Abstract Most terrestrial animals live in natural atmospheric conditions, but some are also adapted to low oxygen (hypoxic) or high‐carbon dioxide (hypercapnic) conditions, such as in social insect nests, soil, caves, wood, and decaying material. Although it is possible that individuals adapt their behaviour to the environmental condition of their habitats, mating behaviour under ecologically possible ranges of CO2 has not been well studied. We compared walking activity, duration of mating behaviour, and sperm transfer ability in the West Indian sweet potato weevil, Euscepes postfasciatus Fairmaire (Coleoptera: Curculionidae), in high CO2 (10 000 p.p.m.) vs. normal atmospheric conditions (laboratory air, ca. 800 p.p.m.). We found that high CO2 enhanced walking activity and mounting frequency. Under such circumstances, we predicted that enhanced activities under a high‐CO2 environment would increase the risk of sperm competition, which induces an extended copulation period and an increase in sperm transfer. However, weevils shortened the mating period and did not alter their sperm transfer ability under high CO2. These findings are, as far as we are aware, the first report of the effect of ecologically relevant high CO2 on insect mating behaviour under mass‐rearing conditions. The effect of ambient conditions on mating behaviour and sperm transfer is discussed in relation to the intensity of female refusal behaviour directed against males.

Abstract To conduct population genetics analyses on sweetpotato weevils (Cylas formicarius elegantulus) collected from three populations in the United States, microsatellite loci were developed from sweetpotato weevil transcriptome sequences obtained from a publicly available database. Nineteen of 27 microsatellite loci tested were usable for population analyses. Sweetpotato weevil individuals from Georgia (N = 17), Hawaii (N = 16) and South Carolina (N = 12) were analysed. Here, we present microsatellite primer sequences for 19 loci and population genetics statistics, including diversity, population differences and relatedness. Thirty‐nine alleles were detected in the 45 individuals, and four private alleles were observed in individuals from the Hawaii and South Carolina populations. Observed heterozygosities ranged from 0.00 to 1.00, and expected heterozygosities ranged from 0.00 to 0.44. The mean Shannon's information index ranged from 0.30 to 0.49 for the three populations. Pairwise differences among populations (FST estimates) from individuals ranged from a low of 0.022 between Georgia and Hawaii to a high of 0.036 between Georgia and South Carolina, and cluster analysis (PCA and Structure) indicated two populations independent of geographical location.

Efficacy of Aerially Applied Chlorantraniliprole for Control of Two Sweetpotato Weevil Species, 2019

Efficacy of Chlorantraniliprole for Control of Two Sweetpotato Weevil Species, 2019

Twelve sweetpotato ( Ipomoea batatas var. batatas ) accessions/cultivars/landraces (entries) were evaluated for yield, resistance to pests, and quality in five field trials planted at Pepe`ekeo, Hawai‘i Island, and replicated over time with blocks planted on May and Oct. 2014, Feb. and July 2015, and Jan. 2016. Plots were harvested at 4.5 to 6 months after planting. In the first two field trials, local entries planted were ‘Okinawan’, ‘Mokuau’, and ‘Kona B’, as well as PI 531094, ‘Beauregard’, PI 573309, PI 573330, ‘Darby’, ‘Pelican Processor’, and ‘Picadito’. Yields of ‘Mokuau’ and ‘Kona B’ were low and were replaced in the latter three field trials with ‘Murasaki-29’ and ‘LA 08-21p’ from Louisiana State University (LSU) AgCenter, Baton Rouge. At harvest, storage roots were graded according to State of Hawai‘i standards and marketable yields included grades AA, A, and B. Then, injuries of storage roots due to infestations of sweetpotato weevil ( Cylas formicarius elegantulus ) in each category were estimated. Finally, sugar concentrations, anthocyanins, and β-carotene contents were measured in storage roots. Marketable fresh weight yields of entries differed significantly, with ‘LA 08-21p’ having the greatest marketable yield. However, ‘LA 08-21p’ also had the greatest incidence of damage due to sweetpotato weevil, perhaps because of its growth habit as a tight cluster of storage roots located close to the soil surface. Entries also had significantly different sugar concentrations (fructose, glucose, sucrose, maltose, and total sugars). Concentrations of sucrose ranged from 25 to 68 mg·g −1 fresh weight and were greater than those of monosaccharides analyzed. ‘Beauregard’ had the highest sucrose concentration and total sugars. Purple-fleshed cultivars Okinawan and LA 08-21p contained total monomeric anthocyanins that ranged from 34 to 37 mg/100 g dry weight. Orange-fleshed cultivars Beauregard and Darby contained β-carotene that ranged from 5485 to 8302 µg/100 g fresh weight. These results provide yields of storage roots, susceptibility to sweetpotato weevils, and amounts of antioxidants in purple- and orange-fleshed sweetpotato cultivars to growers interested in producing new sweetpotato cultivars.

Introduction: Combining ability studies in sweetpotato marketable root yield were carried out using ten sweetpotato varieties and their F1 hybrids in Cylas formicarius endemic (Omu Aran) and free (Ibadan) environments during 2012 cropping season.
 Study Design: The genetic material used for this experiment was from the germplasm collection of the Department of Agronomy, University of Ibadan, Nigeria. This material comprised of 10 varieties of sweetpotato: 5 orange fleshed, 3 white fleshed and 2 yellow fleshed.
 Place and Duration of Study: The field trial was carried out in C. formicarius endemic (Omu Aran) and Non-endemic (Ibadan) environments both in South West Nigeria during the raining season of 2012.
 Methods: Collected data were subjected to diallel analysis using Griffing (15) approach in method I (parents, crosses reciprocals together), Model I (fixed effects). Both general combining ability (GCA) and specific combining abilities (SCA) were computed using PBTools, version 1.4. for the 10 parents and their F1 hybrids with respect to C. formicarius.
 Results and Discussion: The result obtained from this study showed that some parents were tolerant to C. formicarius, but level of tolerance varied probably due to differences in genetic background among the parental population or time of planting. Hybrids from the parents resisto, TIS 87/0087 displayed high performance in term of C. formicarius tolerance. These parents and their hybrids appeared to have gene pools for C. formicarius tolerance that can be manipulated and used to develop promising hybrids in South west, Nigeria.

Mulching with organic materials is a management practice with long history for weed suppression, soil water conservation and erosion control. Its potential impact on crop pests is less well explored. Here we report its utility for reducing crop damage by the serious pest, sweetpotato weevil (Cylas formicarius). Laboratory bioassays measured the response of adult female weevils to sweetpotato storage roots beneath mulches of fresh or dried plant materials. Weevils were significant repelled by fresh basil, catnip, basil lime and dry eucalyptus, cypress, lucerne and sugarcane. A subsequent field study found that mulches of dry cypress, eucalyptus and lucerne reduced movement of weevils from a release point to reach sweetpotato plants and lowered level of damage to storage roots. Results demonstrate that mulching with organic materials merits further testing as part of the integrated management of sweetpotato weevil, particularly to protect developing storage roots during dry periods when soil cracking can facilitate access by pests.

Sweet potato (Ipomoea batatas (L.) Lam. is an important food crop adaptable to a broad range of agro-ecological conditions. The knowledge of the performance of the available varieties under a specific ecological condition is important to improve the production. A field experiment was carried out at the University of Ghana farm during the major and minor rainy seasons of 2015 to determine the yield performance of seven improved Ghanaian sweet potato varieties (CRI-Apomuden, CRI-Ligri, Faara, CRI-Bohye, CRI-Dadanyuie, Okumkom, Sauti) and their susceptibility to the sweet potato weevil, Cylas spp. (Coleoptera: Brentidae). Significant difference was found in the storage root yield among the varieties, with CRI-Ligri having the highest in both major (23.11 t/ha) and minor (22.49 t/ha) rainy seasons. CRI-Apomuden and CRI-Ligri scored the highest levels of infestation by sweet potato weevil in the major and minor seasons (1.94 and 2.00, 1.84 and 1.96, respectively) and yield loss (44.44 % and 42.80 %, 23.84 % and 23.87 %, respectively). While the lowest infestation levels in the major rainy season were recorded on Faara and Okumkom (1.18 and 1.31, respectively) with yield losses of 10.32 % and 9.09 %, respectively. However, in the minor rainy season, there was no significant difference among Faraa, Okumkom, CRI-Bohye and CRI-Dadanyuie in terms of infestation level and yield losses. Significant difference was found in all measured root characteristics including the shortest weevil distance, root neck length, root length, root girth and root size index. The storage root infestation had a strong negative correlation with the shortest weevil distance, a strong positive correlation with the root size index and a weak negative correlation with root neck length. In this study, Okumkom appeared to be less susceptible to sweet potato weevil infestation with relatively acceptable yield performance and therefore can be recommended for use by farmers to improve sweet potato production.

Sweet potato weevil, Cylas formicarius (Fabricius) attacks stems and storage roots of sweet potato, Ipomoea batatas, and is a major pest of this globally significant crop. To minimize the immigration of weevils into sweet potato fields from nearby donor habitat, we assessed scope for a barrier plant approach. Here, we report a novel, two-stage, multiple choice olfactometer method to screen candidate barrier plant species and a field study of the effects of shortlisted barrier plants of weevil movement and plant damage. Initial work established that a combination of sweet potato foliage and storage root was significantly more attractive to adult C. formicarius than either tissue alone in the distal chamber of choice arms. Among 15 candidate barrier plant species in intermediate chambers in arms, spring onion, oregano, chilli, basil, sweetcorn, fennel, lime mint and lemongrass significantly reduced passage of C. formicarius. Of these, sweetcorn and lime mint significantly reduced the numbers of oviposition holes in sweet potato storage roots. A field study showed that basil and chives were effective barrier plants for reducing weevil damage to sweet potato storage roots. Our method has utility for screening additional candidate plants, and suggests that weevil dispersal and subsequent oviposition are affected by passage through some plants, suggesting scope for barrier plants to contribute to the management of this major pest. © 2019 Society of Chemical Industry.

Laboratory Evaluation of Local Isolates of Beauveria bassiana and Metarhizium anisopliae against Coffee Berry Borer, Hyphotenemus hampei, using spryaing method. Beauveria bassiana Bals (Vuillemin) and Metarhizium anisopliae (Metschnikoff) Sorokin are two species of fungi that have been studied widely and used as biological control of various insect pests, including coffee berry borer (CBB), Hyphotenemus hampei Ferrari. Laboratory studies were done in June – July 2017, to evaluate local isolates of both fungi species against CBB, the most destructive insect pest of coffee worldwide, including in Indonesia. B. bassiana was isolated from dead sweet potato weevil (Cylas formicarius) and green stink bug (Nezara viridula), and from soil. M. anisopliae was isolated from soil. The pure cultures of the fungi were mass-cultured on corn based media. The conidia harvested from 4 week colonies was hand sprayed directly upon CBB adults (females) and damaged coffee berry at the concentration of 109 ml-1. In additions, the conidia of B. bassiana isolated from C. formicarius alone was diluted to 106- 109 ml-1 and applied to damaged coffee berry. The results showed that when the conidia were applied directly upon the insects, the mortality of beetle were higher in B. bassiana than in M. anisopliae treatments. Pooled data indicated that B. bassiana isolated from death insects significantly caused higher mortality than did M. anisopliae isolated from soil. Beetle mortality was 76.7 and 80.0% for B. basiana, and 60.3 and 60% for M. anysopliae treatments. Application upon damage coffee berry indicated much lower mortality. Application of higher concentration upon damaged coffee berry resulted higher mortality, but data are not consistent. The mortality of CBB larvae was much less and negligible even at the highest conidia concentration.

Quarantine pests in plants can be a serious agricultural problem; many eradication programs using area-wide control measures have been implemented worldwide to combat this threat. Surveillance measures using sex pheromone (in general, male-attractant) traps are also widely implemented for rapid control and eradication of invasive pests. If initial pest colonization can be determined based on temporal count data of trapped insects (i.e., males), and countermeasures are applied only during colonization, costs incurred by these countermeasures would be dramatically reduced, especially in areas with frequent invasions. In this study, we developed a system to detect initial pest colonization, and to narrow down colonized regions using estimated temporal count data of the sweet potato weevil, Cylas formicarius Fabricius (Coleoptera: Curculionidae), in Tsuken Island, Okinawa, Japan. We verified the system by comparing our estimates to actual colonization data obtained via regular host plant surveys. Results indicated that our system was able to successfully detect pest colonization and estimate colonized regions. In this study, we discuss the conditions (i.e., pest biology, environment, etc.) that are optimal for application of our system.

Abstract. Saputro TB, Prayogo Y, Rohman FL, Alami NH. 2019. The virulence improvement of Beauveria bassiana in infecting Cylas formicarius modulated by various chitin based compounds. Biodiversitas 20: 2486-2493. Sweet potato (Ipomoea batatas L.) is one of alternative carbohydrate source with an important role in food production, animal feed industries, and as raw materials for other derivatives. However, severe losses are constantly occurred in its production due to a notorious pest known as sweet potato weevil (Cylas formicarius). The chemical insecticides commonly used to treat the pest, but have not been efficient in eliminating C.formicarius. Beauveria bassiana is well known as a biological control agent, has been identified to effectively eliminate the pest. The aim of this research is to observe the optimum concentration of several chitin-based compounds in improving the virulence of B. bassiana. The research was conducted by the addition of chitin from various sources - insects, crustaceans and mollusk shells in a growth medium of B. Bassiana. Moreover, conidia produced by B.bassiana was exposed to C.formicarius to investigate the mortality rate of this insect. The results showed four different characteristics of colonies - velvety, wooly, pellicular, and farinaceous. The 1% chitin from Tellina sp, (P9), was found to be the best treatment which increased the growth of the colony diameter attaining 6.7cm in 20 days, increased the conidia viability that reaches 93.5%. In addition, the highest mortality percentage of C. formicarius was 91.67% in P9 at 6 days after infection. Overall, this research gave new potential sources of chitin that can be applied in improving the virulence of B. Bassiana in eliminating C. formicarius.

Cylas formicarius F. and Euscepes batatae Waterhouse are the most damaging sweet potato insect pests globally. Both weevils are thought to have invaded the Pacific alongside the movement of sweet potato (Ipomoea batatas (L.) Lam. Convolvulaceae), with C. formicarius having originated in India and E. batatae in Central or South America. Here we compare the genetic relationships between populations of the pests, primarily in the Asia-Pacific, to understand better their contemporary population structure and their historical movement relative to that of sweet potato. Cylas formicarius has divergent mitochondrial lineages that indicate a more complex biogeographic and invasive history than is presently assumed for this insect, suggesting it was widespread across the Asia-Pacific before the arrival of sweet potato. Cylas formicarius must have originally fed on Ipomoea species other than I. batatas but the identity of these species is presently unknown. Cylas formicarius was formerly designated as three species or subspecies and the genetic data presented here suggests that these designations should be reinvestigated. Euscepes batatae has very low genetic diversity which is consistent with its historical association with sweet potato and a recent introduction to the Asia-Pacific from the Americas. The distribution of E. batatae may be narrower than that of C. formicarius in the Asia-Pacific because it has relied relatively more on human-assisted movement. Consequently, E. batatae may become more widespread in the future. Investigating the invasion history of both species will help to understand the probability and nature of future invasions.

In Indonesia tidal land is very wide and quite potential for sweet potatoes, but an obstacle for this cultivation is sweet potato weevil (Cylas formicarius) causes loss of 100%. This research aimed to evaluate the efficacy of biopesticide Be-Bas contains Beauveria bassiana entomopathogenic conidia to C. formicarius mortality at tidal lands. This study was conducted on June-November 2016 in South Kalimantan. The research consisted of five treatments and five replications. Results showed that the application of biopesticide Be-Bas in the planting hole and stem base was effective to cause mortality of 17 and 15 larvae per tuber, respectively. However, the application by soaking cutting was able to kill 3 larvae per tuber. The application of biopesticide Be-Bas in the planting hole and stem base were also effective to suppress the number of eggs laid by C. formicarius in the tuber, hence there was no damage found on the tuber. Meanwhile, the application of conventional insecticide was less effective because a total of 17 eggs and 3 larvae of C. formicarius were still found in each tuber. It caused tuber damage up to 17%, thus the tuber cannot be consumed. Therefore, the application of biopesticide Be-Bas in the planting hole or stem base was considered capable to suppress tubers damage caused by C. formicarius better than that of conventional insecticide.

Sweet potato (SP) weevils, Cylas spp. are important pests of SP throughout the world and particularly in Africa. They cause damage to the crop as a result of their diet and reproduction. This study was undertaken to identify species of Cylas attached to SP production in southern Benin and to assess the distribution of the insects in study areas. A survey was conducted from October to December 2015 in fifteen districts of the departments of Mono, Couffo, Ouémé and Plateau in agro-ecological zones 6, 7 and 8 of Southern Benin. Weevil adults were collected alone in bulk but also along with infested vines and tuberous roots. Sweet potato vines and tuberous roots were incubated in laboratory for emergency of insect adults. Two species of Cylas were identified: C. puncticollis Boheman and C. brunneus Schoenherr. Cylas puncticollis were observed in 82.70% of total samples collected and were found in all districts prospected while C. brunneus were observed in 17.42% of the samples and were observed only in the districts of Adjohoun, Bopa, Houéyogbé, Ifangni and Klouékanmè. The highest incidence (100.00 ± 0.00%) and the lowest incidence (0.00 ± 0.00%) were recorded with C. puncticollis and C. brunneus, respectively, in the districts of Aplahoué, Comè, Sakété, Adja-Ouèrè and Toviklin. All SP farmers used only vine cuttings for planting, with 10% of them treating planting material with chemical insecticides. Eighty percent of farmers use planting materials taken in their own fields whereas 20% obtain them from neighboring fields either free of charge or purchase them. This study gave use more detailed information on the identity and distribution of sweet potato weevils in Benin and was useful for the establishment of control measures against them.

Sweetpotato weevil (SPW), Cylas formicarius elegantulus (Summers), is the most damaging root-feeding insect of sweetpotato, Ipomoea batatas (L.) Poir., worldwide. Larval feeding on storage roots reduces yield and induces terpene production, rendering roots inedible. Selection of sweetpotato cultivars with resistance to insect pests has been carried out for over a century but no high yielding, production acceptable varieties are currently available that are resistant to SPW. A cultivar with resistance to SPW oviposition would be a desirable choice for growers since it will reduce the number of larvae and damage level from SPW. Previous studies have compared cultivar effect on the oviposition of SPW but have not considered the effect of previous rearing experience. Hopkins’ host-selection principle (Hopkin’s HSP) states that phytophagous insects have an oviposition preference for the host that they have been reared on. In this study, we tested cultivar effect on oviposition preference of SPW reared on different cultivars for a minimum of two generations. For adults reared on cvs. Beauregard and Evangeline, adult oviposition preference followed their previous living experience. Thus, our results indicate a strong effect of host fidelity, supporting Hopkin’s HSP. Our results also confirm that cv. Murasaki is a resistant cultivar, resulting in reduced oviposition but not oviposition capacity. It is possible that the reduced oviposition is due to the stress-triggered oosorption from the females feeding on cv. Murasaki.

The sweetpotato weevil (SPW), Cylas formicarius Fabricius, is the main pest in sweet potatoes and spread throughout the world. One of the efforts that can be used to reduce SPW attacks is to use sweet potato genotypes that contain high beta-carotene. The objective of this research was to know the resistance level of some sweet potato genotypes to sweetpotato weevil in the lowlands. This research used a randomized block design with one factor, namely sweet potato consisting of 5 genotypes that came from different accessions (Saribu Dolok Simalungun, Kesemak Simalungu, Batang Beruh Dairi, Binjai accession and National Superior Varieties Beta-1). This research was carried out in Cengkeh Turi, Binjai Utara, Sumatera Utara from April to August 2018. The results showed that the lowest intensity and percentage of attack was on sweet potato accession of Saribu Dolok Simalungun, which was 7.94% and 27.08% respectively while the highest intensity and percentage of attack was on sweet potato accession of Batang Beruh Dairi, which was 18.60% and 48.7% respectively. It is recommended that Saribu Dolok accession is more resistance rather than others and suitable to grow on low land.

Nuclease activity decreases the RNAi response in the sweetpotato weevil Cylas puncticollis

Laboratory investigations were performed to ascertain the efficacies of Dennettia tripetalla (G.Backer), Xylopiaa ethiopica (A. Rich) and Aframomum melegueta (K. Schum) for the control of Cylas puncticolis, African sweet potato weevil. Organic solvent extracts of the leaves and fruits of the test plants were separately applied at concentration of 1, 3 and 5% (w/v) for investigation. The biological assays were conducted for six months under ambient temperature, relative humidity (28±3°C, 65±5% RH) and 12Hr light/dark photoperiods; laid out in a completely randomized design with each treatment replicated four times. Results disclosed that 3 and 5% extracts of the three test plants led to significantly (P<0.05) higher mortality of C. puncticollis when compared with 1% and control. 3.75 extract of the tubers. n-hexane extracts of all the test plant products significantly (P <0.05) repelled more than 60% of C. puncticollis within one-hour of exposure. . Extracts of A. melegueta fruit at 3 and 5% and X. aethiopica fruit at 5% had the most significant (P<0.05) insecticidal activity, followed by extract of D. tripetalla (at 5%). Adult emergence was also significantly higher in control than treated tubers with A. melegueta products giving the lowest significant number of emerged adults. The results of this research demonstrate the efficacies of the test plants extracts for the control of C. puncticollis infesting sweet potato roots during post-harvest storage at the small scale farming level in Calabar, Nigeria.

Biotic constraints cause major crop losses and, hence, food insecurity in sub-Saharan Africa. This study documented the popularity, production constraints, pests and diseases, farmers’ perceptions on the severity of biotic constraints and the impact of related crop losses on household food security for the key root, tuber and banana (RTB) crops (cassava, potato, sweetpotato and banana). Farmer interviews were conducted in 2014 covering 811 households in Rwanda and Burundi. Farmers were asked to list their RTB crop production constraints, name insect pests and diseases of RTB crops, estimate crop loss due to pests and diseases, and mention if their household experienced any form of food insecurity due to pests and diseases. Cutworms and late blight in potato, banana weevils and banana Xanthomonas wilt in banana, cassava whitefly and cassava mosaic disease in cassava, sweetpotato weevils, and sweetpotato virus disease in sweetpotato were the most predominant pests and diseases reported. Crop losses due to pests and diseases for sweetpotato, banana, potato and cassava were estimated at 26%, 29%, 33%, and 36%, respectively, in Rwanda and 37%, 48%, 38%, and 37% in Burundi. Pests and diseases reduce the profitability of RTB crops, threaten food security, and constitute a disincentive for investment. Sustainable and affordable integrated pest management packages need to be developed.