Ant-aphid mutualism

Phloem sap is a nutrient-rich resource that is of less chemical defense. However, the phloem sap is not widely exploited because it is not easily accessible, lack of essential amino acids and has a high osmotic potential (i.e. too concentrated) relative to the insect bodies (Corlett, 2009). Hemiptera, including aphids, is the major insect group that consumes the phloem sap, so-called sap-suckers. They have specialized mouthparts and excrete the excess sugar as 'honeydew'.

The honeydew excreted by the Hemiptera generally contains more amino acids as the sap being processed by the symbiotic micro-organisms inside the Hemiptera bodies (Corlett, 2009). The honeydew also has lower osmotic potential so it serves as a better food sources to other insects (Corlett, 2009). Ants have established an obvious mutualism with aphids as they harvest the honeydew whilst protecting the aphids from their predators, parasites and pathogens in the meantime.

I have observed this interesting mutualism on the plant Goniothalamus tapisoides where the whole plant individual was covered with these aggressive weaver ants. It is interesting to know if a 'triple alliance' is present as the plant is also benefited as the ants protect the plant from other herbivores, which can probably compensate the loss of phloem sap (Moog et al., 2005).

The weaver ant harvesting the 'honeydew' excreted by the aphid. 

This ant is guarding the aphids on the inflorescence and waiting for the honeydew production. 

References:

Corlett, R.T. 2009. The ecology of tropical East Asia. Oxford University Press, Oxford, UK.

Moog, J., Saw, L.G., Hashim, R. and Maschwitz, U. 2005. The triple alliance: how a plant-ant, living in an ant-plant, acquires the third partner, a scale insect. Insectes Sociaux 52: 169-176.

Agriocnemis lacteola

Got some luck to see this locally rare small damselfly!

Neolucanus sp.

Coleoptera, largely known as beetles, is the largest member amongst all insects in the world. There are about 350,000 described species within the family in the world which represents more than 40% of all insects and nearly 30% of all animal species. However, the number of the described insects is still thought to be highly underestimated.

The photographed Neolucanus sp. was found at high elevation in Hong Kong. I've seen a number of this species appearing mainly around late May to Mid July these two years.

Agathia lycaenaria

A moth with great camouflage was hiding under a leaf. Its flattened body and green wings with dark spots blends itself into the background very successfully.

After passing an exceptionally warm February, Lepidoptera is unexpectedly much active.

Vespa discolor

Genus Vespa, also known as hornets, contains 22 species all over the world and eight (V. mandarinia is newly discovered) can be found in Hong Kong so far. They will construct their own colony comprises of a queen, males and workers. The nesting sites vary from one species to another and also intraspecifically.

Vespa discolor is one of the most common hornets in Hong Kong. This species is un-aggresive and will not attempt to attack deliberately unless too much disturbance is caused to their nests. It is a generalist hunter and scavenger which prey on any kind of insects which they are able to kill (A wandering glider Pantala flavescens is killed in the picture). The nesting period of V. discolor is quite long which reaches 9 months from colony initiation to disintegration.

Creobroter gemmata

It is recently reported that a mantid (identified as Creobroter gemmata) was seen jumping into a stream and a horsehair worm emerged through its anus in Hong Kong. Mantids are the common hosts of horsehair worm (Nematomorpha) in tropical and subtropical regions worldwide.

The horsehair worms copulate in its free-living stage and produce aquatic larvae. They are then actively ingested by other insects with aquatic larvae such as mosquitoe. They serve as vectors between the aquatic and terrestrial environment. The horsehair larvae continue their development if the insects are captured and eaten by mantids which are the final hosts of the worms. The worms then grow inside the mantids' abdomen and get maturity. They will then influence the hosts to approach water and emerge from the hosts. The factor influencing the hosts are still not understood.