Category Archives: Coleoptera

5 Fascinating Facts about Ladybirds.

Ladybirds are members of the beetle family Coccinellidae, and are predatory insects that control populations of aphids in gardens and in fields. Ladybirds, or ladybeetles/ladybugs, are well recognizable insects that are adored for their beautifully spotted bodies, but there are several things about ladybirds that one should know…

1. Ladybirds practice cannibalism

When food is scarce, ladybirds may resort to eating whatever soft-bodied organism is nearby, including other adults, pupa, larvae and even eggs of other ladybirds. Even the ladybird larvae which are the first to emerge eat their future siblings (unhatched eggs), but some of these have not even been fertilised by the adult, presumable for the purpose of giving the first hatching young more of a chance of survival.

2. Ladybirds bleed from their knees when threatened.

Ladybirds signal their toxicity using aposematic coloration (black spots upon red, white spots upon orange…), but they have another defence. When startled, ladybirds will seep toxic and foul-smelling hemolymph (rich in alkaloids) from its leg joints, leaving yellow stains on the surface below it. Predators are deterred by the prospect of eating such a rank smelling and bad looking prey item, and are repulsed enough to search elsewhere.

3. Ladybirds are highly promiscuous

Ladybirds are so promiscuous that in 2-spot ladybirds clutches often contain eggs fertilised by more than 3 different males. Because of this, ladybirds can transmit mites that feed on blood below the elytra to one another during mating- an STD! A mite-infested ladybird can reduce the size and viability of clutches. And as expected the higher the number of mating partners, the more mites a female ladybird will catch- sometimes up to 81 mites!

4. Ladybirds aggregate in the winter to hibernate

When temperatures fall and days become shorter, ladybirds seek shelter in protected locations- under leaves, behind bark and even in houses. Thousands of ladybirds may gather in one location to take advantage of the collective heat for energy conservation.

5. A ladybird may eat as many as 5000 aphids in its lifetime

Aphids are beneficial predators that control populations of pest aphids, whitefly, scale insects and mealybugs. An extremely hungry ladybird can consume 50 aphids per day. To ensure that ladybird larvae have access to plenty of aphid prey, their eggs are laid among a young aphid colony.

MYTHS:

“You can tell a ladybird’s age by the number of spots” Spots actually indicate species. (Two-spotted ladybird, 10-spotted ladybird..)

“Those big white spots are the ladybird’s eyes”. Those white spots are there to scare predators.

Further Reading:

Majerus, M. E. (1994). Ladybirds. HarperCollins Academic.

Roy, H., Brown, P., Frost, R., & Poland, R. (2011). Ladybirds (Coccinellidae) of Britain and Ireland. Natural Environment Research Council (NERC).

Featured image from www.alexanderwild.com.

Cells from Insects could Create Everlasting Paint.

blue-morpho-butterfly-size-pic-1173_11

Durable, cheap and environmentally friendly paint may soon be on sale since scientists at the Natural History Museum in London have unlocked the key to paint that never fades, using unique cells from butterflies and other insects. The Blue Morpho butterfly, Morpho peleides, is just one of many insects that have transparent, iridescence wings created by small three-dimensional structures that alter the way light is reflected.

The phenomenon is created by ‘structural colouration’. The wing is made up of transparent scales that have intricate shapes, which scatter light when it hits them. This is what creates the vibrant colour that changes when looking at it from different angles. Professor Andrew Parker, Oxford University, has grown cells from butterfly wings and weevil shells that have this nano-property.

Cells dissected from the blue morpho chrysalis were used to culture an entire forewing. The team attempted to convert the cells to scales, but part of the original cell was lost, so that the cells couldn’t be used to produce more scales. This means that butterfly cells are suitable for mass production of coloured scales, but other insects like the Blue Weevil, genus Metapocyrtus, could be used instead. These weevils use a different type of cell, also found in the opal gemstone, which can be used to make any colour.

Traditional dyes and pigments fade over time, whereas paints, clothes and make-up that use structural colouration could retain their colour and vibrancy forever. Cosmetic and paint industries would require huge quantities for commercial use, which may only be achievable using the weevil cells. With a sufficient supply of nutrients and growth hormones, cells from weevils could be used to make industrial quantities of everlasting paint.

Source: Natural History Museum.

Detecting invasive species: the case of the wood-boring beetle

wood boring beetle

Invasive species are mostly likely to invade an area through a port. We need a better understanding of the factors affecting their arrival and establishment if we are to detect them. Davide Rassati and colleagues from the university of of Padua in Legnaro, Italy, looked at how the port size and surrounding landscape (i.e. forests) influenced the occurrence of the wood-boring beetle, Cordylomera spinicornis.

At 15 Italian international ports, the surrounding forests and ports themselves were monitored using multi-funnel traps with bait. Both alien and native bark beetles (subfamily Scolytinae), longhorn beetles (family Cerambycidae) and jewel beetles (family Buprestidae) were found. Overall 14 alien species were found, 4 of which are new to Italy.

Alien species richness was positively correlated with imported commodities. However total forest cover near ports was positively correlated with the occurrence of native but not alien species. The alien and native species richness was higher in surrounding forests than the ports themselves.

Early detection of the invasive wood-boring beetles can be improved by identifying sites where the arrival and establishment of aliens is more probable, combined with an efficient trapping protocol. Ways to detect these insects include pheromone traps and encounter rate models (forecasts).

Byers, J. A., & Naranjo, S. E. (2014). Detection and monitoring of pink bollworm moths and invasive insects using pheromone traps and encounter rate models. Journal of Applied Ecology.
Rassati, D., Faccoli, M., Toffolo, E. P., Battisti, A., & Marini, L. (2014). Improving the early detection of alien wood‐boring beetles in ports and surrounding forests. Journal of Applied Ecology.