Biology and integrated pest management for the banana weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae)

The banana weevil Cosmopolites sordidus (Germar) is the most important insect pest of bananas and plantains (Musa spp.). The larvae bore in the corm, reducing nutrient uptake and weakening the stability of the plant. Attack in newly planted banana stands can lead to crop failure. In established fields, weevil damage can result in reduced bunch weights, mat die-out and shortened stand life. Damage and yield losses tend to increase with time. This paper reviews the research on the taxonomy, distribution, biology, pest status, sampling methods, and integrated pest management (IPM) of banana weevil. Salient features of the weevil's biology include nocturnal activity, long life span, limited mobility, low fecundity, and slow population growth. The adults are free living and most often associated with banana mats and cut residues. They are attracted to their hosts by volatiles, especially following damage to the plant corm. Males produce an aggregation pheromone that is attractive to both sexes. Eggs are laid in the corm or lower pseudostem. The immature stages are all passed within the host plant, mostly in the corm. The weevil's biology creates sampling problems and makes its control difficult. Most commonly, weevils are monitored by trapping adults, mark and recapture methods and damage assessment to harvested or dead plants. Weevil pest status and control options reflect the type of banana being grown and the production system. Plantains and highland bananas are more susceptible to the weevil than dessert or brewing bananas. Banana production systems range from kitchen gardens and small, low-input stands to large-scale export plantations. IPM options for banana weevils include habitat management (cultural controls), biological control, host plant resistance, botanicals, and (in some cases) chemical control. Cultural controls have been widely recommended but data demonstrating their efficacy are limited. The most important are clean planting material in new stands, crop sanitation (especially destruction of residues), agronomic methods to improve plant vigour and tolerance to weevil attack and, possibly, trapping. Tissue culture plantlets, where available, assure the farmer with weevil-free material. Suckers may be cleaned by paring, hot water treatment and/or the applications of entomopathogens, neem, or pesticides. None of these methods assure elimination of weevils. Adult weevils may also invade from nearby plantations. As a result, the benefits of clean planting material may be limited to a few crop cycles. Field surveys suggest that reduced weevil populations may be associated with high levels of crop sanitation, yet definitive studies on residue management and weevil pest status are wanting. Trapping of adult weevils with pseudostem or corm traps can reduce weevil populations, but material and labour requirements may be beyond the resources of many farmers. The use of enhanced trapping with pheromones and kairomones is currently under study. A combination of clean planting material, sanitation, and trapping is likely to provide at least partial control of banana weevil.Classical biological control of banana weevil, using natural enemies from Asia, has so far been unsuccessful. Most known arthropod natural enemies are opportunistic, generalist predators with limited efficacy. Myrmicine ants have been reported to help control the weevil in Cuba, but their effects elsewhere are unknown. Microbial control, using entomopathogenic fungi and nematodes tend to be more promising. Effective strains of microbial agents are known but economic mass production and delivery systems need further development.     

Economic analysis of cut-and-carry,and alley cropping systems of mulch production for plantains in south-eastern Nigeria

Organic mulch is beneficial to plantain because it maintains soil fertility, prevents erosion and suppresses weeds. Mulch availability is however a major constraint. Mulching in a cut-and-carry system withPennisetum purpureum Schum. (elephant grass) was compared with mulching with the prunings ofAlchornea cordifolia (Schum. & Thonn.),Dactyladenia barteri (Hook. f. ex Oliv.)Engel. (Syn.Acioa barteri),Gmelina arborea (Roxb.) andSenna siamea (Lam.) Irwin & Barneby (Syn.Cassia siamea) in alley cropping systems. Plantain inPennisetum mulch treatment gave the highest bunch yield, but similar net revenues per hectare as theDactyladenia treatment, whileGmelina, Alchornea andSenna treatments produced the lowest incomes. But when the land required to producePennisetum mulch was included in the economic analysis, the net revenue per hectare was negative over three years of cropping. The returns to labour were also much lower for thePennisetum compared to the alley cropping systems. Among the in-situ mulch sources,Gmelina had the highest labour requirement because of the high pruning frequency. In addition, weeding inGmelina, Alchornea andSenna treatments resulted in high labour demand due to the rapid decomposition of the mulch materials leaving the soil bare for weeds to invade.Dactyladenia alley cropping was the most profitable of the five plantain production systems studied.IITA Journal Paper No: 94/004/JA.     

壳聚糖纯化车前草水提液的研究

为了优化壳聚糖对车前草水提液的纯化工艺,以多糖损失率、蛋白质去除率和脱色率为指标,通过单因素试验和正交试验,分别考察了壳聚糖用量、溶液pH值、絮凝温度、絮凝时间对纯化效果的影响。结果表明,壳聚糖纯化车前草水提液的优化工艺为:壳聚糖用量1.0mL/g、溶液pH值9.0、絮凝温度45℃、絮凝时间2.0h。此工艺条件下多糖损失率为20.03%、蛋白质去除率为80.26%、脱色率为52.67%。     

车前子提取物及不同溶剂萃取物对小菜蛾的杀虫活性

以乙醇超声法提取车前子中的活性物质,采用浸虫法测试提取物对小菜蛾的触杀活性;采用石油醚、氯仿、乙酸乙酯、正丁醇对提取物依次萃取,且跟踪测试各萃取物的活性.结果显示,车前子乙醇提取物对小菜蛾3龄幼虫具有一定的触杀活性,LC50为10.300mg/mL;不同溶剂萃取物活性均远低于提取物的活性,初步判断车前子中各物质对小菜蛾的杀虫活性具有一定的增效或协同作用.     

蒲公英和车前草在山东境内的春季物候特征及对气候变化的响应

基于2000-2015年山东省对蒲公英和车前草物候及气象观测资料,利用正交经验函数、相关分析、偏最小二乘回归研究了蒲公英及车前草在山东境内的春季物候变化特征及其对气候变化的响应规律。结果表明：1）2000-2015年蒲公英与车前草春季萌动与展叶总体表现为推迟的趋势且半岛沿海站点表现更明显,开花始期的年际变化具有局地性。2）冬季平均气温、2月平均气温升高会极显著促进两种植物的萌动、展叶。1月累积降水量与两种植物的萌动、展叶、开花始期总体显著负相关。鲁东地区两种草本植物的萌动、展叶与冬季日照时长显著负相关。在开花始期,除了冬季热量累积之外,从鲁东到鲁西3月平均气温及活动积温的影响逐渐加强,车前草表现更为明显。3）蒲公英与车前草偏最小二乘物候回归模型拟合结果表明,在萌动、展叶始期,2月平均气温、冬季平均气温、冬季0 cm平均地表温度、冬季正积温VIP值均大于1。在开花始期, 3月平均气温、3月活动积温、冬季平均气温、冬季0 cm平均地表温度在所有地区VIP值均大于1。     

Genetic relationships among cultivated bananas and plantains from Asia and the Pacific

Summary Isozyme variation was studied to determine genetic relationships among 563 accessions of Musa, including diploid (AA and BB), triploid (AAA, AAB, and ABB), and a few tetraploid (ABBB) clones from Asia and the Pacific. Several open-pollinated seedling progenies of wild, diploid M. acuminata and M. balbisiana were also studied. Cryogenic preservation of leaf tissue in liquid nitrogen allowed sampling of a wide array of germplasm from Papua New Guinea and several Pacific Islands without transporting propagules which are subjected to quarantine regulations. Electrophoretic variation was recorded in three enzyme systems, MDH, PGI and PGM. In total, 52 distinct electromorphs were identified among 192 different isozyme phenotypes (zymotypes). Multivariate analyses of the data clearly differentiated the major genome groups and revealed patterns of association within groups. The isozyme data suggest that the genes contributed by the M. acuminata genome to the triploid Pacific plantain AAB subgroup are similar to those of the acuminata/banksii complex of Papua New Guinea. It is likely that the Pacific plantain subgroup, including the Hawaiian Maoli, Pp'ulu and Iholena cultivars, originated in Papua New Guinea/Melanesia, rather than in Asia or the Malay Archipelago.Journal Series no. 3783 of the Hawaii Institute of Tropical Agriculture and Human Resources.     

GROWTH AND YIELD RESPONSES OF PLANTAIN GENOTYPES AS INFLUENCED BY ORGANIC AND INORGANIC FERTILIZERS

A field experiment was conducted for two cropping cycles to evaluate the growth and yield responses of four plantain genotypes (29525, 30456-3, PITA 14 and Agbagba) to fertilizer source (inorganic, organic fertilizer and no fertilizer) in a 4 × 3 factorial in a complete randomized block design. Genotype 29525 flowered and matured earliest, produced heaviest bunches and highest number of hands and fruits per bunch. Agbagba produced the tallest plants, longest, widest and heaviest fruits. Bunch weight was heavier with the application of inorganic or organic fertilizers. There were genotype and fertilizer interactions for bunch and fruit weights and length in the plant crop with genotype 29525 having the heaviest bunches whereas the heaviest and longest fruits were produced by Agbagba when no fertilizer was applied. Bunch yield per hectare increased with organic fertilizer application.     

Influence of different plantain cropping systems on physical properties of soil and plantain bunch yield

Information on the effects of soil physical properties on plantain yield is rare. A factorial trial was conducted in three southern Cameroonian villages comparing four cropping systems comprising: two planted legumes, (1) Flemingia macrophylla and (2) Pueraria phaseoloides; a crop, (3) hot pepper; and (4) natural regrowth, all planted to plantain established in old forest versus young bush fallow. Initially, bush fallow had significantly higher sand content, mean weight diameter (MWD) and proportion of macroaggregates, but lower clay content and lower proportions of mesoaggregates and microaggregates than forest soil. Between 2002 and 2006, clay and silt content, MWD, geometric mean diameter and the proportion of macroaggregates increased, whereas sand content, bulk density, and the proportions of mesoaggregates and microaggregates decreased in all villages, fallows and cropping systems. Changes in aggregate stability parameters were greater in forest than in bush fallow at Ngoumou and Mfou, and greater in the F. macrophylla and natural regrowth systems than in the pepper and Pueraria systems. In Ngoumou and Nkometou, available water capacity increased. Plantain fresh-bunch yield was unaffected by village, fallow and cropping systems, and was not correlated with soil physical properties or their changes.     

Herbicide application and direct drilling improves establishment and yield of chicory and plantain

The herbs chicory ( C ichorium intybus L.) and plantain ( P lantago lanceolata L.) are increasingly popular summer forage cropping options for dairy producers. However, the impact of different establishment methods on their productivity is largely unknown. Four establishment methods for chicory and plantain crops sown into non‐cultivated ryegrass pastures in spring were compared. Establishment methods included direct‐drilling or broadcasting seed into existing pastures, with or without herbicide application before sowing in a 2 × 2 factorial design. It was hypothesized that plant establishment and growth would be enhanced by spraying to kill existing ryegrass pasture and direct‐drilling herbs (Spray and Drill, SD) compared with broadcasting seed with no herbicide application (Unsprayed and Broadcast, UB). This hypothesis was supported with an additional 2·1–2·3 t DM ha^?1 grown over 201 d from swards established by SD, compared with swards established by UB. The SD method also increased the plant density of the herbs and reduced the proportion of weed species. Spraying and direct drilling is more expensive than broadcasting seed with no herbicide application, but the increase in yield means that extra feed can be supplied at less than half the cost of purchasing the equivalent amount of feed. Therefore, for optimal economic outcomes, chicory and plantain swards should be established by applying herbicide to existing pasture and direct‐drilling seed.