A male fitness advantage to wing reduction in the oriental chinch bug,Cavelerius saccharivorus okajima (heteroptera: Lygaeidae)

A male fitness advantage to wing reduction was investigated for the oriental chinch bug, Cavelerius saccharivorus, which is wing dimorphic. Field surveys for the frequency of matings between wing morphs showed that the mating probability was much higher in brachypterous males than in macropterous males in the early breeding season. Brachypterous males copulated with not only brachypterous females but also macropterous females in this season. This led to a considerable rate (30%) of insemination of macropterous females just before emigration even in the early breeding season. A rearing experiment for the pre-reproductive period of females revealed that females mated with brachypterous males copulated and oviposited earlier than females mated with macropterous males. These results indicate that there is a fitness advantage to wing reduction in the males of C. saccharivorus in terms of the earlier sexual maturation.     

Locomotor activity in adult Pyrrhocoris apterus (Heteroptera) in relation to sex, physiological status and wing dimorphism

The pattern of locomotor (walking) activity was studied in adult males and females of short‐winged (brachypterous) and long‐winged (macropterous) morph of the flightless bug Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) under constant laboratory conditions. Walking activity was measured with a computerized video system and analysed with respect to sex, physiological status (reproduction, diapause and reproductive arrest of non‐diapause type) and wing dimorphism of the bugs. The largest duration was observed in the macropterous females with reproductive arrest of non‐diapause type (average 6 h per day) and the shortest duration in diapausing brachypterous females and males (average less than 2 h per day). This was reflected also in the overall time spent by walking during the first 14 days after imaginal ecdysis. The time spent by walking significantly increased in the macropterous morph as the bugs aged, whereas in diapausing brachypters the time spent by walking decreased with age. No linear relationship between walking activity and age was found in reproductive brachypterous morph. The bugs of all experimental groups moved mostly during the photophase and were almost inactive during the scotophase. Thus, walking activity in P. apterus is diurnal, irrespective of the wing morph, physiological status, sex and age. Contrary to the macropterous morph, where the locomotor activity of females during photophase was significantly higher than in males, no significant differences were found between the locomotor activities of brachypterous males and females. The observed differences in locomotor activity are discussed in relation to different roles of two wing morphs in the life history of this heteropteran.     

Wing morph-specific differences in the metabolism and endocrine control of reserve mobilization in adult males of a flightless bug, <Emphasis Type="Italic">Pyrrhocoris apterus</Emphasis> (L.) (Heteroptera)

The differences in the metabolism and endocrine control of reserve mobilization in long-winged (macropterous) and short-winged (brachypterous) males of a flightless firebug (Pyrrhocoris apterus) were studied. We found that protein content in the gut was significantly lower in 5–10 day-old macropterous males due to their fasting and higher in 28 day-old ones than in the same aged brachypterous counterparts as the result of renewed food intake. Overall protease activity was significantly lower in 10–14 day-old macropters, while an abrupt increase in the activity starting on day 21 after adult ecdysis was also associated with renewal of the food intake. The levels of carbohydrates in haemolymph were only slightly lower in 1–10 day-old macropterous males than in the same aged brachypters. However, more than twofold higher lipid content in haemolymph of 7–10 day-old macropterous males than in the same aged brachypterous males was found. Higher mobilization of lipid reserves from the fat bodies in macropterous males was accompanied by more intensive adipokinetic response and higher levels of adipokinetic hormone in the body. It is the first report of endocrine regulation of wing morph-related differences in the lipid mobilization in males of wing-polymorphic insects.     

稻飞虱翅型纯系后代个体的翅型分化对光周期变化不敏感

【目的】为了明确光周期和遗传因子在稻飞虱翅型分化中的作用, 研究了3种稻飞虱（褐飞虱Nilaparvata lugens、白背飞虱Sogatella furcifera和灰飞虱Laodelphax striatellus）翅型纯系或近纯系在不同光照时数下的翅型分化比率。【方法】以经过5~45代连续翅型筛选后的褐飞虱、白背飞虱和灰飞虱的长翅型和短翅型纯系或近纯系为材料, 在室内分别测定了其在长光照（16和20 h）、短光照(4~12 h)和正常光照(14 h) 3类光周期条件下饲养后, 雌、雄成虫中长翅和短翅个体出现的比率及存活率。【结果】白背飞虱和灰飞虱的长翅型纯系M♂×M♀或短翅型纯系B♂×B♀在不同光周期下的翅型比率均无显著差异（P>0.05）。褐飞虱短翅型近纯系B♂×B♀的雌虫短翅率和成虫总短翅率在不同光周期下也无显著差异（P>0.05）, 但雄虫短翅率在正常光照14 h和短光照4 h下显著高于长光照20 h下的（P<0.05）。当褐飞虱短翅型达到纯系后, 其后代翅型在6~16 h光照条件下无显著差异。褐飞虱长翅型近纯系M♂×M♀的后代虽有短翅个体出现, 但是雌虫和雄虫的各自短翅率在不同光周期下无显著差异（P>0.05), 仅总体短翅率在12 h光照条件下的显著高于16 h下的（P<0.05）。褐飞虱长、短翅型杂交筛选品系M♂×B♀的雌虫短翅率随光照时数的延长而升高; 灰飞虱杂交筛选品系M♂×B♀的短翅雄虫随光照时数的缩短而增多（P<0.05）, 但当筛选代次达到45代时, 这种趋势不再显著。3种稻飞虱长翅型和短翅型纯系或近纯系若虫的存活率会稍低于长、短翅型杂交后代的存活率, 但长、短翅型品系的存活率在6~16 h光照条件下差异不显著(P>0.05)。【结论】稻飞虱翅型分化对光周期的反应受飞虱本身遗传背景的影响, 翅型纯系后代个体的翅型分化对光周期变化不敏感。     

Systemic fungicides reduce the abundance of yeast-like symbiotes and the performance of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae)

Delphacodes kuscheli is the main vector of Mal de Río Cuarto, the most important viral disease of maize in Argentina. This planthopper harbours obligate fungal mutualists, known as yeast-like symbiotes (YLS), which play a key role in the host life cycle. Here, we evaluated the efficacy of six systemic fungicides, prothioconazole (P), prothioconazole & trifloxystrobin (PT), pyraclostrobin & epoxiconazole (PE), pyraclostrobin, epoxiconazole & fluxapyroxad (PEF), picoxystrobin & ciproconazole (PC), and tebuconazole (T) on the reduction of the abundance of YLS in nymphs and newly emerged adults, and the impact of such reduction on the vector performance. All fungicides, except PE, reduced the number of YLS in nymphs treated from 3rd instar five days after starting treatments. When 3rd instar nymphs were allowed to reach adulthood, the fungicides P, PT and PC caused the highest nymphal mortality, significantly reduced the number of YLS in newly emerged adults, lengthened development time and negatively affected morphometric variables of females. There was also a trend towards a higher occurrence of brachypters. In females, the fungicides P, PT and PC caused a greater reduction of YLS when nymphs were treated to these fungicides from 3rd instar compared with nymphs treated from 4th instar. In males, the YLS number was significantly less when nymphs were fed on plants treated with P, PT, PC, and T in 3rd instar. This showed that fungicide treatments caused a greater reduction of YLS when they were applied in early stages of development. Our results provide an effective method to reduce the abundance of YLS in D. kuscheli, contributing to understand the ecological role that these symbionts could be playing in the success of this maize planthopper pest.     

Adaptive significance of wing dimorphism in males ofNilaparvata lugens

The trade-offs associated with macroptery in males were investigated in a wing-dimorphic planthopper, Nilaparvata lugens (Stål) (Delphacidae, Hemiptera). Developmental time of brachypters was significantly shorter than that of macropters across a wide range of population densities, while no within-population differences between wing morphs in body weight were found. In mating experiments, brachypterous males 12 to 24 h old were almost three times more successful in competition for females than macropterous males of the same age, while in five days old males, macropters were twice as successful as brachypters. In competition for females involving direct body contact between males, brachypterous and macropterous males were equally successful. It is suggested that macroptery and delayed peak in sexual activity in males may both be influenced by the titre of juvenile hormone, as is known from females. The combination of prolonged development and delayed maximum competitive ability for mates, associated with macroptery, is likely to be disad vantageous, representing probably a penalty associated with macroptery in males in undisturbed habitats.     

Temporal pattern of feeding activity in the firebug Pyrrhocoris apterus and its relation to sex, wing dimorphism and physiological state of adults

Abstract.  The present study tested whether the pattern of feeding activity in the firebug Pyrrhocoris apterus (L.) is sex- and wing morph-related, diurnal or nocturnal, as well as whether the feeding rhythm persists in constant darkness. Temporal patterns of feeding activity are analysed in macropterous and brachypterous adults reared under long-day (LD 18 : 6 h) and short-day (LD 12 : 12 h) photoperiods, and in adults transferred to constant darkness. In females, the total feeding activity is highest in long-day reproductively active brachypters, intermediate in short-day diapausing brachypters, and lowest in macropters; the differences among males are substantially smaller. Although the total feeding activity of macropterous males is higher than in macropterous females, no sex-related differences are found in feeding activity of diapausing and reproductively active brachypters. The frequency of feeding exhibits sex-related differences, with obviously higher values in males. Mean feeding periods of macropterous and reproductively active brachypterous males are shorter than in females of the same wing morph. Mean interfeeding periods are longest in macropters, intermediate in diapausing brachypters, and shortest in reproductively active brachypters, and always lower in males than in females. The study shows that the feeding activity of P. apterus adults is age-, sex- and wing morph-related, and exhibits a diurnal pattern, except in reproductively active brachypterous females. The latter do not express a clear diurnal rhythm of feeding, presumably because of interactions with cycles of egg development and oviposition. The persistence of diurnal rhythm of feeding activity in short-day brachypterous females transferred to constant darkness indicates an endogeneity of this rhythm in P. apterus .     

Genetic correlation of wing polymorphism between females and males in the oriental chinch bug,Cavelerius saccharivorus Okajima (Heteroptera: Lygaeidae)

Genetic correlations of the wing form and the relative wing length between females and males were estimated in the oriental chinch bug, Cavelerius saccharivorus, by calculating the correlation between the sexes of the proportion macropterous or the mean relative wing length in full-sib families obtained from different wing forms of parents emerged in a high density population. There was a significantly positive genetic correlation between the sexes in both the proportion macropterous and the mean relative wing length. However, the appearance rate of macropters tended to be much lower in males than in females under the rearing conditions which promote the appearance of macropters. This was evident especially in the offspring of brachypterous parents. These indicated that in C. saccharivorus the wing polymorphism of males is not a simple result of the genetic correlation of wing morphology between the two sexes. It was considered that both of the female and male fitness advantages to wing reduction, as well as the genetic correlation between the sexes, would influence the evolution of wing polymorphism in this species.     

The effect of adult feeding on the fecundity,weight loss and survival of the pine beauty moth,Panolis flammea (D&S)

Summary Adult females of the pine beauty moth, Panolis flammea, fed on a saturated honey solution, laid significantly more eggs than those individuals given water only or not fed at all.At 20°, the longevity of both male and female moths was significantly increased when they were supplied with a food source. At 10° fed male months were not significantly longer lived than unfed moths. Fed female moths at 10° were however, significantly longer lived than unfed individuals. At 20°, fed male moths lived longer than fed females (8.17 days as compared with 5.95 days). At 10°, fed female moths lived longer than fed males (16.00 days compared with 11.41 days).At 20°, weight loss in unfed females over the reproductive period was proportional to the number of eggs laid and the survival time of the individual. In fed females, no significant weight loss occurred over the reproductive period, irrespective of the number of eggs laid or the longevity of the individual.Egg production, even in fed females, over the life span of an individual was only a fifth of the total eggs present in the reproductive tract at eclosion.It is concluded that adult females of P. flammea are likely to require an extra external food source to achieve their full reproductive potential.     

Temperature-dependent wing dimorphism in a Japanese strain of tobacco thrips, Frankliniella fusca (Thysanoptera: Thripidae)

A Japanese strain of Frankliniella fusca (Hinds) was reared under 4 temperature and two photoperiodic conditions on leaves of green bean. On the basis of the ratio of fore wing length to head width (RWL) of adult thrips we defined individuals with RWL above 3.7 as macropterous forms and those with RWL below 3.5 as brachypterous forms. Percentages of macropterous individuals among females were 0 % at 18 °C, 10.6 % at 22.5 °C, 21.8 % at 25 °C, and 77.5 % at 27.5 °C, under 15L–9D. The proportion of macropters among females developing under 15L–9D was no different from that among those developing under 10L–14D. These results indicate that photoperiod does not affect wing form, and suggest that the proportion of macropterous females increases with temperature. Although development time from hatching to adult eclosion, adult pre-oviposition period, adult head width, adult longevity, total fecundity, and fecundity schedule were compared between macropterous and brachypterous females developing at 25 °C and 15L–9D, these traits were not significantly different between the wing forms. Males of this experimental strain were all brachypterous.     

Differences in adipokinetic response of Pyrrhocoris apterus (Heteroptera) in relation to wing dimorphism and diapause

Three experimental groups of adult females (reproductive and diapausing brachypters, and macropters with reproductive arrest) of Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) from a temperate population were analysed for their adipokinetic responses. The adipokinetic response, expressed as an increase of haemolymph lipids after injection of adipokinetic hormone from Locusta migratoria (Lom-AKH-I), was assessed in relation to age, wing dimorphism and type of reproductive arrest. Two pmols of Lom-AKH-I were used for determination of adipokinetic responses. The increase of haemolymph lipids in all experimental groups of females induced by this dose of the hormone was comparable with that induced by crude extract of the bug’s own corpora cardiaca. The level of adipokinetic response after injection of 2 pmol of Lom-AKH-I was significantly higher in macropterous and diapausing brachypterous females than in reproductive brachypterous females. However, significantly higher contents of haemolymph lipids in control macropterous females than those found in the control reproductive and diapausing brachypterous females of the corresponding age revealed wing-morph-related differences in lipid metabolism. The observed wing morph- and diapause-related differences in the content of haemolymph lipids and adipokinetic response, respectively, are discussed in relation to the different roles of two wing morphs in the life history of this heteropteran.     

Differential allocation of protein resources to flight muscles and reproductive organs in the flightless wing-polymorphic bug, <Emphasis Type="Italic">Pyrrhocoris apterus</Emphasis> (L.) (Heteroptera)

Differences in the growth of dorsolongitudinal flight muscles and gonads in 1–28 days old long-winged (macropterous) and short-winged (brachypterous) adults of the firebug (Pyrrhocoris apterus L.) and the resource allocation to these organs were studied by means of total protein analysis. We found predominant allocation of food resources to flight muscles compared to reproductive organs in both macropterous males and females during the first 5 days of adult life. Subsequent histolysis of developed flight muscles coincided with increased total protein content in some reproductive organs. Initiation of intensive food intake after starvation or application of higher dose of methoprene on macropterous adults changed the resource allocation in favour of growth of reproductive organs and induced precocious histolysis of flight muscles. It indicates an involvement of juvenile hormone in wing morph-related differential allocation of resources in the bug. Increased total protein contents in the ovaries and accessory glands of starved macropterous females and males treated with methoprene, respectively, indicate that proteins derived from the methoprene-induced histolysis of the flight muscles are re-utilized for the growth of the reproductive organs. It is the first report of persistence of differential resource allocation to flight muscles and reproductive organs in the wing-polymorphic insects with non-functional macropterism.     

First report of wing dimorphism in the genus Orthomus (Coleoptera: Carabidae)

Wing polymorphism has been reported for several carabid beetles. Traditionally, a great number of ecological and evolutionary studies have focused on this peculiarity, which has implications on dispersal power. Research based on Orthomus berytensis specimens from two sampling areas of Tenerife (Canary Islands, Spain) has shown that this species exhibits a wing dimorphism, instead of being brachypterous. This makes O. berytensis the first Orthomus wing dimorphic species to date. Statistical differences in macropterous percentage between both sexes and localities were found. Also, a sexual dimorphism in elytra length and width was found, both being higher in females.     

褐飞虱翅型分化的组织学研究

利用石蜡切片的方法,观察并比较了褐飞虱Nilaparvata lugens (Stal)长翅型和短翅型纯系各龄若虫及成虫的翅芽和间接飞行肌的发育情况。发现在4龄的第8h以后间接飞行肌就开始分化,长翅型若虫的间接飞行肌正常发育而短翅型若虫间接飞行肌的发育则被抑制。在5龄初始时方可明显观察到翅芽分化,短翅型若虫前翅芽细胞增殖速度明显慢于长翅型,并且其后翅芽停止发育。本文还比较了长翅型雌、雄性个体之间间接飞行肌的发育情况。     

三种稻飞虱翅型分化的遗传分析

为了明确褐飞虱Nilaparvata lugens、 白背飞虱Sogatella furcifera和灰飞虱Laodelphax striatellus 3种稻飞虱翅型分化的遗传规律与差异, 采用翅型筛选与杂交遗传的实验方法, 研究了3种飞虱在秧苗期水稻上的翅型选择响应与杂交遗传规律。结果表明： 3种稻飞虱的翅型具有较强的选择响应, 并且长翅型纯系在白背飞虱中最易筛选得到, 灰飞虱的次之, 而褐飞虱的最难。3种稻飞虱的长翅(M)雄虫与短翅(B)雌虫配对(M♂×B♀)筛选3~5代后, 95%~100%的雄虫和雌虫分别稳定为长翅型和短翅型。筛选和杂交实验结果表明, 褐飞虱的翅型决定基本符合常染色体上的一对等位基因调控的从性性状遗传规律, 雄虫中长翅为显性, 而雌虫中短翅为显性。翅型的表型还受除基因型外的其他条件的影响, 利用长翅雄虫与长翅雌虫后代中出现的极少数的短翅雄虫与短翅雌虫进行配对, 其后代中各翅型出现的比率与长翅雌虫和长翅雄虫配对的无显著差异; 同样, 在短翅雄虫与短翅雌虫配对的后代中也有相同的结果。白背飞虱和灰飞虱在该筛选条件下很少有短翅雄虫出现, 两者翅型的遗传调控较为相似, 可用由两对等位基因控制的性状来解释筛选和杂交实验的结果, 其中一对等位基因位于性染色体上, 调控雄性的翅型, 且长翅为显性; 另一对位于常染色体上, 调控雌性的翅型, 且短翅为显性。据此认为, 3种飞虱翅型决定基因的显隐性在不同性别间的差异, 以及翅表型与基因型的不一致性, 是稻飞虱种群在不同条件下均可灵活调控翅型的重要遗传机制。     

Seasonal changes in the flight apparatus of winged females and sexual males of the aphid <Emphasis Type="Italic">Tuberculatus quercicola</Emphasis> (Hemiptera: Aphididae)

Tuberculatus quercicola (Matsumura) feeds on Quercus dentata Thunberg, and has mutualistic interactions with ants. Tuberculatus quercicola has two winged morphs in its life cycle, winged females appear in summer and sexual males appear in autumn. Previous studies have shown that wing loading (ratio of body volume to wing area) is higher for the winged females, because of ant attendance, resulting in extremely low dispersal. It is known that the nutritional quality of host plants is high in spring and autumn, when leaves are growing or senescent, and low in summer when leaves are mature. This study examined the effects of seasonal plant deterioration on the development of flight apparatus (wing size and flight muscle) of winged females and males. Moreover, field intercept traps were used to examine the extent of dispersal of males. The results showed that seasonal plant deterioration affected development of the flight apparatus of winged females, particularly flight muscle. Flight muscle development was significantly higher in winged males in autumn than in winged females. However, winged males were not caught in any of the traps. The different resource allocation to the flight apparatus of winged females and males is discussed.     

Effects of elevated CO2 and transgenic Bt rice on yeast‐like endosymbiote and its host brown planthopper

The effects of elevated CO₂ (750 vs. 375μl/l) on population abundances and metabolism enzyme of AChE and protective enzymes of SOD, POD and CAT in brown planthoppers (BPH) Nilaparvata lugens, and on size and abundances of yeast‐like endosymbiotes (YLES) were studied as BPH fed Bacillus thuringiensis (Bt) rice expressing pure Cry1Ab after successively two generations in open‐top chambers. The results indicated that: (1) Brachypterous and macropterous subpopulations and total population increased with elevated CO₂. Significant increases were found as BPH fed non‐transgenic rice while only significant increase as macropterous‐BPH fed Bt rice. (2) The responses of brachypterous and macropterous‐BPH to Bt rice were different. Brachypterous‐subpopulation significantly decreased (13.6%) while macropterous ones significantly increased (43.8%) as fed Bt rice relative to non‐transgenic rice at elevated CO₂. (3) Elevated CO₂ only significantly inhibited AChE activity as brachypterous‐BPH fed non‐transgenic rice. Significant increases in POD and SOD, and significant decrease in CAT were found as brachypterous‐BPH fed Bt rice, while significant increases in CAT and significant decrease in POD were also observed as fed non‐transgenic rice in elevated CO₂ relative to ambient CO₂. (4) Bt rice significantly inhibited POD and SOD activity at ambient CO₂, while only significantly enhanced SOD activity at elevated CO₂. (5) Elevated CO₂ significantly decreased YLES per mg/head of brachypterous‐BPH females while only significantly decreased YLES per mg/head as brachypterous‐BPH males fed Bt rice. And there were significant differences in YLES width or length between females and males. Elevated CO₂ can markedly affect the symbiosis relationship between YLES and BPH through the bottom‐up forcing on BPH physiological metabolism. And the damage inflicted by BPH on rice, irrespective of the presence of insecticidal genes, is predicted to be higher at elevated CO₂. Furthermore, transgenic Bt rice can also exacerbate emigrating‐macropterous‐BPH occurring especially at elevated CO₂.     

Developmental time,longevity, reproductive capacity and sex ratio of the mealybug parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Key biological parameters of Anagyrus sp. nr. pseudococci reared on the citrus mealybug Planococcus citri (Risso) were determined. The mean longevity of female wasps was 21.1 days, the median lethal time (LT₅₀) was 22 days, the mean number of offspring per female was 30.2 wasps and the sex ratio of the progeny was slightly male biased (1.1 males per female). Wasps fed with water showed a significantly lower longevity compared to that recorded for wasps fed with syrup for bee nutrition mixed with water. The longevity of female wasps was significantly higher compared to males when the syrup-water solution was provided as food. Longevity was significantly higher for female wasps fed with syrup and water in comparison with those exposed to host mealybugs. The mean development time of female and male wasps was 14.7±0.1 and 14.5±0.1 days, respectively.     

Relation between age–sex classes and dietary selection of wild Japanese monkeys

Dietary selection by wild Japanese monkeys (Macaca fuscata yakui Kuroda) was examined in relation to body size. The monkeys were classified into three age–sex categories: adult males, adult females and immatures excluding suckling infants. Time spent feeding did not differ between age–sex classes, although time spent moving was longer in lighter classes. Heavier individuals fed relatively more on mature leaves, while lighter individuals fed on insects more frequently. Mature leaves were more abundant but had lower energy content than other food items in the forest. Heavier monkeys seemed to feed on greater amounts of lower quality food in this species. This finding agrees with the Jarman–Bell principle on ungulates.     

Consequences of stress induced by heat on fitness of Delphacodes kuscheli and its yeast‐like endosymbionts

The planthopper Delphacodes kuscheli is the main vector of Mal de Río Cuarto virus in Argentina, disease that severely affects maize production. In this study, we investigated the effects of heat stress on fitness traits and on the number of its obligate yeast‐like symbionts (YLS). The exposition of newly‐hatched nymphs to 35°C for 3 days, a well‐known procedure used to reduce the number of YLS in planthoppers, was applied. To compare different fitness components between control and heat‐treated insects, we estimated nymphal instars development time, nymphal survival, adult body length, longevity, fecundity and fertility. Also, correlates of fitness, as proportion of sexes and wing forms of the emerging adults, were evaluated. In heat‐treated group, the nymphal developmental time increased due to an increase in the fifth instar duration, and the nymphal survival, body length of adults and fecundity were reduced when compared to control. There was a significant association between treatments (control and heat‐treated insects) and wing morphs. The heat treatment successfully reduced the number of YLS in third instar nymphs of D. kuscheli. Our results revealed the negative effect of heat stress on development, survival and reproduction of D. kuscheli and on the load of its YLS endosymbionts suggesting that YLS could play a crucial role in the development and reproduction of these planthoppers.