Development of efficient integrated management package against sweet potato weevil (Cylas formicarius [Fabricius, 1798])

<p class="042abstractstekst">The sweet potato weevil (<em>Cylas formicarius</em>, 1798) is one of the most damaging sweet potato pests. To prevent an economic crop loss, it is very important to develop a suitable and efficient integrated pest management strategy. A field experiment was set up with three replications at Jamalpur to select the best integrated management package from eight different treatments against sweet potato weevil. The results showed that the lowest percentage of infestation by number (2.94 %) and mass (3.22 %) was found when the crop was planted on November 01; earthing-up for two times, Carbofuran 5G was sprayed @ 15 kg ha^-1 at 60 days after planting with irrigation and tuber was harvested at 130 days after planting. The marketable yield (23.75 kg) and percent increase of yield than control (50.86 %) performed the highest in the same combination. These findings suggested an effective integration of different management strategies to reduce sweet potato weevil infestation in Bangladesh successfully.</p>

Screening of Five Lamiaceae Essential Oils as Repellents for Sweet Potato Weevil, Cylas Formicarius (F.) (Coleoptera: Brentidae)

In this research, the repellent activity of five Lamiaceae essential oils, Agastache rugosa, Elsholtzia blanda, Elsholtzia ciliata, Elsholtzia penduliflora, and Plectranthus ovatus, was evaluated against sweet potato weevil, Cylas formicarius using a two-choice test between the essential oil-treated filter paper and the control. E. blanda and A. rugosa essential oils have some sweet potato weevil attractant properties at low dose (<47.16 nl/cm2),while N,N-diethyl-3-methylbenzamide (DEET), P. ovatus, E. penduliflora, and E.ciliata essential oils have repellent properties at doses ranging from 15.72 nl/cm2 to 196.49 nl/cm2. The effect of type of essential oil and their dose were interactively associated with repellent efficacy. There was a increase in repellent efficacy as the dose increased for all essential oils. The repellent activities of P. ovatus essential oil and E. penduliflora were higher than the others, and the repellent effects of E. ciliata essential oil and DEET were more dose-dependent than others, indicating that at low dose, P. ovatus and E. penduliflora essential oils have stronger repellent efficacy, but at higher dose DEET and E. ciliata have greater effects. Our findings clearly demonstrate that P. ovatus, E. penduliflora, and E. ciliata essential oils are candidate materials for future investigation as repellent compounds against sweet potato weevil control.

Chromosome-level genome assembly of the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae) and functional characteristics of CforOBP4-6

Cylas formicarius is one of the most important pests of sweet potato worldwide, causing considerable ecological and economic damage. To improve the effect of comprehensive management and understanding of genetic mechanisms, the genetic functions of C. formicarius have been the subject of intensive study. Using Illumina and PacBio sequencing, we obtained a chromosome-level genome assembly of adult weevils from lines inbred for 15 generations. The high-quality assembly obtained had a size of 338.84 Mb, with contig and scaffold N50 values of 14.97 Mb and 34.23 Mb, respectively. In total, 157.51 Mb of repeat sequences and 11,907 protein-coding genes were predicted. A total of 337.06 Mb of genomic sequences was located on the 11 chromosomes, and the sequence length that could be used to determine the sequence and direction accounted for 99.03% of the total length of the associated chromosome. Comparative genomic analysis showed that C. formicarius was sister to Dendroctonus ponderosae, and C. formicarius diverged from D. ponderosae approximately 138.89 million years ago (Mya). Many important gene families that were expanded in the C. formicarius genome were involved in the chemosensory system. In an in-depth study, the binding assay results indicated that CforOBP4-6 had strong binding affinities for sex pheromones and other ligands. Overall, the high-quality C. formicarius genome provides a valuable resource to reveal the molecular ecological basis, genetic mechanism and evolutionary process of major agricultural pests, deepen the understanding of environmental adaptability and apparent plasticity, and provide new ideas and new technologies for ecologically sustainable pest control.

Pengendalian Hama Cylas formicarius pada Tanaman Ubi Jalar (Ipomea batatas L.) Menggunakan Cendawan Entomopatogen Metarhizium sp.

Cylas formicarius merupakan salah satu hama yang merusak dan mengganggu produksi ubi jalar di Kecamatan Wasile Selatan yang perlu segera diatasi. Dalam hal pengendalian hama dapat dilakukan dengan bioinsektisida yakni memanfaatkan cendawan entomopatogen seperti cendawan Metarhizium sp. Pengendalian hama dengan bioinsektisida merupakan salah satu teknik yang cukup efektif dan ramah lingkungan. Penelitian ini dilakukan dalam Rancangan Acak Lengkap (RAL) dengan 3 faktor yaitu penyemprotan dengan suspensi Metarhizium sp., penyemprotan dengan insektisida kimia bahan aktif karbosulfan, dan kontrol atau tanpa perlakuan insektisida. Hasil pengamatan pada aplikasi Metarhizium sp. ketika umbi dibelah terlihat adanya lubang-lubang kecil bekas gerekan yang tertutup oleh kotoran berwarna hijau dan berbau menyengat. Aplikasi insektisida menyebabkan perubahan morfologis pada larva yakni warna tubuh berubah menjadi kecokelatan dan setelah tiga hari tubuh larva mengering. Hasil analisis menunjukan mortalitas tertinggi ditemukan pada perlakuan insektisida ditemukan pada pengamatan hari kelima (10%)., sedangkan mortalitas tertinggi pada perlakuan Metarhizium sp. ditemukan pada hari kelima (8,5%). Hasil yang diperoleh menunjukkan bahwa cendawan entomopatogen Metarhizium sp. dapat dimanfaatkan untuk mengendalikan hama Cylas formicarius dengan efektif.

Development of useful integrated management package against sweet potato weevil.

The sweet potato weevil (Cylas formicarius Fab.) is one of the most damaging sweet potato pests. To prevent an economic crop loss, it is very important to develop a suitable and efficient integrated pest management strategy. A field experiment was set up with three replications at Jamalpur to select the best-integrated management package from eight different treatments against sweet potato weevil. The result showed that the lowest percentage of infestation by number (2.94%) and weight (3.22%) was found when the crop was planted on November 01; earthing-up for two times, Carbofuran 5G was sprayed @ 15 kg/ha at 60 days after sowing with irrigation and tuber was harvested at 130 days after planting. The marketable yield (23.75 kg) and percent increase of yield than control (50.86%) performed highest in the same combination. These findings suggested an effective integration of different management strategies to reduce sweet potato weevil infestation in Bangladesh successfully.

Trade-off Investment between Tonic Immobility and Mate Search in the Sweetpotato Weevil, Cylas formicarius (Coleoptera: Brentidae)

Tonic immobility (TI) is a well-known anti-predator strategy adopted by diverse preys. Numerous studies on the cost–benefit involve in TI have been reported. Although, some studies have reported the effect of mating behavior on TI, few studies highlight the phases of mate search. In the present study, we investigated the relationship between mate search and TI behavior in the sweetpotato weevil (SPW), Cylas formicarius (Coleoptera: Brentidae). First, we found the most active mate search period of male SPW within 24 h. Then, we measured whether the duration of TI of virgin male and female were affected during the mate search. In the end, the Y-tube olfactometer was used to compare the duration of mate search and the proportion of orientation towards the females in two artificial selection groups of the male SPW with longer and shorter duration of TI. Our study confirmed that male mate searching increase after 3 h at night, and up to 73% at midnight, TI was affected by mate search in male, because the duration of TI of the male during mate search (Mean ± SE = 214.53 ± 22.74 s) was significantly shorter duration than the control (679.64 ± 69.77 s). However, mate search did not affect the strength of TI in the females tested. This study determined that mate search was affected by TI due to males from the group with shorter duration of TI who had 28% higher proportion of orientation towards the females than the males with longer duration of TI. Investment trade-off between TI and mate search was confirmed in the males of the SPW.