Macrolophus pygmaeus
“In nature, everything is wisely thought out and arranged, everyone should go about their business, and in this wisdom is the highest justice of life”
(Leonardo da Vinci)
With such a quote, you can start every article about entomophages as biological plant protection products. But now we will pay attention to the Macrolophus, which for many has managed to become, if not the best friend, then at least an indispensable tool in the endless war for a good harvest.
General information
Macrolophus is a predatory polyphage bug. It belongs to the semi-hard-winged insects of the horsefly family. A versatile soldier universally used in the protection of various plants of the Solanales family, pumpkin and ornamental species. In Europe, Macrolophus began to be used back in the 90s as an effective biological method of controlling whitefly on tomatoes. In the CIS countries, interest in entomophage manifested itself later, which is a little surprising, given that the greenhouse industry of the agrarian sector in the CIS is much more developed. Apparently, conservatism in mentality still takes its toll. But this factor also receded after analysing the results obtained by Western colleagues on the shop floor.
There are several types of Macrolophus, among which Macrolophus pygmaeus is recognized as the most famous. It is known to some as Macrolophus caliginosus, but as a result of taxonomic revision, the species used in biocontrol are now correctly identified as Macrolophus pygmaeus.
Description
Macrolophus is an insect of the Miridae family, simply a predatory bug. According to the peculiarities of nutrition, it is a zoophytophage, which means the ability to eat both other insects and plant food. The basis of nutrition is a wide range of insect pests, but with a lack of victims, the Macrolophus begins to feed on vegetable juices. At one time, this feature generated controversy among entomologists about the appropriateness of its use. But with the passage of time and acquired experience, the entomophage has become a panacea against many pests.
Appearance
Macrolophus pygmaeus is a green insect, 3-4 mm long. It has an ellipsoid body covered with small bristles. From the features of the difference, the black colour of the first segment of the insect’s antennae should be distinguished. Sexual dimorphism is expressed by the presence of an ovipositor in imago females. In this regard, the abdomen of males is shorter and more flattened. Imago individuals have 3 pairs of legs and developed wings. The mouthpart of a predator of a piercing-sucking type.
Life cycle
The life cycle of a Macrolophus consists of the stages of an egg, a nymph (5 stages) and an imago.
The egg of the Macrolophus has a yellowish colour, but the tiny size does not allow them to be seen with the naked eye. It is almost impossible to predict the fertility of individuals, the range of the number of eggs laid by a female can range from 30 to 200 pieces per life cycle and depend on many factors. On average, a female lays 5-10 eggs a day. Eggs are laid on the foliage of the plant and develop for 2-3 weeks, depending on temperature conditions.
The larval (nymphal) stage is divided into 5 stages of development and lasts 2.5–3.5 weeks, depending on temperature conditions. But, even despite the temperature comfort zone of the Macrolophus, which is 22 -25 C, the nymphs begin to develop already at +15C, are resistant to any humidity and tolerate temperature increases up to +40C. The highest activity and efficiency are shown by nymphs of 4-5 ages, after which the larva becomes an adult.
Macrolophus imagos are less voracious than older larvae, but are more useful in terms of maintaining the population. Mating of bugs begins 2-4 days after the final moult and continues throughout the adult’s life. The number of eggs laid by a female depends on temperature conditions, the food base and even on the type of victims.
Nutrition and feeding
Developed limbs and wings allow the Macrolophus to move very quickly, which makes it an ideal predator. The basis of the bug’s diet are various types of whitefly at all stages of development. Older individuals can eat about 30 eggs, 15 pupae or 5 imago whiteflies per day. As a result, over the entire life cycle of a Macrolophus, the number of victims of one individual is measured in thousands. If, in addition to the Macrolophus, Encarsia formosa is present in the greenhouse, which infects the eggs of whiteflies, then the bug attacks such eggs much less often, which does not aggravate the effect of the parasitoid wasp’s work. In food, Macrolophus pygmaeus prefers the embryonic and larval stages of whitefly due to the more accessible food base, but does not hesitate to destroy adult individuals. Although in smaller quantities, but this is due to the large size of the victim.
This polyphage, despite its eating habits, with a lack of a favourite dish, eats aphids, eggs of owlet moths, spider mites and larvae of leafminers. As a result, by controlling the whitefly population, he can indirectly control other pests, while not worrying about the lack of a food base for the predator.
If there is absolutely trouble with the food of the Macrolophus, which of course is good, because it means that the enemy is defeated. But alas, the pest control process is cyclical and permanent. Then the bug, in search of food, will begin to feed on the juices of the plant, which will negatively affect both the plant and the fecundity of the entomophage (after all, a predator, anyway). Sometimes the lack of victims leads to cannibalism among the species. In such cases, bait is used, one of the variants of which are the eggs of the grain moth Sitotroga. This bait allows you to preserve the predator population and be ready for another battle for the harvest.
Recommendations for use
No one will give you one sure way how to properly apply Macrolophus. For the effective use of entomophage, it is necessary to take into account many factors, including types of pests, cultivated crops, climatic conditions, etc. It is always better to consult a specialist. After all, in this case, pest control is nothing more than a war, in which the Macrolophus is a soldier, and the agronomist is a general and strategist. With the right strategy, the results will not be long in coming and will be long-term and environmentally friendly.