60±5 RH and 14 h light) on artificial diet. Eight similar pomegranate trees were chosen and every tree covered with a cage. 3-4 days pupas were separated and irradiated at dose range of 160 Gy1 at the following situations: (irradiated males A— irradiated females A— natural males and natural females) and releasing ratio of 7:7:1:1 (irradiated male A— irradiated female A— natural male A— natural female) compared to a control (natural male A— natural female) under 4 replications. Releasing irradiated and non-irradiated insects continued for four times from June to August according to degree days. At harvesting time in September and comparing irradiated and control replications the results were as follows: the damage of Ectomyelois ceratoniae on pomegranate in irradiated cages compared to the control was 0.025 to 37%.

Impact of winter pruning of pomegranate trees on Aphis punicae (Hemiptera, Aphididae) and its natural enemies in Tunisia

SummaryWinter pruning is a cultural practice used to modify vegetative growth, which is likely to affect the development of pests. However, it has been poorly defined as a cultural method for diminishing the population levels of the pomegranate aphid Aphis punicae (Hemiptera, Aphididae) in pomegranate orchards. This study aimed to evaluate the impact of winter pruning of pomegranate on A. punicae population and their natural enemies. The results showed that winter pruning significantly decreased the population of A. punicae (p < 0.05) in pomegranate. Also, number of natural enemies decreased in pomegranate trees after winter pruning. This technical practice affects the number of winged and wingless individuals, the mean relative growth rate, the specific age of the population and the infestation rate. Winter pruning for A. punicae control in pomegranate orchards is highly recommended.

English

In an attempt to find out the reasons of pomegranante fruit drop due to insect attacks, regular collection of all fallen fruits beneath trees of nine different varieties was done during the fruiting season from August 2013 to December 2013 in an organic pomegranate orchard in the Chott-Mariem region of Tunisia. Apparently heatlthy and cracked fruits were dissected in the laboratory to identify insect larvae found inside. Results indicate that fruits were attacked by three larvae insect species: the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera, Tephritidae), the carob moth, Ectomyelois ceratoniae Zeller (Lepidoptera, Pyralidae) and the pomegranate butterfly, Virachola livia Klug 1834 (Lepidoptera, Lycaenidae). Two different insect larvae can be found jointly inside fruits but no fruits were attacked by the three insect larvae together. All fruits varieties harbor the larvae of C. capitata whereas E. ceratoniae larvae were present in eight of nine varieties. Varieties numbered 1, 8 and 9 were free from V. livia larvae attacks and hence can be considered as resistant cultivars. With respect to Lepidoptera larvae attacks (E. ceratoniae and V. livia), we can assume Variety 1 as resistant. Nevertheless, more research was needed to corroborate these results. &nbsp; Key words: Pomegranate, fruit drop, Ectomyelois&nbsp; ceratoniae, Virachola livia, Ceratitis capitata.