Potency Of Jatropha Curcas Seed Crude Extract Againts Nezara Viridula (Hemiptera: Pentatomidae)

Crude extracts of J. curcas

Seeds of J. curcas seed were obtained from the ripe fruits (yellow to brownish) collected in Kabupaten Deli Serdang Indonesia during April 2018. The J. curcas seeds were hulled to get the kernels. After a week of air dried under shade, the kernels were grinded. An amount of 50 g of material was wrapped in a filter paper for extraction using soxhlet extractor (with 200 ml acetone solvent). Total crude extract was obtained after the solvent was dried using a rotary vacuum evaporator.

Rearing of insects

Nezara viridula was obtained by mass rearing with the initial population from a soybean field. Male and female adults were collected in a wired cage (50x50x60 cm) and fed with fresh long beans Vigna unguiculata subsp. sesquipedalis . After about 4 weeks, new adults emerged which were used in the study (5-10 days old).

Application of crude extracts

Study was done at the plant protection laboratory Faculty of Agriculture, Islamic University of North Sumatra, Indonesia from May to August 2018. The assay was performed in a laboratory at temperature 29 ± 2 oC, relative humidity 70 ± 10 % and photoperiod of 12 hours. Tests for residual toxicity (contact poison) and oral toxicity (stomach poison) was performed according to Tilman (2006) with 0.50 %, 0.25 %, 0.125 %, 0.062 %, 0.031 % and 0.015 % concentrations.

Residual toxicity (contact poison) test was done by smearing 2 ml of crude extract on top and bottom of petri dishes (150 by 15 mm). Water was used as the control. After an hour when the solution has dried, 10 N. viridula adults were placed in each petri dish. After 24 hours, the adults were transferred into a transparent plastic jar (9.5 cm diameter and 7 cm height) with a piece of filter paper at the bottom. The jars were covered with muslin cloth. These insects were provided with 5 young soybean pods per jar, as their food. The pods and filter paper were replaced every 2 days.

Oral toxicity (stomach poison) test was done by soaking soybean pods in the crude extract for 30 seconds and then air dried on a screen wire for an hour. The pods were then wrapped with a muslin cloth (to prevent contact of insects) and placed inside a transparent plastic jar (9.5 cm diameter and 7 cm height) with a piece of filter paper at the bottom. Ten N. viridula adults were placed in each jar. After 3 days, the pods were replaced with untreated pods.

For both tests, the mortality rate was recorded daily until ten days after treatment. Number of egg production and nymphs were counted. Statistical analysis was done using one way ANOVA (P<0.05). Data of insect mortality were transformed using Arc Sine Transformation, whilst the number of eggs and nymphs were transformed by log (x+10) (Gomez & Gomez, 1984) for normalization before analysis. Duncan’s Multiple Range Test (DMRT) at 5 % confidence interval was used to measure specific differences between pairs of means. All statistical analyses were done using SPSS Statistic 24 program.

Residual toxicity (contact poison)

There was a significant difference in N. viridula mortality (F = 46.43, df = 6 & 27, P < 0.05), number of eggs (F = 5.19, df = 6 & 27, P < 0.05) and number of nymphs (F = 6.08, df = 6 & 27, P < 0.05) caused by J. curcas seed crude extract concentrations. The mean percentage of N. viridula mortality, and number of eggs and nymphs is shown in Table 01 .

The results showed that all concentrations of J. curcas seed crude extract caused N. viridula mortality and were significant different compared to control. The insect mortality was 75-100 %. The concentrations of 0.25 % and 0.50 % of J. curcas seed crude extract gave total percentage of mortality and therefore act as the best contact poison. There was a trend of increased N. viridula mortality with the increase of extract concentration. The effect was probably due to the bioactive componenst of J. curcas seeds. According to Habou, Haougui, Adam, Haubruge, and Verheggen (2014) J. curcas seed crude extract caused Callosobruchus maculatus mortality up to 72 % at 7 days after treatment. Devappa et al. (2012) reported that phorbol ester from J. curcas oil exhibited contact toxicity. Bourga (2018) also reported a high contact toxicity of the phorbol ester in J. curcas seed oil, and that the oil was observed on the grain aphid Sitobion avenae. The topical and spray applications of a concentration of 2 % of phorbol ester and the seed oil caused a sudden death of the aphids. With both compounds, the aphids died soon after the application of the compounds on the insect cuticle.

Treatment of the crude extract at 0.062 % concentrations caused the lowest number of eggs and nymphs. There were no eggs and nymphs produced when the J. curcas seed crude extract was applied at concentrations of 0.125 %, 0.250 % and 0.5 %. Thus, these concentrations were considered as the contact poison. Although J. curcas seed crude extracts at concentrations of 0.015 %, 0.031 % and 0.062 % caused 75-90 % N. viridula mortality, there were still survival insects producing eggs and progenies.

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The mortality pattern of the insect at 1 to 12 days after treatment is presented in Figure 01 . The graph shows that insect mortality at 0.5 % concentration of J. curcas seed crude extract occurred faster than other concentrations. The concentration of 0.5 % caused 50 % mortality at 5 days after treatment, whilst 0.25 % and 0.125 % concentrations caused lower than 40 % mortality. Although the percentage of mortality reached 75-90 % at lower concentrations, these were not recommended because there were still presence of eggs and progenies at these concentrations.

Oral toxicity (stomach poison)

There was a significant difference in N. viridula mortality (F = 72.25, df = 6 & 27, P < 0.05), number of eggs (F = 2.90, df = 6 & 27, P < 0.05) and number of nymps (F = 3.28, df = 6 & 27, P < 0.05) caused by J. curcas seed crude extract concentrations. The mean percentage of N. viridula mortality, number of eggs and nymphs is shown in Table 02 .

The results showed that all concentrations of J. curcas seed crude extract caused N. viridula mortality and were significant different compared to control. The 0.25 % and 0.5% of J. curcas seed crude extract concentration had the best effect with 100 % mortality, and without production of eggs and progenies. This revealed that J. curcas seed crude extracts could act as stomach poison (oral toxicity). The results are agreement with those obtained by Ingle et al. (2017), who observed 80 % Plutella xylostella mortality when fed with cabbage leaves dipped in J. curcas seed extracts at 0.5 % concentration.

Tukimin, Soetopo, and Karmawati (2010) stated that the mortality of Achaea janata larva was 75 -85 % at 3 days after feeding with Ricinus communis leaves reated with J. curcas seed oil solution (5 ml seed oil + 1 g detergent/l water). The source of the J. curcas seeds which contain the phorbol ester was from South of Sulawesi and East of Java, Indonesia. Bourga (2018) reported the seed oil of J. curcas caused the mortality of aphids after feeding on wheat plants sprayed with 2% of the extract. The oil is rich with dipterpenoids which are considered to be the most important compound synthesized by J. curcas (Devappa, Makkar, & Becker, 2011). Ratnadass and Wink (2012) reported that the seed oil and the phorbol ester of J. curcas had high ingestion toxicity on Hemipteran species (Myzus persicae, Aphis gossypii and Lipaphis erysimi).

The concentration of 0.125% has shown good effect (insect mortality has reached 100%), but some of the insects had managed to lay eggs and produced progenies (nymph) before dying. The number of eggs and progenies were 18.75 and 17.5 respectively. The concentrations of 0.15 % to 0.062 % showed the insect mortality of 75 to 93 %, and the insects still also produced eggs and progenies. These low concentrations were not recommended because the progenies produced could be a source of infestation in further period.

The oral toxicity of the crude extract showed a slower mode of action than the contact toxicity. It needed a longer period to cause mortality effect because the insects need to suck the soybean pods before the toxic materials reached the mid gut. Figure 02 shows the 0.5 % extract concentration caused only 40% at 5 days after treatment and 70 % mortality at 8 days after treatment. Adolf, Opferkuch, and Hecker (1984) reported that J. curcas seeds contain curcin and phorbol ester which could affect the insects. Sauerwein, Sporer, and Wink (1993) found that phorbol esters from J. curcas seed have insecticidal properties. In this study, N. viridula which sucked the soybean pods caused the inset mortality. The insects ingested the toxic material and response occurred when the crude extract reached the mid gut.

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The Jatropha curcas seed crude extract showed a residual toxicity (contact poison) and oral or ingestion toxicity (stomach poison) against Green Stink Bug N. viridula.

The crude extract exhibited a high mortality at concentrations of 0.5 % and 0.25% (100% of mortality, no egg and progeny production).

The crude extract could be an alternative for the control of N. viridula.

Jatropha curcas seed crude extract showed rapid action as contact poison (residual toxicity) if compared to as stomach poison (oral toxicity) against N. viridula.