Integrated Approaches of Mechanical Barrier, Insecticide and Botanicals against Mango Mealybug (Drosicha mangiferae) ()
1. Introduction
Mango (Mangifera indica L.) a member of family Anacardiaceae is known as king of fruits for its sweetness, excellent flavor, delicious taste and high nutritive value [1] [2]. This important tropical fruit is being grown in more than 100 countries [3]. A number of insect pests are known to attack the mango trees, which have been studied in detail [4]-[7]). The nymphs and female bugs suck sap from inflorescence, tender leaves, shoots and fruit peduncles. As a result, the affected inflorescences are shriveled and get dried. Severe infestation affects the fruit set and causes fruit drop. They secrete honey dew over, which sooty mould develops [8]. Due to the growth of sooty mould on the leaves, photosynthetic activity is affected [9] [10] reported that mealybug (Drosicha mangiferae Green.) is the serious pest of mango in Pakistan and is growing as a threat to mango orchards. In Bangladesh mango mealybug population started to increase gradually from December and continued up to February when the ambient average temperature was 20.95˚C, relative humidity 63% and rainfall was absent [11].
Mango mealybug (D. mangiferae) is difficult to control using single plant protection tactic. Use of only insecticides is not sufficient to control the pest [12]. Use of insecticides may cause environmental pollution and destruction of natural beneficial insects [13] [14]. Considerable efforts are being made in various parts of the world to minimize the overuse of insecticidal chemicals and increase the use of Integrated Pest Management techniques. Available reports reveal that botanicals are effective in controlling mealybugs [15]-[17]. Khan and Ashfaq [18] reported that Funnel Type trap is an effective barrier for mango mealybug nymphs and also worked for collecting the egg carrying female. Karar et al., [19] tested nine tree bands to check the upward movement of mango mealybug (D. mangiferae) and found a new band named Haider’s band (plastic sheeting having a layer of 3.8 cm of grease in the middle) is the most effective for preventing insects from reaching the tree canopies. In our previous studies, we found that foliar spray with insecticide Cypermethrin and botanical Turmeric powder extract are effective in controlling mango mealybug. Integrated use of the mechanical barrier, insecticide and botanical may give considerable control of the insect. Considering the above facts, an experiment was conducted to test the efficacy of integrated use of a mechanical barrier around the tree trunk, foliar spray with a chemical insecticide and a botanical against mango mealybug.
2. Materials and Methods
An experiment was conducted in an orchard of Sher-e-Bangla Agricultural University campus, Dhaka, Bangladesh from November to May to test the efficacy of integrated use of a mechanical barrier around the tree trunk, spray with a chemical insecticide and a botanical against mango mealybug. In mechanical barrier, tree trunk was tightly wrapped with a 30 cm wide white plastic sheet at 45 cm above the soil surface. The insecticide was Cypermethrin (@ 1 ml/l) and botanical was turmeric power. Both Cypermethrin and turmeric powder extract were applied as spray on the mango tree. Mango plants of variety Amropali grafted from five-year-old trees were planted in earthen pots at one plant per pot. Three-year-old plants were collected from Green Orchid and Cacktus Nursery, Agargaon, Dhaka. The experiment was laid out in randomized complete block design (RCBD) with three replications (pot with mango plant). The treatments were as follows:
T1. Mechanical barrier: Haider’s band [20] was used as a mechanical barrier to stop the crawling of the nymphal stage of mango mealybug from the soil to the plant canopy. The plant was tightly wrapped with a 30 cm wide white plastic sheet 45 cm above the ground level. A thin layer of grease (7 cm) was applied surrounding the middle portion of plastic sheet from November to April. The barrier inhibits the crawling of nymphs to cross the band and reach the plant canopy. As a result, the nymphs gathered near the lower edge of the plastic barrier which was killed by spraying Cypermethrin @ 1 ml/l of water. Monitoring was done continuously and new grease was applied when the previous grease would dry.
T2. Chemical spray: Mango plants were sprayed once with Cypermethrin @ 1 ml/l of water before crawling of nymphs of the insect.
T3. Botanical spray: Mango plants were sprayed once with turmeric (Rhizome) powder extract @ 15 g/500ml of water before crawling off the 1st, 2nd and 3rd instar nymphs to the canopy.
T4. Chemical + Botanical: Mango plants were sprayed once with Cypermethrin @ 1ml/l of water before crawling of nymphs of the insect. After 15 days of Cypermethrin application, the plants were again sprayed once with turmeric powder extract @ 15 g/500ml of water.
T5. Mechanical + Chemical: Mechanical barrier (T1) and Mango plants were Sprayed with Cypermethrin @ 1ml/l of water (T2).
T6. Mechanical + Botanical: Mechanical barrier (T1) and Mango plants were sprayed with turmeric powder extract @ 15g/500 ml of water (T3).
T7. Untreated control: Selected trees under untreated control were kept without any treatment application.
Preparation of turmeric (Rhizome) powder extract
Turmeric (Rhizome) powder was collected from Townhall Market, Mohammadpur, Dhaka. The requisite quantity of the materials was taken and 400 ml of water was added and ground well in a blender to make into a suspension. The mixture was kept undisturbed overnight, filtered through fine cloth and poured into a 500 ml volumetric flask. Fresh water was added to the flask to make the volume 500 ml.
Data collection
Number of 1st, 2nd and 3rd instars nymphs were counted separately from 2 cm2 area of inflorescence of the treated and untreated mango trees. Percent reduction in insect population over control was calculated using the following formula:
3. Results
The effect of different IPM packages on the infestation of inflorescence and the percent reduction of mango mealybug over control at different stages in various treatments are given in Table 1.
Application of mechanical barrier, Cypermethrin @ 1 ml/l and turmeric powder extract @ 15 g/500ml singly or combination with one another gave significant reduction in the population of mango mealybug at 1st, 2nd and 3rd instars nymphal stages. Higher reduction in their population was observed at 1st instar followed by 2nd and 3rd instar.
Population of 1st instar nymph: Among the treatment, T5 (Cypermethrin @ 1 ml/l + Mechanical barrier) caused significantly highest reduction of 93.90% in population followed by T6 (Turmeric + Mechanical) and T1 (Only Mechanical) and showed 86.04% and 84.59% reduction in insect population compared to control. The efficacy of T1 and T6 was statistically similar and significantly higher than other treatments. The lowest reduction (18.31%) was recorded from T3 (Turmeric spray)
Population of 2nd instar: Like 1st instar nymph, all treatments (T1 - T6) reduced population at 2nd instar nymphs significantly over control. The reduction ranged from 23.77% - 87.06%. Treatments T5 (Cypermethrin @ 1 ml/l + Mechanical barrier) were reduced by 87.06%, T6 (Turmeric + Mechanical) and T1 (only Mechanical) and were reduced by 81.13%, in population of 2nd instar over control. Their efficacy was statistically similar but significantly higher compared to other treatments. Significantly lowest reduction of 23.77% was recorded from T3 (only Turmeric), T4 (Cypermethrin @ 1 ml/l + Turmeric powder extract @ 15 g/500ml) and T2 (Cypermethrin @ 1 ml/) showed 46.39% and 47.27% population reduction.
Table 1. Effect of mechanical, chemical and botanical measures applies in an integrated approach to control 1st, 2nd and 3rd instar nymphs of mango mealybug on mango under pot condition.
Treatment |
Different nymphal stages |
1st instar nymph |
2nd instar |
3rd instar |
No. of
nymphs per 2 cm2 |
Reduction
over control (%) |
No. of
nymphs
per 2 cm2 |
Reduction over control (%) |
No. of nymphs per 2 cm2 |
Reduction over control (%) |
T1 (Plastic sheet barrier) |
03.33d |
84.59b |
03.33d |
81.13a |
03.33d |
83.07b |
T2 (Cypermethrin @ 1 ml/) |
11.00c |
49.12d |
13.33c |
47.27b |
13.33c |
32.19c |
T3 (Turmeric powder @ 15 g/500ml) |
17.67b |
18.31e |
20.33b |
23.77C |
18.00b |
08.42d |
T4 (T2 + T3) |
10.00c |
53.77c |
13.67c |
46.39b |
12.67c |
35.53c |
T5 (T1 + T2) |
01.33e |
93.90a |
01.67d |
87.06a |
02.00e |
89.82a |
T6 (T1 + T3) |
03.00d |
86.04b |
03.33d |
81.13a |
03.33d |
83.07b |
T7 (Control) |
21.67a |
- |
27.67a |
- |
19.67a |
- |
LSD (P = 0.05) |
1.601 |
3.872 |
2.304 |
8.598 |
|
5.372 |
% CV |
9.17 |
3.26 |
10.77 |
7.62 |
|
5.25 |
Population of 3rd instar nymph: At 3rd instar nymphal stage, the highest population (19.67 insects/2cm2) was found under control. All treatments significantly reduced their population over control within the range of 8.42% - 89.82%. Significantly highest population reduction over control was obtained with T5 (89.82%) followed by T6 (83.07%) and which was statistically similar with T1 (83.07%). Treatment T4 (Chemical + Botanical) showed 35.53% reduction in population over control, which was statistically similar to T2 (Table 1).
4. Discussion
This experiment revealed that the highest reduction of mango mealybug population was observed at 1st instar followed by 2nd and 3rd instar. Among treatments, T5 (Cypermethrin @ 1 ml/l + Mechanical barrier) caused significantly highest reduction of 93.90% in population followed by T6 (Turmeric + Mechanical) and T1 (Only Mechanical) and showed 86.04% and 84.59% reduction in insect population compared to control. The lowest reduction (18.31%) was recorded from T3 (Turmeric powder extract spray). The results of this experiment were similar to the findings of other investigators. Atwal and Dhaliwal [21] reported that the mealybug could be controlled by destroying eggs laid under the infested trees; nymphs could be prevented from crawling up the trees by applying 8 cm wide sticky bands with grease material or slippery bands with alkathene or plastic sheets around the trunk. Moreover, Karar et al. [20] found that combined treatment with three measures (cultural, mechanical and chemical) showed the maximum effect in reducing the population of mealybug up to 98.46%. They were also concluded from the results that the measures in integrated form gave better results than the single treatment. Ishaq et al. [22]) worked on the integrated management of mango mealybug and reported that the pest is difficult to control by water based insecticides. So for its management by using sticky bands along with burning and burying treatments significantly reduced the incidence of infestation. Gul et al. [23] also reported that integration of banding of tree trunks, destruction of eggs in the soil and application of insecticides was the most effective control strategy. Cypermethrin (CP) is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as in consumer products for domestic purposes. It behaves as a fast-acting neurotoxin in insects. It is easily degraded on soil and plants but can be effective for weeks when applied to indoor inert surfaces. It is a non-systemic and non-volatile insecticide that acts by contact and ingestion, used in agriculture and in pest control products. Exposure to sunlight, water and oxygen will accelerate its decomposition. Cypermethrin is highly toxic to fish, bees, and aquatic insects, according to the National Pesticides Telecommunications Network (NPTN). It is found in many household ant and cockroach killers. In particular, pyrethroid are commonly used as insecticides and are recommended for insect control because they are considered to be relatively non-toxic to humans in all stages of life. However, recent data show that they are not completely harmless to human health as they may enter the body through skin contact, by inhalation and food or water, and absorption level depending on the type of food. So, the insecticides must be used with great caution [24]. According to [25] to avoid resistance development of cypermethrin it has to be applied at the concentration recommended by WHO and by the manufacturers (label instructions), avoiding over-dosages which are costly and potentially hazardous, as well as under-dosages which are not effective enough and may accelerate the development of resistance. Insecticides of the same chemical group, acting on the same target site, should be considered as a single product as far as resistance is concerned.
5. Conclusion
Application of mechanical barrier, Cypermethrin @ 1 ml/l and turmeric powder extract @ 15 g/500ml singly or combination with one another gave a significant reduction in the population of mango mealybug at 1st, 2nd and 3rd instars nymphal stages. A higher reduction in their population was observed at 1st instar followed by 2nd and 3rd instar. T5 (Cypermethrin @ 1 ml/l + Mechanical barrier) caused significantly the highest reduction of mango mealybug population followed by T6 (Turmeric + Mechanical) and T1 (Only Mechanical) in all stages.
Recommendations
This study may be done further in different regions of the country to explore the results of the treatments in different climatic conditions.
Different insecticides and different botanicals can be evaluated to select more options for combating mango mealybug.
Acknowledgements
We thank anonymous reviewers for their kind review of the manuscript. This research was financially supported by Sher-e-Bangla Agricultural University.
Authors’ Contributions
This work was carried out in collaboration among all authors. Author NA conducted the research work. Author MZA designed and edited the manuscript. Author MAL designed and supervised the study, managed the literature searches and edited the manuscript. Author MAR managed the literature search. Author MRUM and IHM managed the literature searches and edited the manuscript. All authors read and approved the final manuscript.