TWJ VOLUME 3 No.1 MARET 2017 ISSN : 2338-7653 THE POTENTIAL OF SPODOPTERA PECTINICORNIS IN CONTROLLING WATER LETTUCE (Pistia stratiotes) IN FIELD Lyswiana Aphrodyanti, Helda Orbani Rosa, Samharinto Plant Protection Department, Agricultural Faculty, Lambung Mangkurat University Banjarbaru, South Kalimantan, Indonesia Email : [email protected] ABSTRACT power plants (Howard and Harley 1998), lead to the miniaturization of the volume of Spodoptera pectinicornis is a biological plankton (Cai, 2006), and become a habitat control agent that has a great potential to for mosquito malaria vector Anopheles and control water lettuce weeds. Its existence in Mansonia (FL DEP, 2007, Parsons and nature however is still limited, so a mass Cuthbertson, 2001). Water lettuce belongs to propagation is needed by rearing S. harmful weed or invasive aquatic plants in pectinicornis imagoes to produce eggs and to several states of the United States (USDA- hatch them into larvae of 4 days old. The 4- NRCS, 2012), Australia (Queensland year larvae were then released by putting Government, 2016), also in Indonesia water lettuces that contained active larvae (EPPO, 2014 and CABI 2015). into the target area. Observation results on South Kalimantan is one of the the percentage of damage in the watershed widespread deployment areas of water location for 5 times of observation lettuce weeds in Indonesia (EPPO 2014 and consecutively was 25%, 50%, 50%, 75% and CABI 2015), and Spodoptera pectinicornis is 90%. The magnitude of damage showed that found as herbivore on the weeds S. pectinicornis was able to adapt well, so it (Mangoendihardjo et al., 1979). The spread could perform eating activities and cause of this insect is quite extensive and allegedly damage to the water lettuces. Meanwhile, at it is one of the native insect of Indonesia the release site of rice field, the percentage because Kunta’s research results (1977) of damage was 0%, 25%, 35%, 25% and show that this insect is found in Asian 10%. The downward trend in the level of S. countries like India, Sri Lanka, Singapore and pectinicornis attacks was due to its inability to Indonesia. However, the existence of S. keep pace with the growth and development pectinicornis has not been able to overtake of water lettuces. High level of rainfall caused the growth and development rate of water the water lettuces to increase its size and the lettuces in the field, so the manipulation effort number of its tillers so that they could is conducted through an augmentation colonize these waters. The fact that S. technique by doing a mass propagation of pectinicornis still has the ability to destroy the biological agents first before released into the water lettuces gives great hope to the control field. efforts. However, thorough evaluation and The success of other countries, such assessment are required on all aspects, such as India and Thailand, in controlling water as the biological control agents, weed lettuce weeds using S. pectinicornis gives targets, organisms associated with them, and great hope that it could also happen in our the state of the environment so as to country, Indonesia. A biological method that minimize the possibility of failure in the field. has been successful would provide a more permanent and wider scale of control and a Keywords: augmentation, biological agents, minimum negative impact on the Pistia stratiotes, Spodoptera pectinicornis environment. INTRODUCTION MATERIALS AND METHODS Pistia stratiotes, known as water The rearing and mass propagating lettuce, is a weed that is found in almost all were conducted in screen house and the tropical and subtropical waters. Invasion of Entomology Laboratory, Plant Pests and water lettuce can cause damage to Diseases Department, Agriculture Faculty, infrastructure such as blocked drains, reduce Lambung Mangkurat University, from May to the efficiency of irrigation and hydroelectric October 2016, while the release was 10 Lyswiana Aphrodyanti, Helda Orbani Rosa, Samharinto: The Potential Of Spodoptera ................... conducted in Banjar Regency at two locations - watershed and rice field, from The release of S. pectinicornis agents into September to November, 2016. the field The 4-year stadia larvae were invested Rearing of S. pectinicornis agents in the into waters being invaded by water lettuces - Laboratory the watershed and rice field areas. The S. pectinicornis larvae were bred by release was done 2 times, on the first day supplying the feed of fresh water lettuce until and then on the 30th day. The number of they reached pupal stage. The pupae were larvae to be invested with an estimation of collected and placed into a plastic jar with a 100 larvae per square meter and the number diameter of 14 cm, at the base of which needed for the release were to be adjusted to tissue paper and wet cotton were placed to the extent of the area to be invested. keep it moist. Male and female imagoes that emerged were transferred into an enclosure Observation and given honey of 10% on the hanged Observations were made by observing cotton. The imagoes mated and laid eggs on the damage symptoms inflicted and were the water lettuce. performed 5 times with an interval of 10 days. As supporting data, observations were Mass Production of S. pectinicornis carried out on the presence of predators and Biological Control Agents parasitoids which could represent as one of Mass production was done by setting the limiting factors for the activity of the up nurturing containers with a diameter of 50 biological agents. cm. The nurturing containers were covered with gauze cover, and the fresh water RESULTS AND DISCUSSION lettuces taken from the field were put into the containers. Subsequently, the instar III were Mass propagation and release to the field invested as much as possible and kept alive The effort of mass propagation of S. until they became pupae and imagoes. The pectinicornis showed success as evidenced imagoes were allowed to mate and lay eggs. by the ability of S. pectinicornis to complete The breeding of biological agents in bulk its life cycle and continue to proliferate continued until they reached sufficient normally so as to achieve a sufficient number number with the estimation of 100 larvae per for the preparation of the release into the square meter with the release area of about field (Figure 1). 200 square meters so that about 20,000 larvae were required to be released. Figure 1 Mass propagation and breeding of S. pectinicornis pupae and imagoe The rearing of biological agents in bulk George in Center et al., (2000) that 100 was conducted so as to achieve a sufficient larvae of S. pectinicornis were able to number with an estimation of 100 larvae per destroy water lettuces with an area of 1 square meter, with the release area of about square meter. This is reinforced by the 200 square meters, which needed about statement of Memmott et al., (1996) that the 20,000 larvae ready to release. According to optimal release strategy was to consider the 11 Lyswiana Aphrodyanti, Helda Orbani Rosa, Samharinto: The Potential Of Spodoptera ................... relationship between the number of insects to a plant as food, and thus releasing larvae be released and their establishment in the along with the water lettuces originating from field. mass propagation in the screen house would The release of biological agents in the greatly affect the process of adaptation to the larval stage was considered very effective new place. because the larvae would attach firmly on the water lettuce leaves, so the possibility of Damage Percentage death could be overcome. The release was Observations on the watershed carried out by spreading the water lettuces location indicated that the S. pectinicornis containing active larvae evenly in the weed biological agents clearly showed a very high target areas. According to Jolivet (1992), destructive capability, while at the rice field monophagous insects would do the physical, location it showed a different thing, where the mechanical and chemical selection to select damage tended to decrease (Figure 2). Watershed Rice field (%) Intensity Damage of Observation period (week) Figure 2. Percentage of damage to water lettuce caused by S. pectinicornis The percentage of damage in the Thailand (Napompeth, 1990) and a similar watershed location for 5 times of observation statement stated by George in Center et al., consecutively was 25%, 50%, 50%, 75% and (2000) that this control technique has also 90%. The presence of damage symptom been able to replace the use of herbicides indicated that the biological agents were able that is very dangerous because it is used in to adapt well and conducted eating activity water areas. immediately after release. According to The last observation at this location Aphrodyanti et al., (2009), S. pectinicornis showed that the 90% damage reinforced the larvae of instar III and IV had high eating notion that S. pectinicornis biological agent consumption ability so that it could cause was a potential natural enemy, but it required severe damage. The success of controlling human intervention to improve its ability to water lettuce by utilizing S. pectinicornis have overcome the problem of water lettuce been able to replace the use of herbicides in weeds. 12 Lyswiana Aphrodyanti, Helda Orbani Rosa, Samharinto: The Potential Of Spodoptera ................... a b Figure 3. Damage to water lettuce weeds due to S. pectinicornis in watershed location a. Prior to the release and b. After the release Observations in the rice fields showed Center, 1989). According to Mangoendiharjo different results, i.e. the damage percentage (1982) water lettuces would experience of 10%, 25%, 35%, 25% and 10%. The optimal growth when the conditions were downward trend in the level of attacks was met, and the improvement of leaves would allegedly due to the inability of S. increase by 10% and the dry weight would pectinicornis in keeping pace the growth and increase by 42% and the number of development of water lettuces that colonized individuals would be doubled.