Studies on the regent and chlorfenapyr against the nymphs of plutella xylostella

Toxicity of 5% Regent SC to the second and the fourth age of diamondback moth, and toxicity of 10% Chlorfenapyr SC to the second age of diamondback moth, Plutella xylostella (L.), were evaluated in the experiment respectvely. It was showed that 5 % Regent SC had high toxicity to the second and the fourth age of P. xylostella. But with the age increase, the LC50 increased, too, but the toxicity decreased. Afer 24hrs of spray, the LC50 of Regent to the second and the fourth age were 73. 56 mg ・ L-1 and 106. 91 mg • L-1, the LC95 were 510. 14 mg ・ L-1 and 858. 42 mg ・L-1. And afer 48hrs of spraying, the LC50 were 20. 19 mg • L-1 and 21. 31 mg • L-1, the LC95 were 66. 90 mg ・ L-1 and 85. 82 mg • L-1. Similarly, 10% Chlorfenapyr SC had high toxicity to the second instar nymphs of P. xylostella. Afer 24hrs and 48hrs of spraying, the LC95 were 554. 27 mg , L-1 and 284. 11 mg ・ L-1. The toxicity of Chlorfenapyr was a bit lower than Regent. In one word, young instar nymphs is the pivotal stage of preventon and control of the pest.

Ultrasonic Technology Applied against Mosquito Larvae

The effective management of mosquito vectors is a timely challenge for medical and veterinary entomology. In this study, we evaluated the acoustic Larvasonic device to control young instars of the mosquito Aedes aegypti in diverse freshwater environments. Under laboratory conditions, we investigated the effect of exposure time and distance from the transducer on the mortality of larvae and pupae of Ae. aegypti. Furthermore, we evaluated the effectiveness of the ultrasound window of the electromagnetic spectrum under different field conditions. Results showed that first and second instar larvae were more sensitive to the frequency range of 18–30 kHz of the Larvasonic device. Ultrasonic waves applied for 180 s at a frequency from 18 to 30 kHz caused 100% larval mortality at a distance of 60 cm from the transducer. No mortality was observed in the non-target copepod Megacyclops formosanus. The exposure to the soundwaves produced by the acoustic larvicidal device over different distances effectively damaged Ae. aegypti through destruction of the larval dorsal tracheal trunk, thorax and abdomen. Overall, results indicated that the Larvasonic device tested can provide an alternative tool to reduce young instar populations of Ae. aegypti, without any effects on non-target aquatic invertebrates like copepods. It turned out to be a useful device for mosquito biocontrol. This technology has a relevant potential to fight the spread of mosquito-borne diseases.