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Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is the most destructive pest of tomato worldwide. Biological control has always been considered as a promising management approach of this pest in tomatoes. In this context, we evaluated the effectiveness of releasing Trichogramma cacoeciae Marchal parasitoids or Macrolophus pygmaeus (Rambur) predators in controlling T. absoluta in greenhouse tomatoes of northeastern Tunisia. Two weekly releases of either M. pygmaeus at 1 adult/m2 or T. cacoeciae at 20 adults/plant were assessed. Our results indicated that parasitism rates were significantly higher on the apical tomato leaves compared to the middle leaves. We found that the number of T. absoluta eggs and larvae was significantly reduced after releasing T. cacoeciae, while releases of M. pygmaeus did not significantly reduce T. absoluta densities. The present study demonstrated the great potential of releasing T. cacoeciae in controlling T. absoluta in greenhouse tomatoes of northeastern Tunisia. However, further studies are needed to evaluate other release rates of M. pygmaeus that could show promising effectiveness against T. absoluta in northeastern Tunisian greenhouses. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Honeydew-excreting hemipterans, such as mealybug pests, can be protected from their natural enemies by tending ants in return for honeydew, thereby compromising the aims of biological control. In this respect, antagonistic interactions between the ant Tapinoma nigerrimum, native to the Mediterranean basin, and the main natural enemies of both the vine mealybug (VMB), Planococcus ficus, and the citrus mealybug (CM), Planococcus citri, were assessed in laboratory conditions. Parasitism of vine and CMs by their respective parasitoids, Anagyrus sp. nr. pseudococci and Leptomastix dactylopii, was negatively affected by the ant T. nigerrimum. Similarly, T. nigerrimum was shown to significantly disrupt the predatory potential of ladybird larvae, Cryptolaemus montrouzieri, when foraging on host CMs. By contrast, the presence of the ant did not negatively influence the predatory activity of C. montrouzieri adults when feeding on CMs. Consequently, the encyrtid parasitoids A. sp. nr. pseudococci and L. dactylopii and the larval stage of the predator C. montrouzieri may be considered as T. nigerrimum-sensitive, whereas the adults of C. montrouzieri may be regarded as T. nigerrimum-resistant predators. Accordingly, the ant T. nigerrimum constitutes a threat to the biological control of mealybugs by either the encyrtids A. sp. nr. pseudococci and L. dactylopii or the larval stage of the ladybird C. montrouzieri. Hence, adequate control of T. nigerrimum is highly recommended before any release of these mealybugs' natural enemies. [ABSTRACT FROM PUBLISHER]