Compatibility and Efficacy of the Parasitoid Eretmocerus hayati and the Entomopathogenic Fungus Cordyceps javanica for Biological Control of Whitefly Bemisia tabaci

Abstract

Biological control is an effective method for whitefly management compared to the potential problems caused by chemical control, including environmental pollution and the development of resistance. Combined use of insect parasitoids and entomopathogenic fungi has shown high efficiency in Bemisia tabaci control. Here, we assessed the impacts of an entomopathogenic fungus, Cordyceps javanica, on the parasitism rate of a dominant whitefly parasitoid, Eretmocerus hayati, and for the first time also compared their separate and combined potential in the suppression of B. tabaci under semi-field conditions. Six conidial concentrations of C. javanica (1 × 103, 1 × 104, 1 × 105, 1 × 106, 1 × 107 and 1 × 108 conidia/mL) were used to assess its pathogenicity to the pupae and adults of E. hayati. Results showed that the mortality of E. hayati increased with higher concentrations of C. javanica, but these higher concentrations of fungus had low pathogenicity to both the E. hayati pupae (2.00–28.00% mortality) and adults (2.67–34.00% mortality) relative to their pathogenicity to B. tabaci nymphs (33.33–92.68%). Bioassay results indicated that C. javanica was harmless (LC50 = 3.91 × 1010) and slightly harmful (LC50 = 5.56 × 109) to the pupae and adults of E. hayati respectively on the basis of IOBC criteria, and that E. hayati could parasitize all nymphal instars of B. tabaci that were pretreated with C. javanica, with its rate of parasitism being highest on second-instar nymphs (62.03%). Interestingly, the parasitoids from second and third-instar B. tabaci nymphs infected with C. javanica had progeny with increased longevity and developmental periods. Moreover, experimental data from 15 day semi-field studies indicate that combined application of C. javanica and E. hayati suppresses B. tabaci with higher efficiency than individual applications of both agents. Therefore, combined applications of C. javanica (1 × 108 conidia/mL) and E. hayati is a more effective and compatible biological control strategy for management of B. tabaci than using either of them individually.

Phototoxicity of Ultraviolet‐A against the Whitefly Bemisia tabaci and Its Compatibility with an Entomopathogenic Fungus and Whitefly Parasitoid

“…Different cotton leaves were caged, and 60 pairs of the whitefly were released into the cage for egg-laying to occur for 24 hours. The adults of the whitefly were then removed after 24 hours, and the plants were kept at a temperature of 26 ± 1°C, relative humidity of 60%, and photoperiod of 14 : 10 (L : D) in an iron-framed and plastic sieve cage (60 × 60 × 60 cm) to allow for whitefly development as outlined by Ou et al [32] (Figure S1).…”

“…In 2015, E. formosa was obtained from the Chinese Academy of Agricultural Sciences, Institute of Plant Protection. Under laboratory conditions at SCAU, the parasitoid population was reared at the temperature of 26 ± 1°C, relative humidity of 60%, and a photoperiod of 14 : 10 (L : D) on cotton plants containing third instar whitefly nymphs placed in an iron-framed and plastic sieve cage (60 × 60 × 60 cm) as outlined by Ou et al [32].…”

“…Potato Dextrose Agar (PDA) media was used to maintain the fungal culture (200 g potatoes, 20 g dextrose, and 20 g agar in 1 L of distilled water) in a glass dish (90 mm Ø) for three weeks under dark conditions at 25 ± 2°C. The methodology followed for maintaining the experimental materials was as outlined by Ou et al [32]. As nymphs reached the second instar, 90 of them were marked on a leaf with each nymph being given a specific number to aid identification.…”

A Review of the Biology and Control of Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), with Special Reference to Biological Control Using Entomopathogenic Fungi

“…Bemisia tabaci can cause significant economic losses to crops by causing damage to the host plants during feeding through secretion of honeydew and transmission of plant viruses [ 45 ]. Both nymphs and adults of B. tabaci cause damage by inserting their mouthparts into the plants during feeding and by transmitting a large number of viruses that can severely damage susceptible plants species [ 27 ].…”

“…The effect of chemical pesticides on the non-target organism, environmental contamination, and resistance of insect pests have led to research on biological control agents as alternative control measures. B. tabaci can be effectively controlled by integrating multiple biological control agents such as parasitoids, predators, and EPF [ 45 , 71 , 72 , 73 , 74 , 75 , 76 ].…”