Natural flightless morphs of the ladybird beetle Adalia bipunctata improve biological control of aphids on single plants

The challenge of using ladybird beetles for biological control of insect pests such as aphids is that the adult beetles tend to fly away from the host plants. Therefore, flightless ladybirds might improve biocontrol. There are several artificial ways to obtain flightless beetles, but it may be preferable to use natural variation in flight ability. We investigated, for the first time, biocontrol by inundative augmentation of natural flightless morphs of the ladybird beetle Adalia bipunctata. Microcosm experiments using single leaves with one of three species of aphid revealed no differences in consumption behavior between flightless and winged beetles. Monitoring for 48 h of single, caged pepper plants infested with aphids of Myzus persicae nicotianae or Aulacorthum solani showed that flightless beetles had a longer residence time on the plants than winged beetles. This only translated into significantly better biocontrol of M. persicae. Despite their difference in residence time, both beetle morphs reduced the population growth of A. solani. This is probably explained by the tendency of A. solani to drop from the plant upon disturbance, and we predict that flightless beetles may outperform winged ones in the long term. Overall, our results provide a proof of principle that natural flightless A. bipunctata can improve biocontrol of aphids by ladybird beetles. However, we recognize that the effect of biocontrol will vary with the species of aphid used and that further examination in long term and large scale experiments is required.     

Genotype-environment interactions for insect growth in constant and fluctuating temperature regimes

Experiments on life history genetics are usually performed using constant temperature environments in the laboratory. However, the dynamics of insect growth can be influenced profoundly by daily fluctuations in temperature such as those which characterize field environments. We report here on experiments using different stocks and selected lines of a tropical butterfly, Bicyclus anynana, to examine whether genotype-environment interactions occur for three traits describing pre-adult growth. These traits were measured over two pairs of environments differing in mean temperature, each of which had a constant, and a cycling temperature regime. Development time, pupal weight and growth rate show genotype-environment interactions, especially at comparatively low average temperatures. Researchers should, therefore, take care when extrapolating from the form of genetic covariance matrices and ''trade-offs'' among life history traits found in constant temperature environments to those likely to occur in nature. <br>     

Evolutionary dynamics of multilocus microsatellite arrangements in the genome of the butterfly Bicyclus anynana, with implications for other Lepidoptera

The sequences flanking microsatellites isolated from the butterfly Bicyclus anynana display high levels of similarity among different loci. We examined sequence data for evidence of the two mechanisms most likely to generate these similarities, namely recombination mediated events, such as unequal crossing over or gene conversion and through transposition of mobile elements (MEs). Many sequences contained tandemly arranged microsatellites, lending support to recombination as the multiplication mechanism. There is, however, also support for ME-mediated multiplication of microsatellites and their flanking sequences. Homology with a known Lepidopteran ME was found in B. anynana microsatellite regions, and polymorphic microsatellite markers with partial similarities in their flanking sequences were passed on to the next generation independently, indicating that they are not linked. Therefore, the rise of these similarities appears to be mediated through both processes, either as an interaction between the two, or by each being responsible for part of the observations. A large proportion of microsatellites embedded in repetitive DNA is representative for most studied butterflies and moths, and a BLAST survey of the B. anynana sequences revealed four short microsatellite-associated sequences that were present in many species of Lepidoptera. The similarities usually start to deviate beyond these sequences, which suggests that they define the extremes of a repeated unit. Further study of these conserved sequences may help to understand the mechanism underlying the multiplication events, and answer the question of why these redundancies are predominantly found in this insect group.     

Optimization of the dilute maleic acid pretreatment of wheat straw

Background  

In this study, the dilute maleic acid pretreatment of wheat straw is optimized, using pretreatment time, temperature and maleic acid concentration as design variables. A central composite design was applied to the experimental set up. The response factors used in this study are: (1) glucose benefits from improved enzymatic digestibility of wheat straw solids; (2) xylose benefits from the solubilization of xylan to the liquid phase during the pretreatment; (3) maleic acid replenishment costs; (4) neutralization costs of pretreated material; (5) costs due to furfural production; and (6) heating costs of the input materials. For each response factor, experimental data were fitted mathematically. After data translation to €/Mg dry straw, determining the relative contribution of each response factor, an economic optimization was calculated within the limits of the design variables.