A comparative study on the virulence of entomopathogenic fungi against Trogoderma granarium (Everts) (Coleoptera: Dermestidae) in stored grains rice

Entomopathogenic fungi (EPF) now a possible safer microbial control measure that could be considered as a substitute for chemical control of insect pests. Three EPF viz., Metarihizium anisopliae, Isaria furnosoroseus and Beauveria bassiana were evaluated for their virulence against the grubs of Khapra beetle, Trogoderma granarium (Everts) under laboratory conditions. The isolates were applied by two methods viz., diet incorporation and an immersion method with 3rd instar 20 grubs of T. granarium for each. The virulence of EPF was determined using percent mortality. Significantly higher mortality was observed in M. anisopliae applied through immersion (98.33%) and diet incorporation (93.33%) methods followed by B. bassiana (90.83 and 85.83%, respectively). The mortality caused by I. furnosoroseus was statistically lower in immersion and diet incorporation methods i.e. 81.67 and 73.33%, respectively. Based on the immersion method, all EPF were studied for multiple conidial concentration i.e., 1×104, 1×105, 1×106, 1×107 and 1×108 under the same in-vitro conditions. All the isolates were pathogenic to grub of T. granarium at the highest conidial concentration. M. anisopliae was proved the most effective virulent resulting in 98.33% mortality of the pest with LT50 4.61 days at 1 × 108 conidial concentration followed by 90.83 and 81.67 percent mortality with 5.07 and 8.01 days LT50, in the application of B. bassiana and I. furnosoroseus, respectively. M. anisopliae showed higher efficacy and could be considered as promising EPF for the development of myco-insecticides against effective biocontrol of T. granarium.

Efficacy of Entomopathogenic Nematodes Against Three Species of Stored Product Insects

Two specis of entomopathogenic nematodes (EPNs), Steinernema riobravi, symbolized by Sr, and Heterorabditisbacterophora, symbolized by Hb,were tested by using five concentrations: 125, 250, 500, 1000, and 2000 an infectiousphase, ml of the type Sr and four concentrations of 500, 1000, 2000 and 3000infectious phase/mlof the type Hb against Cowpea weevil, Callosobruchus maculates,Khapra beetle, Trogoderma granarium, and Rust red flour beetle Triboliumcastaneum, using three exposure times of 24, 48, and 72 h. The mortalityrate increased withincreasing in concentrations and the exposure period. The results showed that the highest mortality rate was 16.67 whole insects recorded for the 2000 infectious phase/ml with Sr nematodes after 72 hours post- treatment ofC. maculatus. The results showed that the highest rate mortality,which is 20 larvae, was recorded for the infectious phase dose of the genus nematode (Hb), all of which are 500, 1000, 2000 and 3000 gastricphase/ml, and for all exposure periods used between 24 hours and up to 72 hours against the larvae of the T. granarium. The results showed that the highest rate of mortality 10.00 whole insects was recorded for the dose of 3000 Infectious stage/ml and at the exposure time 72 hours, while the lowest rate for this mortality of 1.33 adult insects for rusty flour beetle was recorded for the dose of 500 infectious stage/ml and for the exposure time only 24 hours. The resultsindicated that mortality rate was increasing against any increase in both the exposure time and the dose of nematodes of the genus Hb.

Appraisal of quantitative and qualitative losses in six rice genotypes caused by Trogoderma granarium (Everts) and Rhyzopertha dominica (F.)

The present study was conducted to probe out the nutritive losses caused by Rhyzopertha dominica (F.) and Trogoderma granarium (Everts) were quantified in six rice genotypes (KSK-434, KSK-282, Irri-6, Shaheen basmati, Basmati 385 and Chenab basmati). Percent crude protein, ash and moisture content were measured for qualitative losses, while for quantitative losses, frass weight and weight loss were examined after infestation period of 90 days of. Highest weight losses (25.76%) and (15.37%) were observed in KSK-434 by infestation of R. dominica and T. granarium, respectively, compared with un-infested grains after a storage period of 90 days. Highest frass weight (8.57 g) was recorded for KSK-434 while relatively low frass weight (4.16 g) was recorded for Basmati 385 by infestation of R. dominica. Relatively low frass weights of 5.67, 4.46 and 4.01 g were recorded in KSK-434, Chenab basmati and Shaheen basmati, respectively by attack of T. granarium. Highest percentage moisture values (14.03 and 11.24%) were recorded for KSK-434 by infestations of both test insects compared to non-infested (controls). Percent crude protein was decreased (from 6.97% to the 4.92%) due to infestation of R. dominica values by strain were KSK-434 (4.54%), Shaheen basmati (4.89%) and chenab basmati (4.92%). In the case of T. granarium infestation, almost all the varieties sustained the low protein contents except KSK-434 (5.02%) and Basmiti 385 (5.17%) and Shaheen basmati, protein contents loss comparable to non-infested control (7.09%). Ash content was high in genotype KSK- 282 (0.68 %) compared to control. KSK-434 and Chenab basmati had relatively low ash percentage due to high infestation of T. granarium. R. dominica attack produced the highest percent ash content (0.66%) in KSK-282 and the least (0.44%) in KSK- 434. The tested rice genotypes were more susceptible to R. dominica than T. granarium among the different genotypes of selected cereals.