Symbiosis unites natural enemies
The current artificial diet used in the laboratory rearing of the olive fruit fly does not fulfil the mass rearing facility requirements in terms of cost and insect productivity. Discovering ways to improve the quality and quantity of produced insects has been a challenge for each scientist involved in the area-wide integrated pest management programs of olive fruit fly populations. Utilization of gut symbionts as supplements in the artificial diet could contribute to the improvement of mass rearing in both olive fruit flies and their parasitoids.
Panagiota Koskinioti MSc.
ESR - Update The olive fruit fly is considered the most serious threat for olive production worldwide. A wide variety of strategies can be used to control Bactrocera oleae population in the field including bait sprays and mass trapping, but also biological control approaches such as the sterile insect technique (SIT) and parasitoid releases. SIT approach relies on the mass production and release of irradiated sterile males that compete with wild males for mating with the wild females. The offspring occurring from crosses between the irradiated males and the wild females are not viable, subsequently, leading to the decline of the target population. One of the most crucial steps in large scale applications of both the SIT strategy and the parasitoid releases is the successful mass rearing of the olive fruit fly and the parasitoids, respectively. The development of parasitoid wasps can only be achieved by using host larvae as an infestation substrate for the wasps. Thus, the mass production of parasitoids is also heavily depending on the mass rearing of olive fruit fly larvae. However, successful large-scale production of B. oleae is mainly inhibited by the lack of an efficient, cost-effective artificial larval diet.
Our hypothesis is that the addition of insect gut bacteria to the larval diet might contribute to the development of most efficient rearing procedures thus, yielding to insects of better quality and quantity. To that end, several bacteria from both the olive fruit fly and its parasitoid were identified using Next Generation Sequencing (NGS) of 16S rRNA gene approaches and a list of bacterial species were isolated from the olive fruit fly gut using cultivable approaches in bacterial growth cultures. The results retrieved from NGS indicate that the olive fruit flies have several bacteria in common with their natural enemy. These common bacteria might benefit both the fruit fly and the parasitoid rearing. The isolated bacterial cultures will be used as probiotics to the olive fruit fly diet and their effect on the productivity of both the fruit flies and their parasitoids will be assessed.