The red palm weevil Rhynchophorus ferrugineus (Olivier) is an important pest of date palms in many regions of the world. This paper reports the first survey of insecticide resistance in field populations of R. ferrugineus in Pakistan which were collected from seven date palm growing areas across Punjab and Khyber Pakhtunkhwa (KPK) provinces, Pakistan. The resistance was assessed by the diet incorporation method against the formulated commonly used chemical insecticides profenophos, imidacloprid, chlorpyrifos, cypermethrin, deltamethrin, spinosad, lambda-cyhalothrin and a fumigant phosphine. Elevated levels of resistance were recorded for cypermethrin, deltamethrin and phosphine after a long history of insecticide use in Pakistan. Resistance Ratios (RRs) were 63- to 79-fold for phosphine_, 16- to 74-fold for cypermethrin, 13- to 58-fold for deltamethrin, 2.6- to 44-fold for profenophos, 3- to 24-fold for chlorpyrifos, 2- to 12-fold for lambda-cyhalothrin and 1- to 10-fold for spinosad compared to a susceptible control line. Resistant R. ferrugineus populations were mainly found in southern Punjab and to some extent in KPK. The populations from Bahawalpur, Vehari, Layyah and Dera Ghazi Khan were most resistant to chemical insecticides, while all populations exhibited high levels of resistance to phosphine. Of the eight agents tested, lower LC₅₀ and LC₉₀ values were recorded for spinosad and lambda-cyhalothrin. These results suggest that spinosad and lambda-cyhalothrin exhibit unique modes of action and given their better environmental profile, these two insecticides could be used in insecticide rotation or assist in phasing out the use of older insecticides. A changed pattern of both insecticides can be used sensibly be recommended without evidence of dose rates and frequencies used.

Field populations of Helicoverpa armigera Hübner from 15 localities across the Punjab, Pakistan, were assessed by the leaf dip method for resistance against formulated organophosphates, pyrethroids, and newer insecticide groups. Resistance levels in H. armigera have been incrementally increasing for organophosphate and pyrethroid insecticides after decades of use in Pakistan. Resistance ratios (RRs) documented for organophosphates were 24- to 116-fold for profenofos and 22- to 87-fold for chlorpyrifos. For pyrethroids, RRs were 3- to 69-fold for cypermethrin and 3- to 27-fold for deltamethrin. Resistance levels against newer chemistries were 2- to 24-fold for chlorfenapyr, 1- to 22-fold for spinosad, 1- to 20-fold for indoxacarb, 1- to 18-fold for abamectin, and 1- to 16-fold for emamectin benzoate. Resistant populations of H. armigera were mainly in the southern part of the Punjab, Pakistan. The most resistant populations were collected from Pakpattan, Multan, and Muzzafargarh. Of the nine insecticides tested, LC₅₀ and LC₉₀ values were lower for newer insecticide groups; resistance levels were moderate to very high against organophosphates, very low to high against pyrethroids, and very low to low against the newer-chemistry insecticides. These findings suggest that the newer-chemistry insecticides with different modes of action could be included in insecticide rotations or replace the older insecticides. Supplementing the use of synthetic insecticides with safer alternatives could help to successfully lower the farmer’s reliance on insecticides and the incidence of resistance due to repeated use of insecticides against major insect pests.

Aphids are major pests affecting cereals, vegetables, fruit, forestry and horticultural produce. A multimodal approach may be an effective route to controlling this prolific pest. We assessed the individual and combined effect of eight insecticides and the entomopathogenic fungi,Metarhizium anisopliae(Metschin.) against the cotton aphid,Aphis gossypiiGlover (Hemiptera: Aphididae), under laboratory conditions. Six of the insecticides tested were found to be highly compatible (flonicamid, imidacloprid, nitenpyram, dinotefuran, pyriproxyfen and spirotetramat), showing positive integration with the fungus and were selected for bioassays. The combination mixtures (1:1 ratio ofM. anisopliae: insecticide) were significantly more toxic toA. gossypiithan individual treatments. Maximum mortality (91.68%) ofA. gossypiiwas recorded with combination of flonicamid andM. anisopliae(2.4 × 10⁶ cfu/ml) 72 h after application. While minimum mortality (17.08%) was observed with the individual treatment ofM. anisopliae(2.4 × 10⁶ cfu/ml). The insecticides revealed toxicity consistent with their compatibility withM. anisopliae,ranking for efficacy exactly as they did for compatibility. In addition, the synergy factor (SF) and co-toxicity coefficient (CTC) values indicated synergistic interactions at different time intervals. The synergistic efficacy revealed the potential of fungus-insecticide integration against sucking insect pests.