Response of Callosobruchus maculatus (F.) to varying temperature and relative humidity under laboratory conditions

The effect of temperature and relative humidity were determined on the development of Callosobruchus maculatus (F.) on stored bean (Vigna unguiculata) seeds exposed to five temperatures (20, 25, 30, 35 and 40 °C) and six relative humidity levels (40, 50, 60, 70, 80 and 90%). Oviposition and total adult progeny responded in a curvilinear pattern to temperature and relative humidity while developmental period presented a linear response. Egg laying (117.33 ± 3.21) and adult emergence (35.00 ± 1.70) were least at 20 °C and 90% R.H. but those showed the optimal values at 30 °C and 70% R.H. The implication of these findings is that the growth attributes of C. maculatus relate with the weather variables studied in a curvilinear manner and thus quadratic equations generated could be used for the prediction of optimum temperature and relative humidity in a given area for the management of C. maculatus in stored beans.     

Insecticidal activity of Poppy (Papaver somniferum L.) seed oil against cowpea weevil (Callosobruchus maculatus F.) in stored cowpea

In this study, the insecticidal effect of Poppy (Papaver somniferum) seed oil was investigated against Callosobruchus maculatus (Bruchidae) in cowpea, at different concentrations and exposure time. The Poppy seed oil at 2, 4, 6, 8 and 10?ml/kg was tested against adults of C. maculatus, and the mortality was counted after 24, 48 and 72?h of exposure. All tests were conducted at 27–30?°C and 65?±?5% r.h. The experiments were carried out based on the factorial experiment by randomized complete design with four replications. Twenty-five insects with 0–24?h old were used for each replication. The effect of Poppy seed oil on the reduction of emergence of insects in next generation (F₁) was also assayed. The results of experiments indicate the significant differences between concentrations and exposure time (p?<?0.0001), and the increase of concentrations and exposure time increased mortality. The amount of mortality at high concentrations was remarkable, and highest mortality rate (96.91%) was recorded at 10?ml/kg, after 72?h of exposure. The application of oil significantly reduced F₁ progeny production and even at lowest concentration (2?ml/kg), the amount of F₁ production was reduced more than 70%, compared with control treatment. Complete (100%) reduction in progeny production was recorded at the rates of 8 and 10?ml/kg. The results of seed germination assay showed no significant differences between control and treated seed, and no harmful effect was observed on the seed germination. These results proved that Poppy seed oil can be used as a controlling agent of storage pests, especially C. maculatus, although more detailed studies are necessary.     

Comparative seed resistance in eighty cowpea accessions to the seed bruchid,Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)

Eighty cowpea accessions comprising both improved and local were assessed for their resistance to Callosobruchus maculatus (F.) attack under laboratory conditions (29 ± 3?°C and 65 ± 5% R.H.). Sixty-nine accessions were derived from the International Institute for Tropical Agriculture breeding programmes, four were local cultivars, while seven were improved cultivars from national research institutes. Results showed that there were significant differences among the accessions in terms of number of initial bruchid eggs laid on them, adult emergence, number of seeds damaged and bruchid-induced seed weight loss at three months after artificial infestation with C. maculatus. On IT04K-334-2, IT04K-343-1, IT06K-141, IT99K-216-48-1, IT99K-494-6 and IT99K-529-2, fewer initial eggs were laid and no adult emergence, seed damage or weight loss and were considered highly resistant to C. maculatus. On the other hand, IT03K-337, IT04K-217-51, IT04K-332-1, IT04K-339-1, IT06K-188-49, IT81D-1137, IT845-2231-15, IT93K-452-1, IT04K-154-1, IT96K-610, IT97K-1069-6, IT97K-390-2, Ife Bpc, IT99K-573-2-1, Ife Modupe, IT845-2246, Drum, Ife Brown and Oloyin were the most susceptible with the highest damage indices values (p?<?0.05). The range of each of the resistance indices measured in the susceptible varieties was: number of initial eggs laid (61–100), adult emergence (40.0–62.10%), number of seeds damaged (53.0–85.5) and seed weight loss (58.0–66.25%).     

在玻璃表面上短时接触硅藻土和多杀菌素对四纹豆象的致死效应和亚致死效应（英文）

四纹豆象Callosobruchus maculatus (F.)是伊朗豇豆种子上的主要贮藏害虫。控制这一害虫时, 用生物杀虫剂比用常规杀虫剂更为合适。本研究评价了室内条件下在玻璃表面上硅藻土和多杀菌素对四纹豆象成虫的致死效应和亚致死效应。结果表明： 硅藻土处理24 h和48 h后, 对四纹豆象成虫的LC50 值分别为 1.47和0.2 g/m²; 多杀菌素处理24 h和48 h后, 对四纹豆象成虫的LC50 值分别为102.9 和68.8 mg ai/L, 说明两种化合物都对四纹豆象成虫具有较高的急性毒性。通过检测生物学参数, 研究了LC₂₀浓度的硅藻土和多杀菌素对四纹豆象的亚致死效应。LC₂₀浓度的硅藻土和多杀菌素使四纹豆象成虫的繁殖力分别比对照降低了71.5%和17.2%, 卵孵化率降低了57.5%和27.8%, 成虫寿命缩短了74.7%和17.1%。接触LC₂₀浓度的硅藻土和多杀菌素使这一害虫的蛹期分别比对照延长了4.8%和2.3%。亚致死效应研究表明, 硅藻土和多杀菌素对四纹豆象的生命参数均产生了负面影响。总之, 致死效应和亚致死效应综合显示, 硅藻土在防治四纹豆象上具有较大的潜力。     

Effects of search experience in a resource-heterogeneous environment on the oviposition decisions of the seed beetle, Callosobruchus maculatus (F.)

Abstract.  1. This study investigates how female seed beetles, Callosobruchus maculatus , distribute their eggs on various-sized seeds when the size of seed was varied during the egg-laying period.
2. Beetles were allowed to lay eggs on one of three arrays of 64 adzuki beans ( Vigna angularis ). Each array contained four size classes of seed, ranging from small (5.0–5.5 mm diameter) to large (6.5–7.0 mm), but differed in how they were distributed within the environment. In the most heterogeneous condition (the 64-patch design), the four sizes were interspersed, while in the least heterogeneous condition (the four-patch design) they were grouped into four separate blocks. Thus, a beetle exploring the 64-patch design would frequently encounter all four seed sizes, whereas a beetle exploring the four-patch design would only rarely encounter a change in bean size.
3. Beetles experiencing greater seed size heterogeneity were more likely to lay eggs on larger seeds, whereas those in the blocked condition were more likely to oviposit on small seeds. Beetle responses to seed size heterogeneity suggest that the degree of preference for large seeds depends on a female's recent experience.
4. Female beetles exhibited size discrimination throughout their egg-laying process; however, there was a trade-off between seed size and egg discrimination (i.e. avoiding those seeds already containing developing eggs) in response to the change in fitness gained from either laying on larger seeds or lower egg-load seeds during the egg-laying process.
5. Our model provides the first evidence that evolving seed size discrimination ability is adaptive for the seed beetle with egg-discrimination ability.     

Pheromone release by the two forms of Callosobruchus maculatus females: effects of age, temperature and host plant

Abstract. The influence of age, temperature and host plant on pheromone release was investigated in females of two forms of Callosobruchus maculatus (Coleoptera: Bruchidae), referred to as the flightless form and the flight form. The emission of pheromone seemed to be correlated with reproductive status: the flightless-form females which were sexually mature at emergence began to release pheromone on the first day following emergence. The flight-form females which exhibited no reproductive activity at emergence also showed a delayed emission of pheromone. The temperature conditions and the availability of host plant seeds had no apparent effect on pheromone release by the flightless form. In flight-form females pheromone release was stimulated by the presence of host plant seeds. Temperature seemed to affect the age at which females initiated pheromone release for the first time after emergence, pheromonal emission being brought forward slightly by higher temperature. All these results are discussed relative to the specific environment of each form.     

温度对四纹豆象生长发育与繁殖的影响

四纹豆象CallosobruchusmaculatusFabricius是一种世界性分布害虫,危害多种豆类因而具有重要的经济学意义。为准确掌握四纹豆象的生物学特性,并为其综合防治提供一定的理论依据,以绿豆为食料,在20,25,28,32,35和37℃等6个温度和相对湿度75%的条件下,通过逐日观察法对四纹豆象各虫态的发育历期、存活率、成虫寿命及产卵量等生物学特性进行研究。结果表明:四纹豆象卵期、豆内幼虫及蛹期、未成熟期发育点温度分别为12.67,13.86和13.53℃;温度与世代存活率及周限增长率均呈二次抛物线关系,根据相应抛物线方程可知,四纹豆象理论最适生存温度和最适种群增长温度分别为30.2℃和33.7℃,其生长发育繁殖的最适温区为30~34℃。     

四纹豆象发育起点温度及有效积温

在 2 1～ 36℃范围内设置 6个温度对四纹豆象卵、幼虫、蛹的发育速率进行了测定 ,结果表明 :卵在 2 1～ 36℃、幼虫在 2 1～ 30℃和蛹在 2 1～ 33℃之间的发育速率与温度均呈直线关系 ;用直线回归法所得卵、幼虫、蛹的发育起点温度分别为 15.82 ,15.18,16 .0℃ ,有效积温分别为 6 2 .54,151.0 6 ,10 2 .76日度     

Protectability of nine Nigerian medicinal plants against cowpea beetle,Callosobruchus maculatus (Fab.) (Coleoptera: Bruchiidae) in storage

A study was conducted to examine the protectability of nine Nigerian medicinal plants against Callosobruchus maculatus at an ambient temperature of 28?±?2?°C and relative humidity of 70?±?5%. The nine plants used were dried and milled into fine powder before application. Among the nine plant powders used, Zanthoxylum zanthoxyloides effected highest mortality rate of 73.40 and 100% at 5% (wt/wt) concentration within two and three days of application, respectively. The effect of this plant at this level of concentration was significantly (p?<?0.05) different from other plants. However, all the plant powders effected high mortality rate as they all achieved more than 50% beetle mortality within four days of application at 20% (wt/wt) concentration. Only the powder of Z. zanthoxyloides at 10% (wt/wt) concentration was able to achieve 0% adult emergence, 0% seed damage and 100% damage reduction. Moreover, powder of Z. zanthoxyloides, Aristolochia ringens and Colocasia esculenta at 20% (wt/wt) was also able to prevent the emergence of adult C. maculatus, prevent seed damage and achieve 100% damage reduction. All the powders had low weevil perforation index when compared to the control which had above 50% weevil perforation index. At all levels of concentration, the effect of the powders was significantly (p?<?0.05) different from the control. However, Z. xanthoxyloides appeared to be the most effective; therefore, the effective utilisation of Z. xanthoxyloides as a botanical pesticide could minimise the use of hazardous chemicals in stored product pest control since it is of a botanical source.     

Control of stored grain pest,Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), using the essential oils isolated from Zingiber officinale (L.) and Mentha pulegium (L.) in laboratory condition

Fumigant activity of essential oil vapours distilled from Zingiber officinale (L.) and Mentha pulegium (L.) was tested against eggs, larvae and adults of Callosobruchus maculatus (F.). Fumigant toxicity was assessed at 27?±?1?°C and 60?±?5% RH, in dark condition. The influence of different concentrations of the essential oil vapours on egg hatchability, larval and adult mortality was significant. Data probit analysis showed that lethal concentration of the essential oil to kill 50% of the population (LC₅₀) for egg, larvae and adult was found to be 1.151, 2.336 and 2.183?μl/l air of Z. officinale, followed by 0.072, 0.113 and 0.093?μl/l air essential oil of M. pulegium, respectively. Between these essential oils, Z. officinale is almost more toxic than M. pulegium on all growth stages of C. maculatus. The present study suggests that essential oils from these medicinal plants may be potential grain protectants as botanical alternative fumigants and could be used in the management of various life stages of C. maculatus.     

三种植物粉剂对四纹豆象(鞘翅目:豆象科)行为、死亡率和繁殖的影响

The effects of powders from dry flower buds of Eugenia aromatica Baill., seeds of Piper guineense Schum and Thonn and fruits of Capsicum frutescens L. on adult behaviour, mortality and reproductive fitness of the cowpea seed beetle, Callosobruchus maculatus （Fab.） were investigated under ambient laboratory conditions. All experiments were carried out in glass Petri plates. All powders elicited aversion in adult beetles. The contact toxicity symptoms included restlessness, loss of coordination, knock down and eventual death of adult beetles. These behaviours were more pronounced with E. aromatica in which adult beetles died within 16 hours. P. guineense and C. frutescens powders did not cause 100% mortality of adult beetles, even after 24 hours. Each of the three powders significantly （P 〈 0.05） reduced the mating competition of adult males after sub-lethal exposure for one, two, and three hours, respectively. E. aromatica powder caused more reduction in male mating competition for females than any of the other two powders after each period of exposure. Receptiveness of treated females to courting males was also decreased by exposure to any of the three powders. Similarly, E. aromatica powder caused greater decreases in female receptiveness to males than any of the other two powders after each period of exposure. Exposure of either adult male or female C. maculatus to the powders for sub-lethal times of three, six and nine hours significantly reduced the fecundity of the beetles. E. aromatica powder caused the most reduction of eggs laid and also significantly reduced fertility of the eggs.     

Response of cowpea bruchid,Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae) to cheese wood,Alstonia boonei De Wild stem bark oil extracted with different solvents

Cheese wood, Alstonia boonei De Wild stem bark was extracted with five different solvents namely: methanol, ethanol, acetone, petroleum ether and n-hexane. The extracts were tested for insecticidal activity on cowpea bruchid, Callosobruchus maculatus (Fab.). Adult mortality and adult emergence of the insects were investigated. Oviposition deterrences using dual-choice and multiple-choice tests were also investigated as well as percentage damage and weight loss at temperature of 28?±?2?°C and 75?±?5% relative humidity. Results showed that at the rate of 2% extract per 20?g of cowpea seeds, methanol, petroleum ether and n-hexane extracts caused 100% mortality of adult cowpea bruchid after four?days of post treatment. When the bruchid had choice of oviposition substrate, they laid significantly (p?<?0.05) fewer eggs on cowpea seeds treated with extracts compared to untreated seeds. There was no adult emergence in seeds treated with methanol, ethanol, petroleum ether and n-hexane extracts and 100% reduction in F₁ progeny was recorded compared with untreated that had 81.86% adults emergence and 0% reduction in F₁ progeny. The results obtained from this study revealed that methanol, ethanol, acetone, petroleum ether and n-hexane extracts of A. boonei stem bark were effective in controlling C. maculatus and could serve as an alternative to synthetic insecticides for the protection of stored cowpeas against bruchids.     

Fumigant toxicity of essential oil from Tanacetum balsamita L. (Compositae) against adults and eggs of Callosobruchus maculatus F. (Coleoptera: Bruchidae)

The essential oil of Tanacetum balsamita L. was tested against Callosobruchus maculatus F. at the rates of 5.12, 7.23, 10.19, 14.36 and 20.24?μl/l?air for adults and 5.3, 8.5, 10.8, 13.7 and 17.4?μl/l?air for eggs. All experiments were conducted at 27?±?1?°C and 65?±?5% relative humidity. Mortality was counted after 24, 48 and 72?h of exposure and all adults (dead and alive) were taken out of the vials and the vials were left at the same conditions for further 35?days to assess progeny production. For mortality of eggs, unhatched eggs were counted after 7?days. The adults treated with oil were more susceptible than eggs. At highest dose (20.24?μl/l?air) mortality of adults after 72?h, received 75.2%, but this amount for egg at 17.4?μl/l?air after 72?h was 49.06%. The lowest LC₅₀ value on 72?h was observed in adults (1.96?μl/l?air). Also, the lowest LC₉₅ value on 72?h was observed in adults (42.86?μl/l?air). The percentage of reduced progeny on 72?h was 50.92% at 20.24?μl/l?air. Our results suggest that T. balsamita can be used as an alternative to synthetic insecticides but higher dose may be needed.     

Sperm competition and maternal effects differentially influence testis and sperm size in Callosobruchus maculatus

The evolutionary factors affecting testis size are well documented, with sperm competition being of major importance. However, the factors affecting sperm length are not well understood; there are no clear theoretical predictions and the empirical evidence is inconsistent. Recently, maternal effects have been implicated in sperm length variation, a finding that may offer insights into its evolution. We investigated potential proximate and microevolutionary factors influencing testis and sperm size in the bruchid beetle Callosobruchus maculatus using a combined approach of an artificial evolution experiment over 90 generations and an environmental effects study. We found that while polyandry seems to select for larger testes, it had no detectable effect on sperm length. Furthermore, population density, a proximate indicator of sperm competition risk, was not significantly associated with sperm length or testis size variation. However, there were strong maternal effects influencing sperm length.     

The toxicity of Jack bean (Canavalia ensiformis) cotyledon and seed coat proteins to the cowpea weevil (Callosobruchus maculatus)

The seeds of the Jack bean, Canavalia ensiformis (L) DC are known to contain several toxic substances that prevent their utilisation as food for humans and animals. The lectin concanavalin A and the enzyme urease are the best known of these proteins. We have found that many proteins present in the seeds of the Jack bean, like trypsin inhibitors and canatoxin, are detrimental to the development of the bruchid insect Callosobruchus maculatus (F) (Coleoptera: Bruchidae). Among these proteins, canavalin (vicilin, 7S globulin) was found to be expressed in the seed coat. We suggest that seed coat canavalin, in addition to other detrimental proteins expressed in this tissue, may have been of importance in the evolutionary discrimination of the seeds of this legume by non-pest bruchids.     

The effects of copulation duration in the bruchid beetle Callosobruchus maculatus

Control over copulation duration is a potentially importantgenerator of sexual conflict that has received little empiricalattention. The copulatory behavior of the bruchid beetle Callosobruchusmaculatus may reflect a sexual conflict over copulation duration.Males have spines on their intromittent organs that puncturethe female reproductive tract, and females kick their matesduring copulation. If females are prevented from kicking, copulationslast longer and the injuries females sustain are more severe.Males supposedly use the spines as anchors to prolong copulationduration, and females kick to terminate copulations. We manipulatedcopulation duration experimentally and quantified its effectson male and female fitness components to test whether or notthere is a conflict over copulation duration in C. maculatus.Females did not suffer from long copulations but instead experiencedincreased lifetime fecundity. Ejaculate size increased withcopulation duration, and females apparently derive materialbenefits from the ejaculates. Males that mated first and hadlong copulations were relatively unsuccessful when competingwith sperm from other males. However, there was a trend forfemale remating propensity to decrease with long copulationdurations, and first males may therefore also benefit from longcopulations. The copulation duration of the second male to matedid not have a significant effect on sperm precedence. We concludethat even though it seems likely that the male spines have evolvedto act as an anchor during copulation, there seems to be littleconflict over copulation duration per se in C. maculatus.     

Protection of cowpea,Vigna unguiculata L. (Walp.) with Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus (Fabricius)

Evaluation of protectant ability of Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus in cowpea, Vigna unguiculata L. (Walp.) was carried out in the laboratory at ambient temperature of 28?±?2?°C and 70?±?5% relative humidity. Extracts from wood ash, leaf, stem and root bark were tested at different concentrations of 0, 1, 2, 3, 4 and 5%. One hundred per cent mortality of adult beetles was achieved at all concentrations within 72?h of treatment with extracts except in wood ash at 1% concentration, but they were significantly different (p?<?0.05) from the controls. All the extracts were still able to cause high beetle mortality after one, two and three months of cowpea storage at high concentrations (4 and 5%) except wood ash, although there was a slight decrease in mortality during the period of storage. All the extracts significantly (p?<?0.05) reduced oviposition and adult emergence of C. maculatus when compared with the controls although the reduction was higher at 5% concentration than others. Adult beetle emergence was completely prevented at higher concentrations (4 and 5%) except in wood ash. Both oviposition and adult emergence increased during the months of storage probably because of the slight reduction in the effectiveness of the extracts. The root bark extract was much more effective in reducing oviposition and adult emergence than others throughout the period of storage. The plant extracts of N. laevis was able to protect the cowpea seeds from damage and prevent weight loss. Cowpea seed damage and weight loss was significantly more (p?<?0.05) in the controls than other for the three-month duration probably because of the more adult emergence. The extracts from N. laevis did not adversely affect the germination of the protected seeds and seed germination ranged from 86.7 to 100%. It has been shown in this study that the extracts of N. laevis were effective against C. maculatus in cowpea although the root bark extract seemed to be the most effective while the wood ash extract was least effective. Their effectiveness, however, slightly decreased during the period of storage. N. laevis could be incorporated into pest management of stored cowpeas since the products are ecologically safe.     

Deterrent activity of plant lectins on cowpea weevil Callosobruchus maculatus (F.) oviposition

A set of 14 plant lectins was screened in a binary choice bioassay for inhibitory activity on cowpea weevil Callosobruchus maculatus (F.) oviposition. Coating of chickpea seeds (Cicer arietinum L.) with a 0.05% (w/v) solution of plant lectins caused a significant reduction in egg laying. Control experiments with heat inactivated lectin and BSA indicated that the observed deterrent effects are specific and require carbohydrate-binding activity. However, no clear correlation could be established between deterrent activity and sugar-binding specificity/molecular structure of the lectins. Increasing the insect density reduced the inhibitory effect of the lectins confirming that female insects are capable of adjusting their oviposition rates as a function of host availability.