Abstract
Rice, (Oryza sativa L.), is liable to infestation with several insect pests, from which is the rice stem borer, Chilo agamemnon Bles. (Lepidoptera: Crambidae). Field trials were conducted in Egypt during 2015 and 2016 rice seasons to evaluate the efficacy of releasing the egg parasitoid, Trichogramma evanescens Westwood and applying different silica materials to reduce the pest infestation. The most efficient borer control was achieved when the parasitoid was released twice (each at 30,000 wasps/feddan) at Sakha, Gemmiza, and Sirw Agricultural Research Stations in 2015 season, at the maximum tillering stage plus at panicle initiation, as the borer infestation was reduced by (84.77%). Similar results (79.32% borer control) were obtained when the parasitoid was released at panicle initiation and heading rice plant growth stages. The parasitoid release was as efficient as the application of the widely applied insecticide (carbofuran). A large-scale release (17–20 feddans) was performed at the same research stations in the 2016 season. The parasitoid was released twice (each at 30,000 parasitoids/feddan) at the maximum tillering stage, 30 days after transplanting (DAT) and at panicle initiation (45 DAT). Dead hearts (DH) averaged (1.80 and 3.67%) in release and non-release treatments, respectively, with a reduction in DH of (50.95%). The corresponding reduction in white heads averaged (70.64%). Potassium silicate (68% Si, 500 kg/feddan), as basal after last tillage or magnesium silicate (62% Si, 2 kg /feddan), as a spray 20 and 40 days after transplanting achieved (58.25 and 45.31%) white head reduction, respectively, due to borer infestation.
Highlights
Rice (Oryza sativa L.) is an essential food crop for about one half of the world’s population, to Southeast Asian countries
In 2015 rice season, data in (Table 1) revealed that the parasitoid released at tillering stage, 15 days after transplanting (DAT), almost did not reduce the borer’s infestation, which was evaluated as white heads (WH), 3 weeks prior to harvest
The release practiced at maximum tillering stage (30 DAT) or at panicle initiation (45 DAT) induced a moderate borer control (23.20 and 39.62%) insect infestations, respectively
Summary
Rice (Oryza sativa L.) is an essential food crop for about one half of the world’s population, to Southeast Asian countries. In Egypt, rice shares wheat to satisfy the population requirements of cereals. This crop is liable to infestations with several insect pests, from which is the rice stem borer, Chilo agamemnon Bles. The egg parasitoids, Trichogramma spp., are common to parasitize eggs of too many lepidopteran insect species. The eggs of yellow rice stem borer, Scirpophaga incertulas (Walker), was parasitized by Trichogramma japonica with 7–14% (Marub 1993). Asaady and Navai (1995) released T. japonica in rice fields and recorded 12–32% egg parasitism of the white rice stem borer. In Egypt, Sherif et al (2008) recorded about 70% control of the rice stem borer C. agamemnon due to inundative release of T. evanescens West
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