The spotted lanternfly (SLF) (Lycorma delicatula) (White) is an invasive insect pest that was introduced to the United States over a decade ago and has since caused severe economic damages to forestry, ornamental plant, and viticulture industries. The fungal entomopathogen Beauveria bassiana is a promising biological control agent that can infect and kill nymphal and adult SLF. However, spray applications in the field have yielded mixed results, potentially due to low residual efficacy, movement of SLF out of treated areas, or inadequate levels of direct coverage on insects. Here, we tested the efficacy of pieces of fabric soaked in a B. bassiana spore suspension ('fungal bands'), which can be attached to tree trunks and passively disseminate the pathogen to insects that walk across it. In laboratory bioassays, fungal bands (soaked in 1 & times; 109 spores/mL solution) killed over 60% of nymphs five days after exposure. Ninety-four per cent of all treated nymphs were confirmed to be infected with B. bassiana. Under field conditions, there was a 1.4-fold decrease in spore densities on bands after a week, corresponding to a reduction in SLF infection over time. Additional tests also demonstrated that SLF exposed to fungal bands rarely transmitted B. bassiana to other, untreated SLF (similar to 2% infected). Overall, this work demonstrates that fungal bands can successfully kill and infect SLF. Further work is needed to improve the longevity of fungal bands, maximise spore delivery to insects, and determine the number of bands required to provide control in managed areas.
Invasions of the aquatic weed Pistia stratiotes L. (Araceae) challenge the conservation of urban wetlands, as mechanical and chemical control are inefficient under eutrophic conditions. Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae) is a native South American phloem-feeding herbivore that feeds exclusively on this weed and has potential as a biological control agent. This study aimed to determine the initial L. pistiae density required to reduce P. stratiotes vigor and invasiveness under controlled conditions. Laboratory experiments evaluated plant biomass, number of leaves, and daughter plants, using four initial insect densities (3, 6, 9, and 12 individuals per plant) and a control over 30 days. In addition, L. pistiae populations were maintained in outdoor pools for six months under eutrophic conditions. Under laboratory conditions, 3 and 6 insects per plant showed lower biomass, fewer leaves and daughter plants, than the control. Plant biomass increased by 152.5% (+/- 15.58 SE) in the control but by only 8.5% (+/- 14 SE) with six insects per plant. These findings suggest that intermediate L. pistiae densities may reduce plant biomass under eutrophic conditions. Outdoor observations showed a decline in plant cover and vigor potentially related to L. pistiae. These qualitative observations provide valuable information about L. pistiae-P. stratiotes interaction under more realistic conditions. Our results support future augmentative biological control strategies in subtropical urban wetlands and contribute toward understand the potential of L. pistiae as a biological control agent of water lettuce.
Despite extensive optimisation of larval diets for mass-rearing the factitious host Corcyra cephalonica, the biochemical mechanisms linking host nutrition to Trichogramma parasitoid performance remain poorly understood. This study evaluated diet-mediated variation in host egg biochemical quality by quantifying total protein, sugars, free amino acids (FAA), DNA, and RNA across ten cereal-based diet formulations and relating these parameters to parasitisation and emergence of T. chilonis and T. japonicum. Eggs produced on the bajra + sorghum supplemented diet exhibited the highest biochemical enrichment across all measured constituents, increasing by 159 -1,150% over broken rice controls. These eggs supported significantly greater parasitisation (approximate to 79%) and adult emergence (>82%) in both parasitoid species. Egg protein (r = 0.94) and FAA content (r = 0.91) were strong predictors of parasitoid performance, identifying reliable biochemical indicators of host suitability. Parasitisation significantly increased host egg biochemical constituents with species-specific patterns consistent with differential resource utilisation strategies. Dietary fat content emerged as the strongest predictor of egg biochemical richness (r = 0.750-0.811), followed by dietary protein (r = 0.638-0.670). These findings establish practical biochemical benchmarks for host quality assessment (protein >6 mg g(-)& sup1;; FAA >45 mg g(-)& sup1;) and provide actionable guidance for optimising Trichogramma mass-production systems used in biological control programmes.
