The effect of a chemical deterrent, released from the frass of caterpillars of the garden pebble moth, on cabbage root fly oviposition

The cabbage root fly, Delia radicum (L.), was deterred from laying eggs on cauliflower plants that had been sprayed with a suspension of the frass of caterpillars of the garden pebble moth, Evergestis forficalis (L.). Polar extracts of the frass deterred oviposition irrespective of the cruciferous plant species on which the caterpillars had been feeding. Non-polar extracts of the frass had no effect. Spraying plants with macerates from Brassica leaves stimulated fly oviposition whereas spraying plants with macerates from garlic mustard leaves deterred fly oviposition. Macerates from the leaves of all other plants tested had no effect. In field experiments the deterrent effect persisted 2–3 days after leaves were sprayed with frass extracts. Plants infested with feeding caterpillars and contaminated with only a few discrete frass pellets were as deterrent to the fly as those sprayed with frass suspensions.

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Résumé D. radicum a évité de pondre sur des pieds de chou-fleur, qui avaient été pulvérisés avec une suspension d'excréments d'E. forficalis. Les extraits polaires de ces excréments empêchent la ponte quelle que soit l'espère de crucifère sur laquelle les chenilles se sont alimentées. Les extraits non polares sont sans effet. Dans la nature, l'action dissuadante persiste 2 à 3 jours après la pulvérisation des feuilles avec les extraits d'excréments. La pulvérisation tous les deux jours a maintenu l'action dissuadante. Des plantes contaminées par des chenilles en train de s'alimenter et souillées par quelques crottes sont aussi dissuadantes pour la mouche que celles pulvérisées avec une suspension d'excréments.

     

Preliminary analysis of geographical distribution based on cold hardiness for Evergestis extimalis (Scopoli) (Lepidoptera: Pyralidae) on Qinghai–Tibet Plateau

Evergestis extimalis  (Scopoli) is a pest insect present in spring rape fields of the Qinghai–Tibet plateau. A survey of its distribution and analysis of its physiological and biochemical variances of its overwintering larvae were conducted in this study. Prior to 2006, Evergestis extimalis Scopli appeared only sporadically at the east agricultural district of Qinghai Province at 2,100 m elevation; after 2006, there have been frequent outbreaks at 2,200 m or so height. The insect's distribution has extended continuously toward higher altitudes yearly, and the scope of its damage reached 2,800 m height in 2010. These changes indicate that the cold hardiness of E. extimalis is on the rise. Physiological and biochemical analyses were performed for the insect's overwintering larvae from November 2011 to March 2012. The supercooling point (SCP) and freezing point (FP) ranged from ?6.85°C to ?12.49°C and from ?6.23°C to ?8.17°C, respectively, and both were at their respective lowest points in January 2012; the lowest points of water and fat contents (which did not vary to any extreme degree throughout the test period) were also observed in January 2012. Glycogen content varied from 2.42 mg/g to 4.56 mg/g. Protein content increased gradually at the first two months and reached its peak in January 2012 before dropping slightly. The activity of protective enzymes POD, CAT, and SOD varied with changes in environmental temperature, and each was at its lowest point in January 2012. With the exception of protein and glycerol content, other physiological and biochemical variances were generally parallel with environmental temperature, strongly indicating that E. extimalis has indeed developed cold hardiness.     

茴香薄翅野螟发生动态的调查

经调查研究表明:在青海省的油菜种植区,茴香薄翅野螟Evergestis extimalis Scopoli越冬幼虫从6月初开始化蛹,6月中旬化蛹率达为80%,到6月下旬化蛹率达到100%;成虫于7月上旬开始羽化,7月15～20日为成虫羽化高峰;田间卵始见期为6月下旬至7月上旬,7月中旬达到产卵高峰期;越冬幼虫平均死亡率为96.63%。     

A cabbage root fly oviposition deterrent in the frass of garden pebble moth caterpillars

The cabbage root fly, Delia radicum (L.), was deterred from laying eggs on cauliflower plants sprayed with a water-soluble extract of the frass of caterpillars of the garden pebble moth, Evergestis forficalis (L.), which had fed on a range of cruciferous species. Chemical analysis of the extract revealed the presence of a phenolic acid which was not present in the frass of larvae of two other Lepidoptera (Mamestra brassicae (L.) and Plutella xylostella (L.)) that had fed on the same range of cruciferous plants. The deterrent chemical was isolated and identified as sinapic (3,5-dimethoxy-4-hydroxycinnamic) acid. Spraying cauliflower plants with a buffered solution of the acid in water (0.1, 1 and 10 mM) reduced the numbers of cabbage root fly eggs laid by 60–70%. In field experiments, the deterrent effect persisted 5 days after leaves were sprayed with a buffered, aqueous solution of the acid (10 mM).

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Résumé D. radicum L. a pondu beaucoup moins sur des choux-fleurs pulvérisés avec un extrait (polaire) hydrosoluble d'excréments de chenilles de E. forficalis L. qui avaient consommé différentes crucifères. La pulvérisation des choux-fleurs avec une suspension aqueuse d'éluate de méthanol d'une colonne polyamide et d'éluate aqueux d'une colonne florosile a réduit respectivement de 50 et 66% le nombre d'oeufs pondus. L'analyse chimique des fractions actives révèle la présence d'un acide phénolique isolé et identifié comme acide sinapique (3,5-diméthoxy-4-hydroxycinnamique). Cet acide est absent des excréments des chenilles de Mamestra brassicae L. et Plutella xylostella L. qui avaient consommé la même gamme de crucifères. La pulvérisation des plants de choux-fleurs par une solution aqueuse tamponnée d'acide sinapique a réduit la ponte de D. radicum de 60 à 70%. Dans la nature, l'effet dissuasif persiste sur choux-fleurs 5 jours après la pulvérisation avec une solution aqueuse tamponnée à 10 mM d'acide sinapique.

     

Differential susceptibility of Cotesia orobenae, a parasitoid of the cross-striped cabbageworm, to commonly used insecticides in Cruciferae

The larval endoparasitoid Cotesia orobenae Forbes (Hymenoptera: Braconidae) is an effective natural enemy of the cross-striped cabbageworm, Evergestis rimosalis (Guenée) (Lepidoptera: Pyralidae), in southwest Virginia. Routine use of insecticides to control Plutella xyostella (L.) and other lepidopterous larvae in commercial plantings of cabbage, cauliflower and broccoli can disrupt populations of C. orobenae, causing localized outbreaks of the cross-striped cabbageworm to occur. Since the use of insecticides is the choice insect pest management tactic of growers in southwest Virginia, we examined the differential susceptibility of this hymenopteran parasitoid to four frequently used pesticides, methomyl (carbamate), permethrin and esfenvalerate (pyrethroids), and Bacillus thuringiensis Berliner subsp. Kurstaki (bacterium). Filter paper dipped into four different concentrations of methomyl, permethrin, and esfenvalerate were left to dry and then exposed to C. orobenae. Two concentrations of B. thuringiensis were also tested by contact bioassay, and an additional test was conducted by mixing B. thuringiensis with honey and water as a food source for the insects. Ten adult parasitoids were exposed to each treatment, replicated 10 times. Significant differences in mortality among insecticides tested (p < 0.05) were found. Most toxic to C. orobenae was permethrin, followed by esfenvalerate and methomyl. The parasitoid was not affected by B. thuringiensis when placed in contact with B. thuringiensis-treated broccoli leaves, or by ingestion of honey mixed with it (p < 0.05).     

茴香薄翅野螟生物学的研究

茴香薄翅野螟是黑龙江省油菜和十字花科蔬菜的一种害虫,幼虫蛀食果荚、籽粒。1年2代,以幼虫在土中结茧越冬。第二年5月中下旬开始化蛹,6月羽化。6月中旬至7月上旬是第一代幼虫危害期,第二代幼虫发生于8月。幼虫有吐丝结网习性,成虫羽化当天即可交配产卵,卵产在嫩角果或柄上。成虫有趋光性,寿命4—16天。     

A behavioural study to help clarify how undersowing with clover affects host-plant selection by pest insects of brassica crops

Laboratory and field-cage tests were done to determine how undersowing brassica plants (Brassica oleraceae L. and B. rapa L.) (Cruciferae) with subterranean clover (Trifolium subterraneum L.) (Papilionaceae) affected host-plant selection by eight pest insect species of brassica crops. The pest species tested were Pieris rapae (Lepidoptera: Pieridae) (the small white butterfly), Pieris brassicae (Lepidoptera: Pieridae) (the large white butterfly), Delia radicum (Diptera: Anthomyiidae) (the cabbage root fly), Phaedon cochleariae (Coleoptera: Chrysomelidae) (the mustard beetle), Plutella xylostella (Lepidoptera: Yponomeutidae) (the diamond-back moth), Evergestis forficalis (Lepidoptera: Pyralidae) (the garden-pebble moth), Mamestra brassicae (Lepidoptera: Noctuidae) (the cabbage moth) and Brevicoryne brassicae (Hemiptera: Aphididae) (the cabbage aphid). In all tests, except two in which the brassica plants were about three times as high as the clover background, 39%–100% fewer of the pest insect stage monitored were found on host plants presented in clover than on those presented in bare soil. Contrary to claims supporting the ‘enemies hypothesis’, differences in colonization alone appeared sufficient to account for the lower numbers of insects found when host plants are undersown with clover. To be effective in reducing plant colonization, the clover must cover 50%, and preferably more, of the vertical profile of the crop plants. As clover used as an undersown crop often has to be cut to make it less competitive with the main brassica crop, temporal aspects of the condition of the clover during critical periods of pest activity need to be recorded carefully before concluding that undersowing does not produce the effect desired against certain pest species under field conditions. The effective clover barrier is like any other treatment, if it is not present at the appropriate time it cannot be expected to reduce pest insect numbers.     

Taxonomic review of genus Evergestis Hübner (Lepidoptera: Crambidae) from Northeast China

Four species of the genus Evergestis Hübner, 1816–1826 are recognized from NE China, of which E. pallidata (Hufnagel 1767) is reported for the first time from China. The adults and genitalia of the species are briefly redescribed and illustrated with their distributional ranges, host plants and biology. A key to species of the genus based on the external characters is provided.     

茴香薄翅野螟虫口密度与油菜产量损失关系及其防治指标的研究

在网室内人工接茴香薄翅野螟Evergestis extimalis Scopoli卵,研究结果表明,随着幼虫数量的增加,油菜产量损失增加;与对照相比,当接卵数为216、399、858、1665和3279粒时,产量损失分别达3.13%,2.08%,12.5%,25.10%和43.33%。各网室实际接虫数(x)与其相应的小区油菜产量(y)的关系为:y=-0.0007x+4.8129,表明虫口密度与油菜产量为负相关。在青海省油菜种植区内每平米幼虫或卵数超过10头或粒时,应即时防治。