The tomato leaf miner Phthorimaea (syn. Tuta) absoluta Meyrick (Lepidoptera: Gelechiidae) is invasive in many agricultural regions. Its larvae feed inside leaf mines or tomato fruits and are difficult to reach with plant protection products. In contrast, entomopathogenic nematodes (EPNs) are highly virulent and can search for larvae. The challenge is to formulate EPNs to remain protected on a sprayed leaf surface until they enter the mines. We tested 11 formulations, including 2 oils, 4 gels or thickeners, 2 surfactants, 2 UV protectants, water, and combinations with and without the EPN Steinernema carpocapsae (Weiser) RW14-G-R3a-2 (Rhabditida: Steinernematidae), under non-closed low-humidity conditions. Six tomato leaf experiments with 1000 EPNs sprayed per leaf showed that EPNs in 0.25 to 0.5% canola oil or in 5% alkyl polyglycoside surfactant were the most effective (26 to 37%). Other formulations and an insecticide had less or no effect. Seven other bioassays showed that most formulations did not adversely affect EPN survival or pathogenicity. We assume that formulations of EPNs can be further improved, such as with other flowable gels or combinations, and encourage investment in the development of practical and economic protective sprayable formulations of EPNs against leaf miners to reduce reliance on chemical insecticides.

The potato tuber moth, Phthorimaea operculella (Zeller), is an important pest of potato crops capable of boring into and consuming the potato tubers. Although chemical insecticides are employed to control P. operculella populations, their efficacy is frequently limited, raising environmental concerns. Host plant volatiles are important allelochemicals that can be exploited for the management of pests. In our previous studies, we identified five volatile organic compounds (3-ethylacetophenone, 4-ethylacetophenone, geranylacetone, ethylbenzene, and 4-hydroxy-4-methyl-2-pentanone) as allelochemicals potentially influencing the oviposition behavior of P. operculella. Using electroantennography (EAG) and behavioral assays, we found that 4-ethylacetophenone significantly repelled P. operculella at all tested concentrations (1 μg, 10 μg, and 100 μg; p < 0.05), while 3-ethylacetophenone showed no significant effects (p > 0.05). Finally, the effect of 4-ethylacetophenone on preventing P. operculella from laying eggs was determined by an oviposition selection experiment. Our findings indicate that 4-ethylacetophenone derived from potato plants not only repels P. operculella and prevents egg-laying but also has the potential to reduce the number of eggs, making it a promising green alternative for controlling this pest.

Soybean root rot, primarily caused by Fusarium oxysporum, leads to severe root decay and substantial yield losses in Glycine max. This study screened ten entomopathogenic nematode-associated symbiotic bacteria for antagonistic activity against F. oxysporum. Among them, Xenorhabdus budapestensis XH-4 exhibited the strongest in vitro inhibition, suppressing mycelial growth by more than 73%. Antifungal activity was primarily attributed to extracellular metabolites, as both fermentation broth and cell-free culture supernatant were effective, whereas bacterial cell suspensions showed no significant inhibition. In greenhouse experiments, 40% (v/v) XH-4 reduced the disease index by 75–80%, comparable to the chemical fungicide metalaxyl–hymexazol. Genome mining revealed 20 biosynthetic gene clusters encoding diverse secondary metabolites, including fabclavine, fabclavine pyrrolizixenamide A, and putrebactin/avaroferrin, which likely underpin the strain antifungal efficacy. Additionally, XH-4 enhanced soybean antioxidant capacity and activated the phenylpropanoid pathway, indicating a dual mechanism involving direct antagonism and induced systemic resistance. These findings support the development of XH-4 as an environmentally friendly biofungicide for sustainable management of soybean root rot.