Transmission of the pine wood nematode Bursaphelenchus xylophilus through feeding activity of Monochamus galloprovincialis (Col., Cerambycidae)

Abstract:  Transmission of the pinewood nematode (PWN) Bursaphelenchus xylophilus (Steiner & Bührer) Nickle to Pinus pinaster Aiton branches through feeding wounds of its vector in Portugal, Monochamus galloprovincialis Olivier, was studied under laboratory conditions. All the B. xylophilus -infected beetles transmitted nematodes to branches they fed. The transmission was more frequent during the first 6 weeks after emergence, with transmission peaks during the second and the sixth week. The adult M. galloprovincialis transmitted nematodes for a mean of 5 weeks, independently of the beetle's sex or longevity. No relation was found between beetle feeding intensity and effective transmission of B. xylophilus to the branches. The nematode transmission ceased after the ninth week, even in insects which still had B. xylophilus on their bodies. The longevity of the nematode-free insects (control group) was slightly higher than the B. xylophilus -infected beetles, although with no significant difference. The results emphasize the necessity to control the immature stages of M. galloprovincialis prior to emergence and develop efficient strategies to capture and eliminate the recently emerged beetles, as majority of the nematode infection of healthy pine trees occurs during a short period of few weeks after beetle emergence.     

Body size as an indicator of parasitoid quality in male and female Anagyrus kamali (Hymenoptera: Encyrtidae)

The parasitoid Anagyrus kamali Moursi was recently introduced into the Caribbean as a biological control agent against the hibiscus mealybug, Maconellicoccus hirsutus Green. In the laboratory, parasitoid size, as measured by left hind tibia length, was positively correlated with several indicators of the parasitoid's fitness: longevity, mating preference, fecundity, reproductive longevity, progeny emergence and sex-ratio. When fed ad libidum with honey drops, large male parasitoids lived significantly longer (29.1 +/- 6.5 days) than small ones (18.4 +/- 5.7 days). Large females also lived significantly longer (35.4 +/- 10 days) than small females (27.9 +/- 9.6 days). Females showed no significant mating preference between large and small males. Lifetime fecundity was positively correlated with the size of adult females and ranged from 37 +/- 21 eggs for small females to 96 +/- 43 eggs for large ones. The reproductive longevity, daily oviposition rate, and number of progeny were also higher among large parasitoids. The sex ratio of progeny from small female parasitoids was higher (0.76 +/- 0.24) than that of large individuals (0.47 +/- 0.18).     

Temperature-dependent oviposition model of Scopula subpunctaria (Lepidoptera: Geometridae)

Scopula subpunctaria, is one of important defoliating insect pests of tea plants in China. However, the effect of temperature on its longevity and fecundity had not been reported, and the temperature-dependent oviposition model is lacking. The reproductive characteristics of S. subpunctaria were investigated under eight constant temperatures (13, 16, 19, 22, 25, 28, 31, and 33℃), with a 14L: 10D photoperid and 65–85% RH. The results showed that temperature significantly influence oviposition period, longevity, and fecundity of S. subpunctaria. The mean longevity of female adults increased from 10.8 days (33℃) to 33.9 days (13℃). Male lived shorter than female did. The mean longevity of males was shortest at 33℃ (8.1 days) and longest at 23.8℃ (17.6 days). Total fecundity of S. subpunctaria females ranged from 15.4 eggs at 33℃ to 279.9 eggs at 22℃. The temperature-dependent oviposition model of S. subpunctaria was constructed based on four sub-models (developmental rate model, total fecundity model, oviposition rate model, and survival rate model). The results of this study would be helpful in forecasting and predicting population occurrence of S. subpunctaria in tea plantations.     

Attractive responses by Monochamus galloprovincialis (Col., Cerambycidae) to host and bark beetle semiochemicals

Abstract:  The pine sawyer Monochamus galloprovincialis is the European vector of the recently introduced pine wood nematode. This nematode is the causal organism of pine wilt disease, a serious tree killer in East Asia. Efficacious baits and traps to monitor and control this beetle are now required. The effect of bark beetle ( Ips spp.) pheromone components, released individually (ipsenol) or in blends (ipsenol, ipsdienol, cis -verbenol and methyl-butenol), together with host volatiles (turpentine or α -pinene and ethanol) on M. galloprovincialis trap catches has been studied in Spain. A kairomonal response by male and female of M. galloprovincialis to Ips semiochemicals was found. Beetles were more attracted to host blends supplemented with bark beetle pheromones than to host volatiles alone. Ipsenol alone was attractive to pine sawyers, and was synergistic with α -pinene and ethanol. The full blend of the four Ips semiochemicals and the host compounds was highly attractive. Multiple-funnel traps were as effective as black cross-vane traps in capturing this insect when the escape of trapped beetles was prevented. Trapping of non-target bark beetle predators was also evaluated. The trogossitid Temnochila coerulea and clerid Thanasimus formicarius were kairomonally attracted to and killed in traps baited with bark beetle pheromones. These results suggest that effective monitoring of M. galloprovincialis would be possible by baiting any of these traps with host volatiles and Ips semiochemicals, but reduction of the lure components and trap modification to minimize impact on predators should be considered.     

Reproductive activity of Coelomera lanio (Coleoptera: Chrysomelidae)

The Cecropia spp. (Cecropiaceae) trees are attacked by several insects; among them, Coelomera lanio (Dalman) (Coleoptera: Chrysomelidae). The reproductive behavior of C. lanio was studied under laboratory conditions (12 hour photoperiod, 24.1 +/- 0.1 degrees C and mean relative humidity 67.7 +/- 0.6%), in Vi?osa, Minas Gerais, Brazil. The insects were reared in cages and in Petri dishes and fed leaves of Cecropia pachystachya Trec. Reproductive activity began 5.8 +/- 0.2 days after adult emergence and mean copulation time was 2.5 +/- 0.1 min. The female began oviposition only after 25.7 +/- 0.7 days. Each female laid a mean of 4.7 +/- 0.4 times (range 1-9). The mean number of eggs per oviposition and female was 129.2 +/- 2.4 and 587.4 +/- 92.1 respectively, and the time between egg-layings averaged 16.3 +/- 0.8 days.     

Delayed mating reduces reproductive output of female European grapevine moth,Lobesia botrana (Lepidoptera: Tortricidae)

Virgin females of Lobesia botrana Denis & Schiffermüller were mated at ages of 1, 3, 5, 8, 12 and 16 days and the effect of mating delay on reproductive output assessed. Delayed mating did not affect female mating success but fertilization was reduced in 16-day-old females. Increased mating delays substantially affected daily oviposition pattern and resulted in a significant reduction of both fecundity and fertility, so that mean number of viable eggs laid decreased from 150 to 22 in 1- and 16-day-old mated females, respectively. Heavier females were more constrained than lighter ones by mating delays and female reproductive efficiency (no. viable eggs/female body weight) was also significantly reduced. Female longevity significantly increased and oviposition period gradually declined with mating delay. The number of viable eggs was positively correlated with both female weight and oviposition period; female longevity and female weight were also significantly correlated. However, the significance of these correlations declined with increased mating delay. Results overall indicated that mating delay drastically reduces female L. botrana reproductive output. The implications of delayed mating of females are discussed from an ecological perspective in relation to L. botrana control using mating disruption.     

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。     

Reproductive responses to photoperiod and temperature by diapausing and nondiapausing populations of Sesamia nonagrioides Lef. (Lepidoptera − Noctuidae)

Abstract.  The influence of long- and short-day cycles on ovipostion and egg hatch of the corn stalk borer, Sesamia nonagrioides were investigated at a range of temperatures. Oviposition was suppressed when insects are exposed to long days through their immature stages and then transferred to short days after mating. Moreover, mean oviposition and egg hatch increased from 15 to 27.5 °C, whereas oviposition declined significantly at 30 °C at both photoperiodic regimes. Females derived from a diapausing population exposed to long days after mating showed a significantly higher egg production compared to females derived from a nondiapausing population. However, when females from a diapausing population were left to oviposit under short days, fewer eggs were produced compared to those exposed to long days after mating. Thus, photoperiod appears to affect reproductive traits of this species in a quantitative manner. Larval diapause duration is positively correlated with fecundity of the adults. There is also a positive correlation between pupal weight of individuals derived from a diapausing population and the postdiapause fecundity of adults.     

How do sex and sexual maturation influence the response of Monochamus galloprovincialis to host odours?

Finding the right host plant for feeding and reproduction is crucial for herbivorous insects. Usually they need both visual and olfactory cues to locate and colonize their host plants, but the respective role of the two types of stimuli is difficult to disentangle. Model plants mimicking the shape and colour of natural hosts, combined with odours dispensers, are relevant tools for this purpose. We used dummy pines and cut branches of natural pines to investigate host attraction in Monochamus galloprovincialis, the insect vector of the pine wood nematode in Europe. We compared the behavioural response of males and females, sexually mature or immature, in a large climatic chamber and in an olfactometer. Immature females were significantly attracted by the sole odours released by pines. Immature males and mature males and females needed a combination of visual and olfactory cues to find the host tree. These findings suggest that beetles use both visual and chemical cues to locate pine trees but that relevant stimuli likely differ between beetles of different sex and sexual maturation status. Our results question the implementation of precautionary clear‐cuts around infested trees for limiting the spread of PWN.     

Mild winter temperatures reduce survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae)

We tested the hypothesis that mild winter temperatures are detrimental to the survival and reproductive potential of insects. We measured survival, body size, and potential fecundity of a freeze tolerant insect, the goldenrod gall fly (Eurosta solidaginis), after overwintering in the laboratory for ~3 mo. frozen at -22 degrees C, unfrozen at 0 degrees C, or unfrozen at 12 degrees C. Larvae held at 12 degrees C suffered high mortality (70%) and relatively low potential fecundity as adults (mean+/-SEM=199+/-11 eggs/female), while those held at 0 degrees C had both low mortality (11%) and high potential fecundity (256+/-15 eggs/female). Freezing (-22 degrees C) increased mortality (30% overall) but did not significantly reduce fecundity (245+/-13 eggs/female). Egg length and width were constant regardless of treatment group or female body size. Analysis of covariance indicated that reduced fecundity in the 12 degrees C group was related to reduced larval body weight following treatment. Patterns of larval weight loss in the experimental treatments were generally correlated with previous reports of latitudinal trends in weight loss through the winter. We conclude that mild winter temperatures may be detrimental to some overwintering insects, particularly species that do not feed following winter diapause. Low temperature and even freezing are beneficial, allowing conservation of energy reserves to maintain high survival and potential fecundity.     

Effect of Monochamus carolinensis on the Life History of the Pinewood Nematode,Bursaphelenchus xylophilus

The development of Bursaphelenchus xylophilus in pine wood infested with and free of Monochamus carolinensis was investigated. Formation of third-stage dispersal juveniles occurred in the presence and absence of pine sawyer beetles. The proportion of third-stage dispersal juveniles in the total nematode population was negatively correlated with moisture content of the wood. Formation of nematode dauer juveniles was dependent on the presence of the pine sawyer beetle. Dauer juveniles were present in 3 of 315 wood samples taken from non-beetle-infested Scots pine bolts and 81 of 311 samples taken from beetle-infested bolts. Nematode densities were greater in wood samples taken adjacent to insect larvae, pupae, and teneral adults compared with samples taken from areas void of insect activity. Nematodes recovered from beetle larvae, pupae, and teneral adults were mostly fourth-stage dauer juveniles, although some third-stage dispersal juveniles were also recovered. Dauer juvenile density was highest on teneral adult beetles.     

Comparative demography of the sand fly Phlebotomus papatasi (Diptera: Psychodidae) at constant temperatures.

We measured reproductive and population parameters of adult sand flies, Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae), in environmental chambers maintained at temperatures of 15, 18, 20, 25, 28, and 32 degrees C. Based on cohorts of adults at each temperature regime, horizontal life tables were constructed using established laboratory colonies initiated from specimens collected in Sanliurfa Province, southeastern Anatolia, Turkey. The fecundity and longevity of the insects were both highly variable, depending on the temperature. At 15 degrees C, all of the cohort females died before laying eggs, so the construction of a life table for this temperature regime was not possible. Within a range of 18 to 32 degrees C, the longevity of adult P. papatasi increased as the temperature decreased; at 15 degrees C, the mean survival times of females and males were 19.04 +/- 6.94 days (9-35) and 17.84 +/- 7.11 days (9-33), respectively. While the highest number of eggs was found in the cohort at 28 degrees C (44.08 +/- 7.79), this was only 3.60 +/- 1.55 in the cohort at 32 degrees C and 2.8 +/- 0.9 in the cohort at 18 degrees C. This result showed that extreme temperatures negatively affect the fecundity of this species. The cohort reared at 28 degrees C exhibited the highest intrinsic rates of population increase (r(m)) for P. papatasi. The r(m) ranged from 0.098 at 28 degrees C to 0.007 at 18 degrees C. The cohort placed at 28 degrees C was found to be significantly different (P < 0.01) from the other cohorts producing the fewest progeny in terms of net reproductive rate, R(0), (15.87). The values for mean generation time (T) were estimated to vary from 36 days to 271 days depending on temperature. Principal Component Analysis (PCA) confirmed results from the previous studies that the cohort at 28 degrees C orientated and clustered as a distinct group along the first two PCs.     

Effects of fenoxycarb on ovarian development, spring fecundity and longevity in winterform pear psylla

The insect growth regulator fenoxycarb prompts ovarian development in diapausing winterform pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae). We applied fenoxycarb to caged psylla in September, November, and December to test whether premature ovarian development reduced overwintering survival, spring fecundity, or spring longevity. Fenoxycarb prompted ovarian development in all treated psylla, with the largest effects occurring in the September-treated insects. Recovery of live psylla in spring was 46–95% in treated insects and 72–92% in controls; overwintered insects from the fenoxycarb treatment survived field temperatures below –20°C despite having had mature ovaries. Fecundity and longevity of psylla were the same in treated and untreated insects, indicating that overwintering with mature ovaries did not cause reduced spring egglaying capacity. Several treated insects each deposited over 1900 eggs and survived more than 120 days. Due to their more advanced development, treated insects had higher oviposition rates than controls during the first 5 days after removal from the field. The largest impact on spring fitness was due to the effects of fenoxycarb on egg hatch. Eggs deposited on clean foliage by September-treated females were less likely to hatch than eggs deposited by controls, suggesting that fenoxycarb affected developing eggs within the female. Prospects for using fenoxycarb in fall to control pear psylla appear to be limited.     

Comparative Analysis of the Reproductive Attributes of Three Commercially-Produced Trichogramma Species (Hymenoptera: Trichogrammatidae)

The reproductive attributes of commercially-produced Trichogramma platneri, T. minutum and T. pretiosum reared from eggs of both Ephestia kuehniella and Sitotroga cerealella were monitored at 25 C. The age-specific fecundity, longevity and progeny sex ratio and adult size were determined for individual females from all six combinations of Trichogramma and rearing host, using E. kuehniella as the experimental host. Rearing host had a significant influence on the lifetime fecundity, 3-day fecundity and longevity of all three Trichogramma species. In general, the performance of T. minutum and T. pretiosum was better when reared from S. cerealella, but that of T. platneri was superior when reared from E. kuehniella. The lifetime fecundity of the Trichogramma species was linearly related to longevity and the ranking between species was T. pretiosum > T. minutum > T. platneri. The age-specific pattern of oviposition for T. platneri was distinctly precocious, with 40% of its lifetime fecundity oviposited on the first day, in contrast to 17-24% for the other two species. Progeny sex ratio over the lifetime of the Trichogramma females was slightly male biased and differed significantly from 0.5 for T. minutum and T. platneri. Daily sex ratio for parasitoids reared from the most productive rearing host was female biased only for the first day of oviposition for T. platneri in contrast to the first 5-6 days of oviposition for the other two species. There was little evidence that any of the reproductive attributes of these Trichogramma species, reared from small host eggs, was dependent on the size of the adult females.     

Transmission of the Pinewood Nematode, Bursaphelenchus xylophilus,to Slash Pine Trees and Log Bolts by a Cerambycid Beetle,Monochamus titillator, in Florida

Field-collected adults of the southern pine sawyer, Monochamus titillator (F.) (Coleoptera: Cerambycidae), naturally infested with fourth-stage juveniles (dauerlarvae) of the pinewood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1970, were maturation fed on excised shoots of typical slash pine, Pinus elliottii Engelm. var elliottii, for 21 days. During August 1981, a male and female adult beetle were held in a sleeve cage placed on the terminal of a side branch of each of seven replicate, healthy 10-year-old slash pine trees. All seven branch terminals showed evidence of beetle feeding on the bark after 1 week, and pinewood nematodes were present in wood samples taken near these feeding sites. Four of the seven trees showed wilt symptoms in 4-6 weeks and died about 9 weeks after beetle feeding. Pinewood nematodes were recovered from the roots and trunks of the dead trees. Each of seven replicate slash pine log bolts was enclosed in a jar with a pair of the same beetles used in the sleeve cages. After 1 week, wood underlying beetle oviposition sites in the bark of all replicate log bolts was infested with the pinewood nematode.     

Oviposition model of overwintered adult Tetranychus urticae (Acari: Tetranychidae) and mite phenology on the ground cover in apple orchards

The phenology of overwintered Tetranychus urticae was studied on the ground cover in apple orchards in the early season, and an oviposition model of overwintered adults was developed. The movement of overwintered adults from trees to ground cover started from mid-March and continued until mid-April. One life cycle from eggs to new adults (the 1st generation adults) on the ground cover was from late March to early May. The longevity and fecundity of overwintered T. urticae were affected largely by temperature. The longevity ranged from 46.6 days at 10 degrees C to 6.5 days at 35 degrees C. The total fecundity was minimum (0.2 eggs) at 10 degrees C and maximum (45.5 eggs) at 25 degrees C. The relationship between total fecundity and temperature was described well by a nonlinear equation. The cumulative age-specific oviposition rate was described well by the two-parameter Weibull function. The overall adult survival exhibited a reverse logistic curve. Three temperature-dependent components, age-specific cumulative oviposition rate, temperature-dependent total fecundity and age-specific survival rate functions, were incorporated into an oviposition model. The oviposition model simulation described the occurrence pattern of eggs laid by overwintered T. urticae on the ground cover in apple orchards relatively well.     

Argyrotaenia sphaleropa (Meyrick) (Lepidoptera: Tortricidae) in citrus in the State of Paraná, Brazil

Argyrotaenia sphaleropa (Meyrick) is associated with various fruit species in South America. This tortricid was first detected in citrus, Citrus sinensis (L.) Osbeck, in Brazil, in commercial groves in northern Paraná, during the 1994/95-crop season. The aim of this work was to study the biology of this lepidopteran under laboratory conditions (28 +/- 2 degrees C, 70 +/-10% UR, 14h photofase) using the citrus cultivar Pêra. Larvae obtained from egg masses collected in a commercial citrus grove in Rolandia, PR, were individually placed on citrus terminal leaves inside glass shell vials (8.5 x 2.5 cm) until adulthood. A male and a female moth were then transferred to acrylic cages (13 x 10 cm) containing inside a bouquet made with new citrus flush to serve as oviposition substrate. Adults were fed daily with a 10% honey solution. The biological parameters evaluated were duration of development of egg, larval and pupal stages; pupae weight; duration of pre-oviposition and oviposition periods, fecundity and longevity. The length of the egg to adult stage was around 36 days. The pre-oviposition period was almost two days, the oviposition period approximately ten days and the embryonary period around six days. Adult longevity was almost 15 days for females and nine days for males, and the lifetime fecundity was slightly over 180 eggs.     

Biological studies of Oligonychus punicae (Acari: Tetranychidae) on grapevine cultivars

Life cycle, fecundity and longevity of the avocado brown mite, Oligonychus punicae (Hirst), were studied on six grapevine cultivars (Tucupita, Villanueva, Red Globe, Sirah, Sauvignon and Chenin Blanc), under laboratory conditions at 27 +/- 2 degrees C, 80 +/- 10% RH, and L12:D12 photoperiod. Mite-infested leaves were collected from vineyards, placed in paper bags and taken to the laboratory. A laboratory mite culture was established using the grape cultivar Criolla Negra as host plant. To elucidate potential effects on avocado brown mite parameters, we assessed levels of secondary metabolites, such as alkaloids, flavonoids, tannins and polyphenols, of leaves of the six grape cultivars, as well as the thickness of the adaxial cuticle-epidermis. The life cycle of O. punicae differed among cultivars with average values ranging between 8.2 days on Tucupita leaves and 9.1 days on Sirah. Relatively high fecundity was found on Tucupita leaves (2.8 eggs/female/day) during 11.4 oviposition days, while low fecundity values occurred on Sirah and Villanueva leaves, with 0.9 and 1.8 eggs/female/day during 7.9 and 6.7 days, respectively. Average longevity of O. punicae females ranged from 8.1 to 17.5 days on Sirah and Sauvignon leaves, respectively. Intrinsic rate of increase (r (m)) was highest on Sauvignon (0.292) and Tucupita (0.261), and lowest on Sirah (0.146) and Villanueva (0.135). Although significant differences in cuticle-epidermis thickness were detected among the six cultivars, it seemed not to affect mite parameters. Secondary metabolite content also varied between the cultivars. Generally, increasing flavonoid content coincided with decreasing reproductive parameters. The natural plant resistance observed in this study could be useful in the development of an integrated pest management program for mite pests in grape production.     

Effects of temperature on the fecundity and longevity of Zeugodacus cucurbitae (Coquillet) (Diptera: Tephritidae) on artificial diet

The melon fruit fly, Zeugodacus cucurbitae (Coquillett), is an important polyphagous pest that damages to various agricultural crops, whose distribution has become global as a result of human activity. In this study, we investigated the fecundity, pre-oviposition and oviposition periods, and the longevity of adult Z. cucurbitae at various constant temperatures ranging from 15 to 35.2°C. One newly emerged one virgin female and two males of Z. cucurbitae were used, and the longevity of both sexes and the fecundity of the females were examined daily. The longevity of female Z. cucurbitae ranged from 183.8 days at 15.0°C to 30.8 days at 35.2°C, and the maximum fecundity per female was 1204 eggs at 24.5°C. The lower development threshold (LDT) and thermal constant (K) of females were estimated as 14.8°C and 781.13 degree-days, respectively. Female reproduction was modeled using a two-phase oviposition model. Oviposition was estimated using females in the oviposition phase, which had a complete pre-oviposition phase. The oviposition model consisted of two reproductive components (total fecundity and age-specific cumulative oviposition rate during oviposition) and a survival component (age-specific survival rate). The daily egg production of Z. cucurbitae was estimated in relation to adult age and temperature.     

Winter dormancy of the pine sawyer Monochamus galloprovincialis (Col., Cerambycidae) in Portugal

Abstract:  The pine sawyer Monochamus galloprovincialis is the vector of the introduced pine wood nematode Bursaphelenchus xylophilus in Portugal and has a fixed univoltine life cycle, overwintering as larvae inside the wood. We investigated the possibility of the existence of a phase of winter dormancy affecting the larvae, its induction and termination under controlled conditions and its incidence and termination in the field. In the laboratory, the majority of the newly hatched larvae which were maintained at a constant temperature of 23°C and different photoperiods became dormant in <70 days. Part of the population completed dormancy and reassumed development until adult emergence at the constant temperature, without the need for a chilling period. Although no critical photoperiod for dormancy maintenance or termination could be determined, dormancy termination was more frequent for larvae experiencing changes on daylength duration. In the field, dormancy incidence grew progressively from a minimum of 26% in October to a maximum of 100% in April, and dormancy appeared to be completed only during late winter. The results suggest that M. galloprovincialis larvae underwent an obligatory dormancy associated with the last larval instar, which conforms to the general definition of diapause, although presenting some affinities with oligopause. The role of this dormancy on the regulation of the pine sawyer's seasonal development and the number of generations is discussed.