# A Question about Supercovariant Derivative

Let $$\Phi(x,\theta,\bar{\theta})$$ be a complex superfield. Let $$K(\Phi,\bar{\Phi})$$ be a function of $$\Phi$$ and $$\bar{\Phi}$$. How to prove the following identity?

$$\int d^{4}x\int d^{2}\theta d^{2}\bar{\theta}K(\Phi,\bar{\Phi})=\frac{1}{16}\int d^{4}x D^{2}\bar{D}^{2}K(\Phi,\bar{\Phi})|_{\theta=\bar{\theta}=0},$$

where $$D_{\alpha}=\partial_{\alpha}-i(\sigma^{\mu})_{\alpha\dot{\beta}}\bar{\theta}^{\dot{\beta}}\partial_{\mu}$$, and $$\bar{D}_{\dot{\alpha}}=\bar{\partial}_{\dot{\alpha}}-i(\bar{\sigma}^{\mu})_{\dot{\alpha}\beta}\theta^{\beta}\partial_{\mu}$$ are the supercovariant derivatives.