Microscopy-based morphological characterization of rugose spiraling whitefly, (Aleurodicus rugioperculatus Martin)-an exotic pest on coconut in India

Precise identification of exotic whiteflies is a prerequisite to curb the invasive potential on to a new geographical location and to evolve effective management strategies. Conventionally, whitefly taxonomy is based on the description of the fourth-instar nymph or puparium, however, in the current investigation egg to adult morphology along with morphometrics of rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin was critically analyzed and various morphological characteristics were illustrated. The morphometric analysis revealed that in the immature life stages of the pest, the length: width ratio decreased with each successive life stage, such as the egg, first, second, third, and fourth instar (2.472 ± 0.071, 1.913 ± 0.020, 1.550 ± 0.045, 1.297 ± 0.034, and 1.174 ± 0.058 mm), respectively. Across different nymphal instars, the shape of lingula was greatly modified from tongue-like to triangle-shaped. The number and distribution of compound pores also vary among the different nymphal stages. The ultra-structures of the antenna through electron-microscopy depicted finer details of sensory cones. The modulation in the shape and the structural arrangement of microtrichia on the plate was illustrated. The study indicated accurate diagnosis of various stages of RSW for effective interception of goods at quarantine stations and thus preventing the entry of exotic pests into the country. RESEARCH HIGHLIGHTS: Microscopy-based (light and scanning electron microscopy) morphological characterization of rugose spiraling whitefly, (Aleurodicus rugioperculatus Martin).

Insecticide Resistance and Its Management in Two Invasive Cryptic Species of Bemisia tabaci in China

The sweet potato whitefly Bemisia tabaci is a major agricultural pest with a wide host range throughout the world. The species designation for B. tabaci includes numerous distinct cryptic species or biotypes. Two invasive B. tabaci biotypes, MEAM1 (B) and MED (Q), were found in China at the end of the 20th century and at the beginning of the 21st century. MEAM1 (B) and MED (Q) show higher pesticide resistance levels than native strains, and the levels of resistance vary with changes in insecticide selection pressure. Recent studies have revealed metabolic resistance mechanisms and target site mutations in invasive B. tabaci strains that render them resistant to a range of insecticides and have uncovered the frequency of these resistance-related mutations in B. tabaci populations in China. Novel pest control agents, such as RNA-based pesticides and nano-pesticides, have achieved effective control effects in the laboratory and are expected to be applied for field control of B. tabaci in the future. In this review, we discuss the mechanisms of resistance developed by these invasive B. tabaci populations since their invasion into China. We also provide suggestions for ecologically sound and efficient B. tabaci control.