Lebanese Beauveria pseudobassiana fungus killed 90.7% of tomato leafminer in cages and cut mines in tunnels
In cage tests the fungus matched Bacillus thuringiensis, and in commercial tunnel trials it held leaf mines to 1.9–2.3 per leaf. This matters because the pest has become resistant to many insecticides.
A Lebanese isolate of the fungus Beauveria pseudobassiana suppressed the tomato leafminer Tuta absoluta in cage experiments and in commercial high-arched plastic tunnels, according to the Egyptian Journal of Biological Pest Control. The authors compared it with the bacterial biopesticide Bacillus thuringiensis and with conventional pesticide mixtures. biomedcentral.com
Egyptian Journal of Biological Pest Controlbiomedcentral.comOpen source ↗ In cages the fungus gave 90.7% mortality at 20 °C, against 85.4% for B. thuringiensis, and 100% mortality at 14 °C.
Tuta absoluta is an invasive pest that damages tomato crops worldwide, and its resistance to commonly used chemical insecticides has made control harder. In Lebanon, farmers frequently apply pesticide mixtures twice weekly, according to the publication's retelling of the study background.
Cage experiments with controlled infestation
Three preliminary experiments used larvae reared from field-collected adult moths. The first two ran in glasshouses at 25 °C on the AUB-Line 9 tomato cultivar, in insect-proof cages of 55 by 55 by 55 cm. Conidia were applied at 100 million per milliliter with 1% corn oil as an adjuvant. In the second cage trial, corrected mortality was 89.59% for the fungus and 83.88% for B. thuringiensis. The two agents did not differ significantly, and both clearly outperformed untreated plants.
The third experiment used a single-span greenhouse with mature plants at an average of 14.7 °C. Two sprays of the fungal suspension resulted in 100% egg mortality, while 93.18% of control eggs hatched. biomedcentral.com
Egyptian Journal of Biological Pest Controlbiomedcentral.comOpen source ↗
Trials in commercial tunnels
Two field trials were carried out in commercial tunnels under natural infestation. B. pseudobassiana and B. thuringiensis significantly reduced leaf mine incidence, with control comparable to or better than calendar-based chemical sprays.
In fall production the fungus reduced leaf mines to 1.9 per leaf by week 11. Chemical pesticides gave 3.6 per leaf and B. thuringiensis 2.6. In summer production the fungus gave 2.3 and 2.1 mines per leaf at weeks 3 and 4, against 3.1 and 5.8 for B. thuringiensis.
The authors describe this as the first demonstration of the fungus's efficacy in commercial tomato production. They conclude that it is a viable alternative or complement to B. thuringiensis in integrated pest management programs. biomedcentral.com
Egyptian Journal of Biological Pest Controlbiomedcentral.comOpen source ↗
