Impact Analysis Of Food Species And Background Color On Body Color Differentiation Of Noctuid Larvae

Color polymorphism is a widespread phenomenon in many species, insects body color can vary with host food changes, which is the choice of the environment, these changes can help them to escape predators of prey, also can improve its resistance. This study, by using the larva of Spodoptera litura and Helicoverpa armigera as the material, introducing the concept of RGB Tricolor, and with the rid of computer version technology to get the color of food and background and the R (red), G(green), B(blue), L(lightness) of insect larval body color, and adopting SPSS to conduct correlation analysis, has found out the impacts of the color, water content, chlorophyll content of nature food and the color of background on insect larval body color, as well as the relationship of larval body color on its cold resistance. The results are as follows:1The correlation coefficient between the R, G, B and L of Spodoptera litura larval body color and the r, g, b, and1of nature food color are:0.135(R-r),0.078(G-r),0.097(B-r),0.104(L-r);0.116(R-g),0.063(G-g),0.095(B-g),0.089(L-g);0.143(R-b),0.084(G-b),0.092(B-b),0.110(L-b);0.126(R-1),0.076(G-1),0.121(B-1),0.104(L-1), and have extreme significant positive correlation when P<0.01. The R, G, B and L value increase with the increasing of r, g, b, and1value of food color.2The correlation coefficient between the R, G, B and L of Spodoptera litura larval body color and the water content of nature food (>80%) are:-0.149,-0.102,-0.046、-0.115, and have extreme significant negative correlation when P≤0.01. The R, G, B and L value decrease with the increasing of the water content of host plants (>80%).3The correlation coefficient between the R, G, B and L of Spodoptera litura larval body color and the chlorophyll content of nature food are:-0.107,-0.061,0.032,-0.066, and have extreme significant positive correlation when P<0.01. There are negative correlation between the chlorophyll content of host plants and the R, G, L and Color index of Spodoptera litura larval body color, and positive correlation between the chlorophyll content of host plants and the B value.4. Artificial feed color had a significant impact on (P≤0.05) Spodoerpta litura in1and17day old body color. 5The correlation coefficient between the R, G, B and L of Spodoptera litura larval body color and the r, g, b,1of background color are:0.132(R-r),0.074(G-r),0.108(B-r),0.096(L-r);0.127(R-g),0.151(G-g),0.174(B-g),0.148(L-g);0.129(R-b),0.123(G-b),0.153(B-b),0.129(L-b);0.153(R-1),0.146(G-1),0.179(B-1),0.153(L-1), and have extreme significant positive correlation when P<0.01. The R, G, B and L value increase with the increasing of r, g, b, and1value of background color.6.Spodoerpta litura and Helicoverpa armigera SCP changes with different instars, also has a significant change in different body color. The basic rule is:3-5instar larvae supercooling point increasing with it instar (eg:3,4,5instar Spodoerpta litura SCP were-10.96±1.82,-8.01±1.19,-5.59±1.48); For the same instar, its supercooling point also increases with the value of their individual body color brightness (such as third instar bollworm in lightness value38.82,144.19～77.13～81.68respectively, when SCP were-10.28±3.46,-8.33±1.21). This result shows that the higher instar, the cold hardiness is worse to the brightness value of parasites.