Published on International Journal of Agriculture & Agribusiness
Publication Date: March 15, 2019
Khin Myint Mar
Associate Professor, Department of Zoology
University of Magway
This study was conducted to evaluate efficacy of crude extracts of Annona squamosa leaves against the polyphagous pest, mealy bug Phenacoccus solenopsis under control laboratory condition in the Department of Zoology, University of Magway, Myanmar during October 2014 to March 2015. The egg mass of Phenacoccus solenopsis were collected from tomato fields in surrounding areas of Magway University and cultured in the laboratory with food plants. The adults of P. solenopsis were tested with spraying method of A.squamosa leave extracts with only distilled water (control), 60%, 75% and 90% respectively. Three replications of ten adults were tested for each treatment. The results showed that the mortality rate of P. solenopsis was the highest (80.00% mortality) at 90% of A.squamosa leaves crude extracts while the lowest at 60% (60% mortality) and the moderate (66.67 % mortality) at 75% under room temperature of about 29.8˚C. The results from the experiment showed that the insecticidal activities of A.squamosa leaves on the mealy bug adults tested was the most effective at the concentration of 90% crude extract. Moreover, it was suggested that higher the concentration of extract was higher the mortality rate. Leave extract of A.squamosa is a hopeful candidate to contribute integrated pest management program as simple botanical insecticide for local use in Myanmar.
Keywords: Bioefficacy, Annona squamosa, Crude extract, Mortality, Phenacoccus solenopsis.
Mealybugs (Hemiptera: Pseudococcidae) are important plant pests worldwide (McKenzie, 1967; Williams 1985; Williams & Granara de Willink 1992; Miller et al., 2002, 2005b) (cited by Culik and Gullan, 2005). Their feeding may cause leaf yellowing, defoliation, reduced plant growth, and may often lead to death of plants. They may also damage plants as vectors of plant diseases. In addition, production of honeydew causes the development of sooty mold that decreases photosynthesis and may reduce the marketability of plant products such as vegetables and fruits. Besides direct and indirect damage to crops, mealy bugs are also of quarantine concern, adding to costs of production to prevent their presence on plants (Culik and Gullan, 2005).
Chemical control is generally practiced by farmers for higher yield. Over-reliance and non-judicious use of insecticides has resulted in crops to many negative consequences mainly the infamous 3 R’s viz. resurgence, resistance and residue aspects (Mehrotra, 1990 and Kabir et al., 1994), besides the health hazards. Furthermore, their chaotic use has resulted in decline of biodiversity of natural enemies (Sekhon and Verma 1985), outbreak of secondary pests (Praveen et al., 2001), contamination of food (Mitra et al., 1999) and breakdown of food webs in ecosystem. Therefore, among the various possible substitutes to reduce these problems without harming soil, water and living organisms including the human beings, biopesticides are now developing as insect pest management strategies on all crops in order to save human health as well as to diminish parasitoids and predators (Krishnamurthy, 1999).
Tomato is also an economically important crop in Myanmar. In our country, onion and tomatoes form the base of our Myanmar curries and these are generally used to make any traditional curry and in a variety of every salad. Mealy bugs may cause significant economic damage on cotton and a wide range of other cultivated plants (e.g. tomatoes, eggplant, chilli, melon and potatoes) and broadleaf weeds are hosts. Damage is often patchy, and may be worse in areas where the crop is under stress (e.g. poorly drained areas). Heavy infestations that start early and persist can lead to plant death.
Considering the importance of eco-friendly approaches for the management of insect pests, the present study was conducted in the laboratory to evaluate bioefficacy of sugar apple Annona squamosa leave extract against the mealy bug.
1.1 Statement of the problem
The statement of the problem is a study of experimenting the insecticidal activity of Annona squamosa L. leaves crude extract on the mortality of the adult mealy bug P. solenopsis.
There are the following objectives of the study:
• To investigate the bioefficacy of sugar apple leave extract against the mealy bug and
• To observe the mortality of P. solenopsis.
2. REVIEW OF LITERATURE
Culik and Gullan (2005) informed that Phenacoccus solenopsis as pest of tomato is essentially important to control.
Karunaratne and Arukwatta (2009) published efficacy of three plants species on the mortality and food consumption of Epilachna vigntioctopunctata. They reported the comparison of Annona squamosa leaf extract with the other two plants extract, it was very strong antifeedant effect on the larvae at all concentrations tested. Among the three plants tested, Annona squamosa was the most effective against the Epilachna larvae causing significantly very high mortality even after 24 hours.
Nikam (2010) recorded that nine insecticidal treatments yielded significantly higher over untreated check. But these chemical insecticides are not ecofriendly.
Sahito et al. (2011) investigated the efficacy of different insecticides against cotton mealy bug. They recorded that neem oil was effective and then the least toxic against natural enemies of mealy bugs.
Prishanthini and Vinobaba (2014) stated that the botanicals such as A.indica, O.sanctum, C.gigantea, N.tabacum and A.sativum were showed different levels of insecticidal activities. These findings of the present study suggest that Osmium extract can be used as a botanical spray to get better and safe control of cotton mealy bug P.solenopsis. Rasheed et al. (2014) recorded that Most of farmers mainly rely on synthetic chemicals for the management of mealy bug. But the use of synthetic insecticides is extremely toxic to natural enemies of mealy bugs. Plant derivatives can be used as an alternative approach to synthetic chemicals which are cost effective, easily available and safe to environment and biocontrol agents.
Manzoor and Haseeb (2015) investigated the efficacy of Annona squamosa and other locally available botanicals against the 2nd instar cotton mealy bug, Phenacoccus solenopsis under ambient laboratory conditions using leaf and surface treatment. The data on the mortality of the 2nd instar mealy bugs show that all the treatments were highly significant over control.
Online information Services For Non-chemical Pest Management in the Tropics (Oisat) inform pesticidal effect of Annona squamosa leaves crude extract on Spodoptera litua, Spodoptera exigua, Phenacoccus solenopsis and detailed procedure for preparation of crude aqueous extract.
3. Materials and Methods
This experiment was conducted in laboratory of Department of Zoology, University of Magway, Myanmar. The egg mass of mealy bug Phenacoccus solenopsis were collected from tomato plantations in the surrounding areas of Magway University. Then, they were cultured in the laboratory with food plants to be used as test insects. Experimentation was carried out from October 2014 to March 2015.
3.1 Preparation of Annona squamosa leaves crude extract
The fresh leaves of the plant Annona squamosa (sugar apple) were collected from the home gardens near the campus of Magway University. The One kilogram of fresh leaves were washed with running tap water to clean dust and other particles. Then, the leaves of A.squamosa were crushed by a pestle and one litre of lukewarm water was added. The leaves were soaked in water and often stirred for 12 hours. The extract was filtered through a muslin cloth and collected in a glass jar. This extract was considered as 100 per cent solution from which desired concentrations were made. Different concentrations of A.squamosa leaves extract (60%, 75%, and 90%) with their respective dosage were applied to evaluate their insecticidal effects against the adults of mealy bug under laboratory condition. In the extracting of sugar apple leaves, any chemical was not used.
3.2 Experimental Design
A contact bioassay was used to test the insecticidal activity of Annona squamosa leaves extract. The adults of mealy bug P. solenopsis were tested with the three concentrations of leaves extract. Three replicates for each concentration (60%, 75%, and 90%) were made for five day period and control treated only with distilled water. Then, ten larvae of tested insects were introduced into the glass petri-dish 12 cm in diameter. Then, the food leaves were washed with tap water and added into the dish. The adult mealy bug treated with the A.squamosa leave crude extracts were introduced into the dish prepared. Fresh leave food for test insects were added daily. Mortality was examined every 24 h after the treatment and recorded at room temperature. The mortality was determined under the dissecting microscope when they did not respond to mechanical stimulation.