Male mating and female postmating performances in cotton mealybug (Hemiptera: Pseudococcidae): effects of female density

Fatty acyl-CoA reductase influences wax biosynthesis in the cotton mealybug, Phenacoccus solenopsis Tinsley

Mealybugs are highly aggressive to a diversity of plants. The waxy layer covering the outermost part of the integument is an important protective defense of these pests. However, the molecular mechanisms underlying wax biosynthesis in mealybugs remain largely unknown. Here, we analyzed multi-omics data on wax biosynthesis by the cotton mealybug, Phenacoccus solenopsis Tinsley, and found that a fatty acyl-CoA reductase (PsFAR) gene, which was highly expressed in the fat bodies of female mealybugs, contributed to wax biosynthesis by regulating the production of the dominant chemical components of wax, cuticular hydrocarbons (CHCs). RNA interference (RNAi) against PsFAR by dsRNA microinjection and allowing mealybugs to feed on transgenic tobacco expressing target dsRNA resulted in a reduction of CHC contents in the waxy layer, and an increase in mealybug mortality under desiccation and deltamethrin treatments. In conclusion, PsFAR plays crucial roles in the wax biosynthesis of mealybugs, thereby contributing to their adaptation to water loss and insecticide stress.

The role of a fatty acyl-CoA reductase (PsFAR) in wax biosynthesis of cotton mealybug is investigated, RNAi against PsFAR resulted in insects with lower generation of waxy filaments and higher mortality under desiccation and deltamethrin treatments.

Biology, ecology, and management of cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is a highly invasive and harmful pest. It causes considerable loss of cotton crops in China, India and Pakistan. Little is known about its bionomics since it was first recorded in Pakistan and India in 2005. Rapid spread of this pest worldwide has accelerated research on its biology, ecology and management. The P. solenopsis has a short life cycle, and optimal temperatures lead to an increase in the number of generations per year, which is a serious threat to cotton crop production. Cotton mealybug is native to the USA, although it has now spread to >43 countries. Insecticidal control is the primary and dominant practice for this pest, and its resistance to commonly used insecticides is increasing. Biocontrol agents have strong potential for the management of nymphal instar stages. We read >250 articles related to our review title and finally reviewed recent advances in the understanding of P. solenopsis biology, ecology and control approaches, aiming to highlight integrated and biological management practices of this pest. © 2021 Society of Chemical Industry.

A Review on Papaya Mealybug Identification and Management Through Plant Essential Oils

Papaya (Carica papaya L.) production suffers from a multitude of abiotic and biotic constraints, among those are insect pests, diseases, and environmental conditions. One of the seriously damaging pests of papaya is invasive papaya mealybug, Paracoccus marginatus, which can inflict heavy yield loss if not contained. Little information on papaya mealybug species has been documented due to challenges in identification approaches to species level. The current approach is based on the morphological features which are restricted to the mealybug life cycle leading to unclear identification. In Sub-Saharan Africa, where a wide diversity of mealybug species exists, it is essential to have a correct identification of these insect species due to the specificity of control measures. Molecular identification could be the best way to identify the mealybug at the species level. Presently, farmers rely heavily on chemical pesticides as their only available option for papaya mealybug control. The overuse of pesticides due to insect waxy covering has led to the development of pesticide resistance and the negative impact on the local ecosystem. Alternatively, the use of plant essential oils (EOs) with adjuvant is suggested as the safe solution to papaya mealybug control as they contain a rich source of natural chemicals that dissolve the insect wax layer, causing the cell membrane to rupture eventually leading to death. This review provides current research knowledge about the papaya mealybug identification approaches and plant EOs from Sweet orange, garlic, castor, and adjuvant (isopropyl alcohol, and paraffin) as sustainable papaya mealybug management.