Trichogramma egg parasitoids are successfully used for biological control of a wide range of lepidopteran pests worldwide. However, the field success depends upon their performance that could be influenced by the conditions of laboratory mass rearing. Hence, reviewing all scientific information on the most suitable mass rearing techniques of Trichogramma parasitoids is of utmost importance to those seeking successful biological pest control action. Trichogramma mass production techniques, mainly using alternative hosts, and characteristics of artificial diet(s) are explored herein. Scientific and technical information on (i) how diet could influence Trichogramma adult reproductive behaviour, (ii) the effect of continuous rearing on the egg parasitoid genetic diversity, (iii) Trichogramma preferences to host eggs and impact of host quality on the wasp performance, and (iv) effect of storage methods and abiotic factors (temperature, relative humidity and photoperiod) on the fitness of reared Trichogramma parasitoid are emphasised in this review.

Tuta absoluta (Meyrick) is a key insect pest of tomato crop causing major economic losses worldwide. Biological control using Trichogramma parasitoids is considered a promising, eco-friendly management tactic of this pest. We performed inundative releases of Trichogramma cacoeciae (Marchal) (Hymenoptera: Trichogrammatidae) against T. absoluta in Takelsa (northeastern Tunisia). Three weekly releases of either (i) 10, 20 or 30 Trichogramma per plant in protected (greenhouse) tomato crops or (ii) 20 or 40 Trichogramma per plant in open field tomatoes were evaluated for their effectiveness. Results indicated that 20 Trichogramma per plant was the most effective release rate in significantly decreasing the pest’s life stage densities. Parasitism rates were significantly higher on apical tomato leaves (estimated at 58.6% for the rate 20 Trichogramma per plant in greenhouses and at about 56% for the rate 40 Trichogramma per plant in open field) compared to those observed on middle leaves (24.6% and 45.26% for rate 2 respectively under greenhouse and open field conditions). Furthermore, the overall number of T. absolua eggs and larvae was significantly reduced after releases of Trichogramma parasitoids. These results clearly indicate that T. cacoeciae could be a promising biocontrol agent of T. absoluta in the largest tomato-producing area in Tunisia.

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is considered as key pest attacking tomato in Tunisia and in many other countries around the world. In order to investigate the efficacy of Trichogramma cacoeciae (Marchal) (Hymenoptera: Trichogrammatidae) for biological control of this pest in Northeastern Tunisia, releases were performed in open field conditions. T. cacoeciae showed a good efficacy on reducing the number of T. absoluta eggs and larvae when releasing 30 adults/plant in plots covered with insect-proof netting in May 2012. The results showed that this parasitoid may be a promising agent for T. absoluta biological control in Tunisia.