Preliminary Comparison On The Biology And Ecology Of Blattella Germanica And Periplaneta Fuliginosa

Blattella germanica(L),an important health insect pest,spreads rapidly in large area of China in recent years,and it is becoming a disaster.Blattella germanica is replacing Periplaneta fuliginosa(Serville) and is becoming the emerging dominant species of the cockroaches.These years, the control methods and burst investigations about Blattella germanica are widely reported,except the mechanism of how Blattella germanica can replace other species and become the dominant species of the cockroaches.Therefore,this research is based on the comparative studies about the survival time,species figures under the same condition,and interspecific competitions between Blattella germanica and Periplaneta fuliginosa.The adaptability to environment,fecundity,and interspecific competition are studied in this paper.The aim is to find the spreading advantage of Blattella germanica,and the dispersion effect to other cockroaches.This research could provide references for the cockroach IPM(Integrated Pest Managements).The main research results are as follows:1 The comparison of fecundity and growing development between Blattella germanica and Periplaneta fuliginosaThrough observing Blattella germanica and Periplaneta fuliginosa for their duration of generation,then calculating their growing rates under 16℃,20℃,24℃,28℃and 32℃;the author has had the conclusion that the temperature is affective factor to their duration of generation,and under each dose of temperatures Blattella germanica has an higher growing rate than Periplaneta fuliginosa.The author has also discovered that the population of egg and hatchability of eggs is different variation in different temperature;the population of egg and hatchability of eggs which belongs to Blattella germanica is more sensitive than that of Periplaneta fuliginosa,under the same temperature the population of Periplaneta fuliginosa eggs is bigger than that of Blattella germanica eggs,in opposite the growing rate of Blattella germanica eggs is higher.2 The comparison of the survival time in the adversity between Blattella germanica and Periplaneta fuliginosa Both over high or low temperature can affect the both cockroaches lifespan.The results show that the survival time of nymphs and imago in both two species is obviously shortened when the temperature is getting lower between -5℃-5℃.Under the condition of -5,0,5 centigrade,the nymphs of Blattella germanica can live the longest,which is 0.79d,1.98d,25.76d.Periplaneta fuliginosa between 40℃-50℃,the survive time increases with the temperature.Under 40,45,50 centigrade,theBlattella germanica' imago can survive the longest;the time is 10.74d,3.84d,and 2.76d.Blattella Germanic according to that result,Blattella germanica has more adaptability to the high or low temperature than Periplaneta fuliginosa.The lack of food or water can affect the lives of both two types of cockroaches.Under the conditions of supplying water only,supplying nothing,and supplying food only,Periplaneta fuliginosa's imago survives the longest;the time is 45.5d,32.03d,and 33.37d.Water can affect cockroach's life significantly;under the condition of supplying with water,the two types of cockroaches can live longer than without water.Under no water supplying,the survive time of Blattella germanica is increasing obviously by adding of food;the survival time of 1 generate nymphae,female imago,and male imago is rising from 7.43d,15.43d and 8.75d to 9.67d,18.39d and 11.21d;but the circs of Periplaneta fuliginosa is not obvious comparing to Blattella germanica.SoBlattella germanica is more adaptable to the water-lack consistence than Periplaneta fuliginosa.3 The effects of feeding density on the egg hatch rate and weight of 1st instar nymphsThe different feeding density can affect the egg hatch rate of Blattella germanica and Periplaneta fuliginosa.When the density is 10p/b(pest per bottle),20p/b,30p/b,40p/b and 50p/b; the hatch rates of Blattella germanica are 89.55%,86.94%,78.56%,76,03%and 70.54%;those of Periplaneta fuliginosa are 85.64%,80.78%,76.04%,70.37%and 68.54%;and under each density, the Blattella germanica's egg hatch rate is higher than Periplaneta fuliginosa's.With the feeding density increase,1st instar nymphs' weight always decreases.Under the density are 10p/b,20p/b, 30p/b,40p/b and 50p/b,the weight of Blattella germanica of 1st instar nymphs are 14.51mg,13.87 mg,10.13 mg,8.64 mg,7.86 mg;Blattella germanicand the weight ofPeriplaneta fuliginosa 1st instar nymphs are 43.02 mg,40.56 mg,35.74 mg,31.87 mg,26.11 mg.It shows that the feeding density is more affective for Blattella germanica than for Periplaneta fuliginosa.4 The interspecific competition of the two cockroachesThe interspecific competition between Blattella germanica and Periplaneta fuliginosa can be fitted with Lotka-Volterra Model,and the result shows that in both species the population of rearing individually is always higher than that of rearing together.The two species has got an interspecific competitive relationship,and the relationship belongs to the resource utilization-based competition. Periplaneta fuliginosay the individual and mixed feeding,the population of Blattella germanica is always higher than that of Periplaneta fuliginosa,under the mixed feeding condition the two species compete in the dynamic balance,and which one can win the battle rests on the original circs;under the mixed feeding,the population of Blattella germanica is higher than that of Periplaneta fuliginosa,consequently in this system of competition,Blattella germanica is the dominant species.To sum up,we can make to the conclusion that Blattella germanica has a ability that it can be adaptable to the high or low temperature,water-lack,and other uncomfortable condition than Periplaneta fuliginosa;and the population growth rate of Blattella germanica is faster than that of Periplaneta fuliginosa,the two species of cockroaches have an interspecific competition relationship; and in the competitive system Blattella germanica take the advantage.