Can natural enemies of current insect pests provide biotic resistance to future pests?

1. Economic pests jeopardize agricultural production worldwide. Classical biological control, comprising the import of exotic natural enemies to control target pest populations, has a successful history in many countries. However, little is known about how these natural enemies contribute to the suppression of pests that are yet to arrive. Biotic resistance theory, though, posits that communities resist species invasions as a result of natural enemies.
2. We assessed the potential of the resident exotic parasitoid wasp fauna in New Zealand (intentionally‐introduced biological control agents and unintentionally‐introduced species) to provide biotic resistance against possible future pests. A dataset was generated containing resident exotic parasitoid species (Ichneumonoidea: Braconidae; Ichneumonidae) in New Zealand, as well as their known global host ranges and the pest status of host species, to infer the potential for biotic resistance.
3. The known exotic ichneumonoid fauna in New Zealand comprises 65 species. These species associate with 107 host species in New Zealand, of which 54 species are pests. However, the current exotic species could potentially suppress 442 pest species not yet occurring in New Zealand.
4. This approach could be used to inform pest management programmes worldwide. Future research should consider how biotic resistance from the established parasitoid fauna can be used to inform specific decisions with respect to classical biological control.

     

Progression in field infestation is linked with trapping of coffee berry borer, Hypothenemus hampei (Col., Scolytidae)

Phenology of the coffee plant and infestation by coffee berry borer Hypothenemus hampei Ferrari were studied in relation to trapping of adult females in kairomone-baited traps in a coffee plantation in New Caledonia. In a 0.4 ha coffee field, a group of 27 trees located along a transect beginning at an early infestation point was selected. The number of green, red and dry coffee berries, along with the number of larvae, adult males and females per berry was determined monthly from October 1993 to July 1994. Twelve, red multifunnel traps, each baited with a solution of methanol:ethanol (1:1 ratio, a mean solution release rate of 1 g/day) were placed within the coffee field, along the transect, within the selected trees, grouped in four zones named 1–4. Two additional traps were located outside the plantation.
The proportion of infested berries increased as berry maturity and harvest date approached, while the infestation rate decreased with distance from the epicentre. Over the 10 months of the study, beetle populations increased and spread from the original infestation point across the different zones, according to distance and availability of berries or appropriate physiological status. Traps near the epicentre caught the largest numbers of beetles. Linear relationship between trap catch and infestation level was demonstrated. Traps placed outside the field approached zero catch. Trap catch was highly influenced by rainfall events, and the highest captures coincided with rapidly declining berry numbers on trees. There are good prospects for management of this insect using traps.     

The effect of glucagon-induced adenosine 3' ,5' -monophosphate concentrations on bile acid synthesis in isolated rat liver cells

The effect of increased intracellular adenosine 3' ,5' -monophosphate (cAMP) concentrations on bile acid synthesis in isolated rat hepatocytes was investigated. When the cells were incubated in the presence of glucagon (0.2 microM) and theophylline (1 mM) the observed rise in the level of cAMP was accompanied by an increase in bile acid production. Hepatocyte cAMP concentrations after 1 h of incubation showed a highly significant positive linear correlation with the amounts of bile acid synthesised by the cells during this time. These results suggest that bile acid production is related to the concentration of cAMP in isolated hepatocytes and provide evidence for a role for the cyclic nucleotide in the regulation of bile acid synthesis.     

Lateral gene transfer between prokaryotes and multicellular eukaryotes: ongoing and significant?

The expansion of genome sequencing projects has produced accumulating evidence for lateral transfer of genes between prokaryotic and eukaryotic genomes. However, it remains controversial whether these genes are of functional importance in their recipient host. Nikoh and Nakabachi, in a recent paper in BMC Biology, take a first step and show that two genes of bacterial origin are highly expressed in the pea aphid Acyrthosiphon pisum. Active gene expression of transferred genes is supported by three other recent studies. Future studies should reveal whether functional proteins are produced and whether and how these are targeted to the appropriate compartment. We argue that the transfer of genes between host and symbiont may occasionally be of great evolutionary importance, particularly in the evolution of the symbiotic interaction itself.     

Retinoblastoma mutation rate in New Zealand and support for the two-hit model

Summary Age-specific incidence rates for 96 New Zealand patients with sporadic retinoblastoma peaked earlier for bilateral patients than for unilateral patients. The cumulative log survival until diagnosis for bilateral and unilateral patients followed linear and quadratic curves respectively, and supported the two-hit hypothesis for retinoblastoma. The germ cell mutation rate for retinoblastoma, assuming a single major gene, was calculated to be in the order of 9.3×10^-6 to 10.9×10^-6 for the New Zealand population.