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.
The present study was designed to investigate the effect of rice straw compost, recommended mineral fertilizers, Organic Insecticides and chemical Insecticides on the abundance pattern of natural enemies in rice ecosystems. To maximize rice productivity, rice growers tend to use chemical fertilizers and pesticides particularly to control different pest species, regardless of damage levels. Accordingly, rice fauna of natural enemies is severely impaired, leading to unbalanced rice ecosystems. The current investigation was carried out at the experimental farm of Rice Research and Training Center (RRTC), Sakha, Kafr El-Sheikh during 2016 and 2017 rice seasons. Using both D-Vac machine and pit-fall traps, parasitoids and predator insects were surveyed. Twelve hymenopterous parasitoid species were surveyed. Most of the parasitoid species were found belonging to Mymaridae, Trichogrammatidae and Braconidae. Twenty insect predator species, related to 13 families and seven orders, were identified, most of which are belonging to Coleoptera and Hymenoptera. Also this study aimed to surveying natural enemies (parasitoids and predator insects) and the effect of compost as an organic fertilizer on population densities of such beneficial insects. Although the application of insecticides successfully controlled insect pests, these chemicals have almost eradicated (more than 90 % reduction) the natural enemies. Biocide applications, especially Achook (Neem) and Tracer, achieved a considerable insect pest control, with population reductions of 33.30-57.32 and 10-46.01%, respectively. Unfortunately, the evaluated biocides induced mortalities to the considered natural enemies, but with too much less levels than did the insecticides. The current results indicate that the biocides could be applied to control rice insects in case of moderate insect infestations, with taking into consideration that they are not completely safe to the beneficial insects.
An experiment was carried out at the farm of Sakha Agricultural Research Station, Kafr El-Sheikh governorate in 2014 and 2015 seasons. The objective was to study population fluctuations of the spiders and evaluation the efficacy of sampling methods for survey spiders at rice nursery. Specimens were collected from rice nursery by pitfall trap, water pan trap and sweep net were taken to the laboratory after labeling. All samples were taken during April and the first week of May. A total of 346 individuals belonging to 12 species and 8 families were recorded during the study period. The population density of family Tetragnathidae was found highest (28 individuals) followed by linyphiidae (20 individuals) in the first season. While in the second season the population density of family Linyphiidae was found highest (247 individuals) followed by Lycosidae (29 individuals). Indicated that the water pan trap the highest efficacy trap and trapped 51.47% followed by pitfall trap 27.94% , meanwhile sweep net trap ranked the last category and represented by 20.58% during the first season. While the pitfall trap the highest efficacy trap and trapped 45.87% followed by water pan trap40.26%, while sweep net trap came in the last category with 13.86% in the second season.
field experiment was carried out at the Experimental Farm of Sakha Agricultural Station in 2014 rice season using two cultivars, Giza 178 (high tillering capacity) and Egyptian Jasmine (medium tillering capacity) to determine the economic threshold level for control measures of stem borer Chilo agmemnon Bles. in rice. Seven simulated levels of dead hearts; 0, 5, 10, 15, 20, 25 and 30% were adopted to find out their effects on rice yield and yield components. In Giza 178 cultivar, dry matter content was significantly reduced at 25% detillering. Panicle weight, 1000-grain weight and filled grains increased as the detillering level increased. This could be attributed to the compensation phenomenon, as the rice hills that suffered from high detillering produced heavier grains in the remaining tillers. This trend was also obtained with the Egyptian Jasmine. The rice yield was significantly reduced at 15% in the former cultivar and at 20% in the latter one. Economic analysis showed that the economic threshold is 25% damaged tillers in Giza 178 rice cultivar and 20% in the Egyptian Jasmine. This might be due to that Giza 178 is higher tillering cultivar than the Egyptian Jasmine. Thus, control measures, particularly insecticides, should not be applied before dead hearts reach 25% in case of Giza 178 cultivar and 20% in case of Egyptian Jasmine.
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