Oral toxicity of various Stemona collinsiae crude extracts against nymph and adult stages of American cockroach, Periplaneta americana (Dictyoptera: Blattodea)

Bacterial contamination of cockroaches in different wards of hospital, restaurant and home

Cockroaches are very capable of mechanically transmitting harmful microorganisms, which is seen to be a severe hazard to the general public's health. The purpose of this study was the evaluation of cockroach bacterial contamination in various locations throughout Babylon. 300 cockroaches were caught from different wards of the hospital, restaurants, and houses. Using PBS buffer, the external surface of the cockroaches was washed to collect bacteria. Standard phenotypic methods were used to identify and classify bacteria. Afterward, the bacterial resistance to different antibiotics was investigated using the Kirby-Bauer disk diffusion susceptibility test. The 200 (66.6 %) American cockroaches including 56 (18.7 %) Blattella germanica and 44 (14.6 %) Blatta orientalis were identified. Noteworthy, 96.6 % of cockroaches were infected with different bacteria. Bacillus strains, coagulase-negative Staphylococci (CoNs), and Escherichia coli were the most frequent among the isolated bacteria. On average, the highest antibiotic resistance was detected to cefotaxime, ampicillin, cephalothin, and kanamycin. On the other hand, the isolated bacteria showed high sensitivity to gentamicin, nitrofurantoin, tetracycline, trimethoprim/sulfamethoxazole (SXT), and chloramphenicol. high antibiotic resistance in bacteria isolated from different wards of the hospital and the high potential of transmission of these bacteria by cockroaches is a serious warning for the health of society.

Larvicidal activity of Stemona collinsiae root extract against Musca domestica and Chrysomya megacephala

Musca domestica and Chrysomya megacephala, considered synanthropic insects, are medically important flies, as they transmit vector-borne diseases to humans and animals. In Thailand, Stemona (Stemonaceae) plants have been traditionally used as insecticides. This study was designed to determine the larvicidal activity of S. collinsiae root extract against M. domestica and C. megacephala larvae. A 70% ethanol crude extract from S. collinsiae roots was tested against the third-instar larvae of both species using direct and indirect contact methods. The development and mortality rates of the insects were observed, and the LC values were calculated. The extract caused irregular development in both species, shown as segmental puparia that could not emerge as adult flies. The LC50 values of the extract against M. domestica tested by direct and indirect contact methods were 0.0064 ± 0.0005 mg/larva and 0.0165 ± 0.0002 mg/cm2/larva, respectively. In the case of C. megacephala, the LC50 value determined by the indirect contact method was 1.0500 ± 0.0001 mg/cm2/larva. The ethanolic root extract of S. collinsiae was able to kill the larvae of both species after dermal administration. It is of interest to develop S. collinsiae root extract as a natural fly control biopesticide.