Ovariole microstructure and vitellogenesis in Lygocoris pabulinus (L.) and other mirids (Hemiptera: Miridae)

The microstructure of the ovariole of Lygocoris pubulinus is described, and an account is given of the method of yolk production. The significance of variations in the structure of the germarium in Heteroptera is discussed.     

松墨天牛对寄主树木的产卵选择

在室内采用选择行为方法,研究了松墨天牛Monochamus alternatus对几种松属植物的产卵选择行为。结果表明,松墨天牛对黑松Pinus thunbergii的选择性最强,对马尾松P.massoniana的选择性最弱,二者间差异显著,它们与火炬松P. taeda和湿地松P. elliottii间无明显差异。在黑松和马尾松的被松材线虫危害木与健康木之间,松墨天牛明显选择被害木产卵;具产卵痕枝段和虫粪处理过的枝段,对松墨天牛的产卵有显著抑制作用,松墨天牛明显地选择对照枝段产卵。     

Oviposition preference of cotton leafhopper in relation to leaf-vein morphology

Abstract:  The oviposition preference of the cotton leafhopper, Amrasca biguttula biguttula (Ishida) was investigated in relation to leaf-vein characteristics of 12 plant species, namely okra, cotton, castor, pigeonpea, cowpea, cluster bean, green gram, egg plant, sesame, country mallow, portia tree and shoe flower. Observations on the oviposition of the leafhopper under no-choice conditions were recorded on three occasions during the peak period of leafhopper incidence in the field. On all three occasions the leafhopper rejected green gram, shoe flower and portia tree for egg-laying, thereby indicating non-acceptance of these plants for oviposition. For the remaining plants, the number of eggs per leaf differed significantly. Okra received the maximum number of eggs. The lateral veins of castor, cotton, cowpea, egg plant and country mallow leaves received more eggs in comparison with the main vein and subveins whereas in okra the subveins received the highest number of eggs followed by lateral and main veins. The leaves of cluster bean, pigeonpea and sesame were devoid of subveins. In cluster bean and sesame the lateral veins received more eggs than the main vein but in pigeonpea the main vein received more eggs than the lateral veins. Correlations of trichome density and length with the number of eggs laid in different veins were non-significant. All types of veins in okra leaves were thicker than the rest of the test plants, which might have stimulated more egg laying in okra. The thickness of each category of vein, namely main vein ( r =0.60), lateral veins ( r =0.65) and subveins ( r =0.56) was found to be positively correlated with the number of eggs laid. The length of the main and lateral veins were also found to be positively and significantly related to the number of eggs laid. It can be concluded from the present investigations that leaf-vein thickness and length are crucial factors in influencing the oviposition behaviour of the cotton leafhopper.     

Relative preference of Lygus hesperus (Hemiptera: Miridae) to selected host plants in the field

Abstract Information on host plant preference of agriculturally important insect pests, such as Lygus hesperus (Knight), can be helpful in predicting its occurrence and future movement among crop and non-crop host plants. A field study was conducted during 2005 and 2006 to evaluate the host preference of Lygus to cotton and four other host plants in the Texas High Plains, including alfalfa (Medicago sativa L.), wild sunflower (Helianthus annuus L.), Russian thistle (Salsola iberica L.) and pigweed (Amaranthus palmeri L.). Sampling for both nymphs and adults during 2005 (July to November) and 2006 (June to November) showed that alfalfa and Russian thistle were the two most preferred hosts out of the five hosts evaluated. Abundance of nymphs (numbers per 50 sweeps per host plant) during the sampling period also indicated the superior reproductive suitability of alfalfa and Russian thistle. Cotton appeared to be the least attractive host plant for Lygus when Russian thistle and alfalfa were available in the host mosaic. Seasonal abundance of Lygus was found to be lower during 2006 compared to 2005, which may be explained by the difference in rainfall patterns during these two years. In terms of species dominance, L. hesperus was the most dominant species in the sampled population followed by an inconsiderable fraction of L. elisus and L. lineolaris.     

Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 ± 1°C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40°C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15°C to 6.3 days at 35°C. The cumulative thermal requirements for the eggs were 148.6 degree days (°d) and the lower thermal threshold, 10.3°C. The duration of the nymphal instar decreased from 55.9 days at 15°C to 8.6 days at 35°C. The thermal constant for the nymphs was 182.3 °d and the lower thermal threshold 11.7°C. No nymphs survived at 40°C, and the highest mortalities were at extreme temperatures (15 and 35°C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40°C. The highest fertility during an observation period of 18 days following female emergence (79.5–60.0 nymphs per female) was within the temperature range of 20 to 35°C. Fertility was related directly to female weight and temperature (r² = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30°C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.     

Oviposition and feeding preference of Acrolepiopsis assectella Zell. (Lep., Acrolepiidae)

Abstract:  The leek moth, Acrolepiopsis assectella (Zell.), is a recently discovered exotic species in eastern Ontario and western Quebec. This Allium spp. (Asparagales, Alliaceae) specialist can cause up to 40% crop damage. A no-choice experiment was used to determine the relationship between oviposition behaviour and larval survival of the leek moth as the phylogenetic distance from the preferred host Allium ampeloprasum var. porrum L. increased. Results indicate that oviposition preference and larval survival of the leek moth declined as the phylogenetic distance from the preferred host increased. These results support the conclusion that the leek moth is a specialist feeder on closely related Allium spp. although the strength of this preference may decline as the motivation to oviposit increases. This may indicate that the leek moth is able to use closely related novel hosts as temporary refuges if the preferred host plant is unavailable.     

Oviposition, fertility, and longevity and their relation to copulation in Antestiopsis lineaticollis (Heteroptera: Miridae)

Egg production, fertility, and longevity of solitary mated females and control pairs of males and females of Antestiopsis lineaticollis Stål. (=A. orbitalis bechuana Kirkaldy) were studied in the laboratory at 22–23° and 60–70% relative humidity. No significant differences were found in adult longevity, inter-oviposition period, number of eggs, post-reproductive period, and the number of eggs remaining in ovaries after the death of females. Control females had a significantly longer duration of oviposition than solitary ones. Thus, the physical presence of males or multiple mating by females has no influence on egg production in the Antestia bug.

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Zusammenfassung Eiproduktion, Fruchtbarkeit und Lebensdauer isolierter begatteter Weibchen sowie von Kontrollpaaren von Männchen und Weibchen von Antestiopsis lineaticollis Stål. (= A. orbitalis Kirkaldy) wurden im Labor bei 22–23° und 60–70% relativer Luftfeuchtigkeit untersucht. Es wurden keine signifikanten Unterschiede in der Lebensdauer der Adulten, den Perioden zwischen den Eischüben, der Anzahl der Eier, der Postreproduktionsperiode und der Anzahl der nach dem Tode der Weibchen in den Ovarien zurückgebliebenen Eier gefunden. Die Kontroll-Weibchen hatten eine signifikant längere Eiablagedauer als die isolierten. So hat also die physische Gegenwart der Männchen oder wiederholte Paarung der Weibchen bie der Antestia-Wanze keinen Einfluß auf die Eiproduktion.

     

韭菜迟眼蕈蚊对几种植物的产卵和取食选择性研究

为了探究韭菜迟眼蕈蚊对不同植物的选择性,本文通过室内控制实验和Y型嗅觉仪实验研究了韭菜迟眼蕈蚊成虫和3龄幼虫对7种植物的产卵和取食选择性行为。结果发现,韭菜迟眼蕈蚊对韭菜的产卵和取食选择性最高,成虫落卵数量221.67粒/盒,雌雄虫的选择系数分别为0.30和0.20,幼虫取食选择率为33.50%;对茴香和朝天椒的选择性最低,成虫落卵数量分别为81.00和23.00粒/盒,雌雄虫的选择系数分别为-0.27、-0.48和-0.27、-0.39,幼虫取食选择率分别为5%和0%。田间推荐韭菜与茴香或朝天椒间作。     

Disruption of sexual communication in the mirid bug Lygocoris pabulinus by hexyl butanoate

1 The metathoracic scent gland in Lygocoris pabulinus contains mostly hexyl butanoate. As secretions of this gland in Heteroptera may serve as an alarm pheromone, we determined whether hexyl butanoate is released by disturbed bugs, and whether this compound disrupts sexual attraction of L. pabulinus males towards females. 2 Undisturbed males and females, and disturbed males released less than 100 ng/h hexyl butanoate, whereas disturbed females released a highly variable amount, ranging from 25 ng/h to more than 1 μg/h. 3 In the field, traps with virgin females and rubber septa containing 20 mg hexyl butanoate, caught a total of one male in a month. In control traps without hexyl butanoate, 36 males were caught in the same period. 4 In Y‐track olfactometer tests, males were not attracted to virgin females when a dispenser with 20 mg hexyl butanoate was placed in the bottle with females. Males were attracted to females when the dispenser was placed downwind from the females, but upwind from the point of male release. 5 These results suggest that males are not repelled by hexyl butanoate, but that this compound inhibits sex pheromone release in females. Application possibilities for pest management are discussed.     

Olfactory response of Trigonotylus caelestialium (Het.: Miridae) to rice plant and gramineous weeds

Abstract:  The olfactory response of Trigonotylus caelestialium , to rice, Oryza sativa L., and two species of gramineous weeds, Poa annua and Digitaria ciliaris , was investigated with an olfactometer to clarify the role of host-plant odours as olfactory cues in their host-finding behaviour. Third-instar nymphs and adult males were significantly attracted to whole plants (above ground parts) of P. annua . However, adult females were not significantly attracted to whole plants of P. annua . Attractancy of rice to T. caelestialium differed with the growth stage and part of the plant. Adult females were significantly attracted to stems and leaves in the panicle-formation stage, and panicles in the flowering stage. They were not attracted to stems and leaves in the fourth-leaf stage and flowering stage, or to panicles in the milk-and full-ripe stages. Although adult males were significantly attracted to stems and leaves in the panicle-formation stage, they were not attracted to the other rice structures tested. Both females and males were significantly attracted to stems and leaves, as well as panicles of D. ciliaris in the flowering stage. The findings suggest that T. caelestialium use host-plant volatiles as olfactory cues to find their host plants and their invasion to paddy fields were caused by olfactory responses to rice plant.     

Side-effects of three neem (Azadirachta indica A. Juss) products on the predator Macrolophus caliginosus Wagner (Het., Miridae)

The side-effects of three neem formulations (Neem-Amin EC, Stardoor and B.P. 20/S) were tested on the mirid predator Macrolophus caliginosus Wagner in the laboratory. Direct toxicity tests on 1st instar nymphs exposed to fresh dry residues on glass plates at different doses demonstrated that all the products are harmful to the insects with LD₅₀ values much lower than the maximum recommended rate (1.217, 0.264, 1.083 mg a.i./l instead of 15, 31.5 and 80 mg a.i./l for Neem-Amin EC, Stardoor and B.P. 20/S, respectively). Moreover a reduction of fecundity of the surviving females was assessed with Neem-Amin EC and B.P. 20/S. Persistence tests were carried out on sharp pepper plants treated at the maximum recommended rate. High mortality was recorded when the insects were introduced onto the plants just after the treatment, but no significant differences compared with the controls were observed 5 days after the treatment and any consequence on the fecundity of surviving females was detected. Our experiments showed how azadirachtin can be noxious to M. caliginosus , but the short persistence makes this active ingredient a promising solution in integrated pest management programmes, when a lapse of time is guaranteed between the treatment and the introduction of the predator.     

Toxicity of some insecticides and acaricides to the predatory bugDicyphus tamaninii (Het.: Miridae)

Several pesticides were tested in the laboratory for their side-effects upon the mirid bugDicyphus tamaninii, a polyphagous predator used for IPM programmes in some vegetable crops. Residual toxicity to 3rd -4th instar nymphs on tomato leaflets was checked 24, 48 hours and seven days after treatment. The acaricides bromopropylate, dicofol+tetradifon and fenpyroximate were harmless to the nymphs. The insect growth regulators azadirachtin, buprofezin, lufenuron and pyriproxyfen were also harmless to nymphs and teflubenzuron was slightly harmful seven days after treatment. Among the conventional insecticides tested, only pirimicarb and tau-fluvalinate were harmless toD. tamaninii nymphs     

草地螟对寄主植物的选择性及其化学生态机制

田间自然条件下,草地螟成虫产卵对不同植物具有明显的选择性,其中灰菜上落卵量最多,占调查总卵量的50%以上;甜菜、大豆上次之,玉米和马铃薯上最少。在室内条件下,草地螟成虫产卵对灰菜、大豆、玉米和马铃薯的选择性与田间调查结果完全吻合。而且,草地螟幼虫的嗜食性与成虫产卵对寄主的选择性是一致的。吸附、收集上述植物的挥发物后进行GC-MS测定,并利用风洞进行了生测。其中灰菜和大豆的主要挥发物成分为反-2-己烯醛、青叶醇、青叶酯、1-十八烯等;玉米和马铃薯的挥发物性成分包括青叶酯、芳樟醇、香叶醇、紫罗酮、1-十八烯。生测结果表明,灰菜的挥发物对草地螟雌蛾引诱力最大,选择系数为78%;大豆苗挥发物对其也有较高的诱虫活性;但玉米和马铃薯几乎无引诱作用。自然生长的4种植物的诱虫结果与其挥发物的诱虫结果相似。这些生测结果与成虫和幼虫选择寄主的一致性反映了草地螟选择寄主行为的化学机制。     

Potential host plants of Corythucha arcuata (Het., Tingidae) in Europe: a laboratory study

Abstract:  The oak lace bug Corythucha arcuata (Say) (Het., Tingidae), native to North America, was found in Europe on Quercus robur L. and other oaks in the spring of 2000. The potential host plant range of this species in Europe and its development time were investigated in a laboratory study. An assay was performed on leaf cuts of different plant species. On the deciduous European oaks ( Q. robur , Quercus pubescens Willd, Quercus petraea (Mattuschka) Liebl., Quercus cerris L.), as well as Rubus ulmifolius Schott. and Rubus idaeus L., most of the lace bugs (>50%) reached the adult stage; on Castanea sativa Mill., Rubus caesius L. and Rosa canina L., a reduced number of individuals (<25%) reached the adult stage. No nymphs survived on Quercus rubra L. (mentioned in literature as a host plant), on the evergreen oaks Quercus suber L. and Quercus ilex L., on Malus domestica Borkh. and four tested maple species. On plant species where the lace bug reached the adult stage, the development time varied from 13 to 27 days. On European deciduous oak species, the development time was longer on leaves taken in late summer (September) than on those of late spring (June); on the contrary, such differences were not observed on Rubus species, and Castanea sativa .     

Oviposition by Mamestra brassicae (L.) (Lep., Noctuidae) in relation to age, time of day and host plant

The age at which females begin to lay, the daily pattern of oviposition, the influence of host-plant material on egg-laying as well as the host preference of Mamestra brassicae L. (Lep., Noctuidae) were investigated under laboratory conditions. The females began to oviposit during the third, fourth and fifth scotophase after emergence. A great variability in daily female fecundity was observed. The highest level of oviposition occurred during the fifth day. Females oviposited during the whole scotophase, but maximal oviposition occurred during the second hour. The females without host-plant material laid fewer eggs than females with host-plant material (cabbage leaves Brassica oleracea var. capitata ). In two-choice tests, the females preferred to oviposit on cabbage rather than chrysanthemum, but there was no difference in the mean number of eggs laid on cabbage and tomato. There were significantly greater mean numbers of total eggs deposited on tomato than on chrysanthemum.     

Oviposition preference and larval survival of Diprion pini on Scots pine clones in relation to foliage characteristics

1 When laying eggs, adult female Diprion pini discriminated between clones of Scots pine, Pinus sylvestris. 2 Larval survival was affected by Scots pine clone but was not correlated with oviposition preference. 3 Diprion pini laid most eggs on tougher needles of Scots pine. 4 There was no evidence to suggest that D. pini is responding to the monoterpene composition of the foliage.     

Oviposition and development of the tarnished plant bug (Heteroptera: Miridae) on field maize

Reduced insecticide use in cotton, Gossypium hirsutum L., as a consequence of the Boll Weevil Eradication Program and the broad adoption of Bt cotton, have helped make the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), a consistent pest of cotton each year in the mid-south. Maize, Zea mays L., has been implicated as having a role in the season-long dynamics of tarnished plant bug infestations in cotton. To date, no published information exists describing the quality of maize as a host for tarnished plant bug. No-choice field studies indicated that adult tarnished plant bug females oviposited into maize leaves, tassels, and ears. Laboratory studies showed that first-instar tarnished plant bugs could successfully develop to the adult stage when fed maize silks at the R1 growth stage, tassels before (VT) and during (R1) pollen shed, and milk stage (R3) kernels from the tip and base of the ear. The proportion of nymphs surviving to the adult stage on these tissues was often similar to that of broccoli, Brassica oleracea L. Nymphs did not develop to adults when fed V5 or R1 maize leaves. However, survival of first instars to the adult stage was improved when nymphs fed on tassels with pollen for 6 d and then moved to silks or leaves. Another field study showed that tarnished plant bugs reproduced in maize mainly during the tassel (VE and VT) and the R1-R3 ear growth stages, and a single new generation was produced in maize during these stages. The highest population recorded during the study (24 June 2005) consisted mostly of nymphs and was estimated to be 29,600/ha (12,000/acre). These studies showed that maize is a suitable host for tarnished plant bug reproduction and development, and its production plays a significant role in the population dynamics of the tarnished plant bug in the mid-south.     

Seasonal phenology and relative preference of Closterotomus (Calocoris) trivialis (Hemiptera: Miridae) on olive, citrus and associated host plants in the field

The seasonal appearance and population abundance of nymphs and adults of Closterotomus trivialis (Costa) were studied by weekly canopy shaking samplings in an olive and a citrus orchard in Chania, Greece, from January to May 2009. In addition, samples were taken from weeds referred to in the literature as alternative host plants for C. trivialis. Results showed that nymphal instars of C. trivialis were first recorded on weeds in mid-January. The first adult appearance was recorded on Mercurialis annua L. in early March in the citrus orchard, while in the olive orchard, it was recorded 13 days later. A significantly higher population of C. trivialis under field conditions was found on M. annua followed by Urtica sp., Parietaria officinalis L. and Sinapis alba L. Population density on olive (Olea europaea L.) and sweet orange (Citrus sinensis (L.) Osbeck) trees as well as on Sonchus oleraceus L. and Malva sylvestris L. was very low in general. Collected information on host plant preference of C. trivialis may be helpful for the prediction of its occurrence and movement among crop and non-crop host plants and therefore in the development of appropriate control strategies, thus avoiding unnecessary insecticidal treatments.     

Oviposition preference and neonate performance of Mnesampela privata in relation to heterophylly in Eucalyptus dunnii and E. globulus

Abstract

• 1 The autumn gum moth, Mnesampela privata, is an endemic Australian geometrid that utilizes a number of species within the genus Eucalyptus as hosts. Based on field observations, the moth is thought to be leaf‐type specific for juvenile as opposed to adult eucalypt foliage.
• 2 Laboratory binary choice assays of the oviposition preference of host novice M. privata confirmed that eggs were more likely to be laid upon juvenile rather than adult foliage of Eucalyptus dunnii and two subspecies of E. globulus. This oviposition preference was not influenced by differences in leaf size or adherence to leaves by ovipositing moths. The high specific leaf weights common to adult leaves were associated with reduced oviposition.
• 3 Although neonates fed on both juvenile and adult leaves of most of the trees studied, performance was greater on juvenile as opposed to adult foliage. Juvenile leaves typically had lower specific leaf weights and were nutritionally superior to their adult counterparts. Specific leaf weights above 0.236 mg/mm² (associated with low water, i.e. = 56.5%, and nitrogen, i.e. = 1.23%, contents) were associated with reduced larval performance. Younger adult leaves, those with lower specific leaf weights, allowed slightly greater larval consumption.
• 4 When ovipositing, this eucalypt‐specific moth discriminates between leaf types of its heterophyllous hosts in favour of types with the lowest specific leaf weight. Less tough leaf types, which are also higher in nitrogen, enable neonates to attain larger body weights.