Behavior of varroa mites in worker brood cells of Africanized honey bees

The ectoparasitic mite Varroa destructor is currently the most important pest of the honey bee, Apis mellifera. Because mite reproduction occurs within the sealed cell, the direct observation of varroa activity inside the cell is difficult. A video observation method using transparent polystyrol cells containing infested brood was used to analyze the behavior of varroa mites in worker brood of Africanized honey bees. We recorded how mites feed on the larva and pupa, construct a fecal accumulation site and how the bee larva carried out some longitudinal movements around the cell. The feeding activity of the foundress mite varies during the course of the cycle. On the prepupa mites were found to feed often (0.3 ± 0.2 bouts h⁻¹) for a period of 8.7 ± 8.4 min h⁻¹ and there was no preference for a specific segment as feeding site. On the opposite, during the pupal stage mites fed less often (0.1 ± 0.1 bouts h⁻¹) for a period of 6.2 ± 4.0 min h⁻¹ and almost always at a particular site (92.4%). On pupa, 83.7% of the feeding was on the 2nd abdominal segment (n = 92), and only few perforations were found on the thorax. Varroa shows a preference for defecation in the posterior part of the cell (cell apex), close to the bee′s anal zone. We found a high correlation between the position of the feeding site on the pupa and the position of the fecal accumulation on the cell wall. Most infested cells have only one fecal accumulation site and it was the favorite resting site for the mite, where it spent 24.3 ± 3.9 min h⁻¹. Longitudinal displacements were observed in 28.0% (n = 25) of the analyzed bee larvae. Turning movements around the cell, from the bottom to the top, were carried out by these larvae, mainly during the second day (47.7 ± 22.5 min h⁻¹), just before pupation, with a total time of 874.9 ± 262.2 min day⁻¹ (n = 7 individuals). These results in worker brood of Africanized bees demonstrate adaptations of varroa mites to parasitizing the developing bee inside the capped brood cells.     

谈谈昆虫的预蛹

预蛹是全变态类昆虫生长发育过程中的一个特定阶段,但目前不同的学者对预蛹的定义和涵义有着不同的理解和意见,从而导致产生了歧义和困惑。文章对昆虫预蛹迄今的各种定义和描述进行比较分析,根据作者多年来对多种昆虫生物学的研究经历,对"预蛹"提出认为比较合适的定义:"昆虫的预蛹是指老熟幼虫停止取食至脱皮成蛹之前的这个发育阶段。它表现为与幼虫不同的行为学习性,即不再取食、离开幼虫期的生活环境和场所等行为,为化蛹作准备,常表现为入土、寻觅和进入隐蔽场所、吐丝做茧、建造蛹室等习性。同时,也伴随着如虫体缩短等形态特征上的变化"。     

Pathogenicity of three entomopathogenic nematodes against the onion thrips,Thrips tabaci Lind. (Thys.; Thripidae)

Pathogenicity of a native isolate of Steinernema feltiae (H1) and two exotic strains, Heterorhabditis bacteriophora and Steinernema carpocapsae was assessed under laboratory conditions using different concentrations i.e. 4000, 6000, 8000 and 10,000 infective juveniles/ml against second instar larvae, prepupa and pupa of Thrips tabaci Lindeman. The mortality data were recorded 24 and 48?h post-inoculation. The highest mortality rate was recorded for prepupa (62%) than second instar (12.5%) by H. bacteriophora and S. carpocapsae, respectively, 24?h after treatment. No significant differences were found in mortality between prepupa and pupa with increasing the nematodes concentrations (from 4000 to 10,000 nematode/ml) but increasing nematode concentrations increased the mortality of second instar. At the end of the experiment (48?h.), S. feltiae H1 caused the highest mortality on second instar larvae (74%), whereas all other species caused 80–83% mortalities on pupa. This study suggests that native isolate of S. feltiae (H1) had high potential to infect soil-dwelling stages of T. tabaci.     

Paramagnetics melanin and Mn<Superscript>2+</Superscript> in black soldier fly <Emphasis Type="Italic">Hermetia illucens</Emphasis>

Larva, prepupa (last instar larva), pupa, and an empty shell of pupa after hatching of the black soldier fly Hermetia illucens contain eumelanin, an active synthesis of which is observed at the prepupal stage, which is probably due to the release of prepupa from the feed substrate thickness to the open space for pupation. It was shown for the first time that prepupa contains high quantities of the magnetically active form of manganese Mn²⁺. This fact indicates that Mn²⁺ stimulates the copper-containing tyrosinase—the key enzyme in the synthesis of melanin in the period of migration and adaptation of the insect to the solar radiation.     

Melanin and Melanogenesis at Different Life Stages in <Emphasis Type="Italic">Hermetia illucens</Emphasis>

This work has demonstrated that the life stages of the Hermetia illucens fly are characterized by varying melanin contents with the maximum melanin amount being detected in the pupa. It has been observed that active synthesis of the pigment takes place in the prepupa and coincides with the time when the population migrated for pupation. It has been noted that a high manganese content in the prepupa and pupa indicates the important role that this biogenic element plays in organogenesis and melanogenesis in H. illucens. It has been revealed that in the imago and pupa, the melanin demonstrates broad-range antimicrobial activity and contribute to the insect protection against bacterial and fungal infections.     

Time-activity budgets and space structuring by the different life stages ofVarroa jacobsoni in capped brood of the honey bee,Apis mellifera

Varroa jacobsoni reproduces in honey bee brood cells. Here the behavioral activity and use of space by infestingVarroa females and progeny were quantified in transparent artificial brood cells. The time-activity budget of both infesting and developing mites converged toward a stable pattern which was established during the bee prepupal stage of the infesting mites and the protonymphal stage of mite progeny. The pattern was such that infesting females and offspring eventually divided their activity between the fecal accumulation on the cell wall, which served as the rendezvous site for newly molted individuals, and the feeding site prepared on the pupa by the foundress. Other parts of the cell wall were used for oviposition and molting, away from the fecal accumulation on which activity of mobile stages was concentrated. Space structuring and the time-activity budget inVarroa probably evolved to enhance the number of fertilized females produced within the capped brood, where space and time are limiting factors. These behavioral adaptations parallel those of other mite species which show group behavior within cavities.     

菜青虫不同虫态及虫龄的多酚氧化酶性质比较

初步比较了菜青虫Pieris rapae (L.)不同虫态及虫龄的多酚氧化酶(polyphenol oxidase)的性质。结果表明,不同虫态及虫龄的多酚氧化酶活力有很大的不同,其中以5龄幼虫酶活力最高,蛹酶活力最低。酶活力大小依次为： 5龄幼虫> 预蛹>4龄幼虫>3龄幼虫>蛹。以邻苯二酚为底物,研究了pH对多酚氧化酶活力的影响,结果表明酶催化底物氧化均有一个最适pH区域,不同虫态及虫龄的多酚氧化酶最适pH基本相同,其值为7.0±0.2 。不同虫态及虫龄的多酚氧化酶催化底物氧化的最适温度有很大的差异。3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活力的最适温度分别为36.0±0.5℃、38.5±1.0℃、43.0±1.0℃、45.5±1.0℃和50.0±1.5℃,说明蛹期的多酚氧化酶活力的最适温度较高。进一步比较催化底物氧化反应的活化能,测得3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活化能分别为：4 3.10±0.28、36.50±0.27、25.79±0.32、30.10±0.21和58.88±0.39 kJ/mol 。通过测定不同虫态及虫龄的多酚氧化酶催化邻苯二酚和L-多巴氧化反应的动力学特征参数,比较了不同虫期的酶对底物的亲和力。     

A safety band prevents falling of the suspended pupa of the butterfly Inachis io (Nymphalidae) during moult. A comparison with the girdled pupa of Pieris brassicae (Pieridae, Lepidoptera)

 During the pupal moult the suspended prepupa of the butterfly Inachis io completely removes its larval skin (exuvia) from the body. In doing this, the attachment to a silken pad has to be transferred from the anal prolegs of the prepupa to the cremaster of the pupa without losing the hold at any time. Falling is prevented by a short safety band which is drawn off from the innermost layer of the exuvia as it adheres to two prominent, pupal projections when the exuvia is slipped backwards. The projections which lie on the ventral side of the last abdominal segment are covered with numerous, minute spines each orientated in the opposite direction to the removal of the exuvia. The transparent safety band has a gelatinous consistency and is strong enough to withstand the fivefold load of a pupa. By contrast, the prepupa of Pieris brassicae is additionally held in place during moult by a girdle around the back. It usually rests in an upright position. Nevertheless, the pupa also shows the prominent projections covered with spines. The exuvia is held fast by the projections, but only a fold is formed. The formation of a safety band is never observed. The connection of the exuvia to the projections is sufficient to hold the tip of the abdomen within reach of the pad for hooking the cremaster therein. However, the pupae of those species in Satyrinae which pupate lying in cocoons or cells lack any kind of projections as well as spines. Accepted: 21 January 1998     

Radiation-induced lethal mutations appearing in cells of somatic tissue in Drosophila

Exposure of 3-hour drosophila male embryos to gamma-radiation during the topographic segregation of the germ anlage nuclei caused recessive sex-linked lethals in somatic cells only. The selectivity of the screening was determined by the ratio of mutation frequencies induced in embryos and adult males. Analysis of lethal mutations shows that a minimal rate of the divergence between germinal and somatic patterns of the cell development is observed in the embryogenesis, the 3d instar larva and prepupa, and maximal in the 1st and 2nd larva and pupa.     

Temporal focusing of nitrogen release by a periodically feeding herbivorous reef fish

The reef-dwelling jewel damselfish Plectroglyphldodon lacrymatus (Quoy & Gaimard) exhibited a marked diel periodicity in nitrogenous excretion and defecation rates. This temporal “focusing” of soluble and particulate-faecal nitrogen release on the latter part of the day correlated strongly with the pattern of feeding activity. There was a lag after feeding began each day of ≈ 5–6 h before defecation accelerated, but no such lag was apparent in the case of excretion. Both excretion and defecation, however, did lag behind feeding at the end of the day, for they remained above their respective minimum rates for ≥ 8 h after feeding had ceased. Gut evacuation rates were variable, while the excretion of nitrogenous waste appeared to take ≈24 h and to be subject to a physiological rhythm. Defecation, most of which occurred at a single site in each territory, was far more important in the generation of nitrogen by the fish than was excretion. In laboratory experiments the faeces took up ammonium, but in the field most faeces were probably removed quickly by ophiocomine brittlestars and pulled down into interstices of the reef. Nearly all of the nitrogen egested, but perhaps only one-third of that excreted, was transferred initially to the reef framework below the fish's territory.     

Maternal effects of photoperiods on glycogen metabolism related to induction of diapause in Cotesia vestalis (Hymenoptera: Braconidae) from Jilin, China

Most insects must accumulate glycogen before entering diapause. Photoperiod influences diapause beyond the maternal generation in Cotesia vestalis (Haliday) (Hymenoptera: Braconidae). In this study, we measured glycogen content and the activity and messenger RNA (mRNA) expression of glycogen synthase and glycogen phosphorylase at different G₀ (25 °C under light:dark photoperiods of 8L:16D, 12L:12D, and 16L:8D) and G₁ life stages (13 °C under 8L:16D). Glycogen content in G₀ and G₁ increased with shorter light periods, except for G₀ adult males, which showed no significant difference under the three photoperiods. Compared with those under 16 h, in those under 8 h light, glycogen synthase activity was significantly higher at all tested stages, except for G₀ pupa and adult male, for which it was identical; mRNA expression was higher at G₀ larva and prepupa, lower at pupa, and identical at rest stages. Glycogen phosphorylase activity was significantly higher for G₁ egg, lower at G₁ prepupa, and identical at all other stages; mRNA expression was higher at G₀ and G₁ larval stages, and similar at rest stages. These findings suggest that glycogen, being regulated by the two enzymes, may be a consequential factor in the transmission of maternal information and diapause induction of C. vestalis.     

Biology and defensive adaptations in Rodatus major (Coleoptera: Coccinellidae) and its prey, Monophlebulus pilosior (Hemiptera: Margarodidae)

The biology of the Australian coccinellid Rodatus major (Blackburn) and its prey, the hemipteran margarodid Monophlebulus pilosior (Maskell), are described. New predators and a new parasite of M. pilosior are recorded. Rodatus major makes use of elaborate and distinctive defensive adaptations and behaviour to protect itself from predators. They include cryptic coloration, aposematic behaviour, production of wax by larvae, production of a large, thick protective covering concealing the pupa and resembling an M. pilosior ovisac, and reflex bleeding. It is the only known coccinellid species in which both prepupa and pupa are hidden by a protective shroud of wax threads. Rodatus major has a specialized feeding behaviour. Its potential as a biological control agent is assessed. It is only the second Australian margarodid-feeding coccinellid to be studied, Rodolia cardinalis (Mulsant) being the first.     

Effect of temperature on Osmia lignaria (Hymenoptera: Megachilidae) prepupa-adult development, survival, and emergence

The solitary bee Osmia lignaria Say continues to be developed as an orchard pollinator in the United States and southern Canada. Female bees are active during the early spring and construct nests consisting of a linear series of unlined cells delimited by mud partitions. Cells are provisioned with a pollen/nectar mass on which an egg is deposited, and nests are sealed with a mud plug. In 1997, we initiated two experiments on the development, mortality, and emergence of O. lignaria at selected laboratory temperature regimes and outdoors. In the first experiment (published previously), we compared temperature treatments for their adequacy in maintaining healthy O. lignaria populations. In a second experiment (reported here), we determined the relationship between rearing temperatures and prepupa-adult development rates as well as emergence time and longevity after wintering and incubation the following spring. We observed important differences in O. lignaria prepupa versus pupa responses to selected temperature treatments. The relationship between temperature and days to pupa was U-shaped, with additional time to transit the prepupa-pupa interval at temperatures above and below 26 degrees C. The negative relationship between temperature and the length of the pupa to adult interval contrasts with the U-shaped thermal response observed for prepupae. Thus, with each increase in thermal heat units over the range of temperature treatments tested, we observed an additional reduction in the pupa-adult interval. Individuals reared at constant 18 degrees C required 2.4 times as many days to transit the pupa-adult interval compared with those at constant 32 degrees C. Our results suggest that there is a need for the development of regionally adapted, latitude-specific breeding populations of this outstanding orchard crop pollinator.     

Effects of diet-deprivation and physical stimulation on the feeding behaviour of the larvae of the silkworm, Bombyx mori

Continuous observations of larvae of the silkworm, Bombyx mori, revealed that feeding occurred at regular intervals throughout larval development. To investigate possible factors influencing meal-timing, the behaviours of diet-deprived Bombyx larvae were also analysed. Diet-deprivation resulted in longer durations of the first meals after diet replacement, but did not affect feeding patterns. Furthermore, long-term diet-deprivation promoted wandering behaviour and a consequent delay in feeding after diet replacement. Under diet-deprivation conditions, meal-starts appeared to be inducible by defecation and physical stimulation. However, stimulation-induced meal-starts were dependent on the time elapsed since the larvae's previous meals. Provided that more than 1h had elapsed since their previous meals, larvae could be induced to feed by defecation and tapping. At less than 1h post-meal, larvae were less likely to begin feeding after defecation or physical stimulation. Activated locomotions such as wandering and feeding were observed in the long-term diet-deprived larvae only after diet blocks were replaced, while long-term diet-deprived larvae did not show activated locomotion during the absence of diet blocks. Collectively, these data suggest that a combination of elevated locomotion activity and the presence of diet may be necessary for the initiation of feeding in diet-deprived larvae.     

Factors influencing host choice of the honey bee parasite Varroa jacobsoni Oud

Reproducing Varroa jacobsoni obtained from brood cells of Apis mellifera L. with 13–16 day old bees (pupae) and Varroa mites kept on adult bees for at least 8 days were simultaneously tested for their choice in three host types. Comparisons were made of attractiveness of Varroa jacobsoni to nurse bees, pollen foragers as to larvae from nearly capped brood cells. Host choices were observed in Petri dishes and in an Y-shaped olfactometer. Varroa jacobsoni obtained from capped brood cells showed a stronger preference for nurse bees in Petri dish simultaneous choice tests with pollen foragers or larvae than did mites which were previously kept on adult bees. In olfactometer simultaneous choice tests, the two mite test groups showed no clear difference in preferences for bees of different ages. The preference of Varroa jacobsoni for bees of different ages is therefore not only influenced by host factors but also by intrinsic factors in female mites that depend on the mite's reproductive stage.     

榆树隐毡蚧各龄若虫和雄成虫形态及其生物学记述(同翅目: 蚧总科: 毡蚧科)

榆树隐毡蚧 Cryptococcus ulmi Tang et Hao是近年来在北京和山西中部发现的一种榆树新害虫。本文首次详细记述和图示了该虫幼期各虫态和雄成虫的形态特征 ;简要报道了其生物学特性 :一年发生 1代 ,以受精雌成虫在树干裂缝内越冬 ,卵胎生 ,每雌产仔 2 3～ 2 5头 ,平均值 35.2头。     

Grooming behaviour of Apis mellifera syriaca towards Varroa jacobsoni in Jordan

Eight Apis mellifera syriaca colonies at the Jordan University of Science and Technology campus in Jordan were used in the experiments to detect defence behaviour of worker bees against Varroa jacobsoni . This defence mechanism was determined by the degree of damaged mites that dropped from naturally infested colonies on inserts placed under the brood nest from June to October 1998. The average percentage of all dropping mites that were injured was 22.8%. A total of 86.5% of amputated mites were pigmented and 13.5% were less pigmented. Amputation to the first pair of legs was more often seen. Most of the phoretic mites were concealed between sclerites laterally on the abdomen, with distinct preference between second and third tergites. The grooming activity of A. mellifera syriaca provides evidence of active mechanisms of resistance toward the parasitic Varroa -mite.     

扶桑绵粉蚧的过冷却点和体液结冰点测定

本文测定了扶桑绵粉蚧Phenacoccus solenopsis Tinsley除卵期以外其它各虫态的过冷却点和结冰点.结果表明,该虫过冷却点以1龄若虫最低,为-24.02℃;雄虫预蛹次之,为-22.13℃;雄虫蛹、雄虫2龄若虫、雌虫3龄若虫、雄成虫、雌虫2龄若虫、雌成虫过冷却点逐渐升高,分别为-21.08℃、-20.25℃、-19.05℃、-18.42℃、-17.91℃、-16.89℃.体液结冰点也以1龄若虫最低,为-23.2℃;雄虫预蛹次之,为-19.09℃;雄虫蛹、雄虫2龄若虫、雌虫3龄若虫、雌虫2龄若虫、雌成虫、雄成虫体液结冰点逐渐升高,分别为-16.64%、-15.81℃、-13.92℃、-13.20℃、-12.85℃、-12.79℃.试验结果表明扶桑绵粉蚧过冷却点低,耐寒性较强,可能适宜在中国北部更广泛的区域生存.     

Are some prepupae and pupae of male mealybugs and root mealybugs (Hemiptera,Coccoidea, Pseudococcidae and Rhizoecidae) mobile?

It is hypothesised here that some mealybug (Pseudococcidae) and root mealybug (Rhizoecidae) prepupae and pupae are mobile. The prepupa and pupa of the mealybug Promyrmococcus dilli Williams and the prepupa of the root mealybug Ripersiella malschae (Williams) are described and illustrated and their probable mobility is discussed. It is also suggested that the prepupae and pupae of the mealybug Macrocepicoccus loranthi Morrison can move rapidly on the leaves when disturbed.     

Susceptibility of Mocis latipes (Lepidoptera: Noctuidae) to Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae)

The susceptibility of larvae, prepupae, and pupae of the grass looper Mocis latipes (Guenée) to the entomopathogenic nematode Heterorhabditis bacteriophora (Poinar) NC strain was evaluated under laboratory conditions. Concentrations of 0, 5, 10, 20, 40, 60, and 120 nematodes per larva, applied in 1 ml of sterile-distilled water, were bioassayed, applying them to groups of 20 individuals of each instar, prepupa or pupa. Mortality was recorded daily for 5 d. All instars and the prepupal stage were the most susceptible to H. bacteriophora. Mortality ranged from 22.5 to 100%. Prepupae had 97.5-100% mortality starting at 10 nematodes per prepupa. Pupal mortality ranged from 27.5 to 41.3% as nematode concentration was increased. H. bacteriophora presented LC50 values that ranged between 5.26 and 37.66 nematodes per larva and LT50 values that ranged between 1.5 and 4.3 d. Results of this study suggest that H. bacteriophora has potential as a biocontrol agent against M. latipes.