Development of densovirus-based bioinsecticide (Tenebriokiller) for use in the control of mealworm, Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae)

Abstract

Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae) is one of the major storage pests affecting a large proportion of pasta, flour, starch, and rice. Densoviruses are biocontrol agents with a single-stranded DNA genome that is enveloped and very small in size. In this study, crude TmDNV-TR was formulated using bovine gelatin, and the formulation called Tenebriokiller was prepared in Türkiye. The dose of virus in the formulation was determined to be 2.8x108 copies/mL-1. Five different doses were used (2.8x108, 2.8x107, 2.8x106, 2.8x105, and 2.8x104 copies/mL-1) against 10th instar T. molitor larvae. The mortality was detected 100% (LD50: 4 x106 copies/mL-1, LT50: 6 day, LD95: 2.2 x108 copies/mL-1 and LT95: 9 day) by day 14. The stability of the crude virus and Tenebriokiller was tested at different storage temperatures (4 and 25°C) over various periods (3 and 6 months). Accordingly, the mortality rate of the fresh formulation was 100% as in the previous step, while at 4°C the mortality rate at the end of 3 and 6 months remained 100%, and at 25°C, the mortality rate at the end of 3 and 6 months was 98% and 95% respectively, at the end of day 14. Preliminary pathogenicity tests in the laboratory showed that the virus was highly lethal to the target organism. The virus was therefore formulated to maintain its stability during storage, and a prototype formulation was developed.

Keywords

• Biocontrol
• densovirus
• Tenebrio molitor
• virus formulation
• virus stabilization

Un kurdu, Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae)'un kontrolünde kullanılmak üzere densovirüs bazlı biyoinsektisitin (Tenebriokiller) geliştirilmesi

Öz

Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae), makarna, un, nişasta ve pirincin büyük bir kısmını etkileyen önemli depo zararlılarından biridir. Densovirüsler, zarflı ve çok küçük boyutlu tek zincirli bir DNA genomuna sahip biyolojik kontrol ajanlarıdır. Bu çalışmada, sığır jelatini kullanarak ham TmDNV-TR formüle edilmiş ve Tenebriokiller adı verilen formülasyon Türkiye’de hazırlanmıştır. Formülasyondaki virüs dozunun 2.8x108 kopya/mL-1 olduğu belirlenmiştir. Beş farklı doz (2.8x108, 2.8x107, 2.8x106, 2.8x105 ve 2.8x104 kopya/mL-1) 10. dönem T. molitor larvalarına uygulanmıştır. Ölüm oranı 14. günün sonunda %100 (LD50: 4 x106 kopya/mL-1, LT50: 6 gün, LD95: 2.2 x108 kopya/mL-1 ve LT95: 9 gün) olarak belirlenmiştir. Ham virüsün ve Tenebriokiller'in stabilitesi farklı depolama sıcaklıklarında (4 ve 25°C) çeşitli sürelerde (3 ve 6 ay) test edilmiştir. Buna göre, taze formülasyonun ölüm oranı bir önceki adımda olduğu gibi %100 iken, 4°C'de 3 ve 6 ayın sonunda ölüm oranı %100, 25°C'de ise 3 ve 6 ayın sonunda ölüm oranı sırasıyla %98 ve %95 olarak belirlenmiştir. Laboratuvardaki ön patojenite testleri virüsün hedef organizma için oldukça öldürücü olduğunu göstermiştir. Bu nedenle virüs, depolama sırasında stabilitesini koruyacak şekilde formüle edilerek, bir prototip formülasyon üretilmiştir.

Anahtar Kelimeler

• Biyolojik mücadele
• densovirüs
• Tenebrio molitor
• virüs formülasyonu
• virüs kararlılığı

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