Some additive compounds of sorbic acid, glucose and glycine amino acid have been added to improve the potency of some bio-insecticides;(Bactericide) Bacillus thuringiensis var. Kurstaki and (Fungicide) Beauveria bassiana (Balsamo) formulations against newly hatched larvae of Pectinophora gossypiella (Saund.). Results obtained could be summarizing as follows: Bacillus thuringiensis had the most bio-insecticides efficacy on P.gossypiella newly hatched larvae after 1,2&3 days from treatment. Additives of glucose at concentrations of 0.1 and 0.05%, followed by sorbic acid at 0.1% were enhanced B. thuringiensis effect and caused the potentiation interaction on P.gossypiella larval mortality percentages. Other additive compounds caused additive interaction for B. thuringiensis except for additives of glycine (0.1& 0.025%) caused antagonism effect for B. thuringiensis and reduced from P.gossypiella larval mortality. On the other hand, additives of glucose at concentration of 0.1% potentiate B. bassiana efficiency against P.gossypiella larvae. Other additive compounds of glucose (0.05 and 0.025%) and sorbic acid (0.1, 0.05 and 0.025%) caused additive interaction with B. bassiana. Meanwhile, additive of glycine decreased B. bassiana efficacy and caused antagonism effect on P.gossypiella larval mortality.  All additives compounds used had effect on some biological parameters of P.gossypiella when additives had interaction with B. thuringiensis or B. bassiana compared to use each of them alone. Additive of glucose had the best effect on the most biological parameters used, followed by sorbic acid, while; additive of glycine had the least interaction with the two bio-insecticidesagainst the aforementioned pest.