Multicellular living organisms and unmodified parts thereof and – Nonhuman animal
Reexamination Certificate
1992-05-15
2001-02-06
Low, Christopher S. F. (Department: 1653)
Multicellular living organisms and unmodified parts thereof and
Nonhuman animal
C424S410000, C424S405000, C424S093200, C424S093200, C119S006500, C119S006600, C119S006700, C800S008000, C800S281000
Reexamination Certificate
active
06184434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The corn earworm (CEW),
Helicoverpa zea
(also known as
Heliothis zea
), is a prominant pest of cotton, sorghum, tobacco and numerous vegetable crops, particularly corn, throughout the world.
This invention relates to a novel entomopathogenic nematode of the genus Steinernema, which is effective as a biopesticide for the control of insects, and particularly the corn earworm.
2. Description of the Prior Art
Recent studies have shown that the Lower Rio Grande Valley corn crop is a major source for the production of large populations of the corn earworm and fall armyworm which migrate north to infest corn and other crops of higher cash value such as cotton, tomatoes and soybeans, where they cause severe economic damage [Raulston et al., Production of
Heliothis zea
on Corn in Northeastern Mexico and the Lower Rio Grande Valley of Texas: a Potential Source for Corn and Cotton Infestation on the High Plains of Texas, Proc. Beltwide Cotton Conf., 1986, pp. 222-225Memphis, National Cotton Council of America; Wolf et al, Phil. Trans. R. Soc. Lond. B 328:619-630, (1990); and Pair et al, Florida Entomologist, 74:200-213, (1991)]. The primary control strategy for the corn earworm is the application of insecticides that result in egg and larval mortality. In Florida and other southeastern states, insecticides are usually applied at least every 48 hours to protect sweet corn during the silking period. However, the corn earworm has given indications of resistance to organochlorine and organophosphate insecticides [Wolfenbarger et al., Bull. Entomol. Soc. Amer., 27:181-185, (1981); and Sparks, Bull. Entomol. Soc. Amer., 27:186-192, (1981)]. This resistance, in addition to the wide public awareness of the environmental damage resulting from chemical pesticides, has increased interest in biological control, and has resulted in the study of a variety of biological control agents. Entomopathogenic nematodes have shown promise as biological control candidates for a number of insect pests.
Nematodes of the genera Steinernema and Heterorhabditis possess most of the characteristics of an ideal biological control agent for insects [Poiner, Taxonomy and Biology of Steinernematidae and Heterorhabditidae, In Gaugler and Kaya (eds.), Entomopathogenic Nematodes in Biological Control, CRC Press, Boca Raton, Fla., (1990), pages 23-61; and Gaugler, J. Nematol., 13:241-249, (1981)]]. These nematodes search for their insect hosts; they are highly virulent, killing most hosts within 48 hours; they are easily and inexpensively mass produced; and they have a wide range of insect hosts (Poiner, ibid and Gaugler, ibid). The effectiveness of these nematodes is attributed to a mutualistic bacterium of the genus Xenorhabdus associated therewith [Poinar, ibid]. After entry or penetration of the nematode into the insect host, the bacteria are released from the nematode and rapidly multiply, killing the host insect by septicemia. Conversely, the nematodes protect the bacteria from the environment prior to release within a suitable host. The pathogenicity of entompathogenic nematodes to Heliothesis species has been demonstrated previously [Tanada and Reiner, J. Inverteb. Path. 4:139-154, (1962); Bong and Sikorowski, J. Econ. Ent., 76:590-593 (1983); and Howell, J. Inverteb. Path., 33:155-158, (1979)]. However, there exists a negative relationship between larval age and susceptibility to the nematodes [Glazer and Navon, J. Econ. Entomol., 83:1795-1800, (1990); and Samsook and Sikora, Med. Fac. Landbouww. Gent., 46:685-693, (1981)]. Consequently, the use of these nematodes has been against the feeding stages of various insect pests, while their use against prepupal or pupal stages of
H. zea
has been limited.
SUMMARY OF THE INVENTION
We have now discovered a previously unknown entomopathogenic nematode of the genus Steinernema, which is effective as a biopesticide for the control of insects, and particularly the corn earworm,
Helicoverpa zea
, and the fall armyworm,
Spodoptera frugiperda
. This nematode has been identified as
Steinernema riobravis.
The nematode of this invention has been isolated in pure form from pupae and prepupae of the corn earworm form soil samples of corn fields in the Lower Rio Grande Valley of Texas. When applied to the locus of the target insects,
Steinernema riobravis
will provide improved suppression of the insect population.
In accordance with this discovery, it is an object of this invention to introduce
Steinernema riobravis
as a novel biopesticide for the control of insects. It is also an object of this invention to provide new compositions and methods for controlling insect populations incorporating
Steinernema riobravis.
A further object of this invention is to provide a biopesticide that is effective against the non-feeding pupal or prepupal stages of insects and that may be applied to the soil.
Another object of this invention is to provide a biopesticide that remains viable at relatively low moisture conditions, is effective for controlling insects in clay soil types, and that provides effective insect control at low inocolum levels.
Yet another object of this invention is to provide a biopesticide for the suppression or elimination of the corn earworm and fall armyworm insects at their source, thereby preventing their movement to other crops.
Other objects and advantages of this invention will become readily apparent from the ensuring description.
DETAILED DESCRIPTION
The entomopathogenic nematode of this invention,
Steinernema riobravis
, is indigenous to the Lower Rio Grande Valley of Texas and northern Tamaulipas, Mexico and may be recovered from corn fields within this geographical area as will be described in more detail hereinbelow. Indeed, over a five year period, 34% of all fields sampled contained corn earworm parasitized with this nematode, and 24.2% contained fall armyworm parasitized with the nematode. Of all corn earworm and fall armyworm prepuae and pupae collected during this study, 11.6% and 9.3%, respectively, were parasitized with the nematode.
The above-mentioned
Steinernema riobravis
has been deposited under the Budapest Treaty in the American Type Culture Collection (ATCC), 10801 University Blvd., Manassas, Va., 20110-2209, USA, on Apr. 1, 1994, and has been assigned accession no. ATCC 75727.
Steinernema riobravis
n.sp. can be separated from other Steinernema spp. by several characters. Included among the separating traits is the length of the infective juvenile (average length-622 microns; range=561-701 microns). Further the male posterior segment of
S. riobravis
n.sp. lacks a projection or spine of any type which separates it from
Steinernema carpocapsae
and
Steinernema feltiae
. The spicules are generally more curved (a line running parallel with the calomus and lamina forms an angle of 90 to 100 degrees) than those of
S. carpocapsae, S. feltia
and
Steinernema glaseri
. The blunt tip of the spicules on
S. riobravis
n.sp. are distinct from the hooked tip spicules of
S. carpocapsae
. Digestion of genomic DNA with restriction endonucleases generated a unique set of different sized DNA restriction fragments dependent upon the base of the genome sequence. The size distribution of these restriction fragments are different from all known species of nematodes. Morphologically,
S. riobravis
n.sp. resembles
Steinernema intermedia
, however, controlled mating studies indicated that
Steinernema intermedia
n.sp. and
S. intermedia
do not mate with each other.
The nematode described herein is effective for controlling a variety of insects. Without being limited thereto, pests of particular interest known to be susceptible to treatment are agronomically important insects, especially the corn earworm,
H. zea
, and the fall armyworm,
S. frugiperda
. The nematode may be applied for the control of these agronomically important insects on a number of crops, particularly but not limited to corn, cotton, tomatoes, and soybe
Enrique Cabanillas
Pair Sammy D.
Raulston Jimmy R.
Fado John D.
Low Christopher S. F.
Ribando Curtis P.
Silverstein M. Howard
The United States of America as represented by the Secretary of
LandOfFree
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