Climate change is adversely affecting wheat yields as the associated rising temperatures damage its reproductive physiology. Heat stress affects wheat at various stages of growth, but flowering and reproductive phases are the most sensitive to high temperatures as flower opening usually occurs in cooler environments. Heat stress at meiosis causes ovule and pollen sterility along with anther dehiscence. During pollen development, temperatures >30°C cause pollen abortion. At anthesis, heat stress limits resource translocation to developing grain, resulting in small grain and low yields. During grain development, heat stress shortens the grain-filling duration and decreases starch and protein accumulation due to reduced activity of grain biosynthesis enzymes and impaired flag leaf assimilatory efficiency and stem reserve mobilization. The development of heat-tolerant wheat genotypes through screening, selection and breeding using genetic engineering, exogenous application of osmoprotectants and agronomic approaches is a high priority. This review discusses the impact of heat stress on flower development and fertilization, grain development and reproductive failure in wheat and outlines strategies (i.e. breeding and selection, genetic engineering, molecular breeding and management) to improve heat tolerance in wheat.

The present study was performed to assess the individual and combined potential of 3 different concentrations of Trichoderma sp. (Ts) and Bacillus thuringiensis (Bt) to control brinjal insect pests. Tested formulations were applied on larval and adult stages of the pest. The Trichoderma laboratory bioassays revealed 73% mortality of the aphid species, Aphis gossypii (Glover), and 53% mortality of the cotton leafhopper (Jassids) Amrasca bigutulla bigutulla (Ishida), while opposite results were observed in case of Bt at the highest concentration (1 × 108 cfu ml−1) used. In vivo results revealed that Ts caused a significant population reduction of the aphid (87%) than the jassid (72%), 7 days of post-treatment, at the highest concentration, while non-significant results were observed at the lowest concentrations. A. gossypii was significantly found more susceptible to the mixture of Trichoderma + Bt than the jassid (62%) and brinjal shoot and fruit borer (65%) even after 48 h of treatment application. The combined application (Trichoderma + Bt) showed maximum population reduction of jassid (88%), aphid (95%), and BSFB (96%), respectively, 7 days post-applications. The positive correlation among time and concentration was observed. The result may imply that consortium of these microbial organisms could be effective and can be incorporated in IPM programs for effective control of sucking and chewing insect pests of brinjal.

The toxicity of seven biorational insecticides [five insect growth regulators (Buprofezin, Fenoxycarb, Pyriproxyfen, Methoxyfenozide, and Tebufenozide) and two oil-extracts of neem and bitter gourd seeds] against Bemisia tabaci and their selectivity for its parasitoid, Encarsia formosa were evaluated in laboratory and field conditions for 2 years (2018–2019) in Pakistan. Toxicity results demonstrate that Pyriproxyfen, Buprofezin, and Fenoxycarb proved to be effective (80–91% mortality and 66.3–84.2% population-reduction) against B. tabaci followed by Methoxyfenozide, Tebufenozide (50–75% mortality and 47.8–52.4% population-reduction), and then oil-extracts of neem and bitter gourd (25–50% mortality and 36.5–39.8% population-reduction) in the laboratory [72 h post-application exposure interval (PAEI)] and field trails (168 h PAEI), respectively. All tested biorationals, except Methoxyfenozide [(slightly-harmful/Class-II), i.e., causing mortality of parasitoids between a range of 25–50%] and Tebufenozide [(moderately-harmful/Class-III), i.e., causing mortality of parasitoids between the ranges of 51–75%], proved harmless/Class-I biorationals at PAEI of 7-days in the field (parasitism-reduction < 25%) and 3-days in the lab (effect < 30%). In laboratory bioassays, exposure of parasitized-pseudopupae and adult-parasitoids to neem and bitter gourd oils demonstrated that these compounds proved harmless/Class-I biorationals (< 30% mortality). Alternatively, Pyriproxyfen, Buprofezin, Fenoxycarb, Methoxyfenozide, and Tebufenozide were slightly-harmful biorationals (30–79% mortality) against the respective stages of E. formosa. We conclude that most of the tested biorationals proved harmless or slightly harmful to E. formosa, except tebufenozide after PAEI of 7-days (168 h) in the field and, therefore, may be used strategically in Integrated Pest Management (IPM) of B. tabaci.

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