Evaluation of Biological Attributes on Trichogramma chilonis and Trichogramma japonicum on different Factitious Hosts under Laboratory Conditions
Abstract
The laboratory experiment was conducted during 2024 to study the different biological parameters of Trichogramma chilonis and Trichogramma japonicum on the factitious hosts Corcyra cephalonica and Cadra cautella. The present study revealed that 94.44 to 96.67 percent egg parasitization was recorded on C. cephalonica, which was found to be statistically at par with C. cautella eggs (93.33 to 96.67%). In the case of T.chilonis, percent parasitization ranged from 90.00 to 93.33% on both C. cephalonica and C. cautella eggs.
A shorter development period of T. chilonis was observed (7.67 days) when reared on the eggs of C. cautella, which was found at par with the eggs of C. cephalonica (8.00 days). In the case of T. japonicum, the development period ranged from 8.33 to 8.67 days when reared on both factitious hosts. Adult longevity was higher when T. chilonis and T. japonicum were reared on C. cautella eggs compared to C. cephalonica eggs.
Fecundity was not affected by the number of eggs or host species, as results were statistically at par. In the case of T. chilonis and T. japonicum, maximum female parasitoid recovery was noticed from the parasitized eggs of C. cautella, which was at par with C. cephalonica. The number of host eggs showed significant differences in percent adult emergence of both parasitoids. The highest percent adult emergence of T. chilonis and T. japonicum was reported when one gravid female parasitoid was exposed to 10 eggs/card, and the results were significantly different from the other two treatments (20 eggs/card and 30 eggs/card).
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Introduction
Trichogrammatids are polyphagous egg parasitoid wasps distributed globally and playa crucial role in biological pest control, especially against lepidopteran pests, by parasitizing the eggs of other insects, thereby supporting ecological balance and sustainable agricultural practices (Jalai et al., 2016; Mahankuda and Sawai, 2020). They are widely used in biological control strategies, especially in inundative releases. Over 200 insect species are parasitized by various strains of trichogrammatids (Tanwar et al., 2006).
Various methods involving the use of chemicals and breeding strategies have helped enhance the efficacy of these parasitoids as bioagents in the eco-friendly management of many crops. Trichogramma wasps are commonly reared on factitious hosts such as Ephestia kuehniella, Sitotroga cerealella, and Corcyra cephalonica to facilitate mass production for biological control applications. These artificial hosts enable controlled rearing conditions, ensuring a consistent supply of parasitoids (Knutson, 2000).
However, it is important to note that prolonged rearing on factitious hosts can lead to host preference shifts, potentially affecting the parasitoid’sefficiency on target pests under field conditions. Therefore, monitoring and managing host use in laboratory settings is crucial for maintaining the effectiveness of Trichogramma wasps in biological control programmes. The present study was carried out to evaluate the efficiency of T. chilonis and T. japonicum on different factitious hosts (Corcyra cephalonica and Cadra cautella) in the laboratory by assessing their biological attributes, i.e., percent parasitism, adult longevity, development period, fecundity, percent adult emergence, and sex ratio.
Conclusion
From the results of the present study, it is concluded that maximum female parasitoid recovery and shorter development periods of T. chilonis and T. japonicum were observed from parasitized eggs of both C. cautella and C. cephalonica. The highest percent adult emergence for both species was recorded when one gravid female parasitoid was exposed to 10 eggs/card, significantly different from the 20-and 30-egg treatments.
These findings are of great importance for utilizing the almond moth (C. cautella) along with the commonly used factitious host C. cephalonica in the preparation of trichocards in biocontrol laboratories.
