Toxicity of entomopathogenic fungi, Beauveria bassiana and Lecanicillium muscarium against a field-collected strain of the German cockroach Blattella germanica (L.) (Dictyoptera: Blattellidae).

The German cockroach, Blattella germanica (L.) has been recognized as a serious health problem throughout the world. Control failures due to insecticide resistance and chemical contamination of environment have led some researchers focus on the other alternative strategy controls. Microbial insecticides such as those containing entomo pathogenic fungi could be of high significance. Lecanicillium muscarium and Beauveria bassiana grow naturally in soils throughout the world and act as a parasite on various arthropod species, causing white muscardine disease. Thus, these two species could be considered as entomopathogenic fungi. The current study conducted to evaluate the toxicity of Beauveria bassiana and Lecanicillium muscarium against German cockroach, Blattella germanica. Conidial formulations of L. muscarium (PTCC 5184) and B. bassiana (PTCC5197) were prepared in aqueous suspensions with Tween 20. Bioassays were performed using two methods including submersion of cockroaches in conidial suspension and baiting. Data were analyzed by Probit program and LC50 and LC90 were estimated. The obtained results indicated that both fungi species were toxic against German cockroach however; Beauveria bassiana was significantly 4.8 fold more toxic than L. muscarium against German cockroach using submersion method.

Toxicity of entomopathogenic fungi, Beauveria bassiana and Lecanicillium muscarium against a field-collected strain of the German cockroach Blattella germanica (L.) (Dictyoptera: Blattellidae)

The German cockroach, Blattella germanica (L.) has been recognized as a serious health problem throughout the world. Control failures due to insecticide resistance and chemical contamination of environment have led some researchers focus on the other alternative strategy controls. Microbial insecticides such as those containing entomopathogenic fungi could be of high significance. Lecanicillium muscarium and Beauveria bassiana grow naturally in soils throughout the world and act as a parasite on various arthropod species, causing white muscardine disease. Thus, these two species could be considered as entomopathogenic fungi. The current study conducted to evaluate the toxicity of Beauveria bassiana and Lecanicillium muscarium against German cockroach, Blattella germanica. Conidial formulations of L. muscarium (PTCC 5184) and B. bassiana (PTCC5197) were prepared in aqueous suspensions with Tween 20. Bioassays were performed using two methods including submersion of cockroaches in conidial suspension and baiting. Data were analyzed by Probit program and LC50 and LC90 were estimated. The obtained results indicated that both fungi species were toxic against German cockroach however; Beauveria bassiana was significantly 4.8 fold more toxic than L. muscarium against German cockroach using submersion method.

First report of family infestation with pubic louse (Pthirus pubis; Insecta: Anoplura: Pthiridae) in Iran--a case report.

The sucking lice including the head, body and pubic louse infest humans and so they are of high hygienic importance. Pubic lice are transmitted during sexual contact in adults. Thus, infestation of children with pubis louse is very rare. A case of infestation with pubic louse (Pthirus pubis) in a family in Kashan was seen. On examination of family members, the parasites were collected and observed under the light microscope. Infestation of eyelashes with P. pubis lice was confirmed. Since this parasite can be observed on the skin, infestation with this louse has always been one of the concerns of human communities. Pthiriasis has frequently been reported in many parts of the world; however, there are few reports on this infestation in Iran, especially familial infestation with this louse. Hence, this article could be the first report on the familial infestation with P. pubis in Iran and it can be suggested that infestation with pubic lice occurs in sporadic form in all over the country.

Insecticide resistance and synergism of three field-collected strains of the German cockroach Blattella germanica (L.) (Dictyoptera: Blattellidae) from hospitals in Kermanshah, Iran.

The development of insecticide resistance in the German cockroach, Blattella germanica (L.) is a serious problem in controlling this medically important household pest. The insecticide resistance status in three hospital-collected strains of the German cockroach using four commonly used insecticides from different classes (permethrin, cypermethrin, bendiocarb and chlorpyrifos) was detected by topical bioassay method and preliminary information on possible involvement of monooxygenases in permethrin resistant strains employing synergist piperonyl butoxide (PBO) was obtained. For each insecticide, four to six concentrations resulting in >0% and <100% mortality were used. Three to six replicates of 10 cockroaches per concentration were conducted. For synergism studies, 100 µg PBO per gram body weight of cockroach as the maximum sublethal dose was administered to the first abdominal segment 1 h before insecticide treatment. The differences between LD50 (µg/g) values were considered statistically significant only when the 95% confidence intervals did not overlap. The resistance ratio and synergism ratio were calculated for each insecticide. All three hospital-collected strains of the German cockroach showed different levels of resistance to permethrin and cypermethrin based on resistance ratios compared with SUS strain. Permethrin and cypermethrin resistance ratios ranged from 11.61 to 17.64 and 11.45 to 26.45 at LD50 levels, respectively. Low to moderate levels of bendiocarb resistance and low level of chlorpyrifos resistance were also observed in the hospital-collected strains under study. The synergist piperonyl butoxide (PBO) significantly enhanced the toxicity of permethrin to all strains with different degrees of synergist ratio, 2.45-, 1.87-, 2.51- and 2.38-fold, suggesting monooxygenase involvement in permethrin resistance.

Susceptibility of field populations of Blattella germanica (Blattaria: Blattellidae) to spinosad.

The German cockroach is an important household insect pest worldwide and acts as a mechanical vector and reservoir for pathogenic agents. The aim of this study was to examine the basic laboratory toxicity of Blattella germanica to spinosad. The M, T, A22, AZAR4, BOOSTAN7 and ABAN21 strains were collected from field populations of six infested kitchen student dormitories and the SAMAN strain was collected from a residential area after insecticide spraying control failure in Tehran, Iran. Technical grade spinosad was delivered in 0.5 microL acetone to the first abdominal sternum of briefly CO2-anesthetize adult male cockroaches by topical application bioassay. Treated males monitored for mortality. Mortality data from the replicates was assessed by probit analysis. The average LD50 of susceptible strain was 494.3, 148.8 and 55.1 ng per insect after 24, 48 and 72 h, respectively. The LD50 of spinosad decreased with time in the field population strains. All German cockroach strains showed a similar susceptibility or lower tolerance (1.6-folds) for spinosad compared with the susceptible laboratory strain and the steep slopes of dose-response curves indicated that the field population of these German cockroach strains was homogenous in response to spinosad. These results indicated that the spinosad was relatively slow-acting in topical application bioassay, with LD50 values decreasing until 72 h and becoming stable thereafter. The effectiveness of spinosad against susceptible and the field population German cockroach strains in laboratory condition showed that spinosad probably could be useful for the control of the German cockroach.