Published on International Journal of Agriculture & Agribusiness
Publication Date: March 29, 2019
Khin Myint Mar
Associate Professor, Department of Zoology
University of Magway
This study was carried out to evaluate the efficacy of the extracts from sugar apple leaves against the first instar larvae of beet armyworm, Spodoptera exigua under laboratory condition in the Department of Zoology, University of Magway, Myanmar. The study period lasted during October 2014 to March 2015. The egg masses of beet army worm were collected from groundnut fields in Magway environs and reared in the laboratory with food plants for test insects. The newly hatched larvae of S. exigua were tested with spraying method of Annona squamosa leave crude extracts 60%, 75% and 90% respectively and control with only distilled water. Three replications of ten adults were tested for each treatment. The data obtained from the experiment showed that 26.67% mortality of S.exigua larvae observed at 60% concentration of crude extract and 20% larval mortality at 90% concentration as well as 75% concentration. No larval mortality was investigated in the control group. On the treatment groups, it does not seem that the higher the concentration of the crude extract of A.squamosa leaves was the higher death rate of individuals. The results from the experiment showed that the insecticidal activities of the extract against the first instar larvae of beet armyworm was the less effective. Furthermore it was suggested that the larvae seem to be developed the resistance easily the crude extract of A.squamosa leaves. For the control of S. exigua populations was probably required in harmonious integration with other safe method of pest control like biocontrol and cultural practices etc. in the fields. IPM practices would therefore be required.
Keywords: Efficacy, Annona squamosa, Extract, Mortality, First Instar larva, Spodoptera exigua.
The beet armyworm Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is known as an economically important and cosmopolitan pest of many crops in South East Asia though it is native to southern Asia (CAB, 1972; Capinera, 2001). Infestation by this pest is often serious in subtropical or tropical regions (Burris et al., 1994; Zheng et al., 2000). A major problem in the controlling of the beet armyworm is the insecticide resistance of the pest because it has developed resistance to many insecticides (Moulton et al., 2000; Ahmad and Arif, 2010; Lai and Su, 2011; Su and Sun, 2014) (cited by Ueno, 2015). The biology of the beet armyworm in groundnut fields and the extent of damage caused by the armyworm have not fully been examined in Myanmar. This insect has attacked on groundnut, tomato, cabbage, onion and many crop plantations. Groundnut is the major oil seed crop and grown extensively as annual, especially in the Central part of Myanmar.
Isman and Seffrin (2014) recorded that many predators and parasites contribute to maintain substantially beet armyworm populations at low levels as natural control. Insecticidal sprays for other pests can disrupt this natural control. The effectiveness of most of the insecticides used has been declining as the insect has developed resistance. The development of new techniques to supplement or replace insecticide sprays is necessary to control this insect (Takai, 1991).
In recent years, many researchers have concentrated on plant based insecticide as alternative of synthetic pesticide in which bioactive chemicals are rich sources of natural substances. These substances can be used to develop ecologically safer methods for insect control (Mumtaz, 2013). The main advantage of plant materials is potentially less expensive, locally available, biodegradable and sustainable and have no undesirable effects on the ecosystem (Jouda, 2012). These potentials tend farmers to alternate into the organic insecticides. Among various botanicals used as organic insecticides, Annona squamsa is the species belonging to family Annonaceae. It has been the most extensively investigated for their insecticidal and antimicrobial activities (Nava Díaz et al., 2000). Poisonous properties of Annona species to insect pests is highlighted around fifty years ago (Puttarodriah & Bhatta, 1955) (cited by Ali, 2017).
Groundnut is an economically important oil crop in Myanmar. In our country, the people in various societies prefer the groundnut oil more than other oil types such as sesame, sunflower, etc. Therefore, the most residents in the Central Myanmar grow especially groundnut crop although other oil crops are cultivated in all parts of the country. Considering the importance of eco-friendly approaches for the management of these pests, the experiment was conducted in the laboratory to evaluate the bioefficacy of the extract of sugar apple Annona squamosa leave against the newly hatched larvae of beet army worm.
1.1 Statement of the problem
The problem statement is a study of testing the insecticidal activity of the crude extract of Annona squamosa L. leaves against the newly hatched larvae of beet army worm Spodoptera exigua, gregarious feeders of crop leaf tend to skeletonization.
There are the following objectives of the study
a. To test the efficacy of crude extract of sugar apple leaves against the newly hatched larvae of beet armyworm and
b. To examine the larval mortality of Spodoptera exigua.
2. REVIEW OF LITERATURE
Prakash (2008) reported the future of botanical pesticides in rice, wheat, pulses and vegetables pest management in which they informed the two main aspects of botanical pesticides viz., one search and exploitation of new botanicals such as isolation, identification and evaluation of active component and another use of botanicals in agriculture in different forms. Moreover, Annona squamosa leaves extract in water inhibited the development of insects.
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 Epilachna larvae causing significantly very high mortality even after 24 hours.
Takai and Wakamura (1987) investigated that sex pheromone treatment combined with a light trap reduced the mating rate of beet army worm up to 2-3% in both the open field and greenhouse. They presented that the pheromone treatment gives effective control of beet armyworm population densities.
Leatemia (2003) recorded the development of local insecticides from Ambon and surrounding areas (Indonesia) for local use in which good efficacy of crude seed extract of A.squamosa showed both in the laboratory and the green house against Lepidopteran pests and a slight economic benefit will make a promising candidate for development as a simple botanical insecticide for local use (Indonesia).
Lai and Su (2011) documented the monitoring of beet armyworm Spodoptera exigua resistance to chlorantraniliprole in China in which it has developed resistance to many broad-spectrum insecticides and field populations of beet armyworm showed detoxification enzymes to chlorantraniliprole insecticide.
Dang et al. (2012) published the current status of botanical pesticides for crop protection in which botanical pesticides have been regarded as attractive alternatives to synthetic chemical pesticides for the pest management. With the growing acceptance of botanical pesticides as an efficient crop protection alternative resulting in increasing demand, plant-based pesticides will play a significant role in achieving sustainable agriculture in future.
Isman and Seffrin (2014) recorded that crude extract from leaves, seeds, barks, twigs and fruits obtained from the plant species of Annona squamisa have been extensively tested in recent years for bioactivity to pest insects and related arthropods worldwide.
Thinzar Hlaing (2015) stated that efficacy of Annona squamosa L. leaf extracts against the larvae of tobacco caterpillar, Spodoptera litura (Fabricius, 1775) in which three replications of ten larvae were tested. The results showed that the mortality rate of S.litura was the highest (33.33% mortality) at 90% A.squamosa leaves crude extracts while the lowest at 60% (0% mortality) and the moderate (20% mortality) at 75% at room temperature of about 26.2˚C. The insecticidal activities of A.squamosa leaves on the larvae tested was the most effective at the concentration of 90% crude extract.
Online information Services For Non-chemical Pest Management in the Tropics (Oisat, 2015) inform pesticidal effect of Annona squamosa leaves crude extract on Spodoptera litura, Spodoptera exigua, Phenacoccus solenopsis and detailed procedure for preparation of crude aqueous extract.
3. MATERIALS AND METHODS
This experiment was conducted in the laboratory of Department of Zoology, University of Magway. The egg masses of beet armyworm were collected from groundnut plantations in Magway environ. Then, they were reared under the laboratory conditions at room temperature (about 30˚C) to emerge newly hatched larvae. Experimentation was carried out from October 2014 to March 2015.
3.1 Preparation of Annona squamosa leaves crude extract
Fresh leaves of Annona squamosa was collected locally during the month of November 2014 to January 2015. 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 pulverized by a pestle and one litre of warm water was added. The leaves were soaked in water and often stirred for 12 hours. The extracts were filtered through a muslin cloth and collected in a glass jar. This extract was considered as 100 % (w/v) solution from which the concentrations to be tested were made by dilution with distilled water. Different concentrations of the extract (60% w/v, 75% w/v and 90% w/v) were experimented to evaluate the insecticidal activity against the first instar larvae of beet army worm at laboratory condition. Any chemical was not used in extraction method.
3.2 Experimental Design
The egg masses of beet armyworm were collected from the groundnut plantations near Magway environs reared for test insects at the laboratory of Department of Zoology, University of Magway (Plate 1&2). A contact bioassay was used to test the insecticidal activity of Annona squamosa leaves extract against the first instar larvae of Spodoptera exigua. The larvae of beet armyworm were treated with the concentrations (60% w/v, 75% w/v and 90% w/v) of A. squamosa leaves extract. Then, ten larvae (first instar larvae) of beet armyworm were introduced into the glass petri-dish 12 cm in diameter. Then, the newly fresh leaves were washed with tap water and used as food for the test larvae in the dish. Ten larvae of pests sprayed with the crude extracts were introduced into the petri dish prepared. Three replicates for each concentration (60%, 75%, and 90%) were made for five day period and controls treated only with distilled water. Mortality of larvae was observed every 24h after the treatment and recorded at room temperature. The mortality was determined under the dissecting microscope when they did not respond to mechanical stimulation.