[Cross-resistance and the underlying mechanisms of clothianidin resistant population of Frankliniella occidentalis to insecticides]. / 西花蓟马抗噻虫胺种群对杀虫剂的交互抗性及机制.

Clothianidin, belonging to neonicotinoid insecticide with systemic and contact mechanisms, is used to control the invasive pest Frankliniella occidentalis. To identify the resistance risk, we examined the cross-resistance to multiple insecticides and mechanisms of clothianidin resistant population of F. occidentalis. The results showed that F. occidentalis developed a high level of resis-tance to clothianidin (56.8-fold) after selecting for 45 generations. The resistant population of F. occidentalis had medium level of cross-resistance to thiamethoxam, imidacloprid, chlorpyrifos, cyhalothrin and emamectin benzoate (18.6>RR50>11.3), and the low level of cross-resistance to phoxim and methomyl, but no cross-resistance to chlorfenapyr and spinosad. The synergists piperonyl butoxide (PBO) and triphenyl phosphate (TPP) had significant synergistic effects on clothianidin in killing the resistant population (CL), Yunnan wild population (YN) and susceptible population (S). Compared with the sensitive population, the CL populations had significantly increased activities of mixed-functional oxidases P450(3.6-fold), b5(2.9-fold) and O-demethylase (4.9-fold), and carboxylesterase (2.5-fold), with no significant difference in the activities of glutathione S-transferases among CL and S populations. The results highlight the role of increasing mixed-functional oxidases and carboxylesterase in the resistance of F. occidentalis to clothianidin.

[Resistance risk and resistance stability of Frankliniella occidentalis to nitenpyram, clothianidin and thiamethoxam]. / 西花蓟马对烯啶虫胺、噻虫胺和噻虫嗪的抗性风险和抗性稳定性.

To effectively control the damage of Frankliniella occidentalis (Pergande), we evalutated the resistance risk and resistance stability of F. occidentalis to nitenpyram, clothianidin and thiamethoxam. With the method of dipping Phaseolus vuglaris, we selected the resistance populations from the susceptible population with nitenpyram, clothianidin and thiamethoxam, respectively. Both the resistance inheritance and resistance risk were analyzed with the resistance reality hereditary. After 30 generations' selections, the selected-populations showed high level of insecticide resistance to nitenpyram, clothianidin and thiamethoxam, with a resistance ratio of 44.7-fold, 45.5-fold, and 32.7-fold, respectively. The development rate of resistance to clothianidin, nitenpyram, and thiamethoxam reduced in turn, with a resistance reality heritability of 0.1503, 0.1336 and 0.1258, respectively. Stopping selection for 10 continuously generations, the resistance levels of selection resis-tance populations declined slowly, but could not regain the original susceptibility to nitenpyram, clothianidin and thiamethoxam. After resistance selection, the sensitivity of F. occidentalis nymphs to clothianidin, nitenpyram, and thiamethoxam was significantly higher than that of adults. F. occidentalis had the great potential to gain high level resistance to nitenpyram, clothianidin and thiamethoxam. Compared with other two insecticides, the resistance of F. occidentalis to thiamethoxam increased slower and decreased faster. Therefore, using thiamethoxam in nymph stage might be beneficial to effectively control F. occidentalis.

Temperature-Dependent Demographic Characteristics and Control Potential of Aphelinus asychis Reared from Sitobion avenae as a Biological Control Agent for Myzus persicae on Chili Peppers.

Aphelinus asychis, a polyphagous parasitoid, has been widely used as an efficient biological control agent against the aphid Myzus persicae. Aiming to evaluate the influence of temperature on the biological characteristics and control potential of A. asychis for M. persicae, we compared the life table parameters and control potential of A. asychis, which included the developmental time, longevity, fecundity, intrinsic rate of increase (r), and finite killing rate (θ). The results showed that increasing the temperature significantly decreased the developmental time and longevity of A. asychis. The r at 24 (0.2360 d-1) and 28 °C (0.2441 d-1) were significantly greater than those at 20 (0.1848 d-1) and 32 °C (0.1676 d-1). The θ at 24 (0.4495), 28 (0.5414), and 32 °C (0.4312) were also significantly greater than that at 20 °C (0.3140). The relationship between population fitness (r and θ) and temperature followed a unary quadratic function (R2 > 0.95). The temperatures for the expected maximum intrinsic rate of increase (rmax) and the maximum finite killing rate (θmax) were 25.7 and 27.4 °C, respectively. In conclusion, A. asychis could develop and produce progenies within the temperature range of 20-32 °C, and its control efficiency for M. persicae at 24, 28, and 32 °C was greater than that at 20 °C. The most suitable temperature range for controlling M. persicae with A. asychis in the field might be between 25.7 and 27.4 °C.

Reproductive Potential and Nutritional Composition of Hermetia illucens (Diptera: Stratiomyidae) Prepupae Reared on Different Organic Wastes.

Hermetia illucens L. (the black soldier fly) has received increased attention because of its great potential in converting organic waste into a renewable resource. The prepupae have high proportions of proteins and fats and can serve as feedstuff for livestock and as feedstock for biodiesel production. With the goal to upgrade the conversion of low-value organic wastes into high-value proteins and fat on a large scale, the effects of the feedstuffs food waste, pig manure, chicken manure, and cow dung on the reproductive potential and nutrient composition of H. illucens were evaluated. The intrinsic rate of increase of H. illucens fed food waste (0.1249 d-1) was significantly greater than the rate of those fed pig manure (0.1167 d-1), chicken manure (0.1154 d-1), and cow dung (0.1049 d-1). The ash content of H. illucens fed food waste (30.8 g·kg-1 lyophilized prepupa matter (LPM)) was significantly lower than that of those fed chicken manure (37.6 g·kg-1 LPM) and cow dung (49.5 g·kg-1 LPM). The contents of crude fat, 372.4 g·kg-1 LPM, and protein, 436.9 g·kg-1 LPM, in prepupae fed food waste were the highest among the four treatments. The reproductive performance and prepupal nutrient composition indicated that food waste was the most suitable feed for H. illucens. The results from this study further demonstrate that the prepupae of H. illucens have great potential for use as a protein and fat source in animal feeds and as biodiesel material.

Brief Heat Stress Negatively Affects the Population Fitness and Host Feeding of Aphelinus asychis (Hymenoptera: Aphelinidae) Parasitizing Myzus persicae (Hemiptera: Aphididae).

Aphelinus asychis Walker (Hymenoptera: Aphelinidae), a polyphagous parasitoid, has been widely used as a biological control agent against Myzus persicae (Sulzer) (Hemiptera: Aphididae) and other aphid species. In order to ensure the successful biological control of M. persicae, we evaluated the influence of brief heat stresses (32.5, 35.0, 37.5, 40.0, and 41.5°C for 1 h), which occur frequently during the summer or under greenhouse conditions, on survival, longevity, host feeding, and parasitism of A. asychis that were reared on chili pepper at 25°C in the laboratory. Our results showed several major consequences on the parasitoid adults after brief heat stress. First, the survival of briefly heat stress-treated A. asychis female and male adults decreased significantly at ≥37.5°C and their longevity decreased as well. Second, the number of M. persicae nymphs infesting chili pepper killed through host feeding by the treated A. asychis females decreased significantly. Third, the cumulative number of mummified aphids and female progeny produced by the treated A. asychis also decreased significantly at ≥37.5°C. Our results indicated that a brief heat stress on A. asychis adults caused severe effects on major life history traits and total numbers of hosts killed by host feeding and parasitism, suggesting that high temperatures should be avoided to ensure the success of biological control of M. persicae and other aphid species using this parasitoid species.

[Resistance mechanisms and cross-resistance of phoxim-resistant Frankliniella occidentalis Pergande population].

To understand the resistance risks of Frankliniella occidentalis Pergande against phoxim, this paper studied the resistance mechanisms of phoxim-resistant F. occidentalis population against phoxim and the cross-resistance of the population against other insecticides. The phoxim-resistant population had medium level cross-resistance to chlorpyrifos, lambda-cyhalothrin, and methomyl, low level cross-resistance to chlorfenapyr, imidacloprid, emamectin-benzoate, and spinosad, but no cross-resistance to acetamiprid and abamectin. The synergists piperonyl butoxide (PBO), s, s, s-tributyl phosphorotrithioate (DEF), and triphenyl phosphate (TPP) had significant synergism (P < 0.05) on the toxicity of phoxim to the resistant (XK), field (BJ), and susceptible (S) populations, while diethyl maleate (DEM) had no significant synergism to XK and S populations but had significant synergism to BJ population. As compared with S population, the XK and BJ populations had significantly increased activities of mixed-functional oxidases P450 (2.79-fold and 1.48-fold), b, (2.88-fold and 1.88-fold), O-demethylase (2.60-fold and 1.68-fold), and carboxylesterase (2.02-fold and 1.61-fold, respectively), and XK population had a significantly increased acetylcholine esterase activity (3.10-fold). Both XK and BJ population had an increased activity of glutathione S-transferases (1.11-fold and 1.20-fold, respectively), but the increment was not significant. The increased detoxification enzymes activities in F. occidentalis could play an important role in the resistance of the plant against phoxim.

[Resistance risk and resistance stability of Frankliniella occidentalis to imidacloprid, emamectin benzoate, and phoxim].

In order to effectively control the damage of Frankliniella occidentalis (Pergande), Phaseolus vuglaris was dipped with imidacloprid, phoxim, and emamectin benzoate, respectively to select the resistance populations of F. occidentalis from its susceptible population, and the resistance inheritance and resistance risk were analyzed with the resistance reality heredity. After 32, 32, and 24 generations' selection, the F. occidentalis populations obtained 13.8-fold, 29.4-fold and 39.0-fold resistance to imidacloprid, phoxim, and emamectin benzoate, respectively. The resistance reality heritability to imidacloprid, phoxim, and emamectin benzoate was 0.112, 0.166, and 0.259, respectively. The resistance development rate to emamectin benzoate was the fastest, followed by to phoxim, and to imidacloprid. The higher the resistance levels of the selected populations, the lower the differences between the larva and adult susceptibility to imidacloprid, phoxim, and emamectin benzoate. Stopping selection for 12 continuous generations, the resistance level of the selected resistance populations to imidacloprid, phoxim, and emamectin benzoate had definite decline, but it was difficult to regain the original susceptibility. F. occidentalis had a greater potential to gain high level resistance to imidacloprid, phoxim, and emamectin benzoate. Compared with the resistance of F. occidentalis to phoxim and emamectin benzoate, the resistance to imidacloprid increased slower and decreased faster, and thus, imidacloprid was more appropriate to control F. occidentalis in practice.