| Cotton spider mites,Tetranychus cinnabarinus(Boisduval),are the most destructive herbivorous arthropods of cotton,in the world and in China.Meteorological factor is one of the factors that affect cinnabar leaf mite populations.Especially,rainfall tends to reduce the population of T.cinnabarinus,in addition,the rainfall can also result in spread of T.cinnabarinus."Spinning silk vertical wave" was an effective way of T.cinnabarinus in long-distance transformation.Effect of simulated rainfall on dynamics of T.cinnabarinus laboratory population,tolerance of adult T.cinnabarinus to submersion in water,temporal dynamic of spinning silk of mites T.cinnabarinus and formation distribution of its silken web,and the water-collecting phenomenon of silken threads of T.cinnabarinus were investigated in Jun.2013 to Nov.2016.The main conclusions are as follows:1.Effect of simulated rainfall on interference transformation of Tetranychuscinnabarinus laboratory populationEffect of simulated rainfall on interference transformation and their rectifying reduction rates of T.cinnabarinus were investigated with simulated rainfall method in cotton seedling,in order to evaluate the effect of simulated rainfall on dynamics of T.Cinnabarinus laboratory population in the Middle Reaches of the Yangtze River.The results showed that rainstorm(49.59% ± 3.09 %),heavy rain(33.21% ± 2.46 %),moderate rain(37.25% ± 0.86 %)and light rain(36.03% ± 2.69 %)significantly decreased the rectifying reduction rate of T.cinnabarinus.The rectifying reduction rate under rainstorm for T.cinnabarinus was most significantly higher than that of heavy rain,moderate rain and light rain,respectively.But there were no significant differences among heavy rain,moderate rain and light rain.As rainfall capacity gradually increased,their interference effect on the quantity of T.cinnabarinus from release points(under side leaves)transfers to upper side leaves and petiole gradually increased.Interference effect on the quantity of T.cinnabarinus transformation among those release points was unnotable among heavy rain,moderate rain and light rain,but there was the most significantly interference effect for rainstorm.2.Tolerance of adult Tetranychus cinnabarinus to submersion in waterTo clearly define the tolerance of mites T.cinnabarinus to submersion in water,and to provide a theoretical basis for evaluating the effect of rainfall on integrated pest management of this pest.The proportion that sank,water survival,and leg sway frequency,of adult T.cinnabarinus,was determined using the slide dipping method and video technology.The proportion of mites that sank was significantly higher when these had fed on cotton leaves for 5 d(92.79±0.55 %)compared to those that had fed for just2 d(42.72±2.37 %).The average survival time in water of 3-day-old male(297.7±7.4)min and female(297.4±16.1)min adults was not statistically different.The shortest survival times recorded for 3-day-old male and female adults were,respectively,45 min and 48 min.Immersion for about 300 minutes was sufficient to kill half of all3-day-old male or female adults.The longest survival time in water of 3-day-old male and female adults were 856 min and 773 min,respectively.The distribution of mortality among male and female adults was uneven in time.In the process of death,adult T.cinnabarinus generally displayed a reduction in leg swing frequency.The duration of leg swinging behavior was not continuous.Adult T.cinnabarinus have some capacity to tolerate submersion in water.3.Temporal dynamic of spinning silk of mites Tetranychus cinnabarinus and formation distribution of its silk web.To clearly define the ability of spinning silk of mites T.cinnabarinus,and provide a theoretical basis for research dispersal and ethology of this pest.Temporal dynamic of spinning silk of mites T.cinnabarinus and formation distribution of its silk web was studied using the bronze method.The length of spinning silk among male and female adults,nymph,larva was uneven in different period.The length of spinning silk in male and female adults,nymph was the longest at the beginning of 0.5 h,Larva was the longest during 5-7 h.This maybe related to adapt to the new environment or in search of food.Besides there was no obvious difference between nymph and larva within 12 h,mites T.cinnabarinus spinning silk length order from high to low were as follows: female adult > male adult> nymph > larva.Behavior patterns of mites T.cinnabarinus in purple bronze web including walking,spinning silk,inactivity.Mites T.cinnabarinus often appear discontinuous phenomenon during spinning silk and often walk while spinning silk.There was single and double silken thread.Distribution of net-like silken web of mites T.cinnabarinus mostly was in the middle of the bronze web.This maybe related with mites T.cinnabarinus to avoid suspension on the edge of the water existence.4.The water-collecting phenomenon of silken threads of Tetranychus cinnabarinusTo clearly define the water-collecting ability of silken threads of mites T.cinnabarinus,provide a theoretical basis for ethology of the pest.The water-collecting phenomenon of silken threads of mites T.cinnabarinus was observed with spraying silken threads method using a Leica stereoscopic microscope(M205A).The size of tiny water droplet of silken threads to be spun with mites T.cinnabarinus was uneven in the bronze web and in the leaves of cowpea.Number of large tiny water droplet was fewer than that of little tiny water droplet.Position has certain interval between tiny water droplets.In the bronze web,mostly tiny water droplets assembled on a single silken thread.In the leaves of cowpea,mostly tiny water droplets assembled on junction of silken thread(two or more thread connection),the size of tiny water droplets at high end silken threads was smaller than at high end silken threads. |
PDF Full Text Request