Competitive interactions between invasive fall armyworm and Asian corn borer at intraspecific and interspecific level on the same feeding guild

Interspecific competition is an important factor in the population dynamics and geographical distribution of insect populations.Fall armyworm(FAW),Spodoptera frugiperda,an invasive species,and the Asian corn borer(ACB),Ostrinia furnacalis,a native pest species are major pests on maize in China,posing a threat to maize yield and grain quality.A series of laboratory,greenhouse,and field experiments were conducted to elucidate the competitive interactions between FAW and ACB.In the laboratory experiments,FAW exhibited aggressive behaviors more frequently when compared with ACB,while the latter species exhibited defense behaviors more frequently.Higher intraspecific competition was recorded in the FAW conspecific rather than in ACB,particularly in the 6th larval stage.FAW had a higher interspecific competitive advantage through intraguild predation over ACB,resulting in partial or complete displacement ACB when initially the ratio of the 2 species was 1:1.The interspecific competition also had significantly influenced on the population parameters,defensive enzymes,and nutrient of these 2 species.Competitive interaction proved that the response of superoxide,catalase,and soluble protein in FAW were significantly increased,whereas the total sugar content in both species was substantially decreased.Survival rate,and the plant damage that co-infested by both species varied significantly among the sequential combinations under greenhouse and field conditions.FAW consistently exhibited stronger intraspecific aggression than ACB under laboratory and field conditions when co-existing on the same feeding guild.These findings contribute to efforts toward the improvement of integrated pest management programs for FAW,in decision making for invasive and native pests’management strategies to reduce the high risks of FAW and ACB outbreaks.

Frequency-modulated continuous-wave dual-frequency LIDAR based on a monolithic integrated two-section DFB laser

We demonstrate a high-resolution frequency-modulated continuous-wave dual-frequency LIDAR system based on a monolithic integrated two-section(TS) distributed feedback(DFB) laser. In order to achieve phase locking of the two lasers in the TS-DFB laser, the sideband optical injection locking technique is employed. A high-quality linear frequency-modulated signal is achieved from the TS-DFB laser. Utilizing the proposed LIDAR system, the distance and velocity of a target can be measured accurately. The maximum relative errors of distance and velocity measurement are 1.6% and 3.18%, respectively.