Population Density of Some Pests and Evaluation of Some Different Control Methods on Cucumber Plants Under Greenhouse Conditions

Population density of some pests were studied on winter plantation of cucumber plant Cucumis sativus L.  of 2019& 2020 seasons under greenhouse condition at Giza governorate, Egypt. Showed that significant difference between the weekly mean number of the pests under investigation.  Bemisia tabaci (Genn.) was the most pests found in cucumber plants in two seasons. Evaluating the efficacy of some chemical insecticides and botanical oils were sprayed against sap-sucking pest, the whitefly, B. tabaci, on Cucumber plantin the greenhouse.The results revealed that there were significant differences between using three systemic insecticides and three botanical oils on the population density of B. tabaci cucumber plants were received two sprays of each tested treatment during the experimental period. Statistically, the percentage of reduction in B. tabaci counts between mentioned treatments was significant, whereas F value = 7.00** and L.S.D. = 1.96 during first spray and F value = 5.97** and L.S.D. = 2.33 for the second spray. Also the general means of reduction of two sprays, it is clear that Mospilan 20 SP (96%) appeared as the high mortality one in reducing rate of B. tabaci members followed significantly by Rosemarie oil (94.67%),  Confidor 20% SL (93%), Garlic oil (92%), Actara (86%) and the lowest one Lemon oil (81.33%), respectively.


INTRODUCTION
The Cucurbitaceae family is the most food used for human consumption. cucurbits represent an important part of vegetable production and are considered very important in agricultural crops in Egypt. The cucumber plant, Cucumis sativus L. (Cucurbitaceous) is one of the most important vegetables, it is widely distributed all over the world. In Egypt, the cucumber plantation is progressing at a relatively fast rate especially in the newly reclaimed area in the open field and greenhouse, fruit cucumber used for local consumption and exportation to the foreign markets. However, cucumber plants in Egypt are subjected to infestation by many pests such as whitefly; Bemisia tabaci (Genn.) and two-spotted spider mite Tetranychus urticae Koch were economically important pest on cucumber (Cucumis sativus L.) in different parts of the world (Baiomy, 2008). This polyphagous pest can attack more than 600 different species of plants that occur in both open fields and greenhouse environments (Gelman et al., 2007). B. tabaci causes directly damage by sucking the sap from the plant foliage, while indirectly damage due to the transmitting plant pathogenic Population density of some pests were studied on winter plantation of cucumber plant Cucumis sativus L. of 2019& 2020 seasons under greenhouse condition at Giza governorate, Egypt. Showed that significant difference between the weekly mean number of the pests under investigation. Bemisia tabaci (Genn.) was the most pests found in cucumber plants in two seasons. Evaluating the efficacy of some chemical insecticides and botanical oils were sprayed against sap-sucking pest, the whitefly, B. tabaci, on Cucumber plant in the greenhouse. The results revealed that there were significant differences between using three systemic insecticides and three botanical oils on the population density of B. tabaci cucumber plants were received two sprays of each tested treatment during the experimental period. Statistically, the percentage of reduction in B. tabaci counts between mentioned treatments was significant, whereas F value = 7.00** and L.S.D. = 1.96 during first spray and F value = 5.97** and L.S.D. = 2.33 for the second spray. Also the general means of reduction of two sprays, it is clear that Mospilan 20 SP (96%) appeared as the high mortality one in reducing rate of B. tabaci members followed significantly by Rosemarie oil (94.67%), Confidor 20% SL (93%), Garlic oil (92%), Actara (86%) and the lowest one Lemon oil (81.33%), respectively. viruses and the excretion of honeydew that is considered as a good media for sooty mold growth (Henneberry et al., 2000;Stansly et al., 2004, Hanafy et al., 2014and Ismail et al., 2020. The induced sooty mold also interferes with light transmission to chloroplasts and therefore reduces the efficiency of plant photosynthesis (Gelman et al., 2002). In recent years the use of synthetic insecticides in crop protection programmers around the world has resulted in environmental hazards, pest resurgences, pest resistance to pesticides and lethal effect to non-target organisms in the agro-ecosystems in addition to direct toxicity to users Therefore, it was necessary to search for safe alternative materials for pest control, which can minimize the use of synthetic pesticides. Botanical pesticides may be one of the important alternatives to reduce synthetic pesticide usage. They possess an array of properties including toxicity to the pest, repellency, antifeedants, insect growth regulatory activities against pests of agricultural importance (Prakash et al., 1990). In recent years, plant extracts and botanical pesticides have shown great importance in agricultural fields due to their cheap and low expenses, with no residual effects, environmentally friendly, and highly toxic against major pests such as thrips, aphids, jassids, whitefly, and mites (Stumpf and Nauen 2001). The present work aimed to study the Population density of some pests and evaluation of certain different treatments on cucumber plants under greenhouse conditions.

Greenhouse Experiments:
Experiments were conducted in the greenhouse experimental area, Dokki, Giza Governorate during two successive seasons (2019 and 2020). Cucumber seedlings were transplanted on September 10, 2019, and September 10, 2020, in the greenhouse. The area of the greenhouse was 9×40 m². The inspection was started on 23 rd Sept., after sowing for 15 days. A sample of 10 leaves / replicate and take three replicates for the greenhouse was collected randomly in the early morning each week until the harvest. Beginning control process when appeared the pest on cucumber plants, the insecticides were sprayed by A knapsack sprayer (10 litters) each treatment was replicated three times. The insecticides were sprayed two times on Oct., 14 and Nov., 11, (2019&2020), respectively. Control was sprayed only by water. The efficiency of the tested products was estimated by counting the target alive pests (Bemisia tabaci (Genn.)) on the lower surface of twenty cucumber leaves per plot. Pretreatment counts were done just before application while post-treatment counts were made on days 1, 3, 7 and 10 days after treatment. Counts were done in the early morning when flight activity.

Control Agents:
In the present study, three insecticides and three natural oil were tested for their efficacy against B. tabaci. Table (1) illustrate trade and common names and rate of application of the studied chemicals.

Statistical Analysis
Reduction percentages were calculated according to Henderson and Tilton equation (1955). The treatments were compared with each other using one-way ANOVA with LSD 0.05 (SAS Statistical Software, 2000).

RESULTS AND DISCUSSION
Population Density of Pests Infesting Cucumber Plant Cucumis sativus L.: Statistical analysis of the data in Table (2) showed a significant difference between the weekly mean number of the pests under investigation, whereas the F values were 18.52*** & 22.15*** and L.S.D. = 21.16 & 18.00 individuals for two successive years, respectively. Bemisia tabaci (Genn.) was the most pests found in cucumber plants in two seasons Bemisia tabaci: Data in figure (1) revealed that the total mean of B. tabaci (nymph) was higher during 2020 (215.08) than 2019 (276.33), respectively.
In the first season 2019, the mean number of B. tabaci nymph was high from the first week of inspection after that fluctuated to increase gradually and recorded four peaks on 7 th of October, 28 th of Oct., 18 th of November and 9 th of December and with mean numbers 189, 350, 390 and 392 nymphs /10 leaves, respectively. In the second season 2020, the population density of B. tabaci nymph started also appear from the first week and recorded three peaks on 14 th of October, 28 th of October and 9 th of December with mean numbers 377, 379 and 421 nymph/ 10 leaves, respectively.
In the first season 2019, the mean number of L. bryonae started also appear from the first week recorded three peaks on 21 st of October, 4 th of November and 25 th of December and with mean numbers 32, 36 and 45 larvae /10 leaves, respectively.
In the second season 2020, the population density of L. bryonae was found also appear from the first week and recorded three peaks on 7 th of October, 28 th of October and 2 nd of December and with mean numbers 31, 44 and 22 larvae /10 leaves, respectively.
The pest found on fruits indicated a rare number in the first season but in the second season, it increases the number to record two peaks on 18 th of October and 2 nd of December with mean numbers 22 and 47 larvae /10 leaves, respectively.
In the first season 2019, the mean number of T. urticae started also appear from the third week recorded three peaks on 21 st of October, 18 th of November and 9 th of December and with mean numbers 41, 98 and 21 larvae /10 leaves, respectively.

The Efficiency of Some Treatments for The Population Density on B. tabaci:
Evaluating the efficacy of some chemical insecticides and botanical oils that were sprayed against sap-sucking pests, the whitefly, Bemisia tabaci, on Cucumber (Cucumis sativus L) in the greenhouse. The results revealed that there were significant differences between using three systemic insecticides and three botanical oils on the population density of B. tabaci, cucumber plants were received two sprays of each tested treatment during the experimental period.
Statistically, the percentage of reduction in B. tabaci counts between mentioned treatments was significant, whereas F value = 7.00** and L.S.D. = 1.96 during first spray and F value = 5.97** and L.S.D. = 2.33 for the second spray. Also the general means of reduction of two sprays, it is clear that Mospilan 20 SP (96%) appeared as the highly mortality one in reducing rate of B. tabaci members followed significantly by Rosemarie oil (94.67%), Confidor 20% SL (93%), Garlic oil (92%), Actara (86%) and the lowest one Lemon oil (81.33%), respectively (Fig. 2).
Data in Table (3) in the First spray of tested indicated that the gradual reduction percentages of whitefly Bemisia tabaci numbers as a result highly significant differences between the six treatments tested these treatments could be divided into five groups. it is clear that the six treatments can be arranged in descending orders as follows: Mospilan 20 SP, showing highly mortality with a mean reduction of 100%, The second, third and fourth groups contained Actara, Confidor 20% SL, Garlic oil, and Rosemarie oil 95.67%, 94.67%, 90.0% and 87.33, respectively. The fifth group was lemon oil showing a lower effect of 77.33%.
As the same results in the second spray, the six treatments tested these treatments could be divided into four groups. it is clear that the six treatments can be arranged in descending orders as follows: Mospilan 20 SP, showing highly mortality with a mean reduction of 96%, The second and third groups contained Rosemarie oil, Confidor 20% SL, Garlic oil, and Actara 94.67%, 93.00%, 92.00% and 86.00, respectively. The fourth group was lemon oil showing a lower effect of 81.33%.