Psocids have become global pests of stored commodities as they can cause considerable economic losses. These insects are difficult to control because they have developed resistance to many chemical insecticides. Therefore, it is crucial to investigate alternative integrated pest management (IPM) approaches, such as the use of light attraction for monitoring and/or controlling psocids. Light attraction has been studied for Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae) but not for other psocid species. In this study, we investigated the response of adults of three psocid species (Psocoptera: Liposcelididae), Liposcelis entomophila (Enderlein), Liposcelis paeta Pearman, and Liposcelis brunnea Motschulsky, to six wavelengths of light from light-emitting diode (LED) in paired-choice pitfall tests. L. entomophila females and males were not attracted to any of the wavelengths tested. L. paeta females responded positively to two ultraviolet (UV) wavelengths (351 and 400 nm) and to green light (527 nm), while males did not respond to any light. L. brunnea females and males responded positively to all six wavelengths evaluated. Most of the LEDs that elicited positive responses to L. paeta females and L. brunnea females and males were also preferred when these lights were presented against brewer's yeast, a food attractant highly preferred by several psocid species. Females of L. paeta and L. brunnea were attracted to white light when compared with a blank, but females of L. entomophila were not attracted to white light compared to a blank.

Insects and mites are common inhabitants and accidental invaders of food, including durable commodities, and their presence can have both direct and indirect effects on human health. The most common direct effect is contamination of food with arthropod fragments and related contaminants, which may be allergenic or even carcinogenic. The most important indirect effect is that their presence can change the storage microenvironment, making durable products suitable for the rapid development of fungi and other microorganisms. Some of these fungi can produce toxins (e.g., aflatoxins) that endanger human health. Insects may actively or passively contribute to the spread of microorganisms, increasing product contamination, and they may host bacteria that have developed antibiotic resistance, contributing to their spread in food. Several species also may host, attract, or transmit tapeworms, predators, or parasitoids that may affect health. This review synthesizes research on these topics and suggests directions for future research.

Psocids, beetles, moths and mites are regarded as the common kinds of stored-product pests in the world. The rapid and correct identification of stored-product pests is significant for quarantine, monitoring and control purposes. Molecular methods and techniques have been studied and applied for stored-product pest identification. Based on collection and analysis of literature in the last decade, this paper reviews the developments, questions and prospects for molecular identification of stored-product pests. As a representative model, the molecular methods and techniques for species identification of stored-product psocid pests were developed and applied systematically based on international collaboration involving China, Czech Republic, the United States and other countries. More than 10 studies on stored-product psocids related to RFLP, DNA barcoding, PCR, real-time PCR and gene chip have been published during this decade. Subsequently, DNA barcoding, PCR and real-time PCR techniques for the identification of common species of Tribolium and Cryptolestes pests of stored products have been reported by the same international team. Recently, a web system called Grain Pests DNA Barcode Identification System (GPDBIS) has been established in China using SOL SERVER and C#. Like a marathon that requires persistence, we should do our best to continue to promote research and application of molecular identification of stored-product pests with more international collaboration.

A series of studies was conducted by exposing young and old eggs, nymphs, and adults of the psocids Liposcelis bostrychophila (Badonnel), L. paeta (Pearman), L. decolor (Pearman), and L entomophila (Enderlein) to -18 degrees C for various time intervals. Survival was assessed as initial and final, at different times depending on the life stage. Young eggs of L bostrychophila were the most tolerant life stage of any of the species, with scattered survival out to 120 h of exposure to -18 degrees C. Eggs were the most tolerant life stage for each species, requiring 24,12, and 2 h of exposure for complete kill of L paeta, L decolor, and L. entomophila, respectively. Nymphs and adults of all species were far more susceptible than eggs, with no final survival after two hours of exposure. Results show the extreme variation between different psocid life stages and species to cold temperatures, and provide guidelines for using cold as a control strategy for psocids. Our results show that 24 h at -18 degrees C is sufficient to kill all life stages of the psocid species tested, except for young L. bostrychophila eggs which will require at least 128 h of exposure at 18 C for complete mortality. (C) 2016 Published by Elsevier Ltd.

Insecticides are an invaluable pest management tool and anthropogenic stressors of widespread environmental occurrence that are subject to biased perceptions based on the targeted application, market value of use, and regulatory requirements. As a result, short-term and simplistic efforts focusing on lethal effects toward individual species and populations prevail. Holistic and comprehensive studies exploring rather common sublethal insecticide exposures are rare, particularly considering their potential role in structuring populations and communities in diverse environmental settings and potentially interfering in a range of ecological interactions. Studies on insecticide resistance, for example, do not go beyond population-based studies, disregarding temporal and spatial effects in the associated community, and rarely considering the whole of sublethal exposure. Some of these knowledge gaps are here recognized and explored.

Insecticide resistance is a broadly recognised and well-studied management problem resulting from intensive insecticide use, which also provides useful evolutionary models of newly adapted phenotypes to changing environments. Two common assumptions in such models are the existence of fitness costs associated with insecticide resistance, which will place the resistant individuals at a disadvantage in insecticide-free environments, and the prevalence of random mating among insecticide-resistant and -susceptible individuals. However, cases of insecticide resistance lacking apparent fitness disadvantages do exist impacting the evolution and management of insecticide resistance. Assortative mating, although rarely considered, may also favour the evolution and spread of insecticide resistance. Thus, the possible existence of both conditions in the maize weevil (Sitophilus zeamais), a key pest of stored cereals, led to the assessment of the mating behaviour and reproductive fitness of insecticide-resistant and -susceptible weevil strains and their reciprocal crosses. The patterns of female and male mating choice also were assessed. Although mating behaviour within and between weevil strains was similar without mate choice, mating within the resistant strain led to higher reproductive output than within the susceptible strain; inter-strain matings led to even higher fertility. Thus, no apparent fitness cost associated with resistance seems to exist in these weevils, favouring the evolution of this phenotype that is further aided by the higher fertility of inter-strain matings. Mate choice reduced latency to mate and no inter-strain preference was detected, but female weevils were consistent in theirmate selection between 1st and 2nd matings indicating existence of female mating preference among maize weevils. Therefore, if female mate selection comes to favour trait(s) associated with insecticide resistance, higher reproductive fitness will be the outcome of such matings favouring the evolution and spread of insecticide resistance among maize weevil populations reverting into a management concern.

The psocid, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), is the most widespread psocid pest of stored products. Because L. bostrychophila has developed resistance to several chemical insecticides, it is important to investigate other integrated pest management (IPM) approaches, and a critical part of IPM programs is an effective monitoring program, Monitoring tools for psocids are limited, and few studies have been conducted on monitoring of psocids, with none on the attraction of lights for psocids. Therefore, we studied the response of L. bostrychophila adults to eight wavelengths of light-emitting diodes (LED) in paired-choice pitfall test. Among the LEDs evaluated, the strongest response by L. bostrychophila adults was to 351 nm UV. When LEDs were tested against brewer's yeast (the most preferred attractant for L. bostrychophila among more than 20 potential attractants found in previous studies), the 351 nm UV wavelength was the only light that attracted more psocids than brewer's yeast. These results suggest that the use of LEDs might be useful in psocid-monitoring programs for L. bostrychophila and other psocid species.

Studies were conducted by exposing different life stages of Tribolium castaneum (Herbst), the red flour beetle, and Trogoderma inclusum (Leconte), the larger cabinet beetle, for different time intervals to -18 degrees C. Assessments were made of direct mortality to eggs, larvae, and adults, and eventual adult emergence of immatures. Data were described by non-linear equations. The eggs and larvae were the most tolerant life stage of T. castaneum. Eight hours of exposure were required for 100% kill of 3-4-day-old eggs and 0-10- and 11-21-day-old larvae, but only 4, 0.5, and 0.5 h respectively were required to completely inhibit adult emergence. For T. inclusum, the most tolerant life stage was 15-28-day-old larvae; 64 and 16 h respectively were required for complete mortality and inhibition of adult emergence. Results indicate that T. inclusum was the more tolerant species, and specific treatment protocols may be required for different stored product beetle species when using -18 degrees C as a disinfestation strategy. (C) 2015 Published by Elsevier Ltd.

The psocid species Liposcelis paeta Pearman, Liposcelis entomophila (Enderlein), Liposcelis decolor (Pearman), Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), and Lepinotus reticulatus Enderlein (Psocoptera: Trogiidae) were evaluated in laboratory bioassays to determine their susceptibility to six concentrations of methyl bromide (0.027, 0.113, 0.280, 0.393, 0.452, and 0.616 g/m(3)) after 48 h of exposure at 27.5 degrees C. The life stages that were evaluated were adults (for all species), nymphs (for all species except Lep. reticulatus), and eggs (for L. entomophila, L. decolor, and L. bostrychophila). Adults and nymphs were very susceptible, and complete mortality was recorded at concentrations between 0.027 and 0.280 g/m(3). In contrast, eggs were by far more tolerant than adults and nymphs for all species tested. At 0.027 g/m(3), mortality did not exceed 53%, while survival was high even at 0.113 g/m(3). Complete (100%) egg mortality was recorded at 0.393 g/m(3) for L. decolor and at 0.452 g/m(3) for L. entomophila and L. bostrychophila; concentrations estimated to give 99% mortality for eggs of these three species were 0.710, 1.044, and 0.891 g/m(3), respectively. These results show that stored-product psocids are susceptible to methyl bromide, but concentrations of >= 0.452 g/m(3) should be used to control all life stages.

We conducted studies using a commercial freezer maintained at -17.8 degrees C to determine the time needed to kill Tribolium castaneum eggs in a pallet of flour. Each bag weighed 22.7 kg, and there were 5 bags in each of 10 layers. The dimensions of the pallet were 109-cm wide by 132-cm long by 123-cm tall, and the weight of the stacked pallet was approximately 1152 kg. We conducted tests for nine internal goal temperatures of -12, -10, -8, -6, -4, -2, 0, 4 and 8 degrees C. Internal temperatures in the most central location of the flour pallet reached: -11.0, -9.4, -6.9, -5.0, -3.5, -1.6, -0.1, 3.3, and 5.6 degrees C and were achieved after 11.0, 9.1, 8.9, 7.2, 6.7, 5.8, 5.5, 5.2, and 4.2 days, respectively. For treatments where the goal temperature for the center bag ranged from -12 to 4 degrees C, egg mortality was 100% in bags located in both the periphery and in the center of the pallet. When the temperature goal for the center bag was 8 degrees C, 7 +/- 2.5% of the eggs survived in bags located near the center of the pallet. Our data showed that temperatures that follow the dynamic temperature curve that takes place over 24.2 days (cool down and warm up for the 0 degrees C temperature goal) resulted in 100% mortality of T. castaneum eggs. The reason for the difference in mortality for a static compared to a dynamic temperature treatment may be due to the fact that the dynamic temperature treatment occurs over a much longer duration. The fact that the treatment only required 5.5 days in the freezer before it could be shipped makes it a practical method to disinfest pallets of flour, especially because the bags do not need to be removed from the pallet and no chemicals are used. Published by Elsevier Ltd.

The maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), is one of the major pests of maize worldwide. We tested one Tripsacorn-introgressed inbred maize line and 42 hybrid combinations between eleven public inbred lines and 16 different Tripsacorn-introgressed inbreds for resistance to the maize weevil to investigate if there is a genetic basis for resistance to the maize weevil that can be conferred to maize. No progeny were produced in 21 of the entries, and only eight entries had progeny production significantly greater than zero. All the lines that exhibited complete resistance (no progeny produced) are F1 hybrids between 10 different Tripsacorn-introgressed inbred lines combined with 8 different public maize inbreds. Results indicate that all 16 Tripsacorn-introgressed inbred lines confer resistance in F1 hybrids. In some of the Tripsacorn-introgressed lines, the degree of resistance expressed varied according to combining ability and heterotic group background. Based on the results, we hypothesize a dominant gene for weevil resistance is inherited from Tripsacorn. The data indicate that Tripsacorn provides a valuable tool for conferring native weevil resistance to maize.

Psocids have emerged as worldwide pests of stored commodities during the past two decades, and are difficult to control with conventional management tactics such as chemical insecticides. Therefore, it is necessary to investigate alternative management strategies, such as the use of attractants for monitoring and controlling psocids, which can be incorporated into integrated pest management programs for psocids. Using a two-choice pitfall test, we studied the response of adults of different ages and sexes of Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae), Liposcelis paeta Pearman, Liposcelis decolor (Pearman), Liposcelis brunnea Motschulsky, Liposcelis corrodens (Heymons), and Lepinotus reticulatus Enderlein (Psocoptera: Trogiidae) to volatiles from different potential attractants including grains, grain-based oils, brewer's yeast, wheat germ, and commercially available kairomone lures. For all species tested, sex and age did not have a major influence on response to the different potential attractants. Brewer's yeast most consistently elicited the strongest response for psocids, but this response frequently was not different from that to wheat germ and wheat germ oil. The percentage response to brewer's yeast varied among the psocid species tested: L. decolor (73-78%), L. entomophila (62-73%), L. brunnea (64-68%), L. paeta (42-57%), Lep. reticulatus (40%), and L. corrodens (15-19%). Two psocids species (L. corrodens and Lep. reticulatus) had low responses to all the potential attractants evaluated compared with the other four species. These results show there is high potential for using these attractants in a psocid-monitoring program.

Traps baited with pheromones are used to monitor the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera-Tenebrionidae), populations in flour mills to aid in making pest management decisions, but the factors that influence T. castaneum movement are not fully understood. We investigated the impact of photoperiod, light intensity, temperature, and relative humidity on flight initiation. The percentage of adults initiating flight reached a maximum at 30 -35 degrees C, and then fell to zero at 22.5 and 45 degrees C. Only 2% of beetles flew in complete darkness, and the number of beetles initiating flight increased to 41% under 18 h of light and then decreased slightly to 37% under 24 h of light. Rates of flight initiation did not vary with light intensities from 1,784 to 4,356 lux or relative humidities from 25 to 85%. Thus, temperature and photoperiod are the main abiotic factors tested that impact flight initiation in T castaneum, which have broad ranges of temperatures and photoperiods over which they can fly. The current results should be useful in helping to interpret trap catches based on abiotic conditions during the trapping period, and the results should be useful in helping to understand T. castaneum movement outside grain storages and processing facilities and their potential to infest structures.

Psocids can cause considerable economic losses to stored products by direct feeding, and they have become global pests during the last two decades. We studied the distribution of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), Liposcelis entomophila (Enderlein), and Liposcelis brunnea Motschulsky in different moisture gradients (11-12-13%, 11-13-15%, and 13-14-15%) and a control (13-13-13%) in wheat using a circular metal arena, which has a removable metal divider that partitioned it into three rings (outer, middle and inner). Lipsocelis bostrychophila and L entomophila preferred grain with the highest moisture content in the different gradients evaluated. In general, populations of Liposcelis brunnea equally preferred grain with moisture contents greater than or equal to 13%. These results showed the moisture contents preferred for three of the main psocid pests of stored grains, and this could help in making better pest management decisions. Published by Elsevier Ltd.

We evaluated the competition among stored-product psocid species by conducting two series of laboratory experiments. In the first series, three species of Liposcelididae were used: Liposcelis bostrychophila, Liposcelis decolor, and Liposcelis paeta. Five adult females of these species were placed in vials containing wheat, either alone or in all possible combinations of two species. The number of adults in the vials was counted after 35, 70, 105, 140, and 175 days. These tests were performed at 25 and 30°C. At 25°C, there were no differences in numbers of L. bostrychophila when this species was reared either alone or with each of the other two species. At 30°C, L. bostrychophila was the dominant species. The presence of L. bostrychophila had a negative effect on the growth of populations of L. decolor and L. paeta. The presence of L. paeta did not affect growth of populations of L. decolor, although the presence of L. decolor occasionally reduced growth of populations of L. paeta. In the second series of tests, L. bostrychophila adult females were placed in vials of wheat either alone or with adult females of Lepinotus reticulatus, at the ratios of (L. bostrychophila: L. reticulatus) 10∶0, 9∶1, 7∶3, 5∶5, 3∶7, 1∶9, and 0∶10. These tests were carried out only at 30°C, and the observation periods were the same as for the first series of tests. Liposcelis bostrychophila was the dominant species in this case as well, regardless of the ratio of the parental females. At the end of the experimental period, L. reticulatus was present only in vials that contained this species alone. Our results showed that L. bostrychophila outcompetes the other stored-product psocid species tested.

The residual effect of chlorfenapyr (Phantom) was evaluated for residual control of three stored-product psocid species: Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), and Liposcelis paeta Pearman (Psocoptera: Liposcelididae). Chlorfenapyr was applied to individual arenas with a concrete surface at rates of 0, 2.8, 13.8, 20.6, 27.5, 55, and 110 mg active ingredient (AI)/m(2). Adults were exposed on the treated arenas and mortality assessed after 1, 2, and 3 d. The procedures were repeated weekly on the same treated arenas for 3 wk to assess residual efficacy. At each week, mortality of all species was low after 1 d of exposure but notably increased after 2 or 3 d. L. entomophila was the most susceptible species, with 99 100% mortality at rates of 13.8 mg/m(2) or higher. Similarly, mortality of L. paeta after 3 dof exposure at the same concentration ranged from 92 to 100%. L. bostrychophila was the least susceptible species, with mortality of <60% during the third week after application at rates <= 27.5 mg/m(2). However, even for this species, mortality after 3 wk was 90% or higher at rates > 27.5 mg/m(2). Complete mortality of all species occurred after 3 d exposure at the highest rate tested of 110 mg/m(2). Thus, our results show that chlorfenapyr is effective against major psocid species at the application rates evaluated in this study.

The psocid, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), can cause significant damage to stored commodities, and its pest status in the United States has been increasing over the last decade. Because L. bostrychophila is difficult to control with conventional methods, it is critical to explore alternative approaches such as the use of attractants that can be incorporated into integrated pest management programs for monitoring psocids. The orientation response of several L. bostrychophila life stages (first and second instars, third and fourth instars, 0- to 7-d-old adults, 21- to 28-d-old adults, and adults of mixed ages) to a range of potential attractants (including whole and cracked grains, grain-based oils, wheat germ, brewer's yeast, and commercially available kairomone lures) was studied using a two-choice pitfall test to identify candidates for further development as lures in traps. Among the potential attractants evaluated, the strongest response by all stages of L. bostrychophila was to brewer's yeast. Other materials for which there was consistently a strong response were psocid diet, wheat germ, and wheat germ oil. These results show the potential for developing monitoring tools for integrated pest management programs for L. bostrychophila and other psocid species.

Heat shock proteins (HSPs) are known as chaperones that help with folding of other proteins when cells are under environmental stresses. The upregulation of HSPs is essential for cold survival during insect diapause. The ectoparasitoid Habrobracon hebetor , a potential biological control agent, can enter reproductive diapause when reared at low temperature and short photoperiod. However, the expression of HSPs during diapause of H. hebetor has not been studied. In this study, we sequenced and characterized the full‐length complementary DNAs of three Hsp70 genes ( HhHsp70I , HhHsp70II and HhHsp70III ) from H. hebetor . Their deduced amino acid sequences showed more than 80% identities to their counterparts from other insect species. However, the multiple sequence alignment among the three deduced amino acid sequences of HhHsp70s showed only 46% identities. A phylogenetic analysis of the three HhHsp70s and all other known Hsp70 sequences from Hymenoptera clustered all the Hsp70s into four groups, and the three HhHsp70s were distributed into three different groups. Real‐time quantitative polymerase chain reaction analysis showed that the expression of the three HhHsp70 genes in H. hebetor reared at different conditions was quite different. HhHsp70I showed higher relative expression when H. hebetor were reared at 27.5°C than at two lower temperatures (17.5°C and 20°C) regardless of the photoperiod, whereas HhHsp70II showed higher expression when H. hebetor were reared at 20°C and 10 : 14 L : D than when reared at 17.5°C and either 16 : 8 L : D or 10 : 14 L : D. In contrast, HhHSP70III was expressed at similar levels regardless of the rearing conditions. These results may suggest functional differences among the three HhHsp70 genes in H. hebetor .

The Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae), is a pest of stored corn, Zea mays L, and other grains throughout the world. Sitotroga cerealella are routinely exposed to temperatures below 20 degrees C in regions of the U.S. where corn is grown, yet there are no data describing adult life history parameters below 20 degrees C. We determined longevity, fecundity, and survivorship of eggs at a range of temperatures that represent environmental conditions to which S. cerealella are exposed in corn stored in the U.S. Longest male longevity was 31 d at 10 degrees C, and shortest male longevity was 4 d at 35 and 40 degrees C. Longest female longevity was 29 d at 15 degrees C, and shortest female longevity was 5 days at 35 and 40 degrees C. Duration of the preoviposition period was as long as 16 d at 10 degrees C and as short as 1 d at 30-40 degrees C. All females laid eggs at 20-30 degrees C, 50-94% of females laid eggs at 15 degrees C, and 17-61% of females laid eggs at 10, 35, or 40 degrees C. Females laid the most eggs, nearly 100, at 20 and 25 degrees C and 75% r.h., while 6 or fewer eggs were laid at 10, 35, or 40 degrees C. Between 68 and 98% of eggs hatched at 20-30 degrees C, while 20% or fewer eggs hatched at 35 degrees C and no eggs hatched at 40 degrees C. An average of less than one egg was laid at 10 degrees C, but 58-100% of eggs hatched at 10 degrees C. Our results emphasize the importance of including data on population growth of stored-grain insect pests at low temperatures in computer models for simulating insect population growth in grain. Published by Elsevier Ltd.