Evolutionary assembly of cooperating cell types in an animal chemical defense system

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Potential interspecific competition and host specificity: hispine beetles on Heliconia

Abstract. 1. Adults of rolled-leaf hispine beetles (Chrysomelidae, Coleoptera) spend their lives in the scrolls formed by immature leaves of Heliconia (Heli-coniaceae, Monocotyledonae) in Tropical America. As many as eight hispine species can intermingle in the host scrolls at a single site. Scrolls of single host species are invariably occupied by adults of more than one hispine species, and as many as five species can simultaneously occupy one scroll.
2. I made virgin scrolls, which had never contained any insects, by growing leaves under the cover of plastic bags.
3. Thirty-seven combinations of single hispine and Heliconia species were experimentally created in the virgin scrolls, at two sites and in two seasons, in Costa Rica. Combinations included all abundant host species at the sites.
4. All beetles left all leaves of the twenty-eight unnatural beetle—host combinations, within 24 h. On the other hand, none of the nine natural combinations was completely abandoned within the experimental period.
5. Thus, host specificity is not broader in the absence of similar hispine species that might be competitors, and interspecies competition does not affect this obvious aspect of resource utilization for these phytophagous insects.     

Genetic studies on seedling vigour in sesame

Genetic studies were carried out on seedling and agronomic characters amongst 50 sesame genotypes to estimate the genetic variation, determine the relationships amongst the characters and identify rapidly growing genotypes with vigorous seedling growth. The contribution of genetic variance was highest for the two mature characters, days to first flower (95.6%) and number of nodes to first flower (95.2%), and was medium/high (50–75%) for most of the seedling characters. Strong positive genetic correlations were obtained between various cotyledon and early leaf characteristics measured at 20 days after sowing. Based on these results several genotypes were identified as having rapid seedling growth and these could form an initial gene pool to provide material for screening for tolerance to sesame flea beetle.     

Foraging behaviour influences the outcome of predator–predator interactions

Abstract.  1. Interactions among predators may influence the total efficiency of a predator complex. The effect of intra- and interspecific interactions of the generalist predators Orthotylus marginalis (Heteroptera: Miridae) and Anthocoris nemorum (Heteroptera: Anthocoridae) was investigated in a laboratory experiment. Outcomes of the interactions were determined by comparing predation rates on eggs and larvae of the blue willow beetle Phratora vulgatissima of single individuals with those of two individuals of the same or different species.
2. A non-additive, antagonistic effect on predation rates due to intraspecific interactions was found between individuals of A. nemorum . No such effect was found in O. marginalis . These results are as expected as a consequence of differences in behaviour of the two predator species: A. nemorum is a much more active and mobile predator than O. marginalis .
3. Contrary to expectation, interspecific interactions between A. nemorum and O. marginalis did not affect the total predation rate.
4. An observation from the field corroborated the results obtained in the laboratory study; there was no negative relationship between the densities of the two predator species, indicating that the two species do not interact negatively in the field at their natural densities.
5. It is concluded that the additive effect of multiple predator species is of potential value in biological control.     

Behavioral interactions between three birch aphid species and Adalia bipunctata larvae

First and fourth instars of three birch aphid species were exposed to first and fourth instars of Adalia bipunctata (L.), the most common aphid predator on silver birch, Betula pendula Roth, in northern California. Defensive behavior differed by aphid species. Euceraphis betulae (Koch) (Eb), the most successful escapee, was highly mobile and frequently walked away from coccinellid larvae. Betulaphis brevipilosa Börner (Bb), a flat, sessile species, was the least successful aphid at actively escaping from A. bipunctata larvae, but could passively escape detection when coccinellid larvae walked over nymphs and did not perceive them. Active escape behavior was much safer for aphids than passive avoidance of detection. Both instars of Eb and fourth instars of Callipterinella calliptera (Hartig) (Cc) escaped from coccinellid larvae more frequently when approached from the front, apparently using vision for pre-contact detection of A. bipunctata. These aphids avoided physical contact with larger predators more often than with smaller predators. Level of predation by A. bipunctata on these three aphid species is dependent upon types of aphid defense.

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Résumé Des larves de premier et troisième stades de 3 espèces de pucerons du bouleau: Betulaphis brevipilosa, Callipterinella calliptera et Euceraphis betulae ont été exposées aux attaques des larves du premier et du quatrième stades d'Adalia bipunctata, prédateur le plus fréquent de pucerons sur Betula pendula en Californie du Nord. Le comportement défensif dépend beaucoup de l'espèce de puceron. E. betulae, qui s'échappe avec le plus de succès, est très mobile et s'écarte fréquemment des larves agressives de coccinelles. B. brevipilosa, espèce plate, sessile, a le moins de succès dans la protection active contre les attaques des larves de A. bipunctata, mais elle peut échapper passivement à la détection des larves de coccinelles qui ne peuvent pas les discerner lorsqu'elles circulent parmi les larves de pucerons. E. betulae (aux deux stades) et C. calliptera (au quatrième) échappent le plus aux larves de coccinelles qui attaquent de front, ce qui laisse supposer que la vision permet de détecter A. bipunctata avant le contact. Le succès des larves de coccinelles varie selon les stades du puceron et de la coccinelle. Les possibilités d'obtention de niveaux de prédation élevés de ces 3 pucerons par A. bipunctata dépend du type de protection du puceron.

     

Dung burial strategies in some South African coprine and onitine dung beetles (Scarabaeidae: Scarabaeinae)

ABSTRACT.

• 1 The dung colonization and dung burial behaviour of twelve crepuscular/nocturnal tunnelling (paracoprid) species of beetles were examined in order to identify mechanisms which might facilitate resource (dung) partitioning. The species were selected from a diverse assemblage of dung beetles, the members of which coexist in the sandy-soil regions of Natal, South Africa.
• 2 The pattern of dung colonization in relation to dung age was examined in the field using baited pitfall traps. Some species, e.g. Onitis deceptor Peringuey, Catharsius tricornutus De Geer and Copris elphenor Klug, showed a marked preference for fresh dung (1–2 days old) whereas other species, e.g. O. viridulus Boheman and Copris fallaciosus Gillet, preferred older dung (3–7 days old).
• 3 Two distinct patterns of dung burial were recognized. In the Coprini, dung burial was complete within 24–48h of pad colonization, and the level of dung burial was similar in the laboratory and in the field. In the Onitini, dung burial occurred progressively over a 12-day period, although the timing of initiation of dung burial varied between species: in O. deceptor nearly all individuals had begun burial within 2 days of pad colonization, whereas only 20% of O. viridulus had commenced dung burial by that time. However, nearly all O. viridulus had buried substantial quantities of dung by day 12.
• 4 The mass of dung buried per pair by the larger coprine beetles (100–300 g) and onitine beetles (400–1000 g) suggests that there is potential for inter- and intraspecific competition, even in pads colonized by relatively few beetles. The colonization and use of dung of different ages are discussed as means of resource partitioning in relation to the relative abilities of species to compete for dung.

     

Temporal and spatial relationships between an herbivorous lady beetleEpilachna niponica and its predator,the earwigAnechura harmandi

The relationships between egg predation of an herbivorous lady beetle Epilachna niponica (Lewis ) and its predator, the earwig Anechura harmandi (Burr ), were examined in both time and space. In spite of little annual, changes in egg densities, egg mortality due to predation varied considerably. There was no, clear relationship between the earwig density and the proportionate predation over the five years. The seasonal occurrence of earwig nymphs on thistle plants, however, was closely synchronized with that of egg predation. Predator attacks on the beetle occurred in a time-restricted manner. Thus, later cohorts mostly escape from heavy predatory pressure. No spatially density-depent egg predation was detected at the level of either thistle plants or thistle patches. Furthermore, there was no indication of aggregative behaviour of the earwig in response to local egg density. The earwig density was more likely to be associated with particular localities with sandy deposits available for its nest site.     

白腹锦鸡机体营养成分的分析与探讨

本文报道笼养和野生白腹锦鸡机体营养成分及其差异。分析表明,笼养的比野生种营养成分含量高的有:腿肌蛋白质高11％,胸肌、腿肌、全血的氨基酸分别高2.64％,1.39％和4.68％,胸肌、腿肌和肝脏的碳水化合物分别高0.076％、0.092％和3.962％,胸肌和腿肌的维生素A分别高188.63和84.09 I.U.,胸肌和腿肌的维生素D分别高47.2和12.8 I.U.。但是胸肌蛋白质含量笼养的比野生的低26％。     

Monogamy to communal breeding: exploitation of a broad resource base by burying beetles (Nicrophorus)

Abstract.

• 1 To investigate the range of resource size that burying beetles (Nicrophorus) exploit, small (21–33 g), medium (50–90 g) and large (120–210g) carcasses, were placed in the field and then exhumed after 1, 4, 8, 12 or 18 days.
• 2 Nicrophorus attempts to utilize carcasses over this entire size range but has greater success on smaller carcasses.
• 3 Larger carcasses were more difficult to exploit because: (a) they took longer to conceal beneath the leaf litter; (b) they were less likely to be rounded into brood balls; (c) they were more likely to be utilized by dipterans; and (d) they were occupied by greater numbers of congeners.
• 4 Larger carcasses, however, did support greater numbers of larvae and contained broods of greater total mass than smaller carcasses.
• 5 Beetles sometimes bred communally on larger carcasses in the field and same-sex adults were observed to feed young.
• 6 Two follow-up experiments were conducted in the laboratory. On a large carcass N.defodiens, N.tomentosus or N.orbicollis can raise a maximum of 35–50 young. Nicrophorus pustulatus, in contrast, appears to be unique among Nicrophorus in that it can raise nearly 200 young on larger carcasses.
• 7 Nicrophorus orbicollis and Nicrophorus sayi are extremely dependent on parental regurgitations and young fail to survive to the second instar if parents are removed. Young of Nicrophorus defodiens, N.tomentosus and N.pustulatus can develop normally without parental regurgitations.
• 8 I discuss these results in the context of reproduction on carcasses of different size and hypothesize that this breeding system is facultatively quasisocial.