A three-year field experiment was conducted to evaluate the tolerance and
compensatory response of rice (Oryza sativa L.) to injury caused by the sugarcane borer,
Diatraea saccharalis (F.). Two mechanisms of within-plant tolerance/compensation
were observed. Stem injured plants produced ca. 0.69 more tillers than uninjured plants,
while tillers with leaf and leaf sheath injury produced larger panicles, up to 39.5% and
21.0% heavier than uninjured tillers, when injury occurred at 3rd tiller stage and at
panicle differentiation, respectively.
A 2-year field cage experiment was conducted to determine the biological control
potential of Cotesia flavipes (Cameron) against the sugarcane borer on rice. The
effective search rate was 49 cm2 ground area (2.2 tillers) parasitoid-1 day-1. A cohortbased
age-structured model was developed to simulate the population dynamics and
economic value of the sugarcane borer and C. flavipes in rice, as affected by
overwintering larval density, timing and rate of parasitoid aerial release, and year-to-year
climate (temperature and rainfall). The results suggest C. flavipes was most effective
when released during the 1st sugarcane borer generation. The maximum simulated economic benefit ($112.05 ha-1) was ca. 7.8% of that provided by insecticide-based
control. The inability of C. flavipes to provide economic control in temperate-subtropical
areas is due to its high rearing cost, a low effective search rate, a low maximum rate of
parasitism per female, and both spatial and temporal asynchrony of parasitoid emergence
with the larval hosts. The biocontrol capability of Trichogramma galloi Zucchi was also
simulated. The maximum economic benefit provided by T. galloi was $1128.75 ha-1, ca.
79.0% of that provided by insecticide-based control.
Theoretical analyses were conducted to estimate the effectiveness of augmentative
releases, using data from previous studies of parasitism of lepidopteran pests by
hymenopteran parasitoids with host and parasitoid density as factors. The maximum
daily parasitism per female was highest for parasitoids that attack exposed larvae,
followed by parasitoids that attack eggs, semi-exposed larvae, and concealed larvae.
Simulation analyses were conducted to estimate the population dynamics and economic
value of D. saccharalis, herein used as a model host, and each of 5 parasitoid categories
(solitary parasitoids that attack eggs, exposed larvae, and semi-exposed larvae,
gregarious parasitoids that attack eggs and concealed larvae) in rice, as affected by
overwintering larval density, timing of parasitoid release, and year-to-year climate.
Among the 13,500 simulations that were conducted, 480 (3.6%) provided a greater
economic value than insecticide-based control. All 480 simulations were obtained using
solitary parasitoids that attack exposed or semi-exposed larvae. Solitary egg parasitoids
provided an average of 42.2% of the economic value provided by insecticide-based
control when released 30 days after planting. Gregarious parasitoids that attack eggs or concealed larvae provided almost no positive economic benefit. For parasitoid species
that do not overwinter successfully in areas where they are released or that exhibit
temporal or spatial asynchrony with their host early in the spring, our results suggest
augmentative biological control is only effective for solitary parasitoids that attack either
exposed or semi-exposed larvae, with current rearing, shipping and release costs.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2008-12-172 |
| Date | 14 January 2010 |
| Creators | Lv, Jiale |
| Contributors | Wilson, Lloyd T. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation |
| Format | application/pdf |
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