Biological traits of Epitrix papa (Coleoptera: Chrysomelidae: Alticinae), a new potato pest in Europe,and implications for pest management

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Biology of the Eucalyptus leaf beetle Paropsisterna selmani (Chrysomelidae: Paropsini): a new pest of Eucalyptus species (Myrtaceae) in Ireland

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Potential damage by Acromyrmex ant species in pine plantations in southern Brazil

1. Acromyrmex species primarily attack Pinus taeda plantations during the first months after planting, with more intense damage in the first 30 days.
2. We evaluated potential damage by Acromyrmex crassispinus and Acromyrmex subterraneus in 30-day-old P. taeda plantations in southern Brazil by assessing the number of attacked plants and the distance reached by each colony, along with the losses in plant development resulting from different levels of defoliation.
3. Both species were significant pests in newly established pine plantations. A single colony can attack a substantial number of seedlings (up to 453 seedlings). Colonies with larger nests attacked more plants and ranged farther; A. crassispinus reached 59 m and A. subterraneus 87 m.
4. After 10 years, no significant losses in plant development were seen in seedlings defoliated less than 50% at 30 days after planting. But when defoliation of the young plants attained 75%, 100%, and 100%, including the cut of the apical meristem, volume losses reached 32%, 37%, and 43%, respectively.
5. Leaf-cutting ant controls should be carried out in plantations of P. taeda within 30 days of planting to avoid attacks. When seedlings are defoliated more than 75%, they should be replanted to avoid future losses in final wood volume.

     

The biology of the phonotactic parasitoid, Homotrixa sp. (Diptera: Tachinidae), and its impact on the survival of male Sciarasaga quadrata (Orthoptera: Tettigoniidae) in the field

Abstract.

• 1 Unlike most parasitoids, tachinid flies of the tribe Ormiini use sound to locate their hosts. Although thought to exert selection pressure on their host's calling behaviour, little is known about the biology of ormiines. Accordingly, this study reports the biology and impact of the ormiine Hornotrixa sp. upon calling males of the univoltine bushcricket Sciarasaga quadrata Rentz in south-western Australia.
• 2 Populations of adult S.quadrata were monitored in the field over two successive calling seasons. Females, which do not call, were not parasitized by Hornotrixa sp., but the risk of parasitism for males increased as the 3-month calling season progressed. Parasitism did not commence until c. 2 weeks into the calling season, but by the end of the season up to 87% of surviving males were parasitized.
• 3 Parasitized males lived for 14 days and were found singing until their penultimate evening before death in the field. Unparasitized males lived on average 69 days and a maximum of 119 days.
• 4 Multiparasitism of hosts was common, with up to sixteen fly larvae found within parasitized males. The number of fly larvae within hosts significantly increased at the end of the season. However, successful emergence of fly larvae from hosts, as well as pupal size, significantly decreased as more than one fly larva developed within the host.
• 5 Hornotrixa sp. has a long pupal duration of 30–31 days at 20°C. As a consequence, only one complete fly generation, which overwinters in the pupal stage, is likely within each host generation.
• 6 No evidence for differential (size-bias) mortality by Hornotrixa sp. on male S.quadrata was found. The size of parasitized and unparasitized males collected in the field was not significantly different.
• 7 It is concluded that Hornotrixa sp. is a significant mortality factor acting on the survival of adult male S.quadrata.

     

The effects of foliage damage on casebearing moth larvae, Coleophora serratella, feeding on birch

ABSTRACT.

• 1 Mechanical damage to birch (Betula pendula Roth) leaves leads to an increase in the concentration of phenolic compounds, which spreads throughout the leaf within 8 days.
• 2 Coleophora serratella L. (Lepidoptera: Coleophoridae) apparently responds to this chemical change over a similar time scale. Within 24 h of pin-pricking leaves the casebearer moves from the immediate vicinity of the damage, but is just as likely to move to an undamaged portion of the damaged leaf as to vacate the leaf entirely. After 8 days mines on undamaged portions of damaged leaves were significantly smaller than mines on undamaged leaves.
• 3 Furthermore, Coleophora serratella reared on damaged trees took an average of 3 days longer to develop than those reared on undamaged trees.
• 4 It has been suggested that increased movement in response to damage-induced chemical changes causes hyperdispersed damage on plant foliage. Both within and between-leaf casebearer damage patterns were shown to be aggregated on birch.
• 5 Thus although mechanical damage can induce chemical and behavioural changes in the field, these are not reflected in the observed damaged patterns. We speculate on several possible reasons for this.

     

Biology of the Collembola Xenylla grisea Axelson and Lepidocyrtus cyaneus f. cinereus Folsom

• 1 Xenylla grisea Axelson and Lepidocyrtus cyaneus f. cinereus Folsom were reared on brown whole wheat flour in culture jars containing a base of plaster of paris and charcoal.
• 2 Sexes in X.grisea may be differentiated by the combination of three characters: length, colour and body shape. No parthenogenesis was observed in either species.
• 3 At room temperature (25–27°C), females of X.grisea began laying eggs after the fourth moult and required 10–15 days (mean of 12.6) to reach sexual maturity from the day of hatching. With L.cyaneus f. cinereus, average periods from hatching to maturity were 16.8, 27.4 and 43.2 days at temperatures of 26.5, 22 and 15°C, respectively.

     

Temperature‐dependent demography of Agriphila aeneociliella (Lepidoptera: Crambidae), a new insect pest of wheat in China

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Temperature can limit the invasion range of the ambrosia beetle Euwallacea nr. fornicatus

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Pupal overwintering,diapause and development in two species of Spilosoma

• 1 Pupae of Spilosoma lubricipeda (L.) and S. lutea (Hufn.) were studied in order to develop a method for estimating the date of emergence of the moths from temperature data. Diapausing pupae stored at 4–5°C for 157 and 171 days showed the fastest development on subsequent incubation at 20°C indicating that diapause had been completed in cold storage.
• 2 Pupae formed in August and October completed diapause in a ventilated insec-tary in March and early April respectively. A 4-month spread in pupation dates was compressed by diapause and low winter temperatures into a 7-day spread in mean emergence dates for S. lubricipeda and a 17-day spread for S. lutea.
• 3 In the insectary, estimated mean emergence dates differed from observed dates by an average of 3.7 days for S. lubricipeda and 2.4 days for S. lutea. Pupae were over-wintered outdoors in S. England and in Scotland. Observed mean dates of moth emergence varied with altitude and latitude, and differed from estimated dates for S.lubricipeda by an average of 5.5 days.
• 4 Mortality did not exceed 30% except in two years in batches kept in wet boxes outdoors at Achnagoichan which is probably beyond the breeding range of both species in Britain. In the laboratory some pupae survived exposure to — 16°C for 192 h suggesting that winter mortality alone does not control the survival of these species at Achnagoichan.

     

An investigation of allelopathic effects of Daphnia

• 1 The hypothesis is tested that large daphnids are able to suppress their own and other species' feeding and reproduction by means of excreting an inhibitory chemical (or chemicals).
• 2 In laboratory experiments with an Australian species, Daphnia carinata, water preconditioned with 3–67 daphnids 1-^?1 for 30 h had the effect of reducing feeding rates of D. carinata and D. lumholtzi provided with Selenastrum capricornutum.
• 3 For the two Daphnia species, there were highly significant negative correlations between feeding rate and the preconditioning density of D. carinata.
• 4 Water preconditioned with 20–30 daphnids 1-^?1 for 1–2 weeks reduced the grazing rates of Daphnia, Moina, and Diaphanosoma 2–3-fold.
• 5 Moina kept in such water for 2 days stopped feeding. Conditioned water kept for 3 days without animals still inhibited grazing by Moina. Hearing to 100°C removed the inhibitory effect.
• 6 Given excess food, and in non-renewed water, a gradient of D. carinata densities developed a strong negative correlation between clutch size and daphnid density after a 6-day time lag. This result may help explain the direct density-dependent regulation of cladoceran reproduction observed earlier in a subtropical lake.

     

The effect of invertebrate and vertebrate predators on the foraging movements of Ischnura elegans larvae (Odonata: Zygoptera)

SUMMARY.

• 1 The foraging movements of late instar Ischnura elegans larvae were monitored in laboratory experiments to study the effects of predators on larval feeding behaviour.
• 2 Ischnura larvae are sit-atid-wait, or ambush, foragers, moving occasionally between perches in search of profitable feeding sites. Larval foraging movements, monitored at different densities of Daphnia prey, increased significantly when prey were absent.
• 3 In experiments without prey, larval movement was inhibited by the presence of fish predators, as well as by invertebrate predators (Notonecta glauca), but not by closely related, non-predatory invertebrates (Corixa punctata) or physical disturbance of the water (intermittent air bubbles).
• 4 Further experiments varied Ischnura hunger levels (0–8 days without food) and illumination (light or dark) with and without notonectid predators. Hunger had no consistent effect on penultimate instar behaviour but final instar foraging activity was significantly modified: movements increased after 4 days starvation and decreased again after 8 days. This response was suppressed by the presence of predators. Both larval instars moved significantly less often in the light, even when predators were absent.
• 5 These phenotypically flexible predator-avoidance responses are likely to decrease the risk of predation by both visual and tactile predators. However, predators clearly have an important influence on the feeding niche of Ischnura larvae, and may decrease the overall feeding efficiency, growth rate, and survival of larvae by constraining their movement in search of profitable feeding sites.

     

Assessment of the range of attraction of pheromone traps to Agriotes lineatus and Agriotes obscurus

• 1 The range of attraction of YATLOR pheromone traps was studied to gain information on the number of traps needed for mass trapping of males of two Agriotes species.
• 2 Male click beetles of the species Agriotes lineatus (L.) and Agriotes obscurus (L.) (25–30 individuals per release point) were marked and released at a distance of 2, 5, 10, 15, 20 and 60 m from a pheromone trap both along and opposite to the known prevailing wind direction. Traps were regularly inspected over approximately 1 month. The percentage of recaptured beetles was calculated and analyzed using analysis of variance. Maximum sampling ranges and effective sampling areas were calculated.
• 3 Averaged over all five trials and distances, approximately 40% of the released beetles (A. lineatus and A. obscurus) were recaptured. The percentage recapture of male adults was significantly affected by release distance, whereas no differences were found for species and release direction.
• 4 Males were recaptured from all release points and the percentage recapture decreased (in part significantly) with increasing distance from 76% (2 m) to 35% (15 m) and 9% (60 m), respectively. Most of the beetles were recaptured within the first 3 days after release, independent of the distance, except 60 m. The effective sampling area for A. lineatus was 1089 m² after 12 days and increased to 1735 m² after 30 days. Corresponding values for A. obscurus were considerably higher: 1518 m² for 12 days and 2633 m² for 30 days.
• 5 We conclude that the range of attraction of the pheromone traps for A. lineatus and A. obscurus is comparatively low, providing high percentage recapture only for release distances up to 10 m. Accordingly, any approach targeted on preventing mating by male mass trapping would require a dense network of pheromone traps.

     

Cold tolerance strategy and cold hardiness of the invasive zigzag elm sawfly Aproceros leucopoda (Hymenoptera: Argidae)

1. The invasive sawfly Aproceros leucopoda causes severe defoliation of various elm species and thus can be a major pest in forest stands and urban environments.
2. The overwintering biology of A. leucopoda has not been investigated so far; therefore, the aim of this study was to determine the cold tolerance strategy and cold hardiness of hibernating A. leucopoda eonymphs.
3. The supercooling points (SCPs) of overwintering individuals varied geographically, monthly and interannually and ranged between ?12.14 °C and ?24.22 °C.
4. As none of the eonymphs survived once the SCP had been reached, A. leucopoda is classified as a freeze‐avoidant species.
5. Survival rates of overwintering eonymphs exposed to different sub‐zero temperatures above the SCP (?1.6 °C and ?4.0 °C for 10, 20 and 30 days and ?10.5 °C for 9 days) ranged between 89.2% and 100%, suggesting that A. leucopoda is not a chill‐susceptible species.
6. Our results suggest that low winter temperatures may not be expected to be an important limiting factor for the overwintering success of A. leucopoda.

     

Aspects of the biology of Staphylinus olens (Müller), Britain's largest Staphylinid beetle

• 1 Methods for rearing Staphylinus olens (Müller) (Col., Staphylinidae) are described, and development compared with other species of Coleoptera.
• 2 The distribution of S.olens over an area of Manchester is noted, and biological comparisons made with a laboratory population from South Wales. In the area sampled, most individuals live on well-drained soils, possibly because successful pupation occurs under dry conditions.
• 3 ‘Courtship’ and mating are described.
• 4 Egg-laying, the egg, and its hatching are described, and compared with other coleopteran eggs.
• 5 Headwidths of laboratory larvae were recorded, and are compared with those of other beetle larvae.
• 6 Instars I and II lasted 44–45 days, although first instar larvae which eventually pupated had a mean duration of 33.5 days. Instar III averaged 102 days, but this time became shorter with later hatching, roughly synchronizing adult emergence.
• 7 Pupation and the obtect pupa are described. Pupal development took 32–37 days, after a 10–14 day prepupation period.
• 8 Newly emerged adults may construct winter burrows after autumn breeding. Second season adults may not hibernate, and often fail to survive another winter.
• 9 Food is manipulated by mandibles and legs, but no solids are consumed. Adults and larvae will eat many foodstuffs.

     

Larval age differences and competition between Drosophila aldrichi and D.buzzatii

Abstract.

• 1 Competitive interactions among larvae of Drosophila species using the same habitat will usually involve individuals varying in age and size. Older, larger larvae might be expected to outcompete younger, smaller larvae.
• 2 Newly hatched laryae of Drosophila aldrichi and D.buzzatii were placed on induced cactus necroses (simulating the natural habitat), either simultaneously, or with a 1 or 2 day difference in the time at which individuals of the other species were added.
• 3 Evidence for competitive differences with larval age were found. In both species, body weight was significantly higher for those larvae added first than for later addition larvae, and a longer time to complete development was required for those larvae added 2 days later. However, pre-adult viability of D.aldrichi was significantly higher for larvae started 1 or 2 days after larvae of D.buzzatii. For D.buzzatii, viability was lowest for larvae started simultaneously with D.aldrichi, but not different between those started either before or after D.aldrichi.
• 4 Considering all three traits, no clear advantage for the early addition larvae was observed.

     

Density-dependent changes in sex ratio in Colias lesbia (Lepidoptera: Pieridae)

Abstract.

• 1 The changes in sex ratio of a population of Colias lesbia were studied for four consecutive years.
• 2 A constant sex ratio was found in the samples taken in the 34 days following the last harvest of the alfalfa.
• 3 For the samples taken 35 or more days after the harvest the sex ratio decreases as the total number of adults caught increases.
• 4 The indirect evidence collected suggests that differences in emigration tendencies between sexes play a major role in determining the sex ratio in this species.

     

Latitudinal variation in body size of Agrilus planipennis and relationship with fecundity

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Prey selection and baculovirus dissemination by carabid predators of Lepidoptera

Abstract.

• 1 The interaction between coleopteran predators and baculovirus-infected larvae was studied in the laboratory and the field in order to assess the potential role of predators in the dissemination of a nucleopolyhedrovirus (NPV).
• 2 Preference tests using three carabid species, Harpalus rufipes De Geer, Pterostichus melanarius Illiger and Agonum dorsale Pont, showed no evidence of discrimination between healthy and diseased larvae of the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae) as prey items.
• 3 Virus infectivity was maintained after passage through the predator's gut. NPV mortality ranged from 97% to 20% when test larvae were exposed to faeces collected immediately after and 15 days post-infected meal respectively.
• 4 The potential for transfer of inoculum in the environment was estimated in the laboratory by soil bioassay. Carabids continuously passed infective virus to the soil for at least 15 days after feeding on infected larvae.
• 5 Field experiments showed that carabids which had previously fed on diseased larvae transferred sufficient virus to the soil to cause low levels of mortality in larval populations of the cabbage moth at different instars.

     

Patterns of macroinvertebrate colonization on fresh and senescent alder leaves in two Michigan streams

SUMMARY.

• 1 Communities of invertebrates colonizing senescent autumn and fresh summer alder leaves (Alnus rugosa) were compared. Leaf packs for each treatment were placed in two hardwater streams in the Upper Peninsula of Michigan in late summer and early autumn. One stream has a cobble-bottom and the other a sand-bottom and both receive fresh leaf inputs by beaver fellings.
• 2 Fresh leaf packs remained intact after 26 days immersion, but thereafter were processed faster than were the autumn leaf packs in both streams.
• 3 In the cobble-bottom stream taxon richness (S), numbers of individuals and biomass were higher on fresh than on autumn leaves.
• 4 Fresh leaves in the sand-bottom stream supported a more diverse (H'), richer (S) and more equitably distributed (J') insect fauna than did the autumn leaves.
• 5 We discuss the simultaneous lack of fresh leaf loss and the presence of more complex insect communities on those leaves during the first 26 days of the study. Invertebrates in both mid-latitude heterotrophic streams and in tropical lowland wet forest streams may rely on fresh leaf inputs, which have received little attention.

     

Population dynamics of the japanese clouded apolloParnassius glacialis butler (Lepidoptera: Papilionidae). I. changes in population size and related population parameters for three successive generations

1. Population dynamics of a univoltine butterfly Parnassius glacialis (Lepidoptera: Papilionidae) was studied with mark-recapture methods for three successive generations in a hilly region in Kanazawa City, Ishikawa Prefecture, Japan in 1981–1983.
2. Jolly (1965) andSeber's (1973) method was applied to the mark-recapture data to estimate population parameters (daily survival rate, longevity, population size, sex ratio, etc.).
3. Sampling ratios were at least 50% and 30% for males and females, respectively.
4. Mean daily survival rate for males ranged 0.81–0.86 and that for females 0.80–0.84. Mean longevity was about 4–7 days for the males and about 5 days for the females. Spiders killed more males than females. Maximum longevity for an individual recorded during the study was 31 days for males and 18 days for females.
5. Emergence of the butterflies was later and less synchronous in 1981 than in 1982 and 1983. This was thought to be due to later extinction of heavier snow in 1981 than in the other years.
6. The population remained relatively stable for the three successive generations, with estimated total numbers of 914, 1277, and 869.
7. Estimated sex ratio (% females) was 30–40% at emergence