The toxicity of aphicide residues to beneficial invertebrates in cereal crops

The toxicity of dimethoate, deltamethrin and pirimicarb residues to Bembidion lampros and Coccinella septempunctata was evaluated by confining groups of insects to winter wheat foliage and soil for 24 h at different times after treatment in the field. Flag leaf residues were found to be more toxic than first leaf residues: soil residues were the least toxic with pirimicarb showing virtually no soil toxicity. In general, dimethoate and deltamethrin showed similar levels of foliar toxicity with flag leaf toxicity on the first day after treatment being in the range 60–80% for B. lampros; deltamethrin was however, less toxic than dimethoate at ground level. Both of these products were more toxic than pirimicarb. The long-term exposure of insects, surviving the 24 h bioassays, to treated soil at different times following application resulted in further mortality and provided estimates of the maximum levels of mortality that populations of predators might suffer migrating into the crop at different times following application. Dimethoate was shown to be particularly harmful at the current recommended field application rate and reduced doses were proposed to limit the severity of the initial effects.     

Evaluation of four co-occurring ladybirds for use as biocontrol agents of the pea aphid,Acyrthosiphon pisum (Homoptera: Aphididae)

The potential of four co-occurring ladybirds, Coccinella septempunctata (L.), Coccinella transversalis (F.), Cheilomenes sexmaculata (F.), and Propylea dissecta (Mulsant), as predators of the pea aphid, Acyrthosiphon pisum (Harris) was investigated. Larger ladybirds were more voracious while smaller ones had higher consumption indices and were more efficient converters of food.     

Ovarian dynamics and oosorption in two species of predatory lady beetles (Coleoptera: Coccinellidae)

Abstract Ovarian development and oviposition dynamics of two species of lady beetle, Coccinella septempunctata L. and C. transversoguttata richardsoni Brown, are examined in laboratory experiments in which pea aphids (Acyrthosiphon pisum Harris) are provided ad libitum and then removed. Both species respond to prey removal by stabilizing at lower body weights, and by laying progressively fewer and smaller eggs of reduced viability, until oviposition ceases altogether after several days of starvation. Dissections of females after prey removal reveal similar patterns of oosorption in both species. However, C. septempunctata reduces oviposition more rapidly after prey removal than does C. transversoguttata. When prey are again provided, C. septempunctata soon lay as many eggs as previously but C. transversoguttata lay fewer. Females, especially of C. septempunctata, that stop producing and resorb eggs in the absence of prey lay more eggs subsequently than do females that feed continually on prey provided ad libitum and lay eggs throughout the experiment. Thus, although both species are responsive to a rapid change in prey availability, C. septempunctata appears to be especially responsive. Rapid responses to changes in prey availability may contribute to the greater abundance and reproductive success of this introduced species relative to the native C. transversoguttata in western North American alfalfa fields that exhibit widely varying pea aphid densities. However, both species engage in oosorption as a means of reserving resources under poor prey conditions and enhancing future reproductive effort when prey conditions improve.     

Survival, development and life tables of two congeneric ladybirds in aphidophagous guilds

Two congeneric aphidophagous ladybirds, Coccinella septempunctata and Coccinella transversalis, were reared on three aphid species, Lipaphis erysimi, Myzus persicae and Aphis nerii, to estimate the effect of prey quality and intra- and interspecific interactions on their survival and development of life stages. Mortality of first instar ladybirds of both species was highest feeding on A. nerii. Preimaginal mortafity was lowest when feeding on L. erysimi （C. septempunctata, 1.6% and C. transversalis, 3.2%）, and highest when feeding on A. nerii （ C. septempunctata, 6.2% and C. transversalis, 8.2%）. Comparatively higher weight and larger size of C. septempunctata along with the lower levels of mortality recorded suggested that it is more likely to have acted as an intraguild predator than C. transversalis. High recorded mortality of C. transversalis is attributed to probable intraguild predation on account of its smaller size. The major sources of mortality were probably cannibalism, intraguild predation and other unknown factors. Lower prey quality increased the incidence of cannibalism and intraguild predation, especially in C. transversalis. The investigation suggests an intrinsic competitive advantage for C. septempunctata over C. transversalis in guilds of three aphid species.     

Field evaluation of aqueous extract of Melia azedarach Linn. seeds against cabbage aphid,Brevicoryne brassicae Linn. (Homoptera: Aphididae), and its predator Coccinella septempunctata Linn. (Coleoptera: Coccinellidae)

Aqueous extract of Melia azedarach seeds were tested against cabbage aphid, Brevicoryne brassicae, and its predator Coccinella septempunctata in a cabbage field. The field experiment was conducted at Bridge to Israel children village farm, around the vicinity of Tewodros campus, University of Gondar, where the cabbage was grown fully organically. A field experiment was started in the middle of April 2011 and completed at the end of May 2011. The experiment was conducted in a randomised block design (RBD). For the field trial, a total of 12 plots were prepared with 1 m² area for data collection. The powdered M. azedarach seeds were used to prepare 5% concentration of aqueous solution and sprayed. Before spraying, percentage of aphid infestation was recorded from the control plot and the experimental plot. The average percentage of cabbage infestation in the control plot was 72% and in the experimental plot before treatment was 80.85%. The percentage reduction of aphid population was 19.06% after the first spraying. However, maximum percentage reduction of 86.5% was recorded after the completion of six-week treatment. The overall percentage reduction increased proportionately from the first to sixth week. The number of predator population was reduced and the reduction was not statistically significant (p > 0.05). The present study proved that Melia seed extracts were effective against cabbage aphids under field condition. Further, it is evident that the beneficial interaction between botanical extracts and biological control organism in the field showed safety to natural enemies. In conclusion, Melia seed extract can be useful for small-scale farmers to protect their cabbage crop against cabbage aphid, B. brassicae.     

The influence of some honeybee products as a diet substitute on the different stages of Coccinella undecimpunctata L. in Egypt

Several natural diets of honeybee products were tested for rearing Coccinella undecimpunctata L. under laboratory conditions. Two groups of tested adult and larval insect have been fed on the tested diets, the first group were fed on the tested honey bee products diets without adding aphids, while the second group fed on the same honeybee products with aphids added. The oviposition period in the first group was significantly shorter than control. The tested diets supplied with royal jelly + aphid and/or pollen grains + aphid caused the longest oviposition period. Diets of aphid alone and bee honey with aphid recorded the shortest oviposition period. Fecundity of ladybird was the highest in the tested diets with aphids than diets without aphid and/or aphid diet alone. The durations of larval and pupal stages were significantly different when compared with the diets with or without aphid and/or aphid diet alone. Further results indicated that the diets of royal jelly caused the shortest duration in larval and pupal stages.     

Functional response of two aphidophagous ladybirds searching in tandem

The functional response of two ladybird species, Propylea dissecta (Mulsant) and Coccinella transversalis Fabricius in combination was studied in an effort to determine the impact of two predators on the increasing density of aphid, Aphis gossypii Glover infesting leaves of bottle gourd, Lagenaria vulgaris Seringe. The ladybirds were exposed to prey density in three combinations using adult females: (i) one P. dissecta and one C. transversalis together, (ii) two P. dissecta, and (iii) two C. transversalis, for 24 h. Prey consumption increased curvilinearly with prey density in all three combinations. It was maximum when heterospecifics searched together. The prey were handled and consumed significantly faster (9.51 min) by heterospecifics in combination, followed by two C. transversalis (11.32 min) and two P. dissecta (12.52 min). The attack rate was maximum (0.00274) by heterospecifics followed by the two C. transversalis (0.00166) and two P. dissecta (0.00092). The synergistic effect on the prey consumption may possibly be due to spatial distribution of P. dissecta and C. transversalis in terms of feeding sites, with the former being negatively, and the latter being positively geotactic. Field release of two predator species in tandem is recommended for biocontrol of A. gossypii because of the potential for synergistic action by these natural enemies.     

温度和光周期影响两种同域发生瓢虫同种和异种组合时的猎物消耗量和利用率（英文）

【目的】印度次大陆是世界上最脆弱的地理景观。气候条件的略微变动可能对其季节周期可能产生不良影响,并引起农业生态系统中蚜虫的大暴发。七星瓢虫Coccinella septempunctata L.和狭臀瓢虫C.transversalis Fab.是该次大陆上广泛分布、同域发生的两种食蚜性瓢虫。【方法】设计异地试验,来探究同种和/或异种组合时的这两种瓢虫用共同的猎物资源(豌豆蚜)饲养时,对增加的温度(15,20,25,30和35℃)和光周期(8L∶16D,12L∶12D和16L∶8D)的响应。【结果】结果表明,在这5个不同温度和3个不同光周期条件下,同种或异种组合时这两种瓢虫表现出了拮抗作用。尽管表现出拮抗作用,但是同种或异种组合的两捕食动物在25℃和长光周期(16L∶8D)条件下消耗、转化和利用的猎物生物量最大。然而,它们的猎物消耗率、转化效率和生长速率在异种组合中最高。在5个不同温度下,4龄幼虫均更有效地利用猎物生物量,将其转变成自身生物量,而雌成虫在3个不同光周期条件下也是如此。【结论】因此可以推断,增加的温度和光周期条件可能不会阻止同种和异种组合中的瓢虫发生拮抗作用,但是在25℃和长光周期(16L∶8D)条件下,相互作用的瓢虫的猎物消耗量和利用率为最佳。     

十一星瓢虫对枸杞棉蚜的捕食作用研究

十一星瓢虫Coccinella undecimpunctata Linnaeus是青海省柴达木地区的一种重要捕食性天敌。为明确其对枸杞棉蚜Aphis gossypii Glover和枸杞木虱Poratrioza sinica Yang et Li.两种主要枸杞害虫的嗜好性,开展了捕食选择性试验,发现当两种害虫共存时,瓢虫成虫更喜食棉蚜。为进一步探究十一星瓢虫对枸杞棉蚜的捕食能力,测定了瓢虫各龄幼虫和成虫在不同棉蚜密度下的捕食量、寻找效应以及种内干扰、自身密度对捕食作用的影响。结果表明：十一星瓢虫各虫态对棉蚜的捕食功能反应均符合Holling-Ⅱ功能反应模型,种内干扰、自身密度对捕食量的影响分别符合Hassell干扰效应模型和Watt模型。十一星瓢虫1~4龄幼虫及成虫对枸杞棉蚜的日最大理论捕食量分别为18.94、44.29、81.57、145.27和126.48头;在一定空间、相同瓢蚜比条件下,瓢虫同一虫态个体间存在种内干扰效应,以1龄幼虫受干扰最大,干扰常数为1.1803。此外,瓢虫自身密度对其捕食作用产生一定影响,以4龄幼虫和成虫尤甚,竞争参数分别为0.7948、0.6848。本研究可为今后更高效地利用青海高原本地十一星瓢虫资源提供理论依据。     

SCANNING ELECTRON MICROSCOPY OF ANTENNAE OF COCCINELLA SEPTEMPUNCTATA (COCCINELLIDAE: COLEOPTERA)

Scanning electron microscopy was done to describe the morphology of antenna of adult male and female ladybeetle, Coccinella septempunctata. Eleven‐segmented, scaly antenna was 950 μm in male and 980 μm in female. Electron micrographs reveal the occurrence of eight types of sensillae, viz. chaetica (Ch), trichoidea (Tr), basiconica (Ba), campaniformia (Ca), ampucellaceous (Am), scolopalia (Sc), placoidea (Pl) and hook shaped sensilla on the antennae of male and female ladybeetles. Ch had long external‐process, with base surrounded by membranous socket and the length was 60 and 70 μm in male and female ladybeetle, respectively. Sensillae Tr were distally curved and inserted into depression, 9.0 and 15 μm long in male and female ladybeetle, respectively. Sensillae Ba were cuticular peg‐like and 0.57 and 0.70 μm long on the male and female antennae. Sensillae Ca were small dome‐like and had diameter of 3.0μm in both the sexes. Sensillae Am were pit‐like in appearance and the diameter of the pit was 1.2 and 1.5 in male and female ladybeetle, respectively. Sensillae Pl were elliptical sunken plates like in both the sexes. Sensillae Sc were broad at their apex and pointed at their tip, 2.5 μm. A single hook‐shaped sensilla of 21.0 μm in length was present on male antenna only. Ch, Ca, Am, and Pl were almost similar in numbers in both the sexes. Sensillae Tr were more numerous on the male antenna and Ba were more numerous on the female antenna.