FIELD OF INVENTION

The present invention relates to a pest control composition comprising entomopathogenic fungi, and a method of using such composition for suppressing plant damaging pests in agricultural environments.

BACKGROUND OF THE INVENTION

Pests such as insects, arachnids and nematodes are a major problem for the agriculture industry, often significantly limiting crop productivity. Of great concern is Psychidae or commonly known as bagworms, belongs to the family of Lepidoptera consisting of at least 1,350 species around the world. Bagworms have a detrimental impact on oil palm plantations of which the impact consequently manifests into poor harvest yield of palm oil and huge economic loss to the country. Metisa plana Walker has become one of the important and dominant oil palm pests in Malaysia and Indonesia to the extent of being declared as the most severe leaf defoliators in oil palm plantations in Peninsular Malaysia (Norman, K., G.S. Robinson and M.W. Basri, 1994. Common bagworm pests (Lepidoptera: Psychidae) of oil palm, with notes on related South-East Asian species. Malayan Nat. J., 48: 93-123) while Pteroma pendula being the second most economically destructive bagworm (Basri, M.W., H.H. Abdul and M. Zulkifri, 1988. Bagworm (Lepidoptera: Psychidae) of Oil Palms in Malaysia. PORIM, Malaysia). Mahasena corbetti is rarely reported as a serious oil palm pest in Peninsular Malaysia, although it is a widely distributed defoliator in the eastern region of Sabah, which constitutes to the largest oil palm plantation land use in Malaysia (Young, S.N., 1971. Some Pests of Oil Palm on the East Coast of Sabah. In: Crop Protection in Malaysia, Wastie, R.L. and B.J. Wood (Eds.). ISP, Kuala Lumpur, pp: 107-114).

The population density of bagworms fluctuates throughout the year due to several factors contributing to the outbreak, including intensive use of chemical insecticides, lack of beneficial crops attracting natural enemies and pest infestation from neighbouring plantations. Dependency of natural enemies of bagworms such as predators and parasitoids are limited prior to the outbreak phase and population outbreak may not be reliably controlled by the natural enemies alone. This inevitably forces plantations to resort to chemical insecticides. Chemical insecticides derived from organophosphates, carbamates and synthetic pyrethroids have been recommended for suppression of bagworm infestation in affect area of oil palm plantations. Despite their effectiveness in controlling pest infestation, excessive use can cause residual seepage in soil, water bodies and air, consequently presenting adverse effects to non-target organisms and the ecological balance. Public concern over potential health hazards of chemical insecticides and recent price hike of chemically-engineered insecticides have led to the exploration of more eco-friendly bagworm management strategies.

Biopesticides have been developed for use as a safer substitute, or alternatively as a supplement to chemical insecticides. Biopesticides are essentially living organisms (for example, bacteria and fungi) that interfere with the life cycles of insects by maiming or killing the insects. Entomopathogenic fungi are one of the biological agents used as biopesticides due to their epizootic nature to insects. Examples of biopesticides include the entomopathogenic fungus Isaria fumosorosea , which has shown huge promise as a biological pesticide. Isaria fumosorosea has been reported to infect a wide range of host including diamondback moth (. Plutella xyllostella ), Russian wheat aphid (. Diuraphis noxia ), spotted spider mite ( Tetranychus urticae ), European red mite (Pan onychus ulmi ) and bagworm ( Pteroma pendula). Multiple approaches for the formulation of biopesticides derived from the entomopathogenic fungus Isaria fumosorosea have been established. Of particular is Chinese Patent No. CN103749441B disclosing a biopesticide formulation incorporating Isaria fumosorosea conidia powder as the active component, a wetting agent, a dispersant, an ultraviolet protection agent and a carrier. Another Chinese Patent Document No. CN104642392A resembling the latter patent document discloses an Isaria fumosorosea-based wettable powder formulation having pure Isaria fumosorosea conidia powder as the active component. Similarly, a Chinese Patent Document No. CN103749545A discloses a wettable powder formulation comprising a combination of entomopathogenic fungus Isaria fumosorosea conidia and soil-borne Bacillus thuringiensis strains. The above-mentioned patent documents present a drawback as they utilize a conventional dispersion of biopesticides using aerial conidia, in which harvest of conidia of Isaria fumosorosea in mass production is significantly complex and difficult.

Accordingly, there exists a need for a mycoinsecticide composition, particularly for suppressing bagworm infestation in crops at oil palm plantations by utilizing entomopathogenic fungal propagules, particularly submerged Isaria fumosorosea propagules, a stable surfactant system and an agriculturally acceptable carrier. Accordingly, a method for suppressing bagworm infestation in crops using the mycoinsecticide composition thereof should be accompanied.

This invention provides such a composition and a method of dispersing the composition therefrom. SUMMARY OF INVENTION

One aspect of the invention is to provide a degradable mycoinsecticide composition for suppressing bagworm infestation in a plant.

Another aspect of the invention is to provide a method of suppressing bagworm infestation in a plant by treating the plant with a degradable mycoinsecticide composition.

At least one of the preceding objects is met, in whole or in part, in which the embodiment of the invention describes a degradable mycoinsecticide composition for suppressing bagworm infestation in a plant comprising a fungal insecticide having submerged propagules derived from a strain of Isaria fumosorosea , a sulfonate surfactant and an agriculturally acceptable carrier.

In a preferred embodiment of the invention, the fungal insecticide may have an insecticidally effective amount of submerged propagules ranging from 10 ⁶ to 10 ⁸ cfu/mL of the mycoinsecticide composition.

In another preferred embodiment of the invention, the sulfonate surfactants are selected from sodium lignosulfonate, sodium xylenesulfonate, sodium cumenesulfonate or a combination thereof.

In a preferred embodiment of the invention, the total amount of sulfonate surfactant mixture may be ranging from 15% by weight to 30% by weight of the mycoinsecticide composition.

In a preferred embodiment of the invention, the agriculturally acceptable carrier may include a bentonite clay in an amount ranging from 50% by weight to 65% by weight of the mycoinsecticide composition.

Yet in another preferred embodiment of the invention, the mycoinsecticide composition may be in the form of a wettable powder.

A preferred embodiment of the invention further describes a method of suppressing bagworm infestation in a plant comprising treating the plant with a degradable mycoinsecticide composition comprising a fungal insecticide, a sulfonate surfactant mixture and an agriculturally acceptable carrier. Preferably, the fungal insecticide may be derived from a strain of Isaria fumosorosea having an insecticidally effective amount of submerged propagules. Also preferably, the sulfonate surfactants are selected from sodium lignosulfonate, sodium xylenesulfonate, sodium cumenesulfonate or a combination thereof. Further, the agriculturally acceptable carrier may preferably include a bentonite clay.

In another preferred embodiment of the invention, the method of of suppressing bagworm infestation in a plant further comprise a step of diluting the mycoinsecticide composition to water at a volume ratio from 1 :200 to 1 :500.

In a preferred embodiment of the invention, the method of suppressing bagworm infestation in a plant may further comprise a step of diluting the mycoinsecticide composition to water to achieve an insecticidally effective amount of 10 ⁶ to 10 ⁸ cfu/mL of submerged propagules derived from the strain of Isaria fumosorosea..

In another preferred embodiment of the invention, the bagworm species (Lepidoptera: Psychidae) may include Metisa plana , Pteroma pendula and Mahasena corbetti.

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiment described herein is not intended as limitations on the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawing the preferred embodiments from an inspection of which when considered in connection with the following description, the invention, its construction and operation and many of its advantages would be readily understood and appreciated.

FIG. 1 depicts a pseudoternary phase diagram for all surfactant system tested.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the invention shall be described according to the preferred embodiments of the present invention and by referring to the accompanying description and drawings. However, it is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim.

The invention relates to a degradable mycoinsecticide composition for suppressing bagworm infestation in a plant. Preferably, the composition comprises a fungal insecticide having submerged propagules derived from an entomopathogenic fungus strain of Isaria fumosorosea , a sulfonate surfactant mixture and an agriculturally acceptable carrier. Advantageously, the mycoinsecticide composition is effective in suppressing bagworm infestation in a plant, particularly oil palm. The mycoinsecticide composition also presents the benefit of selectively infecting the target pest, particularly bagworm, without harming beneficial insect pollinators.

In a preferred embodiment, the mycoinseciticide composition is formed of 10 ⁶ to 10 ⁸ cfu/mL of fungal insecticide. According to the preferred embodiment, the mycoinseciticide composition is comprised of at least one fungal insecticide from the genus Isaria spp., such as Isaria fumosorosea (also may be referred to in the art as Paecilomyces fumosoroseus and Spicaria fumosorosea). Preferably, the fungal insecticide described herein comprises submerged propagules of the strain Isaria fumosorosea. More preferably, the submerged propagules derived from the strain of Isaria fumosorosea comprises blastospore, scloteria and mycelia fragments. The fungal insecticide is obtained via isolation of mycelia of Isaria fumosorosea emerging from mycotized dead bagworms. Subsequently, the fungal insecticide is produced from the mycelia in a liquid culture media or a solid culture media fermentation process known in the art. Fermentation processes is conducted using conventional fermentation processes including shake flask cultivation, aerobic liquid culture techniques and small- scale or large-scale fermentation in industrial or laboratory fermenters; these processes are well known in the art. According to the aforementioned embodiment, following fermentation, the submerged propagules of Isaria fumorososea is recovered using conventional techniques such as filtration, centrifugation and mechanical recovery. Advantageously, submerged propagules of Isaria fumosorosea are cheaper and easier to harvest for mass production in comparison to conidia.

In a preferred embodiment, the mycoinsecticide composition is formed of 15% by weight to 30% by weight of surfactants. According to the preferred embodiment, the mycoinsecticide composition is comprised of one or more surfactants. Preferably, the surfactants described herein are water soluble anionic surfactants. In one preferred embodiment, the mycoinsecticide composition herein comprises one or more water soluble anionic surfactants. Preferably, the water soluble anionic surfactants described herein are sulfonated surfactants. More preferably, the mycoinsecticide composition comprises a mixture of sulfonated surfactants comprising of sodium lignosulfonate, sodium xylenesulfonate and sodium cumenesulfonate ranging from 15% by weight to 30% by weight of the mycoinsecticide composition. According to the aforementioned embodiment, the mixture of sulfonated surfactants in such percentage ranges suitable for the mycoinsecticide composition described herein enhances dispersibility and suspensibility of the mycoinsecticide composition in aqueous solutions (for example, when the mycoinsecticide composition is diluted with water). Consequently following modification of the carrier, the mycoinsecticide composition will be able to be administered efficiently, through a delivery device, without causing adherence of the submerged propagules of Isaria fumosorosea to the inner walls of the delivery device or obstructing the delivery components of the delivery device. It is to be understood that the mixture of sulfonated surfactants in the mycoinsecticide composition may have minimal, if not at all any detrimental effects, on the viability and stability of the fungal insecticide. In a preferred embodiment, the mycoinsecticide composition is formed of 50% by weight to 65% by weight of a carrier. According to the preferred embodiment, the mycoinsecticide composition is comprised at least one solid carrier. Preferably, the solid carrier described herein is bentonite clay. The bentonite clay makes up the total amount of mycoinsecticide composition. Advantageously, the bentonite clay allows the fungal insecticide to remain efficacious, thus allowing the fungal insecticide to be delivered to the body of the pest, particularly delivery of submerged propagules of Isaria fumosorosea onto the bag casing of bagworms, with an effective degree of lethality, enabling the mycoinsecticide composition to be re-dispersed and dispensed into a delivery container and preventing sedimentation of the submerged propagules of Isaria fumosorosea. According to another preferred embodiment, the incorporation of bentonite clay enables the mycoinsecticide composition be formulated as a powder. Preferably, the mycoinsecticide composition is formulated in the form of a wettable powder.

In another aspect, the invention also relates to a method for suppressing bagworm infestation in a plant comprising treating the crops with a degradable mycoinsecticide composition comprising a fungal insecticide, a sulfonate surfactant mixture and an agriculturally acceptable carrier.

Preferably, the fungal insecticide is derived from an entomopathogenic fungus strain having an insecticidally effective amount of submerged propagules of Isaria fumosorosea. More preferably, the fungal insecticide is having an insecticidally effective amount of submerged propagules of Isaria fumosorosea ranging from 10 ⁶ to 10 ⁸ cfu/mL of the mycoinsecticide composition.

Preferably, the sulfonate surfactant mixture comprises sodium lignosulfonate, sodium xylenesulfonate and sodium cumenesulfonate. More preferably, the total amount of surfactant mixture comprising sodium lignosulfonate, sodium xylenesulfonate and sodium cumenesulfonate ranges from 15% by weight to 30% by weight of the mycoinsecticide composition.

Preferably, the agriculturally acceptable carrier is a bentonite clay. More preferably, the total amount of bentonite clay ranges from 50% by weight to 65% by weight of the mycoinsecticide composition. The mycoinsecticide composition described herein may be applied at varying concentrations to perform the method for suppressing bagworm infestation in a plant by treating the crops with the mycoinsecticide composition disclosed herein. In a preferred embodiment, the mycoinsecticide composition is diluted with water. Preferably, the mycoinsecticide composition is diluted with water at a volume ratio from 1:200 to 1:500. According to the preferred embodiment, it is preferred that the mycoinsecticide composition is diluted with water to achieve an insecticidally effective amount of 10 ⁶ to 10 ⁸ cfu/mL of submerged propagules derived from the strain of Isaria fumosorosea. In a preferred embodiment, the method comprises suppressing one or more plant pests. Particularly, the method for suppressing pest infestation described herein is targeted at harmful Lepidoptera insects. According to the preferred embodiment, the harmful Lepidoptera insects include Psychidae family consisting bagworm species of Metisa plana , Pteroma pendula and Mahasena corbetti. Of particular, the latter bagworm species are more prominent in oil palm plantations as defoliators. The method of suppressing bagworm infestation includes treating a plant with the aforementioned mycoinsecticide composition comprising contacting a plant pest with the mycoinsecticide composition. The contacting step may be performed by spraying, dusting or coating. Accordingly, the step of treating the plant is preferably conducted by spraying the diluted mycoinsecticide composition at a vicinity of a plant. The mycoinsecticide composition comes into contact with the bag casing of bagworms, subsequently the submerged propagules of Isaria fumosorosea in the mycoinsecticide composition undergo sporulation thereon, followed by enzymatic penetration and fungal proliferation inside the pest’s body and finally emergence of mycelia into conidia. Consequently, destruction of the pest’s tissues and drainage of nutrients by the fungus causes lethality to the pest.

The present disclosure includes as contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a degree of particularly, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangements of parts may be resorted to without departing from the scope of the invention.

EXAMPLE

The following non-limiting example has been carried out to illustrate the preferred embodiments of the invention.

Example 1 : Mycoinseciticide formulations

Isaria fumosorosea mass production was conducted at Forest Research Institute Malaysia (FRIM). Three types of Isaria fumosorosea wettable powder formulations were prepared at Universiti Putra Malaysia (UPM). Five hundred and twenty-two oil palm (Elaies guineensis) trees of five years old at Federal Land Development Authority at Lepar Hilir were randomly selected for the experiment. The experiment consists of twenty-nine oil palm trees and three replications with five treatments and control. The population oiMetisa plana was monitored from pre- and post- census at 3, 7, 15, and 30 days after treatment (DAT). Further study was conducted on pollinating weevil, Elaeidobius kamerunicus whereby the weevil population was monitored at pre- and post- census at 3, 5, 7 and 14 DAT. The experiment consists of eighty-seven oil palm trees in each of treatment, five anthesis male inflorescence were marked for each treatment using sample population tapping technique. A sample population technique was designed to estimate the weevil population for every sample of male inflorescence.

The experiment was designed in Randomised Complete Block Design (RCBD) with three replications. Data were subjected to Analysis of variance (ANOVA) using Statistical Analysis System (SAS) version 9.4. the means were compared by the Honestly Significant Difference (HSD) at significance level of 0.05.

Result of mass production showed that out of 100 mL broth, propagules were calculated within 5% to 10% of total weight of suspension. Every 250 mL liquid media used, approximately 1.25 g to 2.5 g of wet submerged propagules could be harvested. Mass production of the propagules are easier and could be produced within short period of time by shaking the inoculated liquid culture medium. Only three Isaria fumosorosea wettable powder formulations were prepared using different dispersant and wetting agent which were Lig:PAAS:SNS, Lig:PAAS:SC and Lig:PAAS:SX used for this study as shown in the table below.

FIG. 1 shows a point selected from the mutual stable region for all aurfactant system tested. Mutual stable region has been identified by testing every possible surfactant system from the qualified surfactants from previous experiment. Out of the surfactant system tested, the region selected to find the mutual region has the suspensibility more than 70% and good dispersibility. Point X with percentage ratio D1:D2:W = 52:33:15 was picked as the best point and the safest option to gain god formulation physical stability. Example 2: Mean population of bagworm following treatments and control

Results showed that the mean population of bagworm was decreased over days of treatment, as indicated in the table below. The population of bagworm was reduced to below economic threshold level (ETL), ten larvae per frond within thirty days after treatment application. Nonetheless, the mean population of bagworm was the highest in cniadin followed by flub endi amide, FI 3, FI 1 and FI 2. The control plot was shown the decrease in population number from the previous census p-value of 0.0009 and Tukey’s multiple test showed that there was no significant difference between populations of bagworm in each treatment plots.

Example 3 : Mean population of pollinating insect following treatments and control The mean population of pollinating weevil in the table below shows the number of population of weevil reducing until 7 DAT and recovering on 14 DAT. At 14 DAT, the overall population of weevil was approximately close to the original number of population before the treatment. The mean population of weevil was about 200 weevils per palm exceptforthe cniadin plot, which was recorded only 173.8 weevils on average.