Biological activity of Cassia occidentalis L. against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

In developing countries, traditional control methods are commonly used against stored-product insects and mites. In Senegal, the leaves of Cassia occidentalis L. (Caesalpiniaceae) are used to protect cowpea seeds (Vigna unguiculata L. (Walpers)) against Callosobruchus maculatus (Coleoptera: Bruchidae). The biological activity of the leaves, the seeds and oil of C. occidentalis was evaluated in controlled conditions (28 ± 2°C, 45 ± 5% r.h.) against C. maculatus. At the rate of 10% (w/w), both fresh and dry leaves as well as whole and ground seeds had no contact toxicity on the cowpea beetle. In contrast, seed oil induced an increase in mortality of C. maculatus eggs and first larval instar at the concentration of 10 ml/kg cowpea. The basis of the ovicidal and larvicidal activities are discussed in this paper. Several trials using pure compounds have highlighted that several fatty acids (linoleic, oleic and stearic) are responsible for C. occidentalis toxicity. C. occidentalis seed oil did not reduce the oviposition of C. maculatus at 10 ml/kg seed.     

Simulation studies on the effects of solar heat on egg-laying, development and survival of Callosobruchus maculatus (F.) and Callosobruchus subinnotatus (Pic) in stored bambara groundnut Vigna subterranea (L.) Verdcourt

The effects of simulated solar heat on oviposition, development and survival of Callosobruchus maculatus (F.) and Callosobruchus subinnotatus (Pic) in stored bambara groundnut, Vigna subterranea (L.) Verdcourt, were evaluated at three high temperatures (40°C, 45°C and 50°C) at a constant, low humidity (30% relative humidity). Exposure to these temperatures for 6 h significantly reduced oviposition in C. maculatus and C. subinnotatus females. Females of both species that were exposed to 50°C laid significantly fewer eggs than those exposed to 40°C; and in the case of C. maculatus, females exposed to 45°C also laid significantly fewer eggs than those exposed to 40°C. The percentage of eggs laid by females of both species that reached adulthood after exposure to 50°C for 2–6 h was significantly lower than the percentage that developed from eggs laid by females that were exposed to 40°C. No adult developed from eggs of C. maculatus exposed for 6 h at 50°C or from eggs of C. subinnotatus exposed for 2 h at this temperature. For both species, no adult progeny subsequently emerged from seeds harbouring first instar larvae when exposed at 50°C for 2, 4 or 6 h. Older larvae of C. maculatus were more tolerant of exposure at 50°C: 26.8, 10.2 and 0.9% of late instar larvae exposed for 2, 4 and 6 h, respectively, developed to the adult stage. In contrast, no adults of C. subinnotatus emerged from seeds harbouring late instar larvae when exposed at 45°C for 6 h nor in seeds exposed to the temperature of 50°C for 4 or 6 h. On average, immature stages of C. subinnotatus were more susceptible to heat treatment than those of C. maculatus.     

Effect of constant temperature and humidity on oviposition and development of Callosobruchus maculatus (F.) and Callosobruchus subinnotatus (Pic) on bambara groundnut, Vigna subterranea (L.) Verdcourt

The effect of different conditions of temperature and humidity on oviposition and development of Callosobruchus maculatus and Callosobruchus subinnotatus was investigated in the present study. Four temperatures (25°C, 30°C, 35°C and 40°C) and three humidities (30%, 60% and 90% r.h.) were evaluated on both species in pure and mixed populations on bambara groundnut (Vigna subterranea) seeds. In both pure and mixed populations, temperature influenced oviposition and progeny development of both species significantly more than humidity. Egg-laying and progeny development in C. maculatus were optimal at 35°C. In contrast, oviposition and progeny development in C. subinnotatus were optimal at 30°C. In mixed populations, where eggs were laid by females of C. maculatus and C. subinnotatus held together, more C. maculatus adults than C. subinnotatus adults were produced at the various temperatures and humidities. No adult progeny of either species developed in pure or mixed populations at 40°C. C. maculatus was more fecund than C. subinnotatus and development from egg to adult took much longer in C. subinnotatus than in C. maculatus in both pure and mixed populations. The implications of these findings for the development and survival of both species in the different agroecologies and seasons in Nigeria are discussed.     

Intraspecific and interspecific competition in Callosobruchus maculatus (F.) and Callosobruchus subinnotatus (Pic) on stored bambara groundnut, Vigna subterranea (L.) Verdcourt

Intraspecific competition was studied in Callosobruchus maculatus and Callosobruchus subinnotatus. Interspecific competition between the two bruchids was also studied to determine which of these species is likely to cause more damage to stored bambara groundnuts, Vigna subterranea in cases of joint infestation. Results showed that increasing the adult density up to 8 females per 10 g of bambara groundnut seeds did not significantly reduce the mean number of eggs laid per female, the number of eggs developing to the adult stage, or the weight of emerged adults of either species. The developmental period of the two species was also not significantly affected. The adult emergence curve of C. maculatus was similar to that of C. subinnotatus and was of the scramble type. C. maculatus performed better than C. subinnotatus in interspecific competition and it achieved this through a higher egg-laying ability and a higher rate of progeny production coupled with a shorter life-cycle. The implications of these findings with respect to damage and possible loss of stored bambara groundnut are discussed.     

紫皮豇豆花色苷提取工艺的初步研究

研究紫皮豇豆花色苷高效提取的工艺参数。为提高花色苷的提取率,试验中采用不同工艺参数与生物酶萃取技术相结合的办法,提取紫皮豇豆花色苷,并就其效果进行比较分析。通过单因素试验与正交试验,结果发现紫皮豇豆中花色苷酶法提取以p H值3.0、温度45℃、时间90 min为最佳工艺参数。以上成果可为紫皮豇豆花色苷的提取与相关研究提供科学参考。     

水菖蒲活性成分β-细辛醚对四纹豆象不同虫态的熏蒸毒杀作用

为了确定水菖蒲活性成分β-细辛醚对四纹豆象的熏蒸毒杀作用,研究了β-细辛醚对四纹豆象卵、幼虫、蛹和成虫4种不同虫态的熏蒸作用.结果表明:β-细辛醚对四纹豆象4种虫态均有一定的熏蒸作用.β-细辛醚熏蒸四纹豆象卵120 h后,LC_(50)为0.95 μL/L.对四纹豆象幼虫以200 μL/L的体积比处理后,幼虫的校正死亡率为51.69%.对四纹豆象蛹的熏蒸作用不明显.对四纹豆象成虫熏蒸24 h后,KC_(50)为1.07 μL/L,熏蒸120 h后,LC_(50)为0.73 μL/L.     

Nutrient composition of extruded cowpea products

Three cultivars of cowpeas (Ife brown, Vita 5 and California black eye) were blended with either rice, corn or both rice and corn and banana puree. The blends were dry extruded on a low cost extruder. The average energy content was 440 Kcal/100 g, protein 20% and the trypsin inhibitor activity was reduced by 63–84%. The stachyose contents varied from 0.52 to 2.44%, raffinose 0.16 to 4.32% and sucrose 0.18 to 1.16 g% respectively. The colour of the products was acceptable and there was no evidence of browning in the products.     

A Chitinase and a β-1,3-Glucanase Isolated from the Seeds of Cowpea (Vigna unguiculataL Walp) Inhibit the Growth of Fungi and Insect Pests of the Seed

A chitinase (22000 Da) and a β-1,3-glucanase (26000 Da) were isolated from cowpea ( Vigna unguiculata ) seeds and shown to deter development, in an in vitro assay, of the phytopathogenic fungi Colletotrichum lindemuthianum (agent of anthracnose, a disease of many plants) and Colletotrichum musae (agent of banana peel anthracnose). The isolated chitinase was also shown to negatively affect the development of the cowpea weevil ( Callosobruchus maculatus ) in an artificial seed system. These results suggest that the cowpea seed contains defence proteins that could be, if their levels are properly managed, utilised to promote increased protection of the plant towards attacking fungi and insects.     

水分添加量对豇豆发酵过程中品质变化的影响

以干豇豆为原料,采用自然发酵法,研究水分添加量对豇豆发酵过程中品质变化的影响。结果表明:在发酵过程中,产品品质整体表现为,pH值呈下降趋势;除12%添加量外,水分越高,总酸含量越高;每组都有亚硝峰产生,水分添加量为16%,20%时,产品亚硝酸盐峰迟于其余3组,并且峰值更低;挥发酯含量先上升随后趋于平缓;水分添加量为14%,16%,18%时,挥发酸含量相对较高;第32天时,16%水分添加量产品的氨基酸含量大于其它组;发酵豇豆硬度、胶黏性、咀嚼性随水分含量的升高均呈先下降后上升的趋势。说明水分含量过高、过低,均不利产品的品质,当水分添加量为14%~16%时得所产品的品质最好。     

2021—2023年上海市市售豇豆中倍硫磷的膳食暴露风险评估

目的 评估2021—2023年上海市居民通过豇豆摄入倍硫磷的膳食暴露风险。方法 采用慢性风险商评估方法, 用实测的豇豆中倍硫磷暴露浓度的数值来对风险进行表征, 根据风险商数值的大小对慢性风险进行评估。结果 2021—2023上海市市售2301件豇豆样品中倍硫磷总体检出率为3.00%, 不合格率为2.3%, 倍硫磷含量均值为1.23×10–2 mg/kg, 最大值为4.45 mg/kg。按不同月份分析, 每年2月豇豆中倍硫磷不合格率和平均检出值最高分别为18.9%和0.12 mg/kg。按不同采样点分析, 网络销售的豇豆中倍硫磷的检出率和不合格率最高。上海市居民每日膳食平均暴露量为5.88×10–6 mg/(kg·bw), P95暴露量为3.05×10–5 mg/(kg·bw), 平均风险商为8.40×10–7, P95为4.36×10–6。结论 2021—2023年上海市不同人群的风险商均远小于1, 因此上海市居民通过豇豆摄入倍硫磷对人体的健康风险较低。     

Toxicity of dietary avidin and streptavidin to the cowpea bruchid, Callosobruchus maculatus (F.)

Avidin, a large protein from egg whites, powerfully binds biotin, a vitamin for many insects. When avidin was incorporated into the diets of larval Callosobruchus maculatus (F.), the cowpea bruchid, at relatively low levels (10–30 ppm), there was a marked dose-dependent increase in mortality, as well as a small increase in the developmental time of survivors. Avidin toxicity was prevented when biotin was added to the diet together with avidin. Sub-lethal doses of avidin caused reductions in fecundity. Avidin had no effect on the larval feeding rates during the first three instars, even when the larvae were consuming amounts of the protein that would later cause death. In the fourth instar there was a dose-dependent reduction in the rates of feeding as the avidin level in the food increased. Death of the C. maculatus larvae usually occurred at the pupal/adult stage still within the host seed. Streptavidin, a biotin-binding protein from a bacterial source, had effects similar to chicken egg avidin.     

Legume seed vicilins (7S storage proteins) interfere with the development of the cowpea weevil (Callosobruchus maculatus (F))

Vicilins (7S storage proteins) isolated from the seeds of the legumes Vigna unguiculata (cowpea), Vigna angularis (adzuki bean), Canavalia ensiformis (jack bean), Glycine max (soybean), Phaseolus vulgaris (common bean) and Phaseolus lunatus (lima bean) were shown to be immunologically related and to bind to a chitin matrix. The effect of the isolated vicilins on the development of the cowpea weevil Callosobruchus maculatus was examined. Vicilins from all non-host seeds, including those of the C maculatus-resistant cowpea line IT81D-1045, strongly inhibited larval development (ED₅₀ of 1·07±0·32% to 2·22±0·64%). Vicilins from the C maculatus-susceptible cowpea CE-31 and adzuki bean seeds were the exception with ED₅₀ of 6·25±0·75% and 5·40±1·54%, respectively. These results correlate well with the host range of C maculatus and are possibly a reflection of the low digestibility of vicilins by insect midgut proteinases in addition to the ability they show in binding to chitin-containing structures like the ones found in the bruchid midguts. © 1998 SCI.     

Resistance to Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) in pigeonpea (Cajanus cajan (L.) Millsp.) and other Cajanus species

Seeds of 24 accessions of pigeonpea (Cajanus cajan (L.) Millsp.) and four other species of Cajanus (formerly Atylosia) were evaluated for their resistance to infestation by Callosobruchus maculatus (F.). None of the pigeonpea accessions was resistant but resistance was evident in three species of Cajanus. In C. platycarpus most of the larvae failed to enter the hard seed coats but the few which did enter the seeds, developed normally. Adults did not emerge from the seeds of C. scarabaeoides, even though most of the larvae entered the seeds. In A. sericeus, the number of larvae entering the seeds as well as adult emergence was significantly reduced.     

Technique to isolate Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) eggs

A simple technique to isolate the eggs of Callosobruchus chinensis from the surface on which they are laid is described. An aqueous extract of their natural food, green gram, Vigna radiata, is used to coat glass beads that attract adult females for oviposition. The thin layer of extract on the glass beads allows separation of the eggs from the bead surface after a 15–20 s immersion in water. When transplanted onto fresh grain treated with glue, the separated eggs exhibit normal development and up to 97% hatching.