Predators ladybirds

When disturbed or molested, these insects release small droplets of hemo-lymph from the tibio-femoral joints of their legs, and it is now well established that the deterrency exhibited by many species of coccinellids towards potential predators results from the presence of repellent and bitter alkaloids in that fluid [ 12,13]. In ladybirds, this unpalatability is associated with a bright aposematic coloration and a characteristic smell due to 3-alkyl-2-methoxypyrazines [14, 15]. The beetles use these molecules not only to reinforce the visual alerting signal on an olfactory level, but also as aggregation pheromones [16]. 

Next, pirimicarb, a selective insecticide that kills sap-sucking aphid pests but does not affect the useful predators such as ladybirds (ladybugs) that eat them. It contains a pyrimidine ring—a benzene ring with two nitrogen atoms. 

Aphids extract sap from plant stems, specifically the phloem tissue. They excrete honeydew which still contains plant sugars. Ants collect this honeydew, often by milking the aphids, and use it as food. In return, they protect the aphids against predators. Ants prey on predators of aphids such as ladybird beetles (coccinellids), thus defending the aphids. Ants also shelter aphids by taking them or their eggs into their nests during inclement seasons. In a sense, ants herd aphids like cows. Furthermore, without removal of honeydew, aphid colonies become fouled. 

Watch for natural aphid predators such as ladybird beetles or housefly larvae on each stem under observation. Record kind and numbers. 

We looked at the synthesis of a pyrimidine base from the nucleic acids in Chapter 29. Another example of a pyrimidine is Aphox (89), the ICI insecticide which kills aphids (greenfly) without harming their natural predators, the ladybirds. Disconnection of the ester side chain gives acid chloride (90) (cf. Chapter 5) and (91), more easily disconnected as tautomer (92) into keto ester (93) and guanidine (94). 

The function of alkaloids in 30 species of ladybirds has been discussed. The presence of alkaloids is shown to be related to the existence of aposematic colour and not to their carnivorous or phytophagous nature. Alkaloids constitute an effective defence against predators, e.g. ants, Myrmica rubra, and quails, Coturnix coturnix. 

CigHsgNj, Mr 282.51, yellowish oil, [a] -i-3.95° (ben-zeneX A defence substance of ladybird beetles (Coc-cinellidae) of the genus Harmonia occurring in the he-molymph of mature insects. On attack by a predator, H. is liberated by so-called reflex bleeding from the knee axilla. 

Sloggett JJ, Davis AJ. Eating chemically defended prey Alkaloid metabolism in an invasive ladybird predator of other labybirds (Coleoptera Cocconellidae). J Exp Biol 2010 213(2) 237 1. 

Biological predators. This method consists of releasing a biological predator to control the insect pest. In the United Kingdom its only successes have been in enclosed environments such as glasshouses. However, the technique was used very successfully nearly 100 years ago in California when the Australian ladybird beetle was introduced as a predator for cottony cushion scale which was ravaging citrus trees. 

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